[sxfx]

Hey guys I'm in a dire need of help let me post my problem here from the beginning to now.

About 3 weeks ago i purchased a 1996 awd Astro van, with only 109k miles on it. The van is in awesome shape but I guess it stood around for a while and when I took it and started to drive it home about 200 miles away, the gasket on the rear diff pumpkin went.

I realized way too late and fried my diff. No problem I left my car 200 miles away from home at a local mechanic who replaced my rear diff.

I pick the car up couple days later, and find out that it developed a thump and jerking from the front diff all the way till about 35mph and then it would go away and the van drove beautifully.

So I took it home. Found a front diff from a all wheel drive 93 and swapped it into my 96. Changed the fluid in my transfer case to Dexron 6, changed the filter and fluid in my Trans, and put synthetic gear oil in the front diff.

So I proceed to drive the van and got really really excited no more jerking no more thumping the van drives beautifully.

But I got excited too soon. After about 15 minutes of driving when the van warmed up I started hearing a weird whining noise but couldn't quite possibly put my finger on where its coming from, it sounds like the rear but not sure, and as soon as the whining noise starts happening the van gets kinda wobbly especially when you get to speeds higher then 35mph, now the wobbly effect could also kind of be explain that the steering feels that each wheel is trying to go a different way.

So my question is what the heck before I replaced the front the diff the van ran fine except it had had the thunking and jerking in front until you got to 35mph, with a new front diff the jerking and thunking go away but the above mentioned problem evolves.

Only guess I have right now after doing some research is that the front diff I got from the 93 is a different gear ration then my rear one.

My rear gear ratio is 4:32 like the stock, and like a dumb *** I never checked what gear ratio that front is from the 93 astro i got.

What are the effects of running a differ gear ration in the front, how would the car behave?

Any help or suggestions are much appreciated.

 

[sxfx]

Upon further inspection, I have a feeling that the viscous coupling in my t-case has seized up is causing my problems. I think whats happening is since the viscous coupling sized up its transferring full power between the front and rear wheels none stop even on dry ground, causing my van to become unstable since all four wheels are trying to fight each other.

This would also make sense because these problems don't seem to occur until the van warms up and goes into higher speeds and from what I have learned the viscous coupling works on the basis of the fluid heating up and helping it transfer power to the front and back.

Any thoughts or ideas on this?

 

[Mr_Bowtie]

All I know is that a different gear ratio in the front then the back can do damage to your transfer case real quick. These Vans don't like different size tires either, they should all be the same size tires. Sorry, beyond that I've never personally dug into the AWD system all that much.

 

[grandamle91]

Thats what it sounds like to, two differnent ratios and the back and front tires were trying to spin at different speeds