Guys Please help.

I rebuilt the rear suspension, u joints, trailing arms bearings last year with all stock components (other than KYB shocks). I have a slight vibration under hard acceration. When my foot comes off the gas the vibration stops. If I shift to netruel and rev the engine no vibration. Finally if I am doing 60 and hit hit the brakes hard, it stops long but straight as an arrow. What do you think it is attributiable to:

1) the driveshaft was balanced and it took some of the vibration away. However there was a small ridge in the yolk (slips into the 4 speed). It was polished but there was a slight ridge in the yolk (not visable, but by hand I felt it). Is this the problem?

2) I reused the side yolks as they looked perfect. The original U-joints that attach the half shafts were impossible to get off. I wound up heating them off and smacking them with a hammer. I missed 2 times and hit the side yolk. Was it possible that I bent a side yolk?

3) The pinion shaft seal leaked, I put a new seal in it, but did not change the crush collar. I marked it originally where the nut was prior to removing. As I replaced the seal I tightened the nut to almost the marking but never got there. I say it was up to 7/8's of the original mark. I torqued the nut to specs and the seal does not leak. Could this be the problem

4) should I balance the halfshalfs?

5) should I get realigned ? I had aligned when I finished last year at a reputable corvette shop. However he was pissed that I had the 2 hole shims as oppossed to the shims that slide in. The alignment looks good visually, and even if I take a contruction level and put it both ways.

6) BTW, I also replaced tranny mount.

Please advise. :flag


[Modified by Daren Schneider, 10:11 AM 6/14/2002]


[Modified by Daren Schneider, 10:12 AM 6/14/2002]


[Modified by Daren Schneider, 10:59 AM 6/14/2002]

 

Lots of good info here, and you obviously have thought it out. My FIRST thought (before I finished the first line) was shifter related. I would look closley at the linkages paying attention to the anti-vibe springs on the clutch throw shafts. After I finished reading I leaned towards your half-shaft u-joints. (Still don't understand why they would not come out). Ummmm, lessee, nope.....gonna stay with my first guess. I would look at loose engine/tranny mounts also. Something is touching when under hard accel/torque. :cheers:

 

Did you replace the front differential bracket cushions during your suspension rebuild? I've heard that some of the aftermarket replacement cushions (the poly ones, I think) are too thin and will allow the rear driveshaft U-joint to contact the body under hard acceleration.

 

Waytec.. I replaced the diff bushing with stock. Should I try to put up on a lift, support the rear and accelerate through the gears? :smash:

 

If the vibration only occurs at high throttle openings running it on jackstands probably won't tell you much, but I'd suggest systematically checking all the bolts in the driveline for proper tightening torque.

The fact that it is "torque sensitive" as apposed to "speed sensitive" tells me something is loose!

Duke

 

Which rear suspension/ driveline bolts do you have to tighten while the car is on the ground? :cheers:
Shall I assume all other bolts not mentioned can be tightened in the air

 

The strut rod and trailing arm bushing bolts should be tightened with the suspension at normal ride height. All others may be tightened with the suspension dropping.

duke

 

The ones requiring torquing on the ground are the 4 bolts at the rear spring mount. Mine got the minimum 55 ft lbs.

 

Duke was right (again).

Then rubber bushing connecting the rear end to the frame was loose.
I tightened it up and no more vibration.

Regards,

Daren

 

you da man Dukester. what would we do without you?

 

Screw up a lot, I suppose. ;)

Duke