Chevy & GMC Vans

Can I drive my AWD Astro Van without the front drive shaft? I think there is something wrong with my transfer case. How do I go about checking and diagnosing my transfer case?

Thanks you everyone!

Depending on what year you have.

The reply should be: Most likely not. Some years you could defeat the differential in the transfer case and drive on the rear driveshaft only. You can try it, but be aware; if your van does have a full time differential in the transfer case, it WILL roll with the rear shaft in, even in park. Without a driveshaft in front, the transfer case will just spin the front output freely, no movement will happen.

Like I said...depends on what year it is! When the original poster replies we can respond with the correct info.

I agree, but it's been 6 hours since his original post. In that time I would have gotten tired of sitting on my hands and gone out to try: but thats just me.

Ive been driving my 1991 Astro Van without the front driveshaft, and everything seems ok. I first called a 4x4 conversion shop in Red Bluff, CA and then my local Chevy dealer, and both said it was ok to drive without. I dont need the AWD...not yet anyway. And, I think the transfer case has seized, because when the driveshaft was installed, turns were EXTREMELY difficult. I will put the driveshaft back, just to see how it works with it since Ive changed the fluid in the transfer case, and maybe that has un-seized it, but I think unlikely. Anyway, I will try it again with the driveshaft soon....

Peppy!

if turns are difficult I would suspect the front differential. not the transfer case. Removng the driveshaft may have made the symptoms go away ( because the front diff is no longer driven) but Ithink somethng is going on with the Diff.

I drove my '94 all last summer with no front driveshaft.Be sure to use your e-brake,because as was mentioned it will roll even in park! I knew my T-case was bad already though.May want to hook your shaft back up and try it since you did a fluid change.

How would I go about figuring out whether my transfer case is toast?

Thank you!

peppy wrote:How would I go about figuring out whether my transfer case is toast?

Thank you!

Slather it with butter and jam, then take a bite???!?

Give us some symptoms to work off of, that makes it easier to speculate.

*edit*
I re-read what I missed, and there are a few things that you can try.

The front differential diagnosis does not make sense, as being AWD the front diff is always spinning, due to the fact that there are no unlockable hubs. Front differential test:

Jack and support the front of the van with proper stable jack stands, and chock the wheels with sturdy material, so the van won't roll off the stands and squash you like a bug. With driveshaft out, turn each front wheel forwards and backwards. Any strange noises? Crawl under drivers side of van. Grab and hold the driveshaft flange firmly, and roll the left front tire forwards and backwards. The passenger tire should turn opposite direction of drivers tire. Any strange noises? Turn wheels full lock left. Rotate drivers and passengers side tires one at a time. Noises? Turn them full lock right, and repeat. Noises yet? If yes to any of the above strange noises, suspect one of 3 possibilities: differential, left axle shaft, right axle shaft.

No noises with front end? Move to the rear, again, jack and support with proper means, these vans are heavy, and if you end up wearing one as a tie, it possibly will be your last fancy dress up date. Make sure to chock the front wheels, so the van does not roll off of the jack stands on to you, ruining your day. Grab ahold of the driveshaft and rock it back and forth, up and down, looking for slop in any direction. Take note if it is the front or back of the driveshaft. We are looking for slop in the front of the rear shaft only. Put the transmission in neutral. Spin the driveshaft slowly, listening for noises. Sometimes a slow speed noise won't be heard, like a stretched out front output chain, which will make a heck of a racket whilst driving, unless the output bearings for the front shaft are bad. With the trans in neutral, watch for the rotation of the front output. Turning the rear shaft one way should cause the front output to turn the opposite direction. Any noise? Difficulty turning shaft? Try now turning the front output, listening for noise. Is the rear shaft turning too? Can you move the flange up or down, in or out? Slop in the front output will cause tightness when the front end binds up turning sharply. If it turns freely, you should now be able to gauge how far you have to turn the front to get the rear to start turning. Any more than 1/8 turn, and the chain is suspect. Grinding noises are bad too, if you weren't clear on that.

This will give you a good diagnosis to report back with your findings. Remember that the 2wd models of the Astro/Safari do not turn well in sharp turns, the steering linkage is designed all stupid and stuff, and the vans push through turns. GM's answer was to beef up the power steering capabilities, and make aftermarket steering parts available at every corner store. An AWD model will not only turn hard in corners, but with the outside wheel turning under power with the driveshaft installed, it will feel like you are trying to drive straight through the turn, and the van will buck and resist the forces steering create while the rear end pushes the front.

GM realised this problem with their full time 4x4 pickups and suburbans of the early 70's, when the model 203 transfer case became the only option available for a 4x4 with an automatic transmission. The customers were having extreme problems with pushing into turns, so GM designed a part time kit for the case, and offered the kit with lockout hubs, so the front end components were not under load when driving in 2wd, and the differential in the transfer case was defeated, so the vehicles could be driven without bending leaf springs and replacing tires every 100 miles.

I think you are right, the t-case is seized. It happens when the viscous fluid overheats and turns to a solid. That would certainly make it hard to turn as both the front and rear would be turning at the same speed and that isn't ideal when trying to turn (as all four wheels need to turn at different speeds due to the different paths they follow).

And if the t-case is seized, then you can readily drive without the front driveshaft as the damage is already done. And in theory, you shouldn't have to worry about using the emergency brake while in park either if the t-case is truly seized.

But.... if the vehicle still creeps while in park, then either the t-case isn't fully seized, (but could still be bad), or the t-case isn't the problem, and like ScottS said, it is the front diff. (But I would think a front diff problem wouldn't go away with the driveshaft removed... although it might not be as noticable.)

First of all, I want to thank everyone for their help. Its awesome that everyone is attempting to solve my problem. Well, I should have told everyone from the start that I took the front differential out and apart, and then put it back in the van. Had to use my leg to push it up into its space in the front! The front diff is in perfect condition. Without the front driveshaft, turning is a breeze! Before putting in the driveshaft to see if the change in transfer case fluid made any difference, I have to get the little heat shield on the exhaust pipe welded so that it stops making bird noises while the van is running.

Peppy!

LiftedAWDAstro wrote:Matt...what if he has a 1999+? Without knowing a year as well as symptoms, we can only speculate as to what the problem is.

He said it was a '91 in one of the posts.

(I refrained from saying anything until I saw the year as I know nothing about the later t-cases or their problems.)

LiftedAWDAstro wrote:Matt...what if he has a 1999+? Without knowing a year as well as symptoms, we can only speculate as to what the problem is.

Dean,a few posts up he mentioned it was a '91.
Peppy, Its easier for us to try and help if you fill out your signature with your vans info.
Sorry Dean, Matt snuck his reply in there I guess when I was replying.

Where the hell was I? LMAO I missed the post where he listed the year. Sorry if I pissed off anyone, better than being pissed on I always say!