Quote:
Originally Posted by trader4
I recently replaced the chain on my TC and was looking at sources for
the chain, seals, bearings, etc. I didn't need the part you're talking
about, but I did see that there were not many sources for TC parts
other than the chain, seals, plugs. And I spent a lot of time looking
at what was out there. I too only saw what you're looking
for at Cobra.
The TC case here had 160K miles and the splines, while rusted,
were fine. I think you're assuming that if the shaft splines go, then
the female end on the TC will also be shot. In doing my TC research,
it looked like that definitely happens in some cases, but I'm not
sure it happens in all cases. I agree that they would be suspect
and certainly should be inspected, but I personally would not be
on the costly and difficult repair path without inspecting them.
With it as is, from what I see, the worst you have to lose is the
car becoming disabled again because the splines on the shaft are
shot again and the TC side is too. But then from a repair point,
you're where you are now. You'd need the $400 TC part. And
you'd cut off the fouled spline end of the shaft and replace it
with the longer aftermarket part like you intend to do now.
Another data point is the BMW dealer did what they did. If
they had experience that says the repair is going to fail in
a short time, taking the new shaft with it, then I would think
they would have told your buddy that it needed not only the
shaft, but also the TC replaced too. BMW is certainly not shy
about handing out big repair bills.....
IDK how many miles your car got before the splines went, but
if it's typical high miles, I think you have to wonder if it's worth
it doing the extended shaft thing at all. In my searching, I came
across people talking about the issue and there were people
reporting that the new extended splines failed in only a year
or two. I also saw someone who had been selling them stop
selling them for that reason. Again, I didn't look into it that
extensively, because it wasn't my issue. Those people who
had failures may have been using the original TC female end.
On the other hand, it would seem the extension seats about
twice as far into the TC, so the ends of the new splines should
be about as far into the unused part of the TC female end as
the original shaft was. So, those early failures with the extension
are a mystery to me.
Back to the parts, this is what I found for parts for the NV125,
not sure which TC is on your car:
Chain - Multiple sources, including Cobra and Ebay. They
all seem to be Borg Warner
Seals - Multiple sources, FCPEuro, other typical BMW vendors, and BMW
Sealant - I used Permatex automatic transmission rtv sealant
Fluid - Dexron ATF
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Some people may get away fine with the original output gear in the t-case if they have a failure. However, when you strip the splines off of the drive shaft, the splines remaining in the t-case *are* going to experience increased wear (along with the wear from the rusting that seems to contribute to the initial failure). To what extent? Like snowflakes--no two are going to be exactly the same.
What I *DO* know is that if you sample 100 people with this failure that just replace the drive shaft, and only two of them have an issue with the output gear splines failing and taking out the new shaft--I will be one of those people.
I admire your outlook on BMW's processes at the dealer level, however, having a background where I've worked with many dealers and with a few manufacturer's (on top of reading about other people's BMW dealer experiences), assuming that they're going to do the best procedure in every instance like this is not something I can get on board with.
They (like every dealer) weigh and balance profits on repairs, and getting the job. I can assure you that some (not all, as there are some really good service writers and techs out there) would happily sell a new shaft at full list that they can install quicker than book time as opposed to hard-selling someone the higher cost fix. If it fails? "Well, it looks like you needed a new transfer case too, but we have no way of knowing that for any certainty" (which if the splines don't look too visually damaged--they don't). It's a lot easier to sell a profitable, quick job, than it is to sell a job that will equal 1/2 to 3/4 of the vehicle's overall value.
I have yet to get the car transported and up on a lift, so I can't say for certain at this point, but it seems as though this car/situation is a supporting case for this. The shaft was replaced about a year and 4,000 miles ago.
While you seem to be correct in what you're saying about the new shaft seating into the formerly unused splines just as far as the original did from what I've read thus far, that's another point--there is a seemingly high failure rate with said amount of engagement. While rust is certainly a contributing factor, the load to engagement area is less than ideal. I'd prefer to start out with that extra engagement area from the start as opposed to getting back to the limited amount from the factory.
I appreciate your logic with the aspect of "giving a try" with the longer splines. It does stand to reason. I would just prefer to try to repair the system as completely as I can and (hopefully) not have to worry about it again. At $400 extra, the output shaft does make me pause and examine the situation, I'd certainly rather not spend the money unnecessarily, however with the aspect of having the t-case out, on the bench, and torn down making the gear replacement cost me an extra 15 minutes time vs. an additional 6-8 hours to do the job over again, I'm leaning towards just buying it from Cobra if I can't find it elsewhere cheaper.
I think I'm just remembering my friend's 540 that I had to put a used transmission in (auto, GM tranny) and found that the replacement he had purchased was bad. The 2nd time around it only took me about 2-2.5 hours, but I was still hating life at the time. ;-)
Josh