Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Topics concerning the Tesla front and rear drive unit drop-in board
howardc64
Posts: 166
Joined: Mon Sep 05, 2022 12:16 am
Location: Redmond WA
Has thanked: 8 times
Been thanked: 17 times
Contact:

Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by howardc64 »

LunaticScientist wrote: Mon Dec 19, 2022 6:20 am Thinking about this aspect, what if we COULD make the sealing shaft diameter larger? I.e, a machined aluminum adapter, press fit into the end of the rotor shaft, sealed against the original shaft with RTV?

It could allow less stringent design requirements (possibly an off the shelf seal) with respect to the surface area speed and material while still being removable for service, lightweight to keep added mass and stress down and field installable without removing the whole drive unit.
A few things to consider with this idea

- Larger diameter = higher surface speeds. 40mm over 30mm at 10k RPM is +5m/s (40mm = 20.9m/s 30mm = 15.7m/s) so there will be more frictional heat. https://calculator.academy/surface-speed-calculator/

- Unknown thermal cooling impact of PTFE lips. In particular those running dry. The only way the dry running lips can dissipate heat is via the shaft and coolant cooling the shaft. Something much more conductive than RTV would be desired such as thermal epoxy. Its a similar problem has computer CPU heat sink thermal past.

For ease of replacement. On the Tesla, drive unit has to come out as subframe wraps around to prevent access. Or if experienced enough, can keep LDU on stands and lower the subframe to gain access. Very tight space and challenging if car is on jack stands.

So far, no success story with SKF speedi-sleeve even with @WimV's carefully crafted 2x speedi-sleeve to expand over the entire ~13mm shaft seal mating surface. Parker EPS has a sleeve thats close (12.7mm wide, 31.6mm OD, WS695 WS696 on pg E-5) for 5650 catalog ( https://www.parker.com/content/dam/Park ... s/5350.pdf ) But 12.7mm is really tight margin if using Ceimin triple lip geometry. Would prefer narrower widths so lips will be packed closer together (don't know if thats possible) Sourcing parts out of Parker EPS has been a no go in my 2x effort. Perhaps its actually easier to find shaft spray metal solutions ( viewtopic.php?p=49628#p49628 ). At last only sourcing 1 capability instead of 2 custom parts (custom sleeve and seal)

But yes, certainly desirable to have an easy solution for those with damaged shaft surface which seems quite common with salvaged LDUs that has sat idled for long periods.

@jsimonkeller's effort ( viewtopic.php?p=50073#p50073 ) lathe cutdown original damaged shaft and made a custom stainless steel sleeve that fitted over it presumably to original dimension. No results yet until LDU is running again. I don't know the thermal bonding material used nor do we know the hardness of the stainless stock used to fashion the sleeve. Google shows there are multiple stainless hardness grades ranging from softer to harder, the softest spec of 30Rc is too soft and even the softest PTFE blend will wear against it. But most stainless grades are quite hard. Anyway, am not expert in any of these areas. Just sharing the learning as we go along for those with damaged shaft seeking solutions.
Tesla LDU rebuild website https://sites.google.com/view/teslaldu
2013 Model S85 3rd (Reman RevQ) LDU on 2017 @40k. Coolant seal leak discovered in 8/2022 @ 72k miles
Seattle US
LunaticScientist
Posts: 8
Joined: Tue Dec 28, 2021 2:28 am

Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by LunaticScientist »

howardc64 wrote: Mon Dec 19, 2022 9:24 pm
- Larger diameter = higher surface speeds. 40mm over 30mm at 10k RPM is +5m/s (40mm = 20.9m/s 30mm = 15.7m/s) so there will be more frictional heat.
True, but have found several seal MFG that quote 40 m/s on dry lube PTFE within spec. Pushing to 40mm diameter @18k RPM puts as at 37.7 m/s surface speed.



A thermal paste would certainly help, but with the thermal diffusivity being 5x higher than 1045 steel (68 mm2/s for 6061 vs. 14 mm2/s for ASM 1045) and a surface area of 550mm2 (using a 40mm OD) on the wet side alone, conductivity to the shaft would be negligible compared to the face of the adapter ring. RTV would only be used to seal the potentially imperfect mating between the shaft and adapter ring.



Agreed, but much easier than complete disassembly for shaft reconditioning, metal deposition, or future tear-down like rotor or bearing replacement.

I haven't reached out to these guys yet, but it seems like their ATA/ATB lip seals would fit the bill, even potentially for OE shaft dims?

https://usseal.com/lip-shaft-seals/

Have we considered applying a high-temp silicone-ceramic lubricant between the multi-lip designs to aid in lubrication?
howardc64
Posts: 166
Joined: Mon Sep 05, 2022 12:16 am
Location: Redmond WA
Has thanked: 8 times
Been thanked: 17 times
Contact:

Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by howardc64 »

LunaticScientist wrote: Mon Dec 19, 2022 10:39 pm A thermal paste would certainly help, but with the thermal diffusivity being 5x higher than 1045 steel (68 mm2/s for 6061 vs. 14 mm2/s for ASM 1045) and a surface area of 550mm2 (using a 40mm OD) on the wet side alone, conductivity to the shaft would be negligible compared to the face of the adapter ring. RTV would only be used to seal the potentially imperfect mating between the shaft and adapter ring.
Perhaps you can PM @Johan, he and I have been studying seal designs and he in particular is quite concerned about the thermal dissipation with a sleeve through modeling effort he has done. I'm not as well versed here.
LunaticScientist wrote: Mon Dec 19, 2022 10:39 pm I haven't reached out to these guys yet, but it seems like their ATA/ATB lip seals would fit the bill, even potentially for OE shaft dims?

https://usseal.com/lip-shaft-seals/
I've not reached out to these guys so you should definitely try. So far my efforts at Saint-Gobain/Parker custom division, a few smaller (advanced-emc.com, fluidol.com, ergoseal.com) in US have all ended with no interest. I've not even been able to reach engineering/application engineering other than briefly with Parker custom division. I believe its important to reach engineering/application engineering to understand design choices which is more than just ID/OD/cage width. PTFE blend with respect to shaft hardness/media, lip designs (dual+excluder best? are key decision points.

Waiting for @muehlpower's effort from German seal supplier. Hoping EU's stronger right to repair laws can yield a supplier.

viewtopic.php?p=49619#p49619
LunaticScientist wrote: Mon Dec 19, 2022 10:39 pm Have we considered applying a high-temp silicone-ceramic lubricant between the multi-lip designs to aid in lubrication?
My understanding of how PTFE seal works is a thin layer of PTFE is transferred to the shaft (so shaft needs some roughness ~0.2Ra/8RMS) seal is achieved between this transferred layer and remaining seal material. Blended PTFE material often add harder particles to act as pier pillars (harder than virgin PTFE, but softer than shaft) to prevent the much softer virgin PTFE material wearing out quickly. Based on this understanding, it seems lubrication should be avoided?

But I'm not aware of anyone who has tried lubricant. Youtube channel CarRepairVideos is a Ukraine EV repair shop posting videos. They've shown a failed lubed seal. I believe the excluder lip was also folded (Probably a common installation failure point) Video here. Turn on CC + auto translation

Tesla LDU rebuild website https://sites.google.com/view/teslaldu
2013 Model S85 3rd (Reman RevQ) LDU on 2017 @40k. Coolant seal leak discovered in 8/2022 @ 72k miles
Seattle US
LunaticScientist
Posts: 8
Joined: Tue Dec 28, 2021 2:28 am

Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by LunaticScientist »

I've contacted US Seal with a design envelope and application information (without being 100% explicit to avoid potential CoI).

I also tore-down my 50k mile donor for my project. RevE (non-reman) had the triple seal, no inverter wetness and maybe a drop or two by the encoder. Blue G48 coolant.

There was heavy deposition on the shaft and black gunk buildup between the seal lips. I suspect maybe incorrect surface finish during installation or excessive lip pressure (incorrect ID spec)? Cannot confirm why, but it's hard to keep dry seals sealed... :lol:
howardc64
Posts: 166
Joined: Mon Sep 05, 2022 12:16 am
Location: Redmond WA
Has thanked: 8 times
Been thanked: 17 times
Contact:

Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by howardc64 »

LunaticScientist wrote: Tue Dec 20, 2022 5:06 am I've contacted US Seal with a design envelope and application information (without being 100% explicit to avoid potential CoI).
haha, good idea. I did find as soon as I said 10k RPM, 30mm shaft, PTFE lipped, 20m/s surface speed, coolant media etc. If the seal maker has been engaged by Tesla supplier, they instantly recognized the design :)
LunaticScientist wrote: Tue Dec 20, 2022 5:06 am I also tore-down my 50k mile donor for my project. RevE (non-reman) had the triple seal, no inverter wetness and maybe a drop or two by the encoder. Blue G48 coolant.

There was heavy deposition on the shaft and black gunk buildup between the seal lips. I suspect maybe incorrect surface finish during installation or excessive lip pressure (incorrect ID spec)? Cannot confirm why, but it's hard to keep dry seals sealed... :lol:
Very cool, @WimV's RevQ had triple lip black PTFE seal and his shaft had pitting.

viewtopic.php?p=46359#p46359

What do you mean by "hard to keep dry seals sealed"? All the triple lip pictures I've seen seems to show the middle and excluder lips are mostly rubbered away and destroyed. But very hard to get good pictures with black PTFE material.

Been thinking there are potentially 3 possible reasons

A. Tesla/supplier chose too hard PTFE blend for the shaft hardness in the triple lip black seal
B. Seal lip deterioration stays trapped between the lips causing damage. Consequently Tesla switched to lower leak longevity single lip seal.
C. Improper shaft preparation during Tesla's rebuild (likely multiple shops on multiple continents. We've seen variability within same Revision)

Your data is quite interesting in several ways

- 50k miles without much leaking is impressive. Early rev LDUs with their triple lip seals seems to preform quite well leakage wise. Rev E suggests it is quite early. What is the TXX number? XX = original manufacturing year.

- Non rebuild eliminates case C. But potentially still have initial material quality variable such as shaft hardness. We believe the rotors are sourced out of China (lots of copper haha) and have heard rumors of 20% QC failures at some point. Would be really interesting to see the shaft after cleanup if any pitting or just polishing. I would guess just some polishing because pitting surely would have resulted in much greater leak.

So the mystery is why did Tesla go away from the triple (2 media, 1 excluder) lip? Hope its not case B. Could just be supplier cost pressure. Tesla rebuilders could have switched back to triple lip in more recent rebuilds. We don't really know. Maybe even Tesla is not tracking any of this. We've seen single and triple lip seals in RevQ (mine, WimV) so which seal used may just be what is left in stock at the rebuilder.

Let us know what you find on the shaft surface...
Tesla LDU rebuild website https://sites.google.com/view/teslaldu
2013 Model S85 3rd (Reman RevQ) LDU on 2017 @40k. Coolant seal leak discovered in 8/2022 @ 72k miles
Seattle US
howardc64
Posts: 166
Joined: Mon Sep 05, 2022 12:16 am
Location: Redmond WA
Has thanked: 8 times
Been thanked: 17 times
Contact:

Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by howardc64 »

Probably good if can gather statistics on if Tesla's black triple lip seal damage the shaft surface (other than slight polishing) So far, the only stats collected are ( https://sites.google.com/view/teslaldu/revisions )

- Nathan Sschenk's RevF. His rebuild write up mentions no shaft repair and new PTFE lined V lip seal lasted awhile so we can probably assume no shaft pitting.

- WimV's RevQ had shaft pitting damage under microscope.

@jsimonkeller had triple lip but shaft was too corroded to evaluate seal damage.
Perhaps @LunaticScientist will provide an additional data point.

Ceimin's yellow triple lipped seal install (@Johan and me) won't yield data for awhile. Probably at least 1-2 years out.
Tesla LDU rebuild website https://sites.google.com/view/teslaldu
2013 Model S85 3rd (Reman RevQ) LDU on 2017 @40k. Coolant seal leak discovered in 8/2022 @ 72k miles
Seattle US
LunaticScientist
Posts: 8
Joined: Tue Dec 28, 2021 2:28 am

Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by LunaticScientist »

Serial is T13, so 2013.

I haven't been able to clean up the shaft yet and my picture doesn't convey the thickness of the build up of the PTFE on the shaft.

It almost seems like the bond between the seal and seal body failed vs. wetness on the shaft or corrosion at the encoder. Have we seen any other failure modes before the seal gets destroyed during removal?

I'm curious if a solution might be an FKM or other flouro-compound, greased between the sealing lip and excluder, to be able to run sustained 10K or short-term 18k vs. 100% duty cycle 18k RPM. The thermal dissipation should be good as even 1045 is decent at conductivity, but thin walled and backed with moving coolant. Or, perhaps, too much thermal transfer into the steel-faced seal and causes expansion/excessive movement of the seal...

Tesla LDU Album
howardc64
Posts: 166
Joined: Mon Sep 05, 2022 12:16 am
Location: Redmond WA
Has thanked: 8 times
Been thanked: 17 times
Contact:

Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by howardc64 »

LunaticScientist wrote: Wed Dec 21, 2022 1:03 am Serial is T13, so 2013.

I haven't been able to clean up the shaft yet and my picture doesn't convey the thickness of the build up of the PTFE on the shaft.

It almost seems like the bond between the seal and seal body failed vs. wetness on the shaft or corrosion at the encoder. Have we seen any other failure modes before the seal gets destroyed during removal?
your pics seems to show corrosion on the shaft (mud colors) on various parts of the reluctor wheel chamber which suggest the drive unit was idle long enough for corrosion to form. This seems quite common for salvage LDUs idled for some periods. All the long term running LDUs on tear down seems to show no corrosion around the reluctor housing area.

However, a shiny shaft surface with reluctor wheel mounted will often show an optical illusion through the camera. Here are my pics and another LDU's pics of shaft while reluctor wheel is attached. A shiny smooth shaft looks terrible through the camera but really just the reflection of the reluctor wheel holes.

https://teslamotorsclub.com/tmc/posts/7054101/
viewtopic.php?p=43048#p43048

Note the reflection shows "dashed lines" reflecting alternating holes and non hole areas of the reluctor wheel. You pic also shows these "dashed line patterns" but with muddy colors so its not clear if it is reflection or truly have some dash patterns of corrosion (if true, then would be interesting how that occurred, maybe just a swiping action of pulling the seal off?)

Anyhow, really hard to evaluate shaft surface pictures without reluctor wheel removed, multiple angles and lighting angles etc...

The seal picture looks like every triple lip seal I've seen that shows

1. Seems like most of the dry lips have worn away
2. Worn off PTFE material doesn't disappear, they stick on surfaces. One can only imagine what the chamber between 2 lips would look like. (probably can't tell once the seal has been pulled off) The "contact surface" of the dry lips on Ceimin seal starts out as a curled lip over the shaft ( https://teslamotorsclub.com/tmc/posts/7185566/ ) Tesla's black triple lip seal probably starts life in a similar way but the PTFE lip material eventually disintegrates leaving what appears just to be a PTFE stump on the dry lips. Have heard the primary coolant facing lip is largely intact so need to confirm that when your seal comes out.

One guess is the worn off PTFE debris perhaps just end up packing along the lips in chamber between 2 lips. It doesn't help sealing but perhaps doesn't hurt it either while the worn off PTFE stump remain to energize (seal designer's terminology for pressure) material against the shaft. Leaks occur when too much PTFE lip has worn off and no longer can energize the sealing surface against the shaft. One key question is does the PTFE debris cause pitting on the shaft? One would think no as its the same PTFE lip material and the lips has more energized pressure against the shaft from the very beginning. This makes cause of @WimV's shaft damage all that much more mysterious.

Pics also suggest there has been leak in the past with corrosion around the chamber. Perhaps not much coolant present as LDU sat idle and coolant eventually evaporated through venting towards the rotor/stator chamber via washed out grease bearings or speed sensor vent hole (not sure if you have one from the pic)
LunaticScientist wrote: Wed Dec 21, 2022 1:03 am I'm curious if a solution might be an FKM or other flouro-compound, greased between the sealing lip and excluder, to be able to run sustained 10K or short-term 18k vs. 100% duty cycle 18k RPM. The thermal dissipation should be good as even 1045 is decent at conductivity, but thin walled and backed with moving coolant. Or, perhaps, too much thermal transfer into the steel-faced seal and causes expansion/excessive movement of the seal...

Tesla LDU Album
On FKM seals, I did a write up here. FKM is weak to polar molecules (water) and use a V lip design with much smaller contact surface to the shaft (0.2mm on compressed V tip vs ~2mm for PTFE lip) which results in 10x heat density difference before thermal dissipation.

viewtopic.php?p=49545#p49545

On this type of V shaped lipped seal. A PTFE lined seal might be competitive or do better than FKM? One data showed 40k miles but we don't have much details on the leak characteristics. Usually first sign of leak shows on the speed sensor before enough accumulation drips through an added weep hole. One wouldn't know when the leak started if just observing the weep hole and not religiously pulling the speed sensor.

viewtopic.php?p=49526#p49526
viewtopic.php?p=49553#p49553
Tesla LDU rebuild website https://sites.google.com/view/teslaldu
2013 Model S85 3rd (Reman RevQ) LDU on 2017 @40k. Coolant seal leak discovered in 8/2022 @ 72k miles
Seattle US
WimV
Posts: 25
Joined: Sat Mar 12, 2022 10:21 pm
Been thanked: 3 times

Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by WimV »

howardc64 wrote: Wed Dec 21, 2022 8:11 am One would think no as its the same PTFE lip material and the lips has more energized pressure against the shaft from the very beginning. This makes cause of @WimV's shaft damage all that much more mysterious.
This was a rebuild DU, I wouldn't be surprized if the shaft had wear before the rebuild...
howardc64
Posts: 166
Joined: Mon Sep 05, 2022 12:16 am
Location: Redmond WA
Has thanked: 8 times
Been thanked: 17 times
Contact:

Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by howardc64 »

WimV wrote: Wed Dec 21, 2022 10:38 am This was a rebuild DU, I wouldn't be surprized if the shaft had wear before the rebuild...
True. A reasonable possibility. Tesla LDU rebuilds process and quality control likely spread across multiple contract rebuilders and staff. And who know how long a LDU and/or any used spare parts sat idle before the rebuild.

Looked at your shaft surface closer and the damage. It’s behind the primary coolant lip which would explain how you got 70km before finding leak. Primary lip probably did its job.

viewtopic.php?p=46359#p46359
Tesla LDU rebuild website https://sites.google.com/view/teslaldu
2013 Model S85 3rd (Reman RevQ) LDU on 2017 @40k. Coolant seal leak discovered in 8/2022 @ 72k miles
Seattle US
LunaticScientist
Posts: 8
Joined: Tue Dec 28, 2021 2:28 am

Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by LunaticScientist »

Shaft cleanup will happen later today, we'll see what it looks like.

I was able to pick some residue off the seal lips to reveal which looks like virgin material. Gray and black flakes, similar to graphite-impregnated material. But the lips are STIFF. Which I could see definitely being an issue as they age, imperfect seal, and stationary with hot coolant and higher pressure differential.

I've also reached out to AHP, who has a single lip, PTFE-lined, energizer-backed seal, rated for 35m/s and high pressure, who wanted more information (like production quantity, life cycle, etc), so maybe another option?
howardc64
Posts: 166
Joined: Mon Sep 05, 2022 12:16 am
Location: Redmond WA
Has thanked: 8 times
Been thanked: 17 times
Contact:

Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by howardc64 »

LunaticScientist wrote: Wed Dec 21, 2022 6:03 pm I was able to pick some residue off the seal lips to reveal which looks like virgin material. Gray and black flakes, similar to graphite-impregnated material. But the lips are STIFF. Which I could see definitely being an issue as they age, imperfect seal, and stationary with hot coolant and higher pressure differential.
If able to see under microscope, maybe able to see the blended granules. Here are pics of my LDU's single lipped PTFE seal from Tesla rebuild

viewtopic.php?p=46621#p46621
LunaticScientist wrote: Wed Dec 21, 2022 6:03 pm I've also reached out to AHP, who has a single lip, PTFE-lined, energizer-backed seal, rated for 35m/s and high pressure, who wanted more information (like production quantity, life cycle, etc), so maybe another option?
@dzolotnyuk bought the following from AHP. viewtopic.php?p=46191#p46191. Failed quickly with speedi-sleeve. Actually I don't understand the design of AHP's SB20 seal, its a classic asymmetric angle V shaped seal which relies on compression on v tip to provide pumping aid. Elastomers such as NBR and FKM is suitable for this compression. A completely PTFE seal is too hard and will prevents compression. So the design doesn't make sense to me.

PTFE "lined" seal with same design isn't the same. The thin PTFE lining should deform with the base seal material (NBR, FKM).
Tesla LDU rebuild website https://sites.google.com/view/teslaldu
2013 Model S85 3rd (Reman RevQ) LDU on 2017 @40k. Coolant seal leak discovered in 8/2022 @ 72k miles
Seattle US
LunaticScientist
Posts: 8
Joined: Tue Dec 28, 2021 2:28 am

Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by LunaticScientist »

howardc64 wrote: Wed Dec 21, 2022 10:02 pm
@dzolotnyuk bought the following from AHP. viewtopic.php?p=46191#p46191. Failed quickly with speedi-sleeve. Actually I don't understand the design of AHP's SB20 seal, its a classic asymmetric angle V shaped seal which relies on compression on v tip to provide pumping aid. Elastomers such as NBR and FKM is suitable for this compression. A completely PTFE seal is too hard and will prevents compression. So the design doesn't make sense to me.

PTFE "lined" seal with same design isn't the same. The thin PTFE lining should deform with the base seal material (NBR, FKM).
I saw that and wondered if that would be the best design for pure-PTFE designs... I was looking at the RB-series https://ahpseals.com/product/asrb/ with the PTFE-lined but flexible base with energizer.

Or even a single band PTFE seal. The multi-band seems to be problematic (with trapping wear particles between bands). I cleared out the area between the rings and pulled a ton of black gunk (likely a combination of PTFE dust and coolant), which I'm sure doesn't contribute to cooling nor flexibility. I also noticed quite a bit of lip deterioration on the second media lip. Odd that it doesn't match the primary lip's wear pattern.

Image

The shaft was also pitted under the primary and excluder seals. Actual grooving at the second lip location, so I'm wondering if a speedi-sleeve might be a better option to restore surface finish (especially if AHP is requiring Ra 8-16 uin for PTFE materials) and maintain bore. I know it did not have high success in the last attempt, but that was with an OE style seal. Or, given the 0.020 in. tolerance the energizer allows, a slight bore reduction from a grind/polish job may be negligible.

Image

I've added more pics too to the Google Album (Tesla LDU Album
howardc64
Posts: 166
Joined: Mon Sep 05, 2022 12:16 am
Location: Redmond WA
Has thanked: 8 times
Been thanked: 17 times
Contact:

Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by howardc64 »

LunaticScientist wrote: Wed Dec 21, 2022 11:19 pm I saw that and wondered if that would be the best design for pure-PTFE designs... I was looking at the RB-series https://ahpseals.com/product/asrb/ with the PTFE-lined but flexible base with energizer.
Thats basically a PTFE lined seal on NBR or FKM. Good option for those that wants to try that.

Alternative sources are on the LDU website parts link. Peach Tree Suzuki outboard motor seal PTFE lined NBR and Honda PTFE lined seal, I think both without garter spring energizer which is probably unnecessary given LDU's low pressure application.
LunaticScientist wrote: Wed Dec 21, 2022 11:19 pm I know it did not have high success in the last attempt, but that was with an OE style seal.
Pics shows the pitted shaft surface has already been sleeved. Was that a prior DIY rebuild? If so, what sleeve was used and is any material hardness info known?

And where was the black triple lip seal sourced from if DIY rebuild?
Tesla LDU rebuild website https://sites.google.com/view/teslaldu
2013 Model S85 3rd (Reman RevQ) LDU on 2017 @40k. Coolant seal leak discovered in 8/2022 @ 72k miles
Seattle US
LunaticScientist
Posts: 8
Joined: Tue Dec 28, 2021 2:28 am

Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by LunaticScientist »

howardc64 wrote: Thu Dec 22, 2022 12:23 am Thats basically a PTFE lined seal on NBR or FKM. Good option for those that wants to try that.

Pics shows the pitted shaft surface has already been sleeved. Was that a prior DIY rebuild? If so, what sleeve was used and is any material hardness info known?
Mine has not been rebuilt, as far as I can tell. No sleeve installed (although the tool marks on the interior of the rotor shaft are interesting....

Reading some various literature on PTFE seals, it looks like the preferred surface finish is Ra 0.2-0.6 um(micron). However, it seems to widely vary on how that finish is best achieved. P600 paper? 1000 grit AlO2 paper? Medium polish #2? Electropolishing?

Regardless, refinishing the shaft surface without complete disassembly seems daunting, but could be doable. I imagine a lathe bar-type setup could be used to true and turn the rotor shaft (team it with a shop-vac to minimize debris) for more extreme cases. A Dremel with a polishing wheel would likely still fit (thinking of these "repair in place" people).
howardc64
Posts: 166
Joined: Mon Sep 05, 2022 12:16 am
Location: Redmond WA
Has thanked: 8 times
Been thanked: 17 times
Contact:

Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by howardc64 »

LunaticScientist wrote: Thu Dec 22, 2022 3:32 am Mine has not been rebuilt, as far as I can tell. No sleeve installed (although the tool marks on the interior of the rotor shaft are interesting....
This is the region on your coolant shaft looking like it was sleeved. Or is the chamfered edge really that damaged?
IMG_20221221_164807736.jpg
IMG_20221221_164807736.jpg (10.68 KiB) Viewed 10153 times
Looks similar to @WimV's careful speedi-sleeve effort to match the chamfered coolant opening. See 2nd pic

viewtopic.php?p=46364#p46364

For reference, this is what mine looks like, don't have a high res frontal pic but its definitely single piece.

PIc1 Surface prepped shaft. Can see the lathe cut lines on the chamfered tip in first pic. The chamfered surface is between 1-2mm (13mm where the seal rides between the chamfered edge and bevel rise to reluctor wheel platform)

Pic2/3 Ignore the dashed lines (reluctor wheel hole reflection) on the 3rd pic.
IMG_2898 (1).jpg
IMG_2724.jpg
IMG_2623.jpg
LunaticScientist wrote: Thu Dec 22, 2022 3:32 am Reading some various literature on PTFE seals, it looks like the preferred surface finish is Ra 0.2-0.6 um(micron). However, it seems to widely vary on how that finish is best achieved. P600 paper? 1000 grit AlO2 paper? Medium polish #2? Electropolishing?

Regardless, refinishing the shaft surface without complete disassembly seems daunting, but could be doable. I imagine a lathe bar-type setup could be used to true and turn the rotor shaft (team it with a shop-vac to minimize debris) for more extreme cases. A Dremel with a polishing wheel would likely still fit (thinking of these "repair in place" people).
@Johan and I did 600 grit->1500 grit. A norwegian rebuilder did 2000. The 600 & 1500 sandpaper wants to run along shaft's axis while holding sandpaper still and spin the rotor on bearings sitting on wooden V blocks. PTFE seal literature suggest avoid leads on the prepped surface. I think without removing the rotor is possible with 2 people (1 to hold sandpaper firmly to avoid running along the shaft's axis, the other spin both half shafts)
Tesla LDU rebuild website https://sites.google.com/view/teslaldu
2013 Model S85 3rd (Reman RevQ) LDU on 2017 @40k. Coolant seal leak discovered in 8/2022 @ 72k miles
Seattle US
WimV
Posts: 25
Joined: Sat Mar 12, 2022 10:21 pm
Been thanked: 3 times

Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by WimV »

WimV wrote: Sat Oct 22, 2022 7:49 am By the way: I’ve checked the speed sensor after driving 400 km with the new seal (Ceimin CTLBDYW). Well, that wasn’t what I hoped. There was condensation on the sensor. The drain was still dry (was plugged, so I would know how much it leaked). I collected about one drop of coolant when using some compressed air to flush the reluctor chamber.

I don’t think the speedi sleeves are usable with PTFE seals. I think the seal is stretched too much cause of the increase in diameter.

I’m going to keep driving for a while and keep checking the leak. If it get worse, I’ll pull the rotor to get it welded and grinded to the correct diameter and try with a new seal.
Just did another check after 4.000 km. There was a drop or two collected in the drain tube (flushed the reluctor housing with compressed air). A little bit of small droplets on the sensor. I would say it doesn't leak more than the first 400 km.

I dried the reluctor housing with compressed air and will check again in the future.
Attachments
IMG_20221230_131238.jpg
howardc64
Posts: 166
Joined: Mon Sep 05, 2022 12:16 am
Location: Redmond WA
Has thanked: 8 times
Been thanked: 17 times
Contact:

Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by howardc64 »

WimV wrote: Fri Dec 30, 2022 4:47 pm Just did another check after 4.000 km. There was a drop or two collected in the drain tube (flushed the reluctor housing with compressed air). A little bit of small droplets on the sensor. I would say it doesn't leak more than the first 400 km.

I dried the reluctor housing with compressed air and will check again in the future.
Good result :)

Been thinking about your leak mechanism. I doubt it is due to the addition of 0.5mm shaft diameter from speedi-sleeve. Rather, I think more likely the unavoidable tiny coolant facing lip damage over the tapered speedi-sleeve edge at the shaft tip during installation. Seems not possible to machine the bevel on that edge better than you did but probably impossible to remove tiny sharp edges. Any cut/scrape would be perpendicular to the rotation surface and create the most direct micro leakage path. Consider how a micro helix patterned PTFE seal lip works. In the correct rotational, it pumps the coolant back towards the wet side. But if reversed rotation, pumps coolant to the dry side.

When installing a virgin Ceimin PTFE seal, the coolant facing lips are 2-3mm+ smaller than 30mm. The force required to get them over the chamfered shaft edge is quite significant (so much that when mine finally cleared, the seal sled all the way back and excluder lip ran up over the raised reluctor wheel bevel) I suppose one way to reduce damage from this high force is to first pre-fit the PTFE seal over a clean surface 30mm shaft to increase the PTFE lip diameter (or maybe even 31+mm? which may increase damage risk to the sintered PTFE material). Alternatively, if the SKF speedi sleeve edge can be formed and beveled at 45 degree angle for 1+mm ( prob require some tooling? ) then polished, less chance of micro scraping.

If Ceimin seal lips had concentric cuts (to help bending like the Tesla single lipped seal, cost extra manufacturing step) Then the force required would be lower but any micro sharp edge probably would still cause micro damage.

Just a thought. I'll reach out to Maedler (German bearing/seal supplier https://maedlernorthamerica.com/) to see if can make custom sleeve.
wear sleeve.pdf
(230.56 KiB) Downloaded 60 times
Tesla LDU rebuild website https://sites.google.com/view/teslaldu
2013 Model S85 3rd (Reman RevQ) LDU on 2017 @40k. Coolant seal leak discovered in 8/2022 @ 72k miles
Seattle US
howardc64
Posts: 166
Joined: Mon Sep 05, 2022 12:16 am
Location: Redmond WA
Has thanked: 8 times
Been thanked: 17 times
Contact:

Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by howardc64 »

UPDATE for damaged shaft sleeves

Unfortunately some bad news. German bearing/seal manufacturer Maedler replied after reaching out and said custom sleeve in 0.25mm thickness requires metal stamping which require building tools ($5k-$10k) In fact, they are not sure such thin sleeve can be made by stamping machine. SKF type sleeve could be made via stamping followed by cutting/polishing with shape reinforcement tooling.

In general, I do think sleeved repair has major challenges

- Avoiding micro scrape while inserting the 2 coolant facing PTFE lips. On Ceimin, these lips are > 3mm smaller than 30mm requiring quite a bit of force to slide it over the chamfered edge. IF the seal was test fitted onto a good shaft before inserting into bore and mount onto the shaft, the lips will be stretched and will require lower force to clear this edge. The longer the wait after test fitting, the more the lips will shrink back towards the original diameter. I noticed significant difference between a couple hours to a couple of days. But at least one test fitting will loosen it quite a bit.

Tesla's single lip with concentric groove cut bending aid might go on easier. Don't have a new version of such seal so no way to confirm for sure.

- A good shaft's chamfered edge is ~2-3mm (mine is installed, could someone with one on bench provide the actual measurement?) long at ~30 degree angle. Lathe cut lines are visible but all sharp edges are polished off. This geometry is designed to guide the coolant PTFE lips over this edge without any micro scrape damage.

- I think sleeving require careful machining to original chamfer edge shape, use thermal transfer fillers between any exposed gaps in the edge between sleeve/original shaft, and complete polishing of this chamfered edge to avoid micro scrape damage PTFE seal during install. The bevel angle needs to be correct and the length probably need to match original ~3mm to evenly spread the stretching pressure for the coolant facing lip install.

- Finally, there is the thermo transfer issue @Johan is concerned about. The dry lips on a multi-lip seal will only dissipate heat via the shaft's transfer to coolant. As @Johan notes, its similar problem to thermal transfer CPU+GPU die heat to heat sink.

- Even if speedi-sleeve is installed aligned to the start of the chamfer bevel per @Johan's suggestion in this post ( viewtopic.php?p=49589#p49589 ) I have no idea if micro scrape will occur over the speedi-sleeve edge.

Anyway, why do we need to worry about such micro scrape issue? Don't have to on many other type of seals. Unfortunately this is how the PTFE seal works to seal. The sealing mechanism is completely different than a classical elastomer (NBR, FKM). PTFE is a non elastic material that relies on tiny transfer of material to tiny shaft surface roughness gaps and energized (pressure from shape rather than spring) lip material to form a perfect seal. Pumping aid like micro cut helix grooves into PTFE lips have been around for decades to channel the film of media back to the wet side. In case of Ceimin seal without any micro cut pumping aid, need to avoid any tiny scrapes.

====

I think unfortunately, this likely means spray metal repair is the most desirable. Even then, need to have the correct chamfer edge geometry along with very good polishing to avoid damaging the coolant facing PTFE lips on installation.

====

Reached out to Advanced-EMC with triple lip seal design request/spec outline. Waiting to hear back their assessment for taking this business. Probably $100/seal for low volume. But still require a well prepped shaft surface and installation chamfered edge. Anyway, stay tuned.
Tesla LDU rebuild website https://sites.google.com/view/teslaldu
2013 Model S85 3rd (Reman RevQ) LDU on 2017 @40k. Coolant seal leak discovered in 8/2022 @ 72k miles
Seattle US
User avatar
Johan
Posts: 28
Joined: Thu Jun 02, 2022 11:59 pm
Has thanked: 2 times
Been thanked: 1 time

Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by Johan »

Here's my rotor shaft end measurement in millimeters (sorry British people and their colonies, no inches today). The resulting chamfer angle is ~9°, based on two measured diameters plus the shown 1.5mm chamfer length in axial direction. Of course maybe I made a measurement mistake. Could someone repeat this? Also note, to make things more fun, that there could be different revisions and different numbers due to (my guess) "quality control issues". You could stick a smooth plastic pipe of 30mm outer diameter in the seal until just before final assembly to try to reduce damage.
Capture.PNG
Disclaimer: Despite all efforts, all (which I write) should be conservatively interpreted as a poorly informed, error-prone, non-expert opinion that is subject to continuous change, especially in this age of hyper-specialization and newly gained insights.
User avatar
asavage
Posts: 328
Joined: Sat May 14, 2022 10:57 pm
Location: Oak Harbor, Washington, USA
Has thanked: 269 times
Been thanked: 103 times
Contact:

Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by asavage »

Opinion from what I've read thus far, regarding the triple-lip PTFE seal . . .

I feel that the excluder lip is non-funtional: it doesn't do anything, doesn't add any value. It's not designed to seal anything smaller than a threshold that is much larger than liquid, its place is to exclude larger particles than we need to be concerned with in this cooling system.

The non-wetted lip on the other end of the triple-lip seal is also useless: the pics you've shown of examples removed from service show a non-functional seal (gunk, wear, overheat, whatever). I think it has a place in a proper application, but not this one.

A single-lip PTFE seal will have sufficient heat transfer via the coolant, so thermal transfer properties of sleeves can be ignored for a single lip.

In fitting Teflon (PTFE) seals, it has been common practice to use a resizing tool during installation (random link for such a toolset). From memory, and from the handful of times I've had to handle and install Teflon seals, using the resizing tool to maintain a temporary larger diameter whilst installing is preferred, but it's also possible to use the tool and then rapidly remove it and perform the assembly, without the tool in place -- which would be necessary for our LDUs.

Below is a representation of the type of tool I'm thinking would be appropriate to reduce single-lip PTFE seal damage during assembly.


Tesla Teflon Seal Resizing/Installation Tool 02
Tesla Teflon Seal Resizing/Installation Tool 02

I'm not aware of a cone install tool of these dimensions being available off-the-shelf -- and I'm not convinced the dimensions I've picked are ones I'd settle on -- but it would certainly be easy to fabricate. Certainly for less than $200 for a prototype, probably less then $100 ea. for qty. (50) or so (rough guess using eMachineshop for fab and based on a lot of stuff I've had them prototype for me over the past 16 years). A local facility could possibly be more cost effective, as EM typically has a cost-effecdtive place for only a small range of quantities.

Temporarily changing (deforming) the seal lip reduces reliance on chamfer angle and surface finish during installation.
Al Savage
2014 RAV4 EV
NissanDiesel
howardc64
Posts: 166
Joined: Mon Sep 05, 2022 12:16 am
Location: Redmond WA
Has thanked: 8 times
Been thanked: 17 times
Contact:

Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by howardc64 »

asavage wrote: Tue Jan 03, 2023 10:36 pm Opinion from what I've read thus far, regarding the triple-lip PTFE seal . . .

I feel that the excluder lip is non-funtional: it doesn't do anything, doesn't add any value. It's not designed to seal anything smaller than a threshold that is much larger than liquid, its place is to exclude larger particles than we need to be concerned with in this cooling system.

The non-wetted lip on the other end of the triple-lip seal is also useless: the pics you've shown of examples removed from service show a non-functional seal (gunk, wear, overheat, whatever). I think it has a place in a proper application, but not this one.
This thought make sense. But we just have so little actual data and close up inspection. QC Charge swears by triple lip but I think they really don't know the longevity of their triple lip install until they leak. Tesla's concentric groove cut bending aid single lip does seems to leak quite quickly. But again, limited stats, a lot of hearsay, don't really know the cause.

Univ of Stuttgart PTFE lip seal lab's papers ( viewtopic.php?p=49627#p49627 ) does show test data of their single lip seal with pump aid designs benchmarked against a single lip no pump aid design which leaks 1 g(~1mL?)/hr in with oil media at lower surface speeds than LDU application. Every tesla seal we have seen do not have pumping aid design. If this is true, then I'd expect we see leak immediately with a thinner media like coolant. We see LDUs that have 20k+ miles with no leak evidence on the speed sensor.

Pumping aid design is another topic entirely, Seems quite state of the art from Stuttgard's research. Most manufacturers have only shown classical solutions like unidirectional helix. Some have shown wavy patterns and shallow V patterns (I'll avoid going into detail here)

Ideally, proper analysis requires bench top test jig with properly prepped shaft spinning at 20m/s fully balanced. With matched media, temperature, contaminates (including crystallization over time from coolant filling/exiting/drying in the seal chamber) simulating actual usage conditions (including long term static leaking analysis) Not exactly easy to do. Univ of Stuttgart's PTFE seal research lab showed such a jig. PTFE seal test facilities have the equipment ($10k fee to test the seal) Short of all this, we would need to wait until our installed PTFE seals leak and carefully inspect the seal and shaft. If mine doesn't leak for say 5k miles, I'm debating on pulling the seal just for inspection. But this probably stops the leak longevity test. Once a seal is pulled, probably prone to failure if reinstalled... maybe okay if really really careful... not sure. Proper engineering all takes $$, $$ that Tesla has but we are probably getting summer interns at best and tier1/tier2 suppliers cost cutting efforts at worst.

From my research, multi lipped PTFE seal for heavy industrial machines usually have additional guards between each lip. They are often filled with gas/liquid to prevent original media from leaking through as well as circulation channels between the lip chambers to cycle the filler/contamination from media. Seal makers often even make seals that can be disassembled and replace individual lips. Perhaps this is the proper mult-lipped PTFE seals you've seen.

What is interesting is experienced quality seal producers such as Saint Gobain, SKF, and Parker all have had multiple lip PTFE seal profiles similar to Tesla's triple lip and Ceimin listed in their custom seal design guides (no filler between lip cavities, no circulation channel). So there must be some theory of how these work. But I've not been able to engage with their engineering to gain any technical understanding. Standard design guide literature offers no insight. Nor does any seal design books or research papers have shed any light on these type of multi lipped seals and how they function.
asavage wrote: Tue Jan 03, 2023 10:36 pm In fitting Teflon (PTFE) seals, it has been common practice to use a resizing tool during installation (random link for such a toolset). From memory, and from the handful of times I've had to handle and install Teflon seals, using the resizing tool to maintain a temporary larger diameter whilst installing is preferred, but it's also possible to use the tool and then rapidly remove it and perform the assembly, without the tool in place -- which would be necessary for our LDUs.

Below is a representation of the type of tool I'm thinking would be appropriate to reduce single-lip PTFE seal damage during assembly.


Tesla_Teflon_Seal_Resizing_Tool_01.png


I'm not aware of a cone install tool of these dimensions being available off-the-shelf -- and I'm not convinced the dimensions I've picked are ones I'd settle on -- but it would certainly be easy to fabricate. Certainly for less than $200 for a prototype, probably less then $100 ea. for qty. (50) or so (rough guess using eMachineshop for fab and based on a lot of stuff I've had them prototype for me over the past 16 years). A local facility could possibly be more cost effective, as EM typically has a cost-effecdtive place for only a small range of quantities.

Temporarily changing (deforming) the seal lip reduces reliance on chamfer angle and surface finish during installation.
Resizing tool would make it more install error proof. Having test installed a couple of seals, I can conclude this is the single biggest area for mistake and proper shaft surface preparation is necessary. Definitely much more precision and experience than elastomer seals for oil based media that most people are familiar with.

One note is the install tool can not be too much larger than 30mm depending on the PTFE seal's construction. Ceimin seal for example has no bending aid. It appears to just be lathe cut with very thin tip but gradually thicker base on each lip. PTFE blended material is made via sintered process (melt a bunch of dust particles together) which can have internal voids as source to start cracks (Lots of literature on this for Silicon Nitride ball bearing's sintered manufacturing process in our "ceramic" bearings)

Attaching my latest version of seal design request document. Page 12 contains installation technique. For anyone installing these seals for the first time, read/understand and have 2 seals (1 for practice, 1 for real) Its quite easy to get it onto a known good shaft once experienced. My 2nd one went on easily after figuring out the technique. Just to state what that is again in detail

- Test fit the seal onto a good shaft first. If have excluder lip, tilt seal at slight angle and press about 60 degree region of excluder lip against the shaft to stretch it. Rotate the seal 60 degrees, repeat. Do so all the way around a couple of rotations. Then, with slight tilt and pressure on one side of the lip (usually the bottom where you can't see) the other side lip will just clear the chamfered edge. The excluder lip then goes onto the shaft without any damage. Probably need to apply proper pressure to stretch the PTFE lips to avoid damage from too much pressure or folding the lips from too little pressure while trying to fit it on.

- Minimize time between stretching/test fit PTFE seal lip to install into manifold and mounting manifold onto the motor to ensure seal lips don't shrink. For my rebuild, I simply did all these back to back in about 20min to avoid any chance to damage the seal install.

- On the multi lipped seal like Ceimin, on first test fit, place finger on the reluctor wheel bevel when pushing the coolant facing lips to clear the chamfer, Amount of force required will slide the seal's excluder lip to hop over the reluctor wheel bevel after the last lip clears the chamfer.

Anyway, avoid treat this PTFE seal install like elastomer seals. Its a totally different beast.
Attachments
coolant seal design request (1).pdf
(8.7 MiB) Downloaded 56 times
Tesla LDU rebuild website https://sites.google.com/view/teslaldu
2013 Model S85 3rd (Reman RevQ) LDU on 2017 @40k. Coolant seal leak discovered in 8/2022 @ 72k miles
Seattle US
User avatar
Boxster EV
Posts: 434
Joined: Fri Jul 26, 2019 9:32 pm
Location: UK
Has thanked: 35 times
Been thanked: 26 times

Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by Boxster EV »

This will be a quick write-up and update, but Howard kindly sent me a PTFE lined rubber seal (over steel frame). It's made by a company called Peach Motor Parts in the US. I understand its application is for Snowmobiles but it almost has the required dimensions of the Tesla OE seal, albeit with a large unwanted outer lip.

The critical feature is the PTFE lined characteristic which I'm hoping will play nicely with the SKF Speedi sleave installed in my LDU.

IMG_7395.JPG
Here's the lip preventing it from fitting in the manifold
IMG_7346.jpg
Even when incorrectly installed in the opposite direction, it wont fit flush
IMG_7347.JPG
However the frame of the seal is made from steel so I carefully removed the outer lip, seemingly without compromising the rigidity of the frame
IMG_7387.jpg
IMG_7388.jpg
Decent quality gasket maker placed around the edge
IMG_7389.JPG
The seal can then be carefully pressed into the enclosure.
IMG_7391.JPG
I'm waiting on some translucent plastic pipe to improve my manifold drain set-up and then I'll place this back in the car for testing.


Edit 20th January 2023: I am yet to fit this seal to the car. The reason is explained in my edited post here:

viewtopic.php?p=49499#p49499
Porsche 986 powered by a Tesla large drive unit. Backwards. Build documented here and Instagram @tesla_porsche here.
howardc64
Posts: 166
Joined: Mon Sep 05, 2022 12:16 am
Location: Redmond WA
Has thanked: 8 times
Been thanked: 17 times
Contact:

Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by howardc64 »

Boxster EV wrote: Wed Jan 04, 2023 9:44 pm It's made by a company called Peach Motor Parts in the US. I understand its application is for Snowmobiles
I called Peach Motor Parts (Distributor located in Georgia which is known as the Peach state). Support told me seal came from Taiwan based seal manufacturer's (Would not give me manufacturer's name) standard catalog. Its for a Suzuki outboard motor (boat motor) oil seal.

http://peachmarine.com/files/PeachMotorPartsCatalog.pdf

See PM-SEAL-0065A

Its listed as FTPE everywhere it is sold. Looks like all distributors inherited the typo from the manufacturer. But its pretty clear its a PTFE lining over the NBR seal lip construction. I'd imagine all PTFE lined seal are all similar (PTFE lining over classic V shaped lip)

Unfortunately all the online pictures didn't clearly show the additional OD lip that has to be cut off and I had no idea its metal frame beneath NBR. Hope trimming it off doesn't weaken the NBR+cage bond too much.

The NOS Honda PTFE lined seal may be a more direct fit without this lip

https://www.ebay.com/itm/124615569914

Lets hope we can duplicate the prior reported 40k mile longevity of the Kimpex PTFE lined seal. But we don't have a lot of clarity on that longevity report and that seal was installed over the original shaft (don't know if shaft surface was prepped to approximate 20um roughness) rather than a sleeve. So we'll have to see @Boxster EV's results.
Tesla LDU rebuild website https://sites.google.com/view/teslaldu
2013 Model S85 3rd (Reman RevQ) LDU on 2017 @40k. Coolant seal leak discovered in 8/2022 @ 72k miles
Seattle US
howardc64
Posts: 166
Joined: Mon Sep 05, 2022 12:16 am
Location: Redmond WA
Has thanked: 8 times
Been thanked: 17 times
Contact:

Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by howardc64 »

An update on rotor repair option

Reached out to top tier transmission/valvebody (VB) rebuild kit manufacturer Sonnax (In US) They have internal engineering to analyze trannsmission/valvebody (VB) failure mechanisms and design rebuild kits for rebuilders. They often include upsized metal rod shaped valves for rebulder to enlarge worn bores in VBs to rebuild pressure sealing passages. I'm familiar with Sonnax from their Aisin Warner AW55-50 5sp transversely mounted auto transmission/VB rebuild kits. Used in Volvos, Nissans, and GMs in the 2000-2010s. You can see the amount of detailed engineering and analysis done to develop their rebuild kits

https://www.sonnax.com/tech_resources/1 ... nformation

Spoke to engineering for an hour. Really knowledgable. Asked if they were interested in high volume EV motors like this LDU. Will wait for a reply after they've studied more. Asked any possibility to offer rebuild/reconditioning services for the rotor shaft and possibly worn spline. They are familiar with PTFE seal mounting challenges (stretching, fitting tool, avoid micro scarring etc) but recognize this is a "blind" mount (no way to use a tool during the final mount)

They also provided a company named torquetrends.com who is making a reduction gearbox for custom EV builds based on off the shelf motors.

https://www.torquetrends.com/products

Anyway, this type of company with built in engineering capability to study drive train failure patterns to build solutions maybe more suitable for LDU repair efforts. Perhaps those in EU can look into who makes rebuild kits for ZF and other EU transmission/VB manufacturers to find similar capabilities.

====

As a side note, they asked how repairable is the inverter in case the coolant leak stops the car (this will be the highest volume scenario) This brings up another major challenge to jump start LDU rebuild capability worldwide. Inverter contains Tesla IP control and IGBT boards which someone else probably can't legally make. Harness, bus bars, plastic/metal structural parts are probably not a problem.

In case of coolant damaged inverter. I've seen pictures of

- Coolant soaked harness
- Coolant wicked onto connectors on control board.
- Damaged phase boards. One even look like lightning strike on the inverter housing where the rows of IGBTs are (see 2nd pic in this post)

https://teslamotorsclub.com/tmc/posts/7025439/

If board failures and repair difficulty is high, then this becomes the limiting supply for scaling rebuild capabilities. Anyhow, yet another challenge to overcome from Tesla's disabled parts sourcing.

Tesla HQ is in silicon valley and have hired plenty of Apple engineers. Might be likely they go down the path of security lock all the components together and then to the mothership, For example, even replacing batteries in the last few gen iPhones require marrying to the logic board. Only workaround is to transplant to battery's own mgmt board to a new core cell.
Tesla LDU rebuild website https://sites.google.com/view/teslaldu
2013 Model S85 3rd (Reman RevQ) LDU on 2017 @40k. Coolant seal leak discovered in 8/2022 @ 72k miles
Seattle US
Post Reply