openinverter forum

Sonnax engineering asked to get a rotor to inspect (I think coolant manifold would help as well) Does anyone have one lay around unused to loan or donate? I think even damaged is fine.

Their experience can probably determine repairability and shaft hardness quickly.

Shipping an LDU rotor will require a custom WOOD packing case be made. IIRC, it's ~90 lbs, and during shipment the axial load should be absorbed by the wood case, on the copper-colored rotor end that's around 9" dia, and not on the end of the 30mm shaft where the seal seats.

Even I could knock out a shipping container from scrap wood in a couple of hours, and I'm miserably slow at this kind of thing, but it needs to be done. You can't just throw this thing in a cardboard box with bubble wrap.

asavage wrote: ↑Thu Jan 05, 2023 10:02 pm Shipping an LDU rotor will require a custom WOOD packing case be made. IIRC, it's ~90 lbs, and during shipment the axial load should be absorbed by the wood case, on the copper-colored rotor end that's around 9" dia, and not on the end of the 30mm shaft where the seal seats.

Even I could knock out a shipping container from scrap wood in a couple of hours, and I'm miserably slow at this kind of thing, but it needs to be done. You can't just throw this thing in a cardboard box with bubble wrap.

Noted, will make sure safe transport whenever finding a source. Have reached out to Rich Rebuilds and Electrified Garage in MA/NH to see if they have scrap around. Sonnax is in VT.

BTW, I found Sonnax really interesting. Since they have always developed a complete solution for the mass market. They immediately asked "what about the damaged inverter" for people who don't preemptively rebuild. Totally the dominant scenario. So its probably better to aim at integrated solution providers while attempt to scale the repair options. These providers surely have their own connections to component suppliers for seals etc.

My earlier statement that my single lip Tesla seal was "worn out" was probably incorrect. Instead, it probably already had a smaller thickness from the start (in the reagion where it contacts the shaft) due strains induced by manufacturing and installation. I explain it in more detail on Youtube:

howardc64 wrote: ↑Wed Jan 04, 2023 10:56 pm An update on rotor repair option

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.

Just as a side note on my INVERTER repair, in my case it turned out solely to be a HARNESS issue. As you may recall, my coolant leak made it into the inverter and here are some photos of the condition of the harness before the repairs took place.
I purchased a new 23 pin harness from ZERO EV, since they make one, but no one sells the harness that attaches to the gate drive board on the three phase blocks, so I thoroughly cleaned that harness and when things still did not work, I assumed my damage was in the DU card initially. I replaced it with a new one and that did not solve my issue.

I then moved onto the phase blocks and assumed that was issue based on these scary looking RED LEDs.
With the help of the amazing Boxster EV, I was able to obtain an untested replacement inverter from him quickly. THANK YOU AGAIN! When it arrived, I disassembled it into the three separate phase blocks and brought them to shop. Without HV connected and just 12V power and the car off, I unplugged the harness from the alleged bad gate drive board and plugged it into each of the three replacement phase blocks and in each case, those RED LEDs lit up again. In order to troubleshoot further, I unplugged the harness from one of the other two phase blocks without RED LEDs and when I plugged those into the phase block that had been lighting it up, it did NOT and the same went for the replacement blocks.

At this point, I surmised that the two red LEDs were supposed to be lit up when the car was off with 12V supplied power (sorry if this is obvious to all of you experienced members). When the car starts up, those RED LEDs disappear. Therefore, it turns out that the coolant exposure damaged the phase block harness and two of the blocks were not getting any power.

Luckily, the replacement inverter from Boxster EV came with a harness and when I put that harness into play, all three of the existing phase blocks lit up with 12V and car off and all went off with 12V and car on. At this point, I tested the inverter and it went into RUN mode for the first time in 2 months. I drove the car home from the shop and everything seems to be operating as it should now.

All of this to say that they PCB cards seem to be heartier than we might think and that the coolant exposure to the wiring harness did not short anything out on my inverter and just kept it from powering on. It might be a project at some point in time to fabricate these harnesses since they are not that complicated to replicate and this could be the most cost efficient solution for a coolant leak into the inverter and a first line of testing things after a coolant leak and inverter failure.

Very cool! Glad its up and running with harness change.

Spoke with @jsimonkeller over the phone to confirm the details. He believes the connectors coming out of the control board to the 2 phase gate drivers on top and right of the CANBUS connector (looking at the gearbox) lost signal. The harness+connector to the phase gate driver board on the left of the CANBUS controller was actually okay. Red light was presumably a signal to say "getting power but can't go further"

Anyway, when the coolant makes it way to the inverter and pools on the bottom. Its 1/16" from the CANBUS connector and the wiring harness/connectors to the control board (according to QC Charge tech on teslamotorclub forum). Then the coolant wicks up the wires reaching the connectors to start the corrosion.

I have seen 3 levels of damage from this and summarizing them all here

Very slight coolant in Inverter

This was my case. Inverter was fully functional. The earliest sign of wicking had started along with coolant residue coating on bottom of CANBUS connector. Coolant doesn't really leave a mark along its travels so had to do some forensics to confirm leak was not from the inverter passages.

https://teslamotorsclub.com/tmc/posts/7052908/
https://teslamotorsclub.com/tmc/posts/7053072/

Here is an annotated pic showing this the very early stages of harness coolant wicking. I cleaned it up with ISO prior to reinstall.
Heavier coolant intrusion in Inverter

@jsimonkeller post prior to this one shows coolant caked on all the connectors to the control board. Luckily in his case, all boards survived and just needed replacement harness

Causing IGBT damage?

I wonder if pics here shows IGBT damage. The white lines along the interior of the inverter casing looks like lightning marks to me. Its location is along the row of IGBT heatsinks (mounted just above IGBTs) along the IGBT board. Wonder if it jumped and arced leaving the white residue

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

BTW, here is a simple check to make sure no shorts on the IGBT phase board



CANBUS connector

The CANBUS connector and electronics just behind it seems can be easily damaged. The electronics immediate behind it is actually sealed pretty well filled with gel inside. However, this connector along with the harness is on the bottom of the connector. If the inverter is sitting right side up mounted to the gearbox, probably can easily damage it.

@dzolotnyuk ( viewtopic.php?p=46191#p46191 damaged his and had to source an replacement ) @Johan used foam under the inverter sealing the 2 halves of the gearbox when the inverter housing must remain removed to pull the temp sensor cable through ( btw, mesh sleeve on outside of sticky temp sensor insulation is the trick to make this go way easier https://teslamotorsclub.com/tmc/posts/7182122/ ) And I assembled by LDU halves upside down so there is support for the inverter.

in LDU rebuilder QC Charge's postings. This CANBUS connector is always removed on all inverter pictures presumably for safer handling? Example pic in the link under "Causig IGBT damage?" above.

Fried IGBTs

Finally, I've seen this LDU->1970s American Muscle car build that fired an IGBT. Author claims can happen when power drops out while driving. I'm assuming this uses non Tesla control board that most custom EV builders are using.



====

I'll forward this info to potential rebuild kit manufacturers, a new harness, CANBUS interface, and a PTFE seal stretch tool before mounting on manifold for blind installation is probably desirable in a rebuild kit.

A couple of updates

Rebuild Kit

Spoke with an engineering product line manager at a 2nd transmission rebuild kit company. I'm hoping to bring in kit makers to provide more than just a seal but also a seal install/stretch tool, inverter harness, CANBUS connector as well as technical notes on how to repair the shaft for customer end point rebuilders. Will update when I hear more.

As LDU volume reaches 100k out of warranty with another 300-400k? in warranty gradually exiting, it seems possible to setup this kind of kit developer and rebuilder structure to enable more rebuilders.

In Car LDU Mod

Been thinking if possible to do the weep hole and seal speed sensor vent hole with LDU in the car (Tesla Model S is extra hard fully wrapped in the subframe with less clearance) Vent hole looks easy with sensor out. If weep hole tapping becomes possible without removing coolant manifold and produce no metal shavings in the reluctor chamber, it would allow a huge number of cars to easily reduce leak collateral damage. Not saying can ignore the leak (maybe if a properly installed PTFE seal leak is minute for long time) but certainly buy a lot more time before collateral damage.

Here is a write up on that. Thanks to @asavage and @Johan for suggesting methods. I guess next step is to buy an aluminum block and do some trials if anyone has an interest.

https://teslamotorsclub.com/tmc/threads ... st-7339188
https://teslamotorsclub.com/tmc/posts/7361398/

As I have already written, I am in negotiations with a seal manufacturer in Germany. He sent me an interesting draft. I have pointed out that a Speedi Sleeve may be used. He also takes into account the slightly larger diameter and the limited length.
He also has reservations about using Loctite because of the poor heat dissipation. I did some googling and came across this glue.
https://www.sepa-europe.com/wp-content/ ... 000010.pdf

@muehlpower: I don't have time for this yet I can't let go : Very interesting design! It looks like the lip is CNC machined and definitely not formed using a mandrel. Some questions and remarks in random order (I may be dead wrong of course):

1) Does GFD have experience using this design (and @10k RPM with coolant) or is it highly experimental?

2) The left "primary" lip is too close to the shaft end (at least for my LDU which I measured - see my drawing below). Now it would contact the "shaft end chamfer" and probably leak! It must be moved at least 1mm away from the shaft end (relative to the current position in the drawing) in order to have at least 1mm of clearance from that "shaft end chamfer". Which is maybe still not conservative enough. Simultaneously, the excluder lip is allowed to be positioned a maximum roughly 1mm extra away from the shaft end (relative again), so that it has a (reduced) 2mm clearance from the "shaft reluctor wheel chamfer". Why 2mm and not also 1mm? Because my drawing shows the motor in the "cold" configuration. Once heated up, differential thermal expansion can move the shaft roughly 0.5mm deeper into the manifold because the rotor can get hotter than the stator+housing, and also lateral accellerations can "bounce" the rotor roughly 0.5 to 1mm in axial direction (because the rotor is kept in place by a spring and floating bearing on the manifold side), which reduces the clearance to maybe only 0.5 to 1mm. This design is very tight! Seems like Tesla had very little available space ("bauraum" in german)

2) The garter spring seems to be able to "slip off" the lip easily, so maybe add some more material to "cradle" it (keep in place). Especially because I think that the spring pressure must be relatively small (compared to the classic elastomer lips) because too high pressure results in too much frictional forces and thus heat development.

3) Does the steel ring have an interference fit? It shows 55mm nominal only and no tolerance.

4) The excluder lip should ideally maybe have nearly zero pressure on the shaft, maybe even a very tiny gap like the SKF FKM seals, so maybe reduce the interference.

5) What price range?

6) Maybe increase the primary lip contact area (width) to 2mm in order to reduce contact pressure. This is also a benefit from some formed lips (like the Ceimin lips). Just an observation based on Stuttgart PhD work on PTFE seals.

muehlpower wrote: ↑Fri Jan 20, 2023 10:19 am https://www.sepa-europe.com/wp-content/ ... -LDU-1.png

UPDATE : Have inspected this seal in hand and updates below.
Here is my analysis of this seal profile design compared to curved PTFE lips

- Much better than curved PTFE lips formed on a mandrel. Current Ceimin primary coolant lip is 26.5mm prior to stretching and expanding. Requires tremendous amount of force to ride over shaft chamfer. If the chamfer is damaged (rust etc) and using a SKF speedi-sleeve wth a sharp edge, it is likely these type of seals are damaged on insertion. PTFE is like soft plastic. Just imaging sliding over any sharp edges.

- Tesla's single lip curved PTFE seal has concentric grooves near the contact lips. These become packed with dried silicate from the coolant. Probably a contributor to the sealing deterioration.

- Curved PTFE lip contact pressure is based on the material and shape. Seems rather imprecise but perhaps doesn't matter much.

- Seal is well constructed. Aluminum cage with an o-ring to fit into the bore. Much higher quality material and construction method than curve lip PTFE seals.

- This seal has a much more precise and controlled contact and pressure. The contact surface is about 2mm and slightly smaller diameter on the leading edge before install. This is because everything (spring, seal shape etc) is sized to have a flat contact surface post install. The contact region is at the end of a long PTFE beam providing reasonably amount of flexing to mate the the shaft. Contact pressure is not from PTFE material/curved shape like curved lip seals. It is mostly determined by the garter spring.

- ~$100, contact @muehlpower

I feel this seal offers much more potential of precise pressure and contact region than curved lips. Design also doesn't require any concentric grooves like the Tesla seal to help the lip to bend.

Speedi-Sleeve compatibility?


I believe the seal will land on the speedi sleeve after install (Please carefully check)

If the shaft chamfer is in good condition. Then this seal will not be damaged during install over the chamfer. However, Speedi-sleeve's sharp leading edge might be more concerning. @asavage suggested a coat of nail polish might be sufficient to offer a smooth install over the speedi sleeve.

Just found these on AliExpress:
https://a.aliexpress.com/_EvS09oh

Single, double and tripple lip (CSL, CDL and CTL).

Seller does't seem to have a lot of knowledge. Says that seals are for 5.000 rpm. According to the discription surface speed is 25 m/s (+- 16.000 rpm). He answers in Chinese (automatic translated), so that doesn't make it any easier.

WimV wrote: ↑Thu Jan 26, 2023 8:31 pm Just found these on AliExpress:
https://a.aliexpress.com/_EvS09oh

Single, double and tripple lip (CSL, CDL and CTL).

Seller does't seem to have a lot of knowledge. Says that seals are for 5.000 rpm. According to the discription surface speed is 25 m/s (+- 16.000 rpm). He answers in Chinese (automatic translated), so that doesn't make it any easier.

Thanks for sharing

Fairly typical of most PTFE seals. Really only 2 design parameters (# lips, blended filler to increase longevity while remain softer than shaft)

They did say something interesting on double lip design "The inner lip increase the oil return design. Form pump suction to increase sealing performance" Maybe this provide a clue how dual media facing lip performs better than single? Been wondering what mechanism gives dual lip better performance.

Salesmen and politicians only lie when their lips move.

I received the final proposal from XXX. It should fit the original shaft and also work with the speedy sleeve. I also have prices, depend very much on the quantity purchased, but will be at least €80. Do you think there are enough buyers who are willing to do this?

For estimating purposes, I'd purchase one.

This would be a "for testing purposes"/"guinea pig" use, and I'd be willing to invest <=€180. If it had a proven track record of being more durable than other options, I'd be willing to pay more.

I'm also interested in buying 2 or 3 for testing.

muehlpower wrote: ↑Tue Feb 07, 2023 11:47 am I received the final proposal from GDF. It should fit the original shaft and also work with the speedy sleeve. I also have prices, depend very much on the quantity purchased, but will be at least â�¬80. Do you think there are enough buyers who are willing to do this?
k22_21177_v1-1.jpg

Here is my analysis on selling newly developed seals

Longevity History

#1 problem is no proven longevity history. So how to make longevity history?

Step 1 : Do PTFE rotational seal development testing. This require

• Measuring the rotory shaft's hardness. Duplicating it in bench testing machine.

• Dynamic testing such as rotate at speed, periodically reverse, vary temperature.

• Static testing

• Additional factors such as adding media contaminants

This require investment ($10k?) by manufacturer or distributor.

Step 2 : Install into test vehicles and monitor.

Step1 seems difficult. No one can see near future profit after $10k investment.

Step2 is possible with DIY LDU rebuilders. Custom EVs such as @BoxsterEV is highly valuable with more accessible LDUs compared to the Tesla Model S LDU rebuilders. However, close and precise test monitoring is challenging.

Installation Difficulty

PTFE rotary seal is much more challenging to install properly than elastomer seals (NBR, FKM)

Shaft surface must be prepared with proper roughness (0.2-0.5um Ra). Zero lead? (maybe garter spring reduce zero lead requirement?)

Avoid folding excluder lip is best achieved with stretching sleeve and installation directions. GFD's latest design has no excluder so this shouldn't be an issue for this seal. Maybe Tesla's latest seal also eliminated excluder due to installation difficulty? (I don't know)

Competition

So far, there is 2 alternative seals.

AliExpress Ceimin seal

Western users naturally distrust this seal. It is from China via AliExpress. No way to have any designer contact to gain design skill and experience confidence. This is a common issue working with foreign designers speaking different language. Even GFD have similar issues. However, GFD is a German company so naturally inherits some confidence from historical German design capability

However, I do think its easy to underestimate Ceimin seal. PTFE rotary seal only has 3 design parameters.

#1 is PTFE blend. Need to be as hard as possible (for longevity) but softer than the shaft (avoid shaft damage)
#2 is shape/geometry depending on shaft diameter and coolant manifold seal bore geometry
#3 is how to reduce leakage. I conclude micro structure pumping aid is unavailable (and maybe ineffective after coolant silicate crystallization clogging the structures) so I think the only solution is # of lips. @asavage distrust this kind of design. However, SKF, Parker, Saint-Gobain all show simple 2x media lip + excluder lip PTFE rotary seal designs in their design catalog (not complex ones with leak extracting channels between the lips). Parker design document says these simple multi-lip designs is for submersed/splash applications. Unfortunately I don't have any knowledge without any chance to speak to experienced PTFE rotary seal developer.

I think the knowledge for these 3 design parameters are fairly well known by many PTFE seal makers. Not much proprietary knowledge exist.

Maybe seal material and assembly quality is another factor. But how much quality difference and how much effect on longevity compared to other factors?

Anyway, Johan and I have 2-3k miles without any leak on speed sensor using Ceimin seal on fairly well prepared shaft surface and installation. Of course need more time for longevity data.

Tesla seal

Tesla do not sell this seal at this time (and maybe never?) The current seal installed into Tesla's remanufactured LDUs appears to have very high failure rate. Some people reporting < 2 years.

These seals are not for sale but are installed in Tesla remanufactured LDUs.

How to make longevity history

I guess without $10k investment, its only possible to start with LDU rebuilders. I guess initial quantity 10 for �100 each can probably sell out quickly. However, seal must be installed and used for valuable testing. If just collected and uninstalled, there is no longevity data benefit. But even if just purchased and collected, it helps initial pilot manufacturing quantity and therefore price.

Also seals will only go into new LDU rebuild efforts. Already completed LDU rebuilds are longevity testing other seals (for example, Johan and I are now testing Ceimin) We would only try another seal if/when our Ceimin seals fail.

15-20km data might arrive in 1-2 years. Any failed seal (or removed for inspection) need to be carefully extracted from the manifold and examined in detail.

If 10-20 seals shows no leak in 1-2 years and 10-15km, then longevity data will increase confidence and more LDU rebuilders will use it. Probably professional rebuilders also become interested. They also can not find any source for seal now (Except QC Charge and they will not provide their seal source) Once professional rebuilders start to purchase, volume will increase quickly.

All 2012-2020 RWD Model S, 2015-2020 Performance dual motor Model S and Model X all use LDUs. Probably total of 0.5M LDUs and 20% is no longer under Tesla warranty. Currently probably at least 50-100 LDUs are being replaced daily.

=====

Sorry for the long answer. I have also been thinking how to start distributing a newly designed seal.

Here is the latest version of LDU rebuild kit document. pg 27 shows LDU volume projection. 28 outlines what is necessary in an LDU rebuild kit. Many LDUs will fail after inverter stops working so its highly desirable to prepare replacement inverter harness also.

https://drive.google.com/file/d/1pjLH0i ... sp=sharing

Have an idea on why Tesla's single lip seal has high failure rate. Posting it for thoughts.

How is PTFE Seal Lip Energized

PTFE seal lips are sized smaller than the rotary shaft. In Ceimin's case, the closest lip to coolant is 3.5mm smaller diameter than the 30mm shaft. This size difference AND PTFE material's natural return to original shape is the seal's energized pressure. In Johan's videos, he shows how much pressure this is during a test fitting. Seal's pressure is enough to grab and overcome the inertia to rotate the 70lb rotor on bearings.



An easy way to think about this is to just change the seal lip diameter to 30mm... very obvious that would not seal well at all since there would be zero energized pressure.

Tesla's Single Lip Seal with Concentric Grooves

I learned from talking to a seal manufacturer the concentric grooves are cut into the seal lip to aid bending. Below is diagram from academic paper studying the wear on these types of PTFE seal lip. Note the Tesla seal is slightly different than this diagram (doesn't contain concentric grooves at shaft surface contact section. Just the bending section)
Here are the post with Tesla seal with concentric grooves for reference

viewtopic.php?p=46858#p46858

@Johan and I confirmed both of our seals had concentric grooves.

So what is the effect of these concentric grooves besides helping the seal to bend? Surely, it also naturally reduces the energized pressure. A simple way to think about this is to just imagine cutting the grooves ever deeper. The seal gradually becomes easier to bend and lower the energized pressure.

Furthermore, The PTFE blended material lip have 2 possible additional issues

1. Manufactured with a sintering process (materials original in dust particles and heated to merge together) Sintered material isn't perfect and has microscope voids that act as source points for fractures to start. Now imagine this material with sharply cut concentric grooves, I'd imagine its entirely possible for the cut groove (which is a split in the material) to split ever deeper decreasing energized pressure even further.

2. PTFE blended material is a heterogenous blend. There are natural fracture gaps between the granules (acting like pier posts for additional wear longevity) and virgin PTFE material. These are natural places to further split and lose energized pressure. Here are the microscope pics showing the blended-in granules.

viewtopic.php?p=46618#p46618
viewtopic.php?p=46621#p46621

So I'm guessing this is the failure mechanism of the single lipped Tesla seal with concentric grooves. If true, then it would suggest the following

- Ceimin triple lip seal (or even if it was singled lipped) might do better at keeping energized pressure
- GFD's CNC cut lip seal with spring energizer might do better at keeping energized pressure
- Even PTFE lined NBR seal with spring energizer might do better at keeping energized pressure? (If the NBR substrate can survive the thermal profile)

Anyway, just some ideas to think about.

howardc64 wrote: ↑Tue Feb 07, 2023 10:41 pm Step2 is possible with DIY LDU rebuilders. Custom EVs such as @BoxsterEV is highly valuable with more accessible LDUs compared to the Tesla Model S LDU rebuilders. However, close and precise test monitoring is challenging.

If a goal is to be a provider of a tested-and-guaranteed LDU "reseal kit" or service, then -- maybe -- a USD$10k investment is warranted. For DIY-ers (ie not a repair service or a "reseal kit" reseller), having a seal with some positive track record is sufficient. To achieve that point, some pioneers may have to suffer a few arrows in their backs (if you're not familiar with my tortured version of the aphorism, read here).

DIY-ers will gladly play pioneer, if the alternatives are sufficiently awful . . . or untrustworthy (see below).

howardc64 wrote: ↑Tue Feb 07, 2023 10:41 pm Installation Difficulty

PTFE rotary seal is much more challenging to install properly than elastomer seals (NBR, FKM)

[ . . . ]

GFD's latest design has no excluder so this shouldn't be an issue for this seal.

Installation will be uncomplicated without the excluder, because the direction of shaft install naturally deflects the lip in the normal direction.

howardc64 wrote: ↑Tue Feb 07, 2023 10:41 pm Competition

AliExpress Ceimin seal

Western users naturally distrust this seal. It is from China via AliExpress.

The Ceimin seal might be fine. As more people install them and rack up kms/miles, some people may report success and newer DIY-ers might be more comfortable using them.

But.

A significant problem that I've personally run afoul of is that a "Seal Part No. 123456-01" that you receive today is not the same seal you received three months ago, and this seems to be a problem predominantly with China-(etc)-sources parts. IOW, you cannot trust that a seal you buy today that has the same part No. as a seal someone installed last year, will be the same seal (or made in the same plant, or by workers with the same experience, or same quality controll process, etc.).

That's why I will trust a seal sourced from eg a European mfgr over an eg Asian source: repeatability of results.

howardc64 wrote: ↑Tue Feb 07, 2023 10:41 pm PTFE rotary seal only has 3 design parameters.

#1 is PTFE blend. Need to be as hard as possible (for longevity) but softer than the shaft (avoid shaft damage)

I'm not certain that shaft wear is really an issue. Depending on the compliance of the PTFE material (or its substrate), either the natural seal characteristics, or the garter spring-aided design, may adequately compensate for, say, 0.3mm shaft wear (or sleeve wear).

Put another way, if we assume re-sleeving at every seal change, do we care if the sleeve is worn through completely by the time the seal is due to be replaced?

howardc64 wrote: ↑Tue Feb 07, 2023 10:41 pm #3 is how to reduce leakage. I conclude micro structure pumping aid is unavailable (and maybe ineffective after coolant silicate crystallization clogging the structures) so I think the only solution is # of lips. @asavage distrust this kind of design. However, SKF, Parker, Saint-Gobain all show simple 2x media lip + excluder lip PTFE rotary seal designs in their design catalog . . .

By definition, the excluder lip is not a liquid seal: it excludes particulates and is not expected to seal against liquid, which means the seal's main lip has at least incidental if not total wetting.

In a three-lip design, the "last" lip is deprived of that wetting, so it has to operate at ~10k RPM with only whatever material characteristics it has to prevent it from accelerated wear, and that's what I mistrust: a seal that is both supposed to prevent liquid from getting past it, and also operates dry for some very significant portion of its lifecycle.

There's a reason why you can't run a typical water pump (a type that uses a shaft seal) dry: that quickly destroys the seal. And that's what I see in the triple-lip LDU seal: a seal that runs dry (or, perhaps, with some installation "lubricant") until the main/middle lip leaks, and then that last lip is expected to be a backstop seal? Yeah, I mistrust it.

But I am not any kind of a seal engineer; I've merely had to deal with a lot of failed seals in my life (and I did work in an Engineering department in the 90's, though not as an Engineer).

howardc64 wrote: ↑Tue Feb 07, 2023 10:41 pm How to make longevity history

I guess without $10k investment, its only possible to start with LDU rebuilders. I guess initial quantity 10 for €100 each can probably sell out quickly. However, seal must be installed and used for valuable testing. If just collected and uninstalled, there is no longevity data benefit. But even if just purchased and collected, it helps initial pilot manufacturing quantity and therefore price.

Agreed. I will be in that camp: buying now to aid in getting some into hands at a more-reasonable group-buy-like price, but not installing until I have to, which might be next week or four years hence.

howardc64 wrote: ↑Tue Feb 07, 2023 10:41 pm 15-20km data might arrive in 1-2 years. Any failed seal (or removed for inspection) need to be carefully extracted from the manifold and examined in detail.

Let's not forget that some seals seem to fail when the LDU is not being exercised. Data from infrequent drivers will be just as valuable as raw kms/miles driven on a seal.

asavage wrote: ↑Wed Feb 08, 2023 2:26 am Installation will be uncomplicated without the excluder, because the direction of shaft install naturally deflects the lip in the normal direction.

Actually one more installation challenge I have been thinking of is related to repaired shafts including speedi-sleeve or other methods.

If the seal lip energized pressure is based on the PTFE material alone (see my post above on why Tesla PTFE seal failed ( viewtopic.php?p=52614#p52614 ) with a much smaller than shaft diameter to maintain pressure, these lip will face the challenge of getting micro-cuts on installation over repaired surfaces containing any tiny shape edges. This micro-cut would basically become a direct leak channel during static operation and probably also in dynamic operation as well. This is very different than elastomer seals with the material compress and decompress easily to minimize these imperfections.

A less tight diameter seal such as GFD + energized spring might suffer less. But I think same issue still applies.

Anyway, the chamfered bevel on the shaft where the PTFE lip will have to forcibly slide over has to be smooth to not micro scratch the seal on install. Similar to any bevel/chamfered edge on the speedi-sleeve.

Ceimin yellow seal 2k mile report

Speed sensor is "dry". However with shining different angles of light, can see the tiniest amount of moisture around the bottom of the o-ring. Not enough to even show on picture. I applied a very light coat of silicon lubricant around the o-ring on initial install so could be that. Or it could be the tiniest trace of coolant but no droplets on the sensor body. Saw the samething during last speed sensor pull ~1k mile after install.

Academic papers and seal manufacturers say all seals leak. The key is the acceptable leak rate. Perhaps any seal we put in will leak at some rate. Anyway, Ceimin seal at 2k miles has no coolant drops on speed sensor.

I did find 2 small thin patches stuck on the speed sensor. Scraped it off with finger nail (doesn't wipe off). Here are microscope pics. Ruler grids are 0.5mm.
Wondering what this could be

• PTFE materials breaking off? But the PTFE material is tan colored so unless it got cooked...

• Bearing grease. Don't think bearing grease can form a solid structure. This patch couldn't be wiped off, it had to be scraped off

• Bearing seal rubber coating? SKF ceramic bearing seals are non contacting (don't touch the balls) Kind of hard to imagine these rubberized coating would have come off

• RTV leftover that sealed the coolant manifold. This is probably the most likely candidate. Maybe its not an issue but most likely whatever broke loose got flung by the shaft/reluctor wheel. I didn't put on too much RTV around the reluctor chamber during assembly since it only sealed against air. But had to smear it on a little with finger. Perhaps this is something to consider for proper installation : How much RTV to put around reluctor chamber mating surface to the coolant manifold? The only coolant passage is around the o-ring on the bottom of the manifold far away from this chamber mating face. Perhaps this argues for the very lightest bead/coating of RTV

I've seen many pulled speed sensor pics shows some residue on it. But picture usually blurry (black sensor) and no descriptions on the residue.

howardc64 wrote: ↑Thu Feb 09, 2023 2:28 am
Academic papers and seal manufacturers say all seals leak. The key is the acceptable leak rate. Perhaps any seal we put in will leak at some rate. Anyway, Ceimin seal at 2k miles has no coolant drops on speed sensor.

This is key:

At some point any rotary seal will leak.
There are no rotary seals in any ICE I can think of where if the seal leaks if causes total engine failure.

In my humble any LDU seal fix needs to incorporate seal leakage mitigation - so when it leaks again the coolant is safely diverted away from the electronics into a catch can or back into the cooling system.

On an side note - but related to LDU: a work friend recently had his LDU replaced (Model S P85D - I think 2016my?) - luckily under warranty (the garage who sold him the car covered it!) - Tesla said it was due to water ingress - apparently from the large power cable's insulation/seal braking down and allowing water in the inverter. Something else to ensure is well sealed and the cable's are in good condition.

I agree 100% with SuperV8. I would definitely drill a drain hole, on the one hand to notice a leak and on the other hand to prevent major damage. One of my motors also had water ingress on the inverter side, clearly due to corrosion on the data connector.

SuperV8 wrote: ↑Thu Feb 09, 2023 9:10 am This is key:

At some point any rotary seal will leak.
There are no rotary seals in any ICE I can think of where if the seal leaks if causes total engine failure.

In my humble any LDU seal fix needs to incorporate seal leakage mitigation - so when it leaks again the coolant is safely diverted away from the electronics into a catch can or back into the cooling system.

Drilling weep hole without removing LDU

Here is an interesting update of an LDU that had low stator isolation. Owner drilled a hole on the end plate, suctioned out the sitting coolant and eventually dried it without LDU removal haha. He also just tapped a weep hole with LDU in car carefully drilling, added water in the reluctor chamber to limit any drill debris etc... Quite interesting. Perhaps this pioneers a technique to do in car drain mods on LDUs that hasn't leaked. Note his posts cross 2 different threads

https://teslamotorsclub.com/tmc/posts/7371745/
https://teslamotorsclub.com/tmc/posts/7405590/

I posted this diagram showing him possible drilling solutions. I guess the natural access angle on the stator endplate results on solution A

https://teslamotorsclub.com/tmc/attachm ... ng.898918/

I think this provides initial proof that its doable. With more technique and tooling refinement (and with a removed LDU to do post drilling inspection for debris and landing spot), this probably can mature into a useful solution for those LDUs that hasn't leaked.

Furthermore, speed sensor vent hole can be sealed also with LDU not removed.

These 2 steps would be the biggest modifications to mitigate LDU leak collateral damage. Looks like we are getting close to reaching a solution with LDU mod while mounted in car.

SuperV8 wrote: ↑Thu Feb 09, 2023 9:10 am On an side note - but related to LDU: a work friend recently had his LDU replaced (Model S P85D - I think 2016my?) - luckily under warranty (the garage who sold him the car covered it!) - Tesla said it was due to water ingress - apparently from the large power cable's insulation/seal braking down and allowing water in the inverter. Something else to ensure is well sealed and the cable's are in good condition.

HV cable seal leak

Here is an example of how bad these can get

https://teslamotorsclub.com/tmc/posts/7339499/

Mine looked fine but the design causes natural moisture pooling and attack the cable seal with gravity. To mitigate this, probably need a custom designed boot to seal around the cable to avoid any moisture pooling on top of cable seal.

https://teslamotorsclub.com/tmc/posts/7340120/

Excluder Lip Desirable?

With finding the likely RTV debris on my speed sensor and many speed sensor pictures showing variety of debris (bearing grease? and maybe also RTV?) It seems excluder lip maybe desirable. Maybe this is another potential failure point of Tesla's single media lip seal? Here is a pic of another speed sensor showing grease but no coolant

https://teslamotorsclub.com/tmc/posts/7085069/

SKF's FKM seal's excluder lip looks just slightly larger than 30mm so it should be non contacting or barely contacting the rotary shaft. Here is screen capture from SKF FKM 30x55x7 HMSA10 V's CAD image tab
https://www.skf.com/us/products/industr ... HMSA10%20V

Measured a 30x55x10mm Athena Honda PTFE lined seal with excluder lip. The NBR excluder lip looked to be ~29.5mm so slight contact. Pic shows ~29mm but maybe just camera optics+lighting. Close up inspection with binocular magnifier shows ~29.5mm
Ceimin's excluder lip is 28mm (primary coolant lip is 26.5mm) so its less tension against the rotary shaft. And or course its PTFE high temp tolerance material.

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

I don't know the proper PTFE excluder sizing in relation to shaft diameter. Ceimin seals shows lathe cut marks only on the inside of the primary coolant lip and not the other 5 PTFE lip surfaces so perhaps its mandrel formed. Parker's PTFE document below briefly notes both mandrel and machined primary media lip

https://discover.parker.com/LP=21168?el ... ampaignId=

Installation Challenge

Proper excluder installation is a challenge. Mainly because its a relatively blind install and need to avoid crimping the lip if much smaller than the shaft. Ceimin seal's excluder lip require stretching shortly before install. GFD's earlier excluder design could be trickier.

viewtopic.php?p=51598#p51598

The cross section profile shows a long excluder leg which will likely return to form quickly even after stretching. So probably want to avoid making the excluder diameter too much smaller than 30mm dia. shaft.