At only 28, 000 miles my Supercrew (5.4L engine, auto trans, limited slip differential) beginning having noticeable shudder during light or hard acceleration from a stop AND vibration from the rear end when making a turn (only) from a stop, but not going straight.

Interestingly enough BOTH these problems began occuring VERY shortly after having both systems serviced (fluid change) BY THE FORD DEALER ???

What a coincidence ... what are the odds this just happend to occur after the dealer touched both systems ... hmm?

I suspected they put wrong fluids in both ends, as this would cause the symptoms. But according to the dealer ...


1. There is a Ford Service Bulletin re. tranny shudder when accelerating from a stop. They replaced a bunch of stuff (but not torque convertor). Thank God it was under warranty!

2. Rear differential clutch packs defective ... replaced. Thank God it was under warranty.

Have put a couple of thousand miles since then, no problems.

ps. My wife drives this truck back/forth to work ... no heavy towing etc.

Ford "Quality Is Job 1" comment:

* Transmission problem (see above)
* Differential problem (see above)
* Stereo system replaced (serious static, all stations)
* Driver side power window mechanism replaced (grinding/groaning/squeaking)

 

I wonder if they didn't fill up the rear diff with enough friction modifier -

essentially, that is what happened to me when they replaced my left rear axle for supposedly a slightly out of tolerance run out (I was trying to get another problem fixed, detailed in the SuperCrew forum) and they didn't fill up the rear diff. I started getting the same shudder as you and brought it in - in the gear pack, they found that one of the "ears" on a plate in there had snapped.

 

re. diff ... that's what I thought too. But I watched them put TWO bottles of friction mod in (first one ... no change, then another) ... problem persisted.

 

new clutch pack defective or they did,nt get thier measurments right when they put it back in

 

Have you tried going up a steep hill slowly and turning slightly? Or have you had the truck loaded and tried making slow turns? Does the shudder feel like the tire is breaking free (of course it isn't, but does it almost feel like it?)

If so, I think that points to the limited slip - if they replaced the gear pack and filled it with enough friction modifier, another potential "gotcha" is that the factory shim (and "spec" shim) in the gear pack is way too tight. If they put the same shim in, they could've caused some damage to the new gear pack.

 

have the same shudder under load when accelerating from a stop , could it be the differential torquing up and the u-joint binding?