Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

[howardc64]

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[mrhyde]

Hello everyone! I’ve been lurking for a while and am the owner of the LDU Howard posted speed sensor pics of in the previous post. The car is a 2014 P85d with 67,000 or so miles on it. The tag confirms this is the original LDU and I am thrilled that it looks like I have a unicorn unit produced with the better early seals but likely with ceramic bearings. Howard rode in my car and confirmed it is fairly quiet. My hearing isn’t good and this is my first Tesla so I don’t have the experience/perspective to have an opinion on how it sounds. I’m thrilled the original owner didn’t give Tesla a reason to swap this out for a remanufactured unit!

At any rate, thank you for the great work here. I look forward to following along and contribution whenever I can.

[jrbe]

Oil testing companies might be able to test a sample of the grease and tell you what it is, how it's doing, contaminants, etc.
Cost + time it probably makes sense having an oil analysis company identify it.

The diy route:
Looks like normal Super Lube grease is glycol & ptfe friendly and should be readily available.

PAG greases might also work from a quick search.

I found golden syrup as an option too. A bit odd..

Might be worth narrowing it down to a few different greases that are compatible with both glycol and Teflon to buy. Then do a sniff / finger slip / tacky comparison vs what's in an original greased LDU. Might be able to match the original grease that way.

Can also mix some g48 with the different greases, heat them to almost boiling (maybe a few times) stir them around and see how they do. Freezing the 2 mixed might be a good test as well.

[howardc64]

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[howardc64]

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[howardc64]

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[howardc64]

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[jrbe]

I thought you may have used a linty rag to clean it from a previous pic you posted, that's disappointing. I think you'd be better off with an undersized seal area vs. how porous / rough the repair ended up.

Most plating options will tell you to get the surface as smooth as the desired Finnish before plating. Might make sense to clean it up then get some thick plating over it to bring it back up to seal spec OD. (Skip the metal flame spray) I'm not sure what plating would be ideal for the seal.

Plasma spray deposition could end up a cleaner surface finish if you want to stay on a similar path. Probably could see some repairs that were done to see if it's worth pursuing.

You could passivate the seal area / end to help keep corrosion away.

[howardc64]

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[Boxster EV]

@Boxster EV is is at 15k miles on this solution with a SKF FKM seal.

Yes, with this seal (to be used with Speedi sleeve).

SKF CR30x55x7HMS5V Single Lip Viton Rubber Rotary Shaft

[howardc64]

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[howardc64]

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[jrbe]

I find it very hard to believe that Tesla would go through all the trouble of getting coolant in there if it didn't matter, especially with all the warranties and failures they have had with these.
My assumption is the bypass coolant manifold isn't available because of what is very likely to happen without rotor cooling. It might work for light use but the magnets will likely overheat and lose strength without cooling.

Many shops / people do the wrong thing with good intentions trying to solve a problem, share the fix without long term data, and don't follow up with the unintended consequences of that choice if it goes sideways.

If someone wants to try a coolant bypass, I'd be really interested in how it works out long term.

Installing an ir temp sensor pointed at the magnet area would be a good idea to keep an eye on them. Or some temp indicating paint on the rotor to see how hot it got at the failure point.

[muehlpower]

At least you don't have to worry about the magnets with the LDU. It does not have any.

[howardc64]

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[Antti84]

I have a Tesla Model S2014 Rear wheel drive LDU renovation ongoing. I just replaced the bearings and noticed that the rotor shaft is is very worn out by the seal so the shaft is uneven. I tried with speedi sleeve but it did not work- it still leaked.
Therefore I have machined the shaft end to be good and then i have done the hard chrome treatment on the shaft.
I will then have to machine the shaft into right measurement before installing the ring for the vehicle speed sensor ring and the chenmin 3 lip PTFE Seal.

Question:what is the exact tolerances for the shaft end.It should be 30mm but does someone have the exact tolerances?
The vehicle speed sensor ring was 30,2mm in diameter.

Ptfe seal requires Ra value of 0,4. Is this true?

Thanks in advance!

[howardc64]

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[howardc64]

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[howardc64]

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[muehlpower]

Moodifying an existing manifold should be easy. The tube is difficult to press out, but shortening it up to the retaining ring should work. Then you only need a cover in place of the sealing ring that leaves enough space for the shaft and has a gap to the shortened tube. If the gap becomes too small, a hole can be drilled into the duct below the pipe. I could imagine that omitting the rotor cooling works for lightly loaded engines, but I don't want it for my sport unit!

Plug.png (9.67 KiB) Viewed 13193 times

[howardc64]

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[asavage]

If the coolant circuit through the 4.5mm hole just blend with the much higher volume out of stator inside the gearbox casing, then maybe this small circuit is unnecessary.

It's a reasonable guess that the purpose of that external tube is for air bleeding the circuit (connects to high point of the LDU, moves trapped gasses on), and that it doesn't contribute substantially to thermal transfer.

[muehlpower]

There is no reason to run anything externally. The water comes from below, flows around the cover and exits at the top as before. Only the space for the gap could become tight, so it makes sense to drill a hole in the channel. The hole would then be where the word "seal" is in your picture.

[howardc64]

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[muehlpower]

In case anyone has the idea of removing the pipe. I have tried it. It seems to be pressed in and secured with Loctite 271 (high-strength). I welded mine at the end to get it tight, as the bore was very damaged.