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View Full Version : Posi-trac "chatters" on take-off


RichCal
05-31-2002, 03:13 PM
My 88GW which I bought a few months ago has a strange chatter emanating from the axle or differential, but only when 1) fully warmed up, after driving about 5 mi, and 2) upon starting up from a stop, and disappears upon reaching 5-7 mph.
If I'm at a dead stop and barely creep along I can sustain the noise: "d-d-d-d-d-d".
So, brilliant me, I changed out the wheel bearings. But no improvement.
Weeks later, I decided to change the rear diff. fluid, in case the DSPO had never done so. Tag on the diff. advised to use posi-trac fluid!
Didn't even know I had posi! (This is great - never had posi before)
Anyway, changed the fluid. No change.
Getting desperate, I actually read the tech manual, and in fact it mentions posi-trac chatter, of all things, and that it usually is caused by dirty fluid, and is best solved by changing same. But I already did that (W/ correct fluid.)
So...what's the deal here? Is it something which can go on forever and remain just a harmless nuisance...or is something about to explode all over the highway?

PhilSine
05-31-2002, 05:25 PM
Check out the info on this site, it may offer some insight.

http://www.off-road.com/4x4web/faqs/diffs.html

YAKFSHR
06-01-2002, 09:26 AM
my 87 did the same thing. change the diff lube and if you have the trac lok make sure you put in the additive for the trac lok. it comes in a tube and is a must. if you have the tow package the diff lube is, i think 90-140 not the 85 or 90. after a couple miles the noise went away and never came back. the lube is thick and you will need a small pump to get it in. a mechanic changed it the first time and put 85 or 90 in it without the additive and it still chattered. i did it right and problem fixed. randy

[ June 01, 2002: Message edited by: YAKFSHR ]</p>

RichCal
06-01-2002, 01:45 PM
Tnx...didn't know about Trac-lok additive. And yes I have the towing package. I'll give it a shot & see what happens.