Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Topics concerning the Tesla front and rear drive unit drop-in board
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Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by muehlpower »

Here in Germany there is a manufacturer of PTFE sealing rings. I contacted him 2 years ago and received an offer. At that time I assumed a bearing inner ring with 35mm to repair the damaged surface. The dimensions were 35x55x8 with 2 lips. He wanted 78€/piece for 10 pieces, 61.10€ for 20, 37€ for 100, and 16.70€ for 500.
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Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by howardc64 »

muehlpower wrote: Tue Dec 06, 2022 5:12 pm Here in Germany there is a manufacturer of PTFE sealing rings. I contacted him 2 years ago and received an offer. At that time I assumed a bearing inner ring with 35mm to repair the damaged surface. The dimensions were 35x55x8 with 2 lips. He wanted 78€/piece for 10 pieces, 61.10€ for 20, 37€ for 100, and 16.70€ for 500.
Very cool, can you forward me any design info ( howardc64@yahoo.com ) PTFE blend hardness choice is really important to avoid damaging shaft's hardness. @Johan and I have been studying seal designs and searching for options. I'm in US so all my searches gets directed to US rather than EU.

A possible downside of using even a thin sleeve is thermal barrier to remove heat through the shaft's contact surface with the PTFE lip. A thick (2.5" radius adder) sleeve may have more thermal barrier. Don't really know. But do send us the option info :) But I'm sure they can do 30x55 too.

I think EU offers lots of hope as right to repair laws are much stronger than US. So the entire manufacturing and consumer community are accustomed and generally fosters more solutions. Apple and Tesla are silicon valley (SV) companies that limit right to repair aggressively (Louis Rossmann - famous youtube macbook repair tech and Rich Rebuilds meet and cry over this often haha) These company's DNA is "we design new version every year, you should just buy the new one" $2000 macbooks is painful enough, now we are have $75k cars. SV's high employee turnover rate (worker stay average 2 years) results in new mistakes while learned from old one so net improvement seems like 0. Problems just rotate to different places.

The seal hunt continues haha.
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Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by muehlpower »

That's the company I asked about: https://www.seals.de/en/solutions/shaft-seals.html

IR30x35x16-EGS 13€
IR30x35x13-EGS 11€

EGS means: "Surface ground free from spiral marks for rotary shaft seals to DIN 3760 and DIN 3761"

DIN 3760 means: Ra = 0,2µm-0,8µm, 55HRC above 4m/s
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Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by Johan »

If you plan to use a Speedy Sleeve because the shaft surface is bad, then I would highly recommend using a thermally conductive epoxy to fill the microscopic gap between sleeve and shaft. Not doing that can (according to my heat transfer model) severely increase the seal temperature and cause early seal failure. For more background and a numerical example, see here. Not doing it is like mounting a CPU on a heat sink without thermal grease.

In case you want to try the triple lip Ceimin seal and simultaneously need a Speedy Sleeve: Shown below is a Speedy Sleeve that has been positioned such that the sleeve's "outer" chamfer edge coincides with the shaft's "inner" chamfer edge so that both lips can touch the sleeve. Now the excluder lip interferes with the sleeve flange, so, simply cut off the flange with (for example) a Dremel cutting disc (first wait for the epoxy to dry and wind protective tape around the sleeve!). After mounting the sleeve, that flange has no function anymore anyway. Shallow damage to the shaft from cutting does not matter bc it is ruined anyway, that was the reason to use the sleeve in the first place.

Double check the dimensions of your LDU first, because different revisions may have different dimensions.
1670279963036.png
1670279937729.png
1670279937729.png (52.16 KiB) Viewed 4487 times
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.
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Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by howardc64 »

muehlpower wrote: Tue Dec 06, 2022 7:02 pm That's the company I asked about: https://www.seals.de/en/solutions/shaft-seals.html

IR30x35x16-EGS 13€
IR30x35x13-EGS 11€

EGS means: "Surface ground free from spiral marks for rotary shaft seals to DIN 3760 and DIN 3761"

DIN 3760 means: Ra = 0,2µm-0,8µm, 55HRC above 4m/s
Very interesting and maybe can make what we need.

EGS sounds okay. I think just means smooth. Helix grooves are unidirectional pumping aid. So far, Tesla seals and Ceimin don't have helix grooves. Tesla single lip seal had concentric grooves to help lip bend but Ceimin did not. Tesla triple lip appears to not have grooves from what pictures I see. Hard to take good pics since seal is black.

DIN 3760 Ra and 55HRC seems okay. We need much higher surface speed but PTFE should be able to do 20m/s easily.

x13 x16 is 2x too wide for us. We need closer to 8mm. After PTFE lip spread out mounting on the shaft. It becomes almost 12mm and shaft length for seal is 13mm max. See pg2 of PDF attached at this link

https://teslamotorsclub.com/tmc/posts/7185566/

Also maybe 2 lip + excluder is most desirable profile we know now.

There material table listing ( https://www.seals.de/en/solutions/shaft-seals.html click "material" tab on bottom) shows polymer filled. I think this is for softest shaft material. Probably need to discuss with their engineering on list of PTFE blends for shaft ~55 Rc.

Do you think we can connect with their application engineering to ask some questions? I don't speak German (I think @Johan does)

Thank you for sharing this source. Maybe we can get close to solution :)
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Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by muehlpower »

If I summarize, I come up with a PTFE seal and a good shaft that only needs to be polished, or the use of a speedi sleeve with something for better heat transfer. The PTFE seal would then be the same. So I will ask XXX what the best material and design is. Shaft 55HRC, Ra 0.4µm, medium water/G48, speed 28m/s, pressure max 0.3 bar, temperature max 90°C. And what he thinks about a diameter of 30.5 with a sleeve instead of 30. Did I forget something?
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Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by howardc64 »

muehlpower wrote: Tue Dec 06, 2022 10:21 pm If I summarize, I come up with a PTFE seal and a good shaft that only needs to be polished, or the use of a speedi sleeve with something for better heat transfer. The PTFE seal would then be the same. So I will ask GFD what the best material and design is. Shaft 55HRC, Ra 0.4µm, medium water/G48, speed 28m/s, pressure max 0.3 bar, temperature max 90°C. And what he thinks about a diameter of 30.5 with a sleeve instead of 30. Did I forget something?
Thanks this is greatly helpful :)

I do think for step 1, best to start discussion without worrying about speedi sleeve variation because it has additional variables. It is best to first reduce variables for a known good shaft with well prepared surface. Please allow me to explain

With speedi sleeve

- As Johan showed, sleeve need to be cut and installed on shaft in very precise location. If the PTFE seal lip sit on edge of the speedi edge, it will not work.

- Per Johan's work, there is likely thermal conductivity required for assembly

- A third ambiguity is if extra 0.5mm will make seal performance different. Johan was guessing maybe not but of course we don't know.

- It may also be desirable to make slightly different seal for shaft with single speedi-sleeve mounted. For example, account for 0.5mm increase for 2 coolant lips while excluder lip still assume 30mm. Or single coolant lip to reduce hand installation precision requiremenet etc...

Not suggesting we should ignore damaged shaft problem. Just suggesting we pursue that in step 2 of conversation with seal developer. Step 1 should narrow down key parameters first.

On the parameters

~55HRC is good

- 0.4um shaft surface might be high? Lower end like 0.2 might be more desirable. But I guess it doesn't matter to seal maker. Ra only change how well seal will function with the shaft. It think Johan's video is shooting for ~0.2Ra to ~0.3Ra and Advanced EMC's lower end for liquids (higher end might be for high viscous liquid like oil) is 8 RMS(0.2Ra)


https://advanced-emc.com/selecting-the- ... aft-seals/

But again, I think seal maker doesn't care except will tell you best Ra # to make seal work longer given media/pressure/contaminants etc.

- water/G48 media

- 28m/s (I guess autobahn? haha)

- 0.3 bar

- I don't know if 90C max temp make sense, I think we just need to tell them incoming G48+water is 50-60C max. They can calculate the seal material heat easily by 20+m/s x 30mm diameter. Generally, once using PTFE, seal designers seems much less concerned about lip temperature.

I made the attached slide to give to seal maker to engage discussion. Please free free to use all or part. If they can speak English, I can also join in german time zone (I'm in west coast USA)

====

Actually once initial parameters are fixed, we can also challenge additional consideration such as

- any benefit to cut concentric rings to aid bending for the tighter lips? (primary media facing lip)

- bi directional pumping aid? Or maybe single direction helix is okay since mostly forward? (would need to then make separate seal for Rav4 EV... I don't know MB's rotation direction) Or does pump aid's microstructure likely clog and become useless anyways?

- any chance for a slinger like shape to collect leak and route to exit in guided path?

====

If can reach beyond sales to engineering. Very desirable to hear their expert suggestions :)

Thanks!!!
coolant seal design request.pdf
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Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by Johan »

muehlpower wrote: Tue Dec 06, 2022 10:21 pm If I summarize, I come up with a PTFE seal and a good shaft that only needs to be polished, or the use of a speedi sleeve with something for better heat transfer. The PTFE seal would then be the same. So I will ask GFD what the best material and design is. Shaft 55HRC, Ra 0.4µm, medium water/G48, speed 28m/s, pressure max 0.3 bar, temperature max 90°C. And what he thinks about a diameter of 30.5 with a sleeve instead of 30. Did I forget something?
Seems correct and mildly conservative, which is good. Maybe the 28 m/s (seal slip speed) is a bit high because it corresponds to 250km/h = 155mph for my wheel size. Maybe use 137km/h = 85mph -> 16m/s seal slip speed, which may open up a larger solution space for seal designs? Unless faster driving is a desired.

Also the max coolant pressure could be higher: 1.3 bar (source).

Also mention, just to be sure, that the seal should seal both statically and bidirectional dynamically (duh) and that the shaft is horizontal.

Maybe also request a dynamic service life of at least 500 hours (500 x 100km/h = 50000 kilometers)?

Also there is a bunch of dimensional constraints like the primary lip (touching the coolant) can stick out no further than 2mm from the housing because if more, it may rub the shaft chamfer edge. Also the excluder (if any) cannot stick out further than 3mm (assuming 8mm thick housing) to avoid touching the shaft chamfer edge for the reluctor wheel. Also not sure what the best interference fit size is, i.e. best outer diameter for stainless steel housing (Ceimin is 55.2mm I think).
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.
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Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by howardc64 »

Almost forgot

Johan suggested PTFE blend Carbon+Graphite reinforced (compound # 3 black-grey) under this link

https://www.seals.de/en/solutions/shaft-seals.html

Select "shaft seals without steel housing" tab. Of course we probably want steel housing. This tab include more material listing which surely they can incorporate into steel housing.

This material is good for hot water and steam and not the hardest PTFE blend they have. Thats just our idea based on study so far. Definitely want to hear their expertise suggestion.

====

I have heard in the past seal maker can't guarantee a service life especially given DIY install with unknown shaft preparation. So just keep that in mind but see what they can promise :) Usually, seal maker design to an agreed leak rate. Since we are not high volume OEM, I'm guessing they promise nothing.
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Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by smathermather »

howardc64 wrote: Tue Dec 06, 2022 7:04 am Probably any new version of MB or Rav4 EV LDU are just Tesla's latest LDU revision #s. MB/Rav4 EV volume is much smaller than Model S so likely they will track LDU rev slower.
Makes sense. With a few thousand MBs (and I think a similar number Toyotas) in North America, that's not a lot of incentive for MB to do anything beyond using essentially what Tesla has. I hope that's wrong, but suspect it is not now that you put it that way.

Sigh. Well, I guess I'll be following this thread and checking my speed sensor with some regularity.
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Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by WimV »

For the speedi sleeve: the flange is pre-cut (you can easily pull it off after making an incision.

I do think speedi sleeve is not such a good solution because of the tight tolerances of PTFE seals (0,5 mm diameter increase is probably just to much).
There is also a “speedi sleeve gold” that is coated and more resistant to abrasive (probably better for PTFE seals). The problem is that it’s not offered for a 30 mm shaft.

I thing machining the shaft is the only good solution in case of wear on the sealing surface.
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Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by howardc64 »

Shaft Surface Damage

Been thinking about shaft damage source and repair. Here are some thoughts. Note it is mostly just guesses, no way to confirm without lab level material analysis

Corrosion Damage

EV builders that source salvaged LDUs which has been sitting around awhile shows high rust/oxidization damage. Here is @Boxster EV's original pic

viewtopic.php?p=36449#p36449

Here is a pic of another Porsche EV builder recently reached out to me for LDU seal repair. This LDU sat idle (drained with whatever coolant trapped inside and no drain path in reluctor chamber) for 2.5 years. Installed and pumped with coolant 1 year ago. Manifold just pulled and reveal this pic
image000000.jpeg
image000000 (1).jpeg
This info + what we have heard on shaft metal material suggest it is not stainless. Johan did some guesses and I revised my post on shaft hardness to reflect this thinking it is maybe hardended 1045 steel.

viewtopic.php?p=49511#p49511

Note the seal is a triple lip seal. LDU was a T13 (originally 2013 made) Rev Q Reman

Seal/Debris? Damage


Scientifically, we've been very focused on PTFE lip material hardness in relation to shaft hardness. But the close up on wear pattern may suggest differently...

Here are some close up on my shaft surface before and after 600->1500 grit prep
IMG_2819.jpg
IMG_2898.jpg
Here is @Wim_V's shaft with triple lip seal. We can see the accumulated debris on the rotor facing side of the lips

viewtopic.php?p=46359#p46359

Similar rotor facing side lip surface debris is present on my single lipped seal

viewtopic.php?p=46858#p46858

Given the location of the wear on mine and WimV's shaft, it seems to suggest the shaft scoring might be on the dry side of the lips by debris rather than the PTFE lips? If so, perhaps triple lip with its trapped region between the lips could retain debris including any dislodge lip material and cause scoring? AND maybe this is why Tesla rebuilds shifted to single lip?

Debris is probably left over solids after vaporizing the leaks water content?

What happens to the vaporized water from the leak?

Assuming PTFE lip are hot from friction. Wonder what happens to the water content from minute leaks on the dry side? Would they steam/vaporize and expand? Where does the expansion go inside the triple lip seal? Cavitate back towards media btw the 2 media facing lips chamber and exit the excluder in that chamber?

These are all guesses of course, but putting it out here for all to consider since we have so little data and no lab material study results.
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Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by muehlpower »

A small update. I had a long talk with an engineer from XXX today. He sees no major problem. All shaft versions are possible, i.e. good and polished, speedi sleeve and inner ring. He is relaxed at the temperature, he describes the pressure as low and the speed up to 18000 is feasible. I sent him a small drawing with the installation dimensions and some photos, also with rusty shafts. I will send him a package tomorrow with a water manifold, a destroyed original sealing ring and a Chinese ring. He evaluates all of this and then makes a suggestion. Then he makes samples that I can then test. For this I build a small test stand with which I can run speeds of up to 20000 rpm and change the pressure and temperature. In 4 weeks I can cover 80000km without ruining an LDU! I can't simulate the original tread because I don't know about it. I will use an inner ring with an outer diameter of 30mm as a tread.
I hope google translated correctly :-)
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Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by howardc64 »

muehlpower wrote: Wed Dec 07, 2022 6:01 pm A small update. I had a long talk with an engineer from GFD today. He sees no major problem. All shaft versions are possible, i.e. good and polished, speedi sleeve and inner ring. He is relaxed at the temperature, he describes the pressure as low and the speed up to 18000 is feasible. I sent him a small drawing with the installation dimensions and some photos, also with rusty shafts. I will send him a package tomorrow with a water manifold, a destroyed original sealing ring and a Chinese ring. He evaluates all of this and then makes a suggestion. Then he makes samples that I can then test. For this I build a small test stand with which I can run speeds of up to 20000 rpm and change the pressure and temperature. In 4 weeks I can cover 80000km without ruining an LDU! I can't simulate the original tread because I don't know about it. I will use an inner ring with an outer diameter of 30mm as a tread.
I hope google translated correctly :-)

Very impressive if you can build bench test machine. I will share valuable Germany PTFE information below.

University of Stuttgart has professor and laboratory (lab) studying PTFE lip seal for 20 years. I emailed lab leader professor in English but didn't receive reply. His PhD from Stuttgart is PTFE lips with helix pattern. Now running lab researching PTFE lips. They are probably supported and closely affiliated with German automotive industry.

Primary research focus is pumping aid. Pumping aid is designing structure to create pressure to to push lubricating media film back towards media side rather than leaking to dry side.

Stuttgart PTFE pumping aid research is very practical and focused on real industry problems. But research designs are too advanced for DIY. PTFE seal manufacturers have not used these research designs yet.

This lab have bench testing machines. Explain testing procedures. Many papers are in German language (some in English) So this maybe helpful in your bench testing.

Here is the professor, lab and key papers including bench testing description

Stuttgart "PTFE" search result https://www.uni-stuttgart.de/en/search/?query=PTFE
Frank Bauer is key professor https://www.ima.uni-stuttgart.de/en/ins ... uer-00011/
2018 research presentation in English https://elib.uni-stuttgart.de/bitstream ... _Bauer.pdf
2014 paper provide detailed bench testing procedure https://elib.uni-stuttgart.de/bitstream ... _Seals.pdf
2012 paper show bench testing machine. https://elib.uni-stuttgart.de/bitstream ... r_Haas.pdf

I googled paper author Mario Stoll. Now working for Bosch related transmission company https://www.linkedin.com/in/mario-stoll ... bdomain=de

I also found key PTFE lip wear study paper from Univ of Hamburg (2 papers attached. Same study but slightly different presentation)
951055.pdf
(493.5 KiB) Downloaded 67 times
1-s2.0-S0043164898003068-main.pdf
(1.36 MiB) Downloaded 69 times
Looks like many knowledge in Germany :)

====

I have a question on bench testing

Are you really able to do 20k RPM on high speed bearing with low axial runout, balanced and low eccentricity test shaft with 0.2Ra without vibration? If you can, its seems impressive.

I think even without bench testing, DIY members are ready to try new seal from high quality designer from Germany. Everyone is now trying every seal type without bench testing anyways.
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Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by howardc64 »

Spray Metal Deposition Shaft Repair

Was curious about what is involved. Here are the Ukraine rebuilder's quick video. Turn on CC + auto translation can hear what they are saying



Youtube shows machinists doing this.



This guy goes through it in more detail. Can handle few 10s of thousands of damage in narrow region. Requires an undercut to promote adhesion, preheat, and turning on lathe while spray probably yields the desired evenness? Also provides the type of metal power used



Here is the metal power (19985) Its 200HV (Vickers scale) which translates to 16Rc ( https://en.wikipedia.org/wiki/Hardness_comparison ). Obviously very soft. Don't know if this hardness matters once on shaft (probably should?) or if harder materials are possible?



This spray metal power company also have 2 videos showing ~60Rc sprayed products (10009 and 12496) looks like higher preheat temp required 250C instead of 100C for 19985)




There are other ways to repair shafts including cold epoxy like process (claims benefit is less disassembly of machinery) Probably need to research resulting hardness and thermal transfer properties.

Anyhow, probably best to find well experienced machinist with rotary shaft repairs. Rotary shaft will typically require dealing with seal and bearing fitting surfaces.
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Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by howardc64 »

@muehlpower

If GFD engineer has interest to include a sling. I don't know how to solve mounting problem. Coolant seal bore and shaft are on 2 different body on LDU. Mounting 2 object with sealing interface (object A to shaft and object B to body) in LDU seems not possible with LDU design? 2 face seal, isolator, slinger all have same assembly problem.
coolant seal design request.001.jpeg
If they are interested and have answer, I am very interested to know. I make new version of design request (PDF attached), pg18 include this picture and explanation.
coolant seal design request.pdf
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Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by crasbe »

howardc64 wrote: Wed Dec 07, 2022 7:02 pm University of Stuttgart has professor and laboratory (lab) studying PTFE lip seal for 20 years. I emailed lab leader professor in English but didn't receive reply. His PhD from Stuttgart is PTFE lips with helix pattern. Now running lab researching PTFE lips. They are probably supported and closely affiliated with German automotive industry.
It is not really untypical for a Prof to forget answering a mail. You have to imagine the flood of mails arriving each day. The prof of the institute where I work explained it like this: He sees a mail and when he forgets to answer, it's so far up in the mail inbox after just a day or two, he'll never find it again.

You can either try to send the mail again or try to contact one of the research assistants/PhD students who might have a project that's in the research area. The research assistants usually reply a lot more reliably than the profs :D
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Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by howardc64 »

crasbe wrote: Thu Dec 08, 2022 11:48 am It is not really untypical for a Prof to forget answering a mail. You have to imagine the flood of mails arriving each day. The prof of the institute where I work explained it like this: He sees a mail and when he forgets to answer, it's so far up in the mail inbox after just a day or two, he'll never find it again.

You can either try to send the mail again or try to contact one of the research assistants/PhD students who might have a project that's in the research area. The research assistants usually reply a lot more reliably than the profs :D
Yes indeed, academia haha. I'll give it another try.

Actually finding past PhD student (from 2018 paper) in Bosch transmission company is exactly my attempt to find more contact points. But 2018 era PhDs already graduated. By the time they publish, they are probably already 1-2 year from graduation. New PhDs are more invisible to me if no major published papers. However, many small German language documents on Stuttgart PTFE search results can reveal key PhD students who have not yet published or completed thesis.

But if anyone in Germany can help connect, I'd be very appreciated. Meanwhile, I'll email professor again to see if any results :)
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Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by howardc64 »

@muehlpower

Maybe this is better slinger design. But we better ask experts if they think solution is possible. v5.0 of design request attached.
slinger.001.jpeg
coolant seal design request.pdf
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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
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Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by howardc64 »

Question for those experienced at rebuilding gearboxes

I have low level whine post LDU rebuilding. starts around 30mph and gets drowned out by wind noise at 40+. This was not present before rebuild. There was a downhill regen whine prior to rebuild (going about 25mph) but no whine when motor does the driving.

During the rebuild. found the old 6207 bearing (primary shaft counter bore) had spun in its bore and outer race face to the bore damage when it spun and locked in the bore. New 6207 was installed with retaining compound and my regen whine went away. Also changed 6208 on primary shaft and the FAG counter bore bearing on the intermediate shaft (no retraining compound) Also the 2 ceramic bearings on the rotor of course.

I think there were 2 mistakes during gearbox asseembly

1. Didn't index the gear tooth to each other during disassembly and reassemble in same matching tooth to gears as original. Nor did I match the index paint marks between rotor spine and primary gear from original balancing. Maybe both of this doesn't matter much. Primary shaft is fairly narrow diameter and doesn't weigh much.

2. Assembled all the shaft side ways AND upside down to avoid putting pressure where inverter had no firm footing. Differential gear is quite heavy as is intermediate gear. Diff also has a shim that was presumably sized properly when initial case halves got combined. Would side way install load the heavier gears/shaft's bearings incorrectly? Correct install is probably install all shafts pointing up and fit inverter half top down to close up the gearbox. This is challenging of course. Completed assembly would be quite tall and heavy. Probably good to build some kind of stability cage for the motor half to seat firmly while mating the gearboxes.
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Maybe even side way assembly would be okay if gear set were assembled pointing up. The locking bracket on all 3 shafts would have correct even loading around the bearings during install. But probably best to do the whole assembly vertically.

Thoughts on removing and reinstall properly to see if get rid of the whine? Or first try loosening and retightening the diff gear hex nuts?

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

Post by muehlpower »

A little tool I made to pull the gear off. Should also work to dismantle a Speedy Sleeve.
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jsimonkeller
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Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by jsimonkeller »

I wanted to share my coolant leak experience, since it is now "patched up" thanks to the help and resources of Howard. I believe he shared some photos already, but I obtained my LDU back in 2018 and it sat for a little more than a couple of years before coolant was added to the system and then maybe close to another year before the coolant was running through the system with pumps on a regular basis with testing. I got about 90 miles of driving before the erratic behavior began. I posted about that on here before I knew the issue. It started with losing power on braking and having to be towed home in shame :cry: . . . and then the overcurrent issues that I thought was in the programming . . . and finally the pot settings went awry and the temp was reading -1230 c, which is below absolute zero!!!!
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I was assuming the card was bad and when we opened up the inverter to replace the card, we saw the coolant invasion.
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This meant we needed to check the other side of the motor and sure enough . . .
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After cleaning off the rust, it was clear the shaft was pitted, which was not unexpected by Howard.
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CONTINUED IN NEXT POST
jsimonkeller
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Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by jsimonkeller »

CONTINUED . . . .

Howard explained all of the options and since my car was in a shop with lots of cool tools and my partner on this build has a lot of experience in metal work and welding, we went for the option to undercut the shaft and then add a new outer sleeve of stainless steel at the same length as the shaft to accommodate the seal.
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We closed up the breather hold and drilled out the new emergency drain and set the new seal (courtesy of Howard's stock) and re-installed everything.
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We also added drain holes on the Inverter side.
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Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by jsimonkeller »

I am reusing the DU card that was in there during the coolant leak, along with same harness (thorough cleaned) for now and it powered on fine and temp readings are correct again and pot nom is back in line with where it should be and voltage readings are accurate.

I am getting NO ERRORS at the moment BUT the OPMODE is staying in OFF and I have not been able to get it back to ON. I am trying to determine if the card just has some damage I cannot see that is causing this or if the inverter has any damage. No visible damage to the inverter.
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I am not sure if there is any troubleshooting anyone would suggest at this point. I plan to swap the card out for an older one I have in a box somewhere to see if that solves the problem and answers the OPMODE not coming on and damaged DU card issue.
LunaticScientist
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Re: Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

Post by LunaticScientist »

howardc64 wrote: Wed Sep 14, 2022 5:17 am All make sense. However, the rotor's shaft locks in 30mm diameter and ~8mm seal width so these can't be changed. Only remaining design variables are material + shape + shaft surface prep.
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.
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