Transfer Case Blues

[drtwofish]

On a whim I decided to do the jack test today, even though I was sure my TC was working properly - the car grips great on even snowy hills, so I figured it would just be a little feather in its cap. Unfortunately, you can guess how this turned out:



And, just for fun and since I'd never seen anyone do it before, I jacked up the front:



So, it appears that's that, though I still don't quite understand how it routes power through the TC to the wheels that have the least traction. Time to start buffing up on the multi-page TC threads. From an hour or so of reading, though, it looks like I have a few options, none of which are very appealing:

1) Try to score a used TC. These seem to run $500-$800 and, since they can't be bench tested, appear to be a crapshoot.
2) Try to rebuild it myself. This appears to involve tracking down close to a grand in parts and looks to be quite a complex job. Whee.
3) Buy a rebuilt one for $2k - not a chance, unfortunately.
4) Profit?

I guess I don't really have any questions, but this wasn't how I wanted to finish my week. Advice is welcome from those of you who've been there. I guess for now I'll drive as-is, though it sucks to know the car's not right where it counts, and keep my eyes open for a reputable person selling a TC fresh out of a verified car. Have a good weekend, ya'll.

[canadiankid]

Maybe get one from a wreckers?
Car-part.com It really is a crapshoot though you're right.

Does it affect the car if you continue driving with a bad vc or is essentially a rwd car with 2 extra axles that just spin with no power?

[drtwofish]

There are threads that explain this in more depth than I understand, but it seems that the power gets routed to the wheels with less traction, with the TC acting as an open differential. Hence when I jacked up the back the rear wheels spun, and vice versa with the front. From what I've read (and have felt) it's not that big a deal when driving in the dry (and it worked ok in the snow), but apparently I've never driven with a proper TC since I just got the car late last year. Like I said, I honestly thought mine was working properly!

The problem with wrecking yards, as I understand it, is that there's no way to bench-test a TC before you install it. Too risky a gamble for me, unfortunately. Thanks though!

[z122643]

Have you checked the fluid level in your TC? First thing I would do before going to defcon(1) is drain and refill the TC. Then drive it around a bit to allow for the new fluid to lube the coupler. Then repeat the jack test.

Depending on your mechanical skill, replacing the coupler inside the TC is more bark than bite. The only scary bit about rebuilding TC's is the apparent lack of a manual. But there are two DIY's that I know of that are idiot proof and were very well done.

BEWARE salvage TC's. Do not trust them.

If the coupler has indeed gone bad, I would rebuild it myself. Usually all you need is a new coupler which is ~$700 for a brand new one. Trust me I would get a new one rather than kick myself later when the "professional serviced" coupler doesn't work.

[drtwofish]

Have you checked the fluid level in your TC? First thing I would do before going to defcon(1) is drain and refill the TC. Then drive it around a bit to allow for the new fluid to lube the coupler. Then repeat the jack test.

Ah, unfortunately I just changed it a month ago using the proper spec vegetable oil. (Kidding, I used Redline D4 ATF, which I thought was the correct stuff - was I wrong?) The PO supposedly changed it 10k miles previous, but I'm particular about doing these things myself.

Depending on your mechanical skill, replacing the coupler inside the TC is more bark than bite. The only scary bit about rebuilding TC's is the apparent lack of a manual. But there are two DIY's that I know of that are idiot proof and were very well done.

I know my way around tools, but am not sure if I'm up to this level or not (suppose you never know until you try). I found one 11-page thread on e30tech, but I'd be much obliged if you were to send me the ones you've found. I'll keep using that fancy search button though.

BEWARE salvage TC's. Do not trust them.

If the coupler has indeed gone bad, I would rebuild it myself. Usually all you need is a new coupler which is ~$700 for a brand new one. Trust me I would get a new one rather than kick myself later when the "professional serviced" coupler doesn't work.

I appreciate the advice and am leaning in that direction now. I found one at getBMWparts.com for $635, which is in the range of a used TC of unknown quality. Thanks for your post!

[z122643]

The E30Tech page is a good one I also have the BMW manual for servicing the TC. However when I serviced my TC I found that the manual didn't make sense just by itself. I used the E30Tech page and the manual in conjunction and that worked out great. There is a finish page, which is unfortunately in Finish but has a ton of pictures.

http://juubi.hlan.net/index.php?page=car/325ix/transfercase

The first TC I worked on need a new chain, front output shaft, and a coupler. it took me about 2 days to stubble through it. The second one I did just needed a new coupler and it took me about 3 hours minus beer break.

So Bavarian Autosport also base the coupler for ~$700. The nice thing about Bavarian is that the parts are new and they guarantee the parts.

[Chruby99]

The VC is a sealed unit. Your oil in the transfer case is for the chain. The VC must be wasted. If your case ran dry on the oil it would probably start getting really loud. You need a VC out of either a auto or manual case.

[drtwofish]

The E30Tech page is a good one I also have the BMW manual for servicing the TC. However when I serviced my TC I found that the manual didn't make sense just by itself. I used the E30Tech page and the manual in conjunction and that worked out great. There is a finish page, which is unfortunately in Finish but has a ton of pictures.

http://juubi.hlan.net/index.php?page=car/325ix/transfercase

Thanks for the info!

[canadiankid]

Heres an interesting question. If someone realized their transfer case was pooped, and didnt want to rebuild it, could they not pull the awd to regain the lost hp. I know I am treading in heresy territory here. What is actually required?

From what I can tell:
Pull front axles, driveshaft, transfer case and front diff(sell)
Buy i/is rear driveshaft(with money from previous sale).
Install from transmission to back diff.
Buy i/is oilpan and install?(not sure if this is necessary)
And front hubs?(Would you need to do anything to them?)

From what I can tell, you would actually come out ahead $ wise, you hp lost in the t-case and you never worry about cv axles again. You wouldn't lose any car value either because I don't think an ix with non operational awd is worth any more than a is. Only issue that is left over is your shock inserts cost a little more.

Flame suit on.

FWIW I am not going to do this as I just dug up a gravel road this morning with my ix all four tires spinning, but if my t-case pooped out on me I would definately consider this option.

[drtwofish]

Heres an interesting question. If someone realized their transfer case was pooped, and didnt want to rebuild it, could they not pull the awd to regain the lost hp. I know I am treading in heresy territory here. What is actually required?

Interesting post. I suspect you would end up with something worth substantially less than an 'i' or 'is', simply because the front end is entirely different and not set up to have proper handling balance with RWD. I think you'd end up with a bastard car with the worst of both worlds. Someone should try it and report back though :-D

Also, fwiw, the AWD *does* work with a blown viscous coupling; when I jacked up the front of the car the front wheels still spun. It just doesn't route torque properly, but I suspect that only matters when the wheels are on surfaces of differential traction. In all-over-slick conditions (like the snow last winter), the power has to go *somewhere*, so I think all 4 wheels ended up gripping anyway. At least, it scrambled up a snowy hill better than my 530i with snow tires did!

[nando]

Heres an interesting question. If someone realized their transfer case was pooped, and didnt want to rebuild it, could they not pull the awd to regain the lost hp. I know I am treading in heresy territory here. What is actually required?

From what I can tell:
Pull front axles, driveshaft, transfer case and front diff(sell)
Buy i/is rear driveshaft(with money from previous sale).
Install from transmission to back diff.
Buy i/is oilpan and install?(not sure if this is necessary)
And front hubs?(Would you need to do anything to them?)

From what I can tell, you would actually come out ahead $ wise, you hp lost in the t-case and you never worry about cv axles again. You wouldn't lose any car value either because I don't think an ix with non operational awd is worth any more than a is. Only issue that is left over is your shock inserts cost a little more.

Flame suit on.

FWIW I am not going to do this as I just dug up a gravel road this morning with my ix all four tires spinning, but if my t-case pooped out on me I would definately consider this option.

it would work but the car is going to handle like crap. it would be better to sell it and buy a RWD car.

what's the point of an AWD car that doesn't have AWD? also, with a bad VC, it's still AWD.

an ix with a bad VC is worth less than an is or a working ix. an ix that's been gutted to remove all the AWD components, is a parts car..

[Kershaw]

^ this.

[audiquattrot]

^ 2nd. Car handled like crap when my TC kicked the bucket.

[canadiankid]

DRTWOFISH Go out to your car right now! Make sure both cv axles are seated in the front diff properly. My front driver axle wasnt seated and I failed the jack test. I popped it in and it passed. Here is how to test. Jack up the entire front of the car. Spin one wheel. The other should spin opposite. If it doesnt, and axle isnt seated properly. Go try it now!

[nando]

DRTWOFISH Go out to your car right now! Make sure both cv axles are seated in the front diff properly. My front driver axle wasnt seated and I failed the jack test. I popped it in and it passed. Here is how to test. Jack up the entire front of the car. Spin one wheel. The other should spin opposite. If it doesnt, and axle isnt seated properly. Go try it now!

that could be true for jacking up the rear wheels, but it also didn't move with the front wheels off the ground. in that case, it would make no difference whether any of the front drivetrain was there or not.

regarding the OP's original question "how does it route power". with a bad VC, it's just like an open rear diff. the planetary gear is like the ring and pinion, the VC would be like the clutch pack. if you lifted one rear wheel of an open-diff car, it would not move (and may not move with a clutch style diff either).