View Full Version : Rear End Chattering

08-13-2003, 09:39 AM
When the car is cold and I roll around a corner the rear end "chatters".

I have an Auburn Pro traction loc unit with Red Line synthetic 75w-90 lube and somewhat less than 1/2 a bottle of friction modifier.

Should I simply add a little more of the friction modifier?

FearThis SC
08-13-2003, 10:07 AM
Have you checked the level of oil in the differential. I would not add anything until you know what the current level is. You added a HALF of bottle of friction modifier? Only 4oz is required!


08-13-2003, 10:17 AM
Well......I had the differential rebuilt over a year ago, at that time the shop put a bottle (4oz) of friction modifier in but no lube. Over the course of the year that sucker got moved a hundred times and a bunch of the modifier was spilled out. How much I don't really know. Two weeks ago I installed the thing, filled it with lube but added no additional modifier.

I tried to get away with the abbreviated version of the story but now you get the whole deal.

However, the question is should I try just adding some more modifier (assuming the lube is full since nothing is dripping out)?

I thought maybe because I used the synthetic lube it would be slickery enough without the added modifier. Maybe I was wrong.

08-21-2003, 11:41 AM
OK I've now added another ounce of modifier and checked the fluid level, rear end still chatters.

The Auburn Gear site is very specific about using conventional oil and 3 oz per quart of friction modifier which is more modifier than even Ford specs.

I would think that the Red Line synthetic I'm using would be slipperyer (is that a word?) than the conventional but the web site is very specific about using conventional and modifier.

What do you guys think?

08-21-2003, 11:46 AM
I had this 'chatter' on corners, too - turned out to be a loose wheel nut. Sounds a lot cheaper to fix, right? :D

08-25-2003, 06:20 PM
Well I did just like Auburn recommends: two quarts of 80w-90 with 6oz (1.5 bottles) of friction modifier and wouldn't you know that rear is as smooth as can be.

Go figure that conventional gear lube with 50% more modifier than Ford recommends would do the trick.