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I'm not crazy, the attack has begun.
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No, I hadn't missed Donald's point, I just said, I'd never experienced any problems with new or used cars.
I'd say that fits in with my 1 in 1000 events, then?

I'd also say that it is not worth changing the oil if you have a deep pocket and like gambles;-
Probability of failure; 1:1000 (say)
Cost of oil change; £50 (say)
Tipping point of gearbox price where it is worth while; £50,000

Ergo, cheaper to not do it.

However, that is of no consoluation whatsoever if you suffer from this, and also it would be my proper advice that in any case, this DOES lead to a reduced box life over 100k miles, so it is not worth doing if;
a) it's not your car
b) you are happy with a gamble and don't plan on keeping the car beyond 6~8 years
c) you are happy if your car fails at 100k miles

If any of those apply, forget my advice, I am needlessly worrying you and gearbox failures never happen....

.... oh, hang on .... :unsure:
 

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@donald - do you think that putting in a one-way oil filter into an EV gearbox would be a positive step? It would presumably help catch any swarf as well as filter out the stuff that remains in suspension. Since oil quality and lifetime aren't the issue here then it would seem sensible?
 

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@donald - do you think that putting in a one-way oil filter into an EV gearbox would be a positive step? It would presumably help catch any swarf as well as filter out the stuff that remains in suspension. Since oil quality and lifetime aren't the issue here then it would seem sensible?
How would a one way filter help in a splash lubed gearbox like the Leaf's?🙄
 

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How would a one way filter help in a splash lubed gearbox like the Leaf's?🙄

Be about as useful as a chocolate teapot!

Given that we have decades of experience that shows that simple measures, like magnetic plugs, keep splash lubed gearbox oil pretty free from harmful debris, there seems to be no reason for more complex solutions.
 

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Discussion Starter · #205 ·
After a long day in the searing heat I now have the driveshafts out (lower ball joints were pretty stubborn!) so not far off being able to drop the gearbox, just a few brackets and cable guides to remove.

147438


Unfortunately the new driveshaft seals won’t arrive until Monday so I’m wondering whether to do the swap anyway and fit the seals in-situ when they arrive before the driveshafts go back in or just take a break until the seals arrive and I have everything needed to finish the job.

Driveshafts seem in good condition - joints, splines and intermediate bearing all seem fine and the mating surface on the CV joint that presses into the hub is free of rust as are the mating surfaces of the hub.
 

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After a long day in the searing heat I now have the driveshafts out (lower ball joints were pretty stubborn!) so not far off being able to drop the gearbox.

View attachment 147438

Unfortunately the new driveshaft seals won’t arrive until Monday so I’m wondering whether to do the swap anyway and fit the seals in-situ when they arrive before the driveshafts go back in or just take a break until the seals arrive and I have everything needed to finish the job.
Take a break and take stock. The end is in sight and hopefully an end to your bad luck too.
 

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I agree with @farmergiles , having got this far and pretty much pinned down the fact that the gearbox is definitely shot, it seems to make sense to fit the new seals before refitting the box. It's got to be easier to do this with the box on the bench than back in the car, I'd have thought.

PS: Completely off topic, but as typing the above I remembered that we went to see an old Oxfordshire cart last year that had been built for my great, great, great, great, great uncle, who was a farmer called Giles Harris, so he really was a "Farmer Giles".
 

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PS: Completely off topic, but as typing the above I remembered that we went to see an old Oxfordshire cart last year that had been built for my great, great, great, great, great uncle, who was a farmer called Giles Harris, so he really was a "Farmer Giles".
Unlike me who is not a farmer, nor called Giles ! (I do live on a farm though and with the hot dry weather, the Leaf gets very dusty inside and out)
 

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Unlike me who is not a farmer, nor called Giles ! (I do live on a farm though and with the hot dry weather, the Leaf gets very dusty inside and out)
147439
147440


My family were still farming near there until about 30 years ago. My mother was farming until she died three years ago, but down in Cornwall.

Anyway, enough of this diversion off the topic!
 

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Discussion Starter · #210 ·
Take a break and take stock. The end is in sight and hopefully an end to your bad luck too.
Could be a longer break than I thought - I just realised that the left and right side oil seals are two different sizes and I had not noticed this when ordering, (I bought two of the same size) so I've had to place another order for the seal for the other side which means additional delay. A bit of a stupid mistake on my part. Hopefully will still get them later next week though.
 

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Wow that box is toast. Looks like A piece of a gear. Be interesting to open it up and see what has actually happened.
 

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@donald - do you think that putting in a one-way oil filter into an EV gearbox would be a positive step? It would presumably help catch any swarf as well as filter out the stuff that remains in suspension. Since oil quality and lifetime aren't the issue here then it would seem sensible?
Yes, if you like, but again it is a question of cost. Fit one for £50 to save a 1:1000 event that costs £3k to fix?

Oil filters on gearboxes is not remotely uncommon, a very normal thing in some applications. You might recall, not seen one for a long time, but there was one particular design of rear truck axle, I think it was Foden, which was easily seen when you drove behind one, and the central diff had this large cylindrical protrusion, this was a filter (just for the differential).

Really, this is 'normally' about longevity and not early life failures as has been regrettably suffered here, but is part of the same problem. An early oil change or two, and then another every ~100k miles will see an effective unlimited lifespan of the gearbox. Do nothing and your 'box (and differentials, if separate) will last as long as the manufacturers want it to last, PLUS you are more likely to suffer an early life failure.

You are more likely to get away with never seeing any problems at all. Here's to good luck and those that benefit from it. Meanwhile..... I hope the OP has managed a good repair for himself at modest cost.
 

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I'd also say that it is not worth changing the oil if you have a deep pocket and like gambles;-
Probability of failure; 1:1000 (say)
Cost of oil change; £50 (say)
Tipping point of gearbox price where it is worth while; £50,000

Ergo, cheaper to not do it.
The cost price to VAG from Quaife for a Bugatti Veryon gearbox was £100k in 2014 so clearly it is worth doing in some cases. You also need to factor in the cost of replacement which is a lot of labour as Simon is finding out. However, as production EVs (with the exception of the Taycan Turbo front axle) are really only final drives/differentials your point is extremely valid.
 

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Yes, if you like, but again it is a question of cost. Fit one for £50 to save a 1:1000 event that costs £3k to fix?

Oil filters on gearboxes is not remotely uncommon, a very normal thing in some applications. You might recall, not seen one for a long time, but there was one particular design of rear truck axle, I think it was Foden, which was easily seen when you drove behind one, and the central diff had this large cylindrical protrusion, this was a filter (just for the differential).

Really, this is 'normally' about longevity and not early life failures as has been regrettably suffered here, but is part of the same problem. An early oil change or two, and then another every ~100k miles will see an effective unlimited lifespan of the gearbox. Do nothing and your 'box (and differentials, if separate) will last as long as the manufacturers want it to last, PLUS you are more likely to suffer an early life failure.

You are more likely to get away with never seeing any problems at all. Here's to good luck and those that benefit from it. Meanwhile..... I hope the OP has managed a good repair for himself at modest cost.
Missing the point????

A filter would require a pressurised lube system, splash nah.
 

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Missing the point????

A filter would require a pressurised lube system, splash nah.
It would require the oil to be pushed through a filter, yes.

After the filter it can be put back into a splash sump or better some benefit to be pumped to top of box and released there.

Small pump, small flow, little pressure, but filtered.
 

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Part of the reason why the box oil gets dirty is because cutting a perfect 3D non-sliding gear shape is virtually impossible. Very good yes, but perfect, never.

As a result, when a box is first used, the various 'most sliding' parts of the gears will work away at each other and literally smooth each other off.

I'm not talking chunks, but super fine dust removing a dimensionally unmeasurable amount of material, the particle size of which means they stay in oil suspension rather than find the magnet appealing.

The particulate content can then be high or low depending on the quality and accuracy of the gear cut that day.

No cutting tool is free from any wear, so of course each gear cut comes out very slightly different. If you get a gearbox cut from tools right at the start or end of their life, then the geometry will be less accurate than it could be.

As a result the gear faces will slip slightly as they mesh and rotate.

The point of the gear involute geometry is that it is the only shape for which two rotating parts can engage and roll without slipping. There is only one such geometry. Now add in a need for clearance and backlash and there will always be some slip on the gear teeth surfaces, some 'boxes more so than others.

Gears will tend to reshape each other by this wear/slide process in the first few thousand miles, then settle down to a long and quiet life. Get rid of the junk that process creates early on and enjoy a long lived gearbox.
 

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Discussion Starter · #217 ·
Interesting speculation posited in discussion on another forum about the cause of this fault suggesting that "one of the bolts holding the final gear to the differential cage coming loose and it has been hitting the gear on the intermediate shaft, gradually knocking chunks off of the bolt head"

So the metal fragments could be chunks off a bolt coming loose in the differential which has been hitting one of the gears. Seems as plausible as any other theory? Bolt not torqued enough at the factory and eventually came loose until it started hitting a moving part ?

Only one way to find out...
 

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Interesting speculation posited in discussion on another forum about the cause of this fault suggesting that "one of the bolts holding the final gear to the differential cage coming loose and it has been hitting the gear on the intermediate shaft, gradually knocking chunks off of the bolt head"

So the metal fragments could be chunks off a bolt coming loose in the differential which has been hitting one of the gears. Seems as plausible as any other theory? Bolt not torqued enough at the factory and eventually came loose until it started hitting a moving part ?

Only one way to find out...
That's about the most plausible explanation so far!

Now if you split the old box and find evidence of this, what checks would you perform on the replacement????
 

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Discussion Starter · #219 ·
That's about the most plausible explanation so far!
One of these bolts I think is meant:

147469


If it was loose it would hit on the intermediate gear once per revolution but potentially only when the slack on the helical gears were taken up in one direction.
Now if you split the old box and find evidence of this, what checks would you perform on the replacement????
I'm not sure that I want to split the replacement box open and mess around with it - not sure what's required to reassemble and seal it...and I might do more harm than good. Chances of the replacement having the same fault are very slim I think.
 

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One of these bolts I think is meant:

View attachment 147469

If it was loose it would hit on the intermediate gear once per revolution but potentially only when the slack on the helical gears were taken up in one direction.

I'm not sure that I want to split the replacement box open and mess around with it - not sure what's required to reassemble and seal it...and I might do more harm than good. Chances of the replacement having the same fault are very slim I think.
Well it's a balance of risks to be sure...

Any chance of poking in a boroscope in through the filler plug hole, would in be in the correct area?
 
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