So I had the rear diff fluid changed on my 95 Bronco (8.8" with LS, 87K on the odo.) and now I get a chatter around corners. The chatter happens under load only. If I coast around the turn, nothing. The chatter starts about 10 or 15 minutes into a drive and gets worse the longer I drive.

After doing some searches here, I am thinking that additional friction modifier might be the ticket. Anyone got some thoughts on this?

For adding the FM, I assum that the square plug on the diff cover is removed and you just dump it in? Never changed the rear diff fluid so any other hints/tips would be welcome. I have been doing searches on the site for more info but not finding the answers.

Thanks in advance.

 

Welcome to FTE Stick around. Learn al kinds of stuff here.

Thats exactly right. Just llike that. If you didnt add the FM from the start, thats very much the problem.

 

Alright, Added 4oz of Ford Friction Modifier today. Took her for a test ride. Getting the same problem. Everything is fine when cold, the longer I drive, the worse the shudder gets. Only around corners. Does anyone know if the FM takes some time work?

I checked the level of the fluid in the diff. It was about a quarter inch below the plug.

Any other suggestions to check?

 

Who changed the fluid? Did they add any friction modifier? If not, then 4 oz is not enough.

Also did they use the right gear lube? Some differentials use ATF instead of gear lube. I do not know your model diff so can't say either way.

With Dino gear lube you will need probably 8 oz or more. Experience with some synthetics say 16 oz is better. I don't think ATF requires any.

I assume the 8.8 diff is relatively small capacity, I could be wrong. If it is actually larger capacity, you will need more modifier.

The way I check is to drive slowly and make tight turns. If it chatters I add more. After adding modifier it helps to make a few figure 8 turns to slosh things around, but I don't think it hurts if you forget.

Good Luck,

Jim Henderson

 

Chiltons calls for 8 ounces. Sorry, guess I should have told you that in the first place.

 

The clutch pack is also suppose to be soaked in the FM fluid for 15 minutes before installation to help this problem, but thats when you've had the cluthes out. You can try the 8oz of fluid, that should be the ticket.

 

Thanks Guys,

I had Ford change the diff fluid and assumed they would do it correctly. This problem definately started right after the service was performed.

As far as the amount goes, I checked the manual and it mentioned 2oz. I figured I'd try the whole 4oz bottle. What the heck, lets go with 8.

Don't know if they changed the clutches, certainly don't remember paying for a LS rebuild or anything.