Slight shudder/vibration concern.

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I have a slight vibration when I first start moving. I think it feels like it’s coming from the rear, but I’m not sure yet. It seems to be more evident when I turn when I first start movement , like pulling out of a parking spot.
I’ll add that I can wiggle the driveshaft up and down a little at the transmission.
I just set my pinion angles. From the front to back, the transmission up 1* in back, shaft is down 1* in back and rear diff is nosed down 3*. The rear end was almost at 0* and that made the shaft almost 0* also.
Any ideas? I feel like it could be a u-joint, but I just replaced them about a thousand miles ago.
 

melloelky

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it's only when you start moving?which came first the angle adjustments or this new problem?
 
it's only when you start moving?which came first the angle adjustments or this new problem?
Vibration was there first. I think I remember it last year already. I thought it was a shudder in the trans, but that was just rebuilt and it’s still there.
 
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TURNA

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If you can wiggle something, then i would start there
 
Update: I added a 4oz tube of limited slip additive and it seems to have quieted the noise considerably.
Something I didn’t mention is there is a clunk when I put it in drive. That too got better with the additive, but still noticeable.
I scribed a line on the yoke washer across the diff housing and held the tire as I turned the drive shaft. That measures 0.089”. The car just turned 62K mi.
I also dug up my receipt from two years ago when I had the drive shaft balanced (had it built in 2011) and there’s no record of new u-joints, so I’ll probably replace them to see if the clunk goes away completely. There is no noticeable vibration, even at higher speeds.
 
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69hurstolds

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Looks like you found your problem. A clunk from the rear putting it in gear usually means that your backlash in your gears may be a bit on the high clearance side. May have something to do with your transmission pressures too, but my money would be on the rear gears. The U-joints are relatively easy, so those can always help tighten it up.

Always add the limited slip additive. I do it even if I use that so-called "limited slip" fluid supposedly not requiring it. My 85 442 had that as just ONE of the QC problems when it was built. They didn't put any in. Clunked and chattered going around turns right off the bat.
 
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