Transfer case slipping; van creeping in park

[ball]

Hi. I have issues with my 1993 AWD Astro which are seemingly related.

1) The van, if parked on an incline without the e-brake applied, will not stay where I parked it but will instead creep down until the incline is maybe 10° or less.

2) When the e-brake is engaged, the van makes a loud creeking noise seemingly from the drum brake. I don't think there is any way to check drum brake wear on the road.

3) I got stuck in the sandy snow recently and had to get yanked out. Only the rear wheel was slipping; the front wheels didn't appear to engage at all. Last time I got stuck I had at east two wheels spin: one front and one rear. The situation was one where I should not have gotten stuck.

This leads me to believe the transfer case is slipping. I haven't noticed any noise of any kind.

Unfortunately, I'm in the middle of a long road trip otherwise I would have put this van on jacks and inspected it more thoroughly instead of merely posting a hunch. As it were, so long I treat the van as a 2wd with no park I can probably complete my trip as-is, but if this is a simple matter like changing fluid I would like to know! Also, if this is something that is likely more serious (read: $$$) then that would also be useful so I don't spend money fixing other issues like the torsion bar adapter thingy which is bent.

Thank you!

[Drummernaut]

First check and see if your front drive shaft is still there. If it is I would say your viscous fluid in your transfer case is toast. This creeping problem is known to happen on the years before 99 because the input and output shafts of the transfer case are of a two piece design.

Missing front drive shaft, bad viscous coupler are the causes. It is amplified by loose emergency brakes.

[LiftedAWDAstro]

Sounds like the transfer case is toast. You can look on Ebay, Craigslist and local junk yards for a used one or have yours rebuilt. You need a Borg-Warner 4472 case from a 1990 to about 96. They did change the front half of the case slightly around 96 or so. The total cost really depends on what you find. You can try flushing the fluid out with 2 quarts of fresh Dextron 3 ATF and see if it helps but I bet it won't. For now, keep driving it and use the parking brake like you are. The loud creaking noise is definitely from the shoes on the drum but it nothing to worry about. Using the parking brake is actually very good for the rear brakes as it keeps them adjusted correctly. The only issue you may have is a stretched cable that needs adjustment over time. This will be evident if the parking brake lever goes to the floor and doesn't hold the van.

Another transfer case option is going to a 2 speed manual or electric shift one. See the swap threads on here for more info.

[ball]

Thanks guys. A voice from the wilderness is often welcome even if not otherwise useful

Any idea what specifically gets toasted?

Dex is pretty cheap and easy to change on the road if I get a pump. Does that need a wrench or a large allen socket?

Are there other vehicles which have the exact same transfer case? I know a few junk yards which don't keep good records of what they have and it's up to pickers to know their stuff. Knowing which 2-sp transfer cases also fit would also be nice. I do a lot of off-roading with this van for better or worse so a Lo setting on a AWD case would be useful. However, I'm unsure how useful 4wd would be without either lockers or positrack.

I'm not shy about wiring; if it's a bolt-in replacement (without adapters) I could definitely look for a Blazer t-case. To be honest I'm surprised they fit because of my epic finding a replacement transmission when I first bought this van; IIRC the blazer transmissions had a 6-bolt pattern while the AWD Astro had a four bolt.

Getting a t-case which didn't fit would be a nightmare.

[Drummernaut]

The viscous fluid can leak out do to expansion from overheating(boiling as they call it). There is no way to refill this unit for a consumer. Once enough has leaked out you will not have any power transferred to the front which is what happened in your case.

The transfer case needs the thickness of the fluid and the gearing of the front differential along with the parking pin to keep the output shaft from turning when parked on a hill. Ebrake helps when adjusted properly.

In my opinion, it is tire miss-management that causes most transfer cases, mechanical and electronic, to fail. To big difference from font to back, not rotating your tires properly. This is very important with any AWD vehicle. You just never know what that previous owner has done!

You can replace the viscous coupler and it will probably outlast the van but like LiftedAWDAstro said, do some research. There have been allot of good swaps done on this site. Just search LiftedAWDAstro's AWD swap work.

Like he said get those brakes adjusted for now.

If you follow these steps after change: http://www.rsgear.com/tsguides/Borg-War ... -4404F.pdf you should not have anymore problems

[LiftedAWDAstro]

I don't remember for sure but I think it is a 3/8 allen. Drain and fill are the same size. In reality, I doubt flushing the fluid is going to help any other than making sure the bearings last until you can swap it out.

You can find the BW4472 transfer case in the Cyclone and Typhoon trucks as well. Good luck finding one of them in a junk yard though. Your best bet for a direct swap is looking on Ebay or on this or the other van forum.

Read through the swap sections for info on what to look for for a 2 speed. There has only been 1 2 speed AWD swap done and it was a custom build by photovan. Lots of reading for you to do.

Here is a parts breakdown for the 4472.

[ball]

Yea, I drove about 30mi on a spare, which probably toasted it. I now carry a full size spare. Too late, of course.

Given the age and condition of the vehicle, I'll probably look for the cheapest option. I know a couple wrecking yards and will check them out. Failing that, I might junk the vehicle. It only has 160k, but it has lots of nagging issues like just now I got dumped on (snow at the Needles in the Kern River Valley) and the engine is cutting out when coasting on 1st gear. Labor-wise, I was already prepared to replace a torsion bar adapter so taking off the cross member wouldn't add much.

[ball]

Is this the part that's toasted?

http://www.ebay.com/itm/90-98-BORG-WARN ... 4897.l4275

[Drummernaut]

Yes that is the part. The area that is showing does not look burnt.

[ball]

I got a bad feeling about this…

So, I got a t-case from the pick-a-pull and I've just about finished swapping it in (including that bitch bottom bolt!) I was just about to start bolting in the front driveshaft when I noticed it spun freely.

I'm pretty sure it's NOT supposed to do that, and that I likely swapped out a perfectly good t-case.

*Darth Vader NOOOOOoooooo!*

Should I even bother bolting in the front drive shaft or just remove it altogether at this point? Is there a way to test the viscous coupling of the original t-case now that it's on the floor?

Signed: dirty, greasy, and tired

[photo_van]

The Needles? If you are anywhere near Bishop CA, I've got a "low" mileage (98k) 4472 I'd love to get out of my shed. We can instal it here in the driveway!!

I just read your last post; do you mean the drive shaft turns freely while connected to the front axle? With both wheels on the ground? If so, uh oh is right; front diff is toast....

[Drummernaut]

I got a bad feeling about this…

So, I got a t-case from the pick-a-pull and I've just about finished swapping it in (including that bitch bottom bolt!) I was just about to start bolting in the front driveshaft when I noticed it spun freely.

I'm pretty sure it's NOT supposed to do that, and that I likely swapped out a perfectly good t-case.

*Darth Vader NOOOOOoooooo!*

Should I even bother bolting in the front drive shaft or just remove it altogether at this point? Is there a way to test the viscous coupling of the original t-case now that it's on the floor?

Signed: dirty, greasy, and tired

This thing should not spin freely.

Read the last page of this pdf to get a good idea on how to test.

http://www.rsgear.com/articles/1996_12.pdf

[ball]

Thanks a bunch. That was the document I was looking for but never found. I have a torque wrench handy and will test it right now. If it's good, I'll get greasy again and swap the original one back in and take the other one back, grabbing a front drive assembly in the process. The front drive assembly looks much easier to install.

I do recall someone posting somewhere that the blazer front assembly can be used without modification (same dimensions and bolt pattern) and with a little trickery can also have the diff fixed for better mud/snow performance. Anyone have that info? I'd need to know what year blazer to look up in their system.

[ball]

My t-case seems good. I don't have a supremely accurate reading, but it takes about 40ft-lbs one way and 20-25 the other. It's within 'spec' of that PDF blurb.

I don't know if this is good news or bad news, but I guess I'm putting the old t-case back in, taking out the front driveshaft, and heading back to the pick-a-part for another chapter in our adventure

[photo_van]

I've got a Blazer/S-10 front end in mine. I'm not sure of the years, but it is a wide range. You need to be sure of the gear ratio match. If you don't want to mess with the right front axle disengage, you can swap out the right side axle and tube from your existing front end.