Quote:
Originally Posted by kwmech
Still waiting for a pic of the driveshaft
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No pictures as of now.
Back story: Always had a vibration at 50+ MPH blurred the rear view mirror.
Totally stock C20 suspension with HD suspension and leafs in back
Always thought it was tires.
New wheels and tires: no change
balanced tires multiple times: no change
Went from TH350 trans to 2004R trans: no change
Brand new crate 350 engine: no change
Had driveshaft rebuilt including carrier support and balanced: no change
swapped out th2004r for 7004r and had driveshaft shortened and rebalanced: no change
Disc brake upgrade in front with rebuilt suspension: no change
New rear brake drums: no change
New tires (thinking old ones were the cause): no change
Now I really started getting into this
Put truck on jack stands supporting the rear end.
Could duplicate vibration at speed.
Remove tires: no change
Removed brake drums: no change
Removed rear half of driveshaft: smooth
I reinstalled drums and wheels and only lifted one side of rear (open diff so you can do this) ran truck up to speed in gear: no change
reversed sides up and retried: no change
This told me it definitely was not axle or wheel assembly on either side:
Read up on this as much as possible and shimmed center carrier support down 1": made it smoother on acceleration at lower speeds
Rearend shop said my pinion angle was bad. Shimmed the rear up 2 degrees and replaced all the leaf spring bushings: no change at hwy speeds
Rearend shop still says pinion angle is bad after test drive. I added a 1/8" or so plate moving rear of trans up and another 1/8" plate dropping center carrier support down. The addition of the 2 shims had the effect of changing the rear driveshaft angle a little. No change
From what I can see without measuring the trans tailshaft is centered in the frame as well as the center carrier support. Looks like the pinion yoke is slightly on the passenger side of the frame.