Vibration/shuddering when starting off from stop

[Randy Hinebaugh]

'04 Sport Trac, 4X4, limited slip rear, 80K miles. When I come to a stop and then take off again, I feel a strong vibration throughout the truck. It has done it for quite some time, I'm not sure when it started but it has gotten worse lately. This is my first limited slip rear, I initially thought it was typical of the limite slip because it was only doing it on turns but now I'm not so sure since it's gotten worse. I've got changing the diff fluid on my to do list to see if that does anything. There was a recall early on for the diff for friction modifier to be added, which was taken care of several years ago.



My second thought is something is going on with the parking brakes. They don't work at all. I do need to pull the hubs/rotors off to inspect them, but I hate dealing with drums and early quick attempts to get them off when having a wheel off were not successful, so I'll need to plan to spend more time and put more effort into it.



Anybody have other suggestions to check or what might be wrong?

 

[rod denton]

take a good look at tires sounds like a broken belt



that would be my suggestion

 

[EddieS'04]

If the diff fluid has been changed. Add a bottle of ford friction modifier. Might add some anyway. If it doesnt stop the shuddering. LS clutches are most likely worn.

Be shure to usethe ford or motocraft friction modifier. Pay no attention to the differential fluid that says the modifier is in it. Ford 8.8 LS works best with its own.



The parking brake has shoes inside the rear rotor hat. the problem could anywhere from a broken cable to shoe adjustment. or burned up shoes.

 

[Vic Sorlie]

I'd start with a differential lube service with AMSOIL Severe Gear 75W-140. We also have the Slip Lock additive if you want it, though it's usually not needed. After the service, do 5-6 "figure eights" in a parking lot to work the fluid into the differential clutches. For a quick check on the parking brakes, jack the rear wheels off the ground (chock the fronts) and spin them with transmission in neutral, parking brakes off. You should be able to tell if they're binding.

 

[Scott Tanner]

I only get the shuddering if I'm starting out from stop and turning..

If I do the figure 8's, then it goes away for awhile.. I changed my fluid about 3 years ago at 150,000, and it has been shuddering for about 5 months... I have 206,000 on the trac, so , from what I've read, the clutches have given up the ghost... I am going to try an additional bottle of friction modified soon to see if it helps..

 

[swshawaii]

Any chance the parking brake is binding? When I've accidentally driven with

them engaged, they caused an awful vibration and grinding I could feel at the

brake pedal. You should have working parking brakes anyway, check them first.

 

[Randy Hinebaugh]

My driveway is probably a 20 degree grade, I mash the ebrake pedal to the floor, put it in neutral and it doesn't hold for squat. I meant to get it looked at during my last state inspection, but forgot to tell them. I know how to work with drum brakes, I just don't like it and when I've tried to get the rotor/drum off before (did I mention that it's disc with the drum ebrake?), it didn't come off easily and I didn't have time to get into something time consuming.

 

[Gavin Allan]

Be sure to release the parking brake before trying to pull the disc/drums. You may have to manually back off the adjusters to get it to release, especially if there is a ridge worn in the parking brake drum.

 

[Todd Z]

Check U joints, Drive train and Rear end fluid !! add 2 TWO bottles of friction modifire FIRST then the fluid.....

I did that on my 2004 and the issue went away



Todd Z