G body rearend shake?

[smokes468]

I'v been fighting this problem ever sense i installed a 9" last year, at least i'm sure that's when it started, It develops a shake starting around 40-45 MPH & never goes away, even at 85-90 MPH, Its extremely annoying & i'm to the point of stripping everything out & junking the body, its kicking my butt & the car is no fun....Ok, at times its worse then others, I thought i had it found & it was smoother when i loosened up the brakes, but a week later it was back just as bad, I have changed everything, & i mean everything including other tires/rims, It is definitely not a "vibration", the driveshaft has been checked twice & ruled out & the pinion angle was checked, it is a shake, doesn't matter if your under hard throttle or just cruising, It is tire speed related.

The 9" is all new from Quik Perf., it have a full spool, even had the 3rd. member re-checked for run-out & a another yoke installed, all there was good, it has adj. upper/lower bars. The only thing i haven't checked is to see if these drums are in balance, There new from quik perf., there 11.2", but what strikes me is it has 3 weights, All i have ever seem on them is 2, there the multi lug drums. As for the axles, there new also, they look straight & i checked run-out, I will say when its up on jack stands & i go through the gears you can feel the shaking but its not as bad as when your driving it. This is a 78 Cutlass Supreme.

Any ideas would be great.

 

[383S10]

I had a condition like this on my truck .....did everything driveshaft, balancing, turned out it went away when I replaced the tires on my truck months later......broken belt I guess.....how old are you tires.....you might want to try switching the fronts to the back to see if it goes away or moves to steering wheel........

 

[smokes468]

I had a condition like this on my truck .....did everything driveshaft, balancing, turned out it went away when I replaced the tires on my truck months later......broken belt I guess.....how old are you tires.....you might want to try switching the fronts to the back to see if it goes away or moves to steering wheel........

I would rotate tires, but the backs are 275/60/15s & the fronts are the narrow metrics, It does feel just like a separated tire though, but even after i installed a completely different set of tires/rims its still there, I even had the tire shop get another tire & we sent one of them back defective, also sent a rim back to jegs as it took alot of weight, now 1 tire is taking more weight, a good 7-8 onces, but the other tires i put on are 14s & hardly have any weight, shakes still there. How many bad tires/wheels can there be.

 

[crazy87]

Normally a high speed shake is a balance issue, low speed shake is a component issue, loose u joint etc. Do you have a u-joint tight in the yoke? Remove the driveshaft and make sure the rotate smooth. Try pulling the tires first then the axles and eliminate shake while running in the air. I would think if the brake drums were the issue you might have a brake pulsation in the pedal. Without seeing/being there it's always hard, I hope it helps good luck.

 

[85blacksalon]

you could take the drums to a tire shop to ck the balance, at least you would know. did you try running it on stands with the tires off?

 

[85blacksalon]

If you have a tire that needs 7-8 ounces you got a problem. try turning the tire on the rim and rebalance

 

[smokes468]

If you have a tire that needs 7-8 ounces you got a problem. try turning the tire on the rim and rebalance

We tried this, took about the same weight.

The biggest proplem i'm having is i'm in an area that most mechanics/shops are more interested in making money off the tourist.

 

[smokes468]

Normally a high speed shake is a balance issue, low speed shake is a component issue, loose u joint etc. Do you have a u-joint tight in the yoke? Remove the driveshaft and make sure the rotate smooth. Try pulling the tires first then the axles and eliminate shake while running in the air. I would think if the brake drums were the issue you might have a brake pulsation in the pedal. Without seeing/being there it's always hard, I hope it helps good luck.

I'v had the tires off & on he stands, it does seem to be smooth.

 

[383S10]

Don't some tires have valve stem marks that are suppose to alligned with the rim when mounted? Another thing to check is make sure the universal caps have slid outward under the clamps this slight vibration happened a about before I flung a drive shaft at about 75 mph coming from a cruise in....

 

[pontiacgp]

Normally a high speed shake is a balance issue, low speed shake is a component issue, loose u joint etc. Do you have a u-joint tight in the yoke? Remove the driveshaft and make sure the rotate smooth. Try pulling the tires first then the axles and eliminate shake while running in the air. I would think if the brake drums were the issue you might have a brake pulsation in the pedal. Without seeing/being there it's always hard, I hope it helps good luck.

I'v had the tires off & on he stands, it does seem to be smooth.

were the stands on the axle tube or the frame? I would put the wheels back on with the stands on the frame and try it again