Rear end question

TBirdJKC

TBirdJKC

Registered User
Hi, I just swapped my extra 3.27 TL rear end from my old 95 SC into my 93 5.0 LX which had a 3.08 open diff. Now after the rear end is warm it feels like the clutches are grabbing around corners. I refilled the rear end with conventional Valvoline 80-90 thats supposed to be made for Limited Slip Differentials. Should I try adding friction modifier? It only does this when its warm after a few miles of driving.

Thanks,
Jim
 
If you get on it from a stop, does one wheel spin a bit before they both grab? Chattering in corners (w/an otherwise healthy diff) typically signals a need for modifier.

I would add some Ford modifier, but the question is how much, I think. Maybe like 1/2 bottle first, then another 1/2 if needed. Problem might be adjusting the level that way, tho...
 
If i get on it, it will lay rubber from both tires right away. I just dont understand why its not unlocking the clutches if the fluid supposedly already has a friction modifier in it.
 
What did that oil cost, if I might ask?

Perhaps it's only meant to be 'compatible' and it's up to you to add modifier if needed.
 
That may be the case, i didnt think about that. I think it was around $9 a quart. I thinl im going to stop and pick up some friction modifier tomorrow, add a little at a time in and see if it quiets down.
 
Well i cheked the bottle and KMT, you were right. It is limited slip "compatible." It doesnt necessarily say it contains any additives. My fault for listening to the guy at the auto parts store and not looking carefully myself. I added almost the entire bottle of modifier and it quieted down significantly on my test run. So i'll add the rest when its light out tomorrow morning.
 
On their computer it should tell u how many oz's to add it was a whole little bottle like 2 or 4oz its been a while since i changed it.
 
Ok, so I added the rest of the bottle. Still chattering around corners at very low speeds. So I drained the fluid, it still looked clean. No metal or debris. Refilled with another 4oz bottle of friction modifier and Motorcraft synthetic 75w-90. Still chattering. Am I missing something? This was a fully functional, non-abused rear end from my other bird. Do I need more than 1 bottle of modifier? My 93, nor my 95 FSM specify the exact amount needed.
 
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