# PLEASE HELP!used differential didnt work out : (



## badgoat91 (Jul 13, 2009)

so my diff was whining like crazy , it had 77k on it, i get a used one with documented 22k on it, i install it and first two days, everythings perfect ,no whining no nothing, now the thing doesent whine but it intermittently makes a nasty rubbing or grinding noise when going slow and turning, for example up a driveway. can anyone help me, im thinking the posi unit is bad on this diff ha, maybe i should combine the two diffs? idk please help, thanks


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## GTO JUDGE (May 14, 2005)

My opinion? Do a total rebuild of the unit. You may have gotten one that was defective. I would start from scratch. Just swapping this and that may not solve your problem. Now you have 2 units neither are up to snuff.

I think you'd be better off and do it right which means a total rebuild paying close attention to tolerances. Unless you are versed in building these units you'd be better off having it done by an outfit that does. You don't want to go through this a 3rd time.


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## AlaGreyGoat (Jul 6, 2006)

Did you change the fluid? Sounds like the clutches sticking.
If it doesn't make a noise or feel a vibration going straight on a
hard pull, I don't think the unit is hurt.
Make sure it has the right oil. I use Royal Purple Synthetic Max-Gear 75W-140
with the Limited Slip additive already in it. Be sure to add this to any
oil that doesn't have it.
Some people add more additive (very small amount at a time) to help make the
clutches operate smoother.

Larry


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## badgoat91 (Jul 13, 2009)

ya i put mobil 1 75w 140 and limited slip additive just like the manual calls for. it definitely seems like the clutch is sticking, im really bummed ha, should i add more limited slip additive and see if that works?


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## AlaGreyGoat (Jul 6, 2006)

If it was me, I'd add about an oz. more additive and take it to a parking lot or open area
and do some tight figure 8's to see if the clutches are working. If it seems to be OK,
do a short burn out and see if both wheels lay down rubber.
Don't see how it could hurt anything.

Larry


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## GM4life (Mar 18, 2007)

Good luck with it. My first diff started the clunking around corners, reverse, and on and off throttle in a stright line. I performed two diffrent fluid changes, Mobil 1 and RoyalPurple none of them fix the problem. I end up having the diff replaced under warranty. Now this one is doing the whining but no clunking yet. One of these days I'm going to tare into it to see whats going on.


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