Chevy & GMC Vans

OK just bought a 03' Astro AWD in Nov. with 139K on it. It crow hopped a little when I bought it wasn't sure what it was at first. Now knowing what it is trying to figure out how to fix the problem. 1st attempt was to and did drain the rear pumpkin flushed it thoroughly with brake cleaner checked the magnet (nothing major) did a little JB Weld job on the rearend cover plate and refill with Lucas Oil 75W-90 synthetic gear lube. I took the the time and found an empty parking lot to do 5-10 mins of figure 8s to work in the new lube to try to unstick anything, and it still does the crow hopping both directions in low speed tight turns.

What is the next step into trying to remedy this problem??

Ohh yeah RPO codes are GU6 (3.73) with G80 locker

Also if I have to, to replace gears how hard would it be to change gear ratios entirely to 3.23 to get better fuel mileage on the highway since most of my driving is at 65+mph ??

Change the fluid in the transfer case, be sure to use GM Autotrac II

Yeah, should really change the Auto Trac II fluid in the transfer case once, maybe twice.

I don't think you'd see enough of a fuel economy improvement to justify changing the gears.

To add to the mayhem may I add the following. My 99 AWD had an open rear diff when I got it. It drove perfectly. There was no crow hopping. I put a torsen carrier in the rear and now mt van does that thing when in a slow tight turn. I really think the limited slip/locker G80 will enhance this effect. I pulled the quote below off the web

"The G80 used in GM brand trucks combines the clutch plates of a traditional Limited Slip differential with the positive engagement of the traditional mechanical locker.

It does this by using a mechanical flyweight and a governor inside the differential, hence the "Gov Lok."

Point your browser to the following Eaton URL for a detailed description. You'll probably want a broadband connection to see the movie on how the parts go together and work, it's almost 3 MB."

http://www.traction.eaton.com/prod2.htm

http://www.traction.eaton.com/images/G80.mpg

So change the tc fluid and do some figure 8's. keep an eye on front end parts and have fun

OK will do the front TC lube change next weekend, funds are tight this weekend.

Other than the Auto trac II fluid what else do I need to get for the front TC?? Gasket/s ? and what should I look for while in there as well ??
Might just have the local Mobile 1 station do it they're fairly reasonable for these types of things.

Transfer case is next to transmission, fill plug and a drain plug, don't overtighten, Auto Trac II fluid.

Front differential is at the front and same deal, just fill and drain plug with (usually) reusable nylon washers, no gaskets. 75w90 or 80w90 gear oil, I use a long tube attached to the gear oil bottle from above as there's not much room underneath to pour from gear oil bottle.

You will find there is no drain plug on the front differential so you will need to syphon
Or vacuum the old fluid out. Silly setup

There is indeed a front diff drain plug, both my '97 and '04 have one - driver's side just below the side cover plate.

OK thanks guys good to know info right their.

Will get
AC/Delco Autotrac II lube for TC
Lucas Oil 75W-90 full synth gear lube for front diff, same as rear


Hopefully after some more figure 8s this will be the end of this problem on this van and on to the issues on my 03' RWD van

Troy