I have a vibration that comes in around 85mph and gets worse with speed. If I let off the gas and coast it gets worse. Tires are all in balance, and I looked over the rear end and everything is tight and bolted, but I think I have too much backlash in the gears. With the rear end off the ground I can rotate one wheel back and forth a bit without the other moving. This is accompanied by a clunk. Would too much backlash cause this? Could I just be low on fluid?

 

could be in the rearend or universal joint. i have the same issue and have replaced everything except the rearend and thats next when i can afford the 12 bolt or 9 in.

 

I checked the U joints and there doesnt seem to be any slop in them (trying to turn the driveshaft by hand). Ill look again. Im also going to check the fluid level in the diff in the next day or two.

When you say you replaced everything, what all did you replace?

 

drive line including u joints, wheels and tires, tried a adjustable torque bar, new ring and pinion with bearings, brakes, also have a new transmission. have not replace the axles or the center section ie posi unit.

 

Well, it has new brakes and the u joints have grease fittings on them. Was that standard? If not I would bet they have been replaced also. Wheels and tires are good, only thing left is the bearings or posi unit in the rear end. Any good ways to check the bearings in the axle housing or diff carrier without taking it apart? I willing to put my money on the posi cause I get a little bit of wheel spin on the inside tire under hard cornering.

 

a wheel bearing will usually grind all the time. yah mine is slipping on one side sometimes.

 

Thanks Craby! I will be on the lookout for a "new"/better center section.