Rear driveshaft backlash

[92strokersmoker]

I noticed I have quite a bit of backlash on my rear driveshaft. I have a pretty annoying shake from 40mph on up and thinking maybe this has a lot to do with it. i have tightened the motor and tranny mounts to book specs replaced the drag link and bushings up front with no success. Also thinking maybe since my zerks on the rear shaft are not all in line it might be throwing it off balance a tad. Any ideas?

[ciamcoop]

Do you mean backlash between the ring and pinion? I doubt that the shake is because of that. Who modded the driveline after the trans swap? If someone did it themselves without balancing it that could give you a vibration, doubtful it's from the zerks. Is it a shake or a vibration? Do you have a 2 piece shaft with a carrier bearing? Maybe the rubber isolator is loose in the steel, or maybe it's just your tires.

[92strokersmoker]

Yeah I put the shaft back on after doing to the trans swap, and yeah I never balanced it. Any way its like a side to side shake at 40mph to 50 and up but not as noticeable at high speed

[dazedandconfused]

Get it ballanced before it causes a bearing failure in the pinion or transfer case if you modded it.

[slow_90firebird]

The grease zerks wont cause a shake.

Worn u-joints with loose or missing needle bearings will.

Also, if your shaft has the factory slip joint like mine does, there is a blue plastic coating on the splines in the slip joint that can cause loosness if it is not intact. I had to disassemble mine to change the carrier bearing, and regreased the slip joint. Luckily the plastic was alright.

[Mark Nixon]

Look for bent rims, too.
Might sound crazy, but I have not actually had a single-segment driveshaft cause a "side to side" shake at a particular speed.
It's nearly always been bad tires/balance or bent wheels.
Or the carrier bearing assembly on multi-piece driveshafts.

Mark.