Any ideas? decceleration vibration

[wrathchild]

I was reading another post and someone mentioned rear end chatter from not using friction modifier.

Here is my problem. I started having this vibration only while decclerating in 3rd gear and it seemd that it was only when i upshifted to third. If i downshifted to 3rd it didnt do it. Then it was the same in 5th. Now it seems that it does it in 2nd and 4th also.

I checked to see if the bolts on the ujoint were loose and they are tight.

I also had 4.10's installed last summer and it didnt do it directly after the install.

So what do you guys think? Tranny, ujoints, rear end?

 

[HISSIN50]

to check u joints, not only check bolts, but grab each yolk and turn them against eachother to see if there is slop of any sort.

vibs/rumbling only on downshifting points to gear adjustment (backlash) i think. im not great with car rear ends. i would really check the u joints again. i have had them even test ok, but they were rusted inside (needles werent allowing proper movement). hear any squeaks ever? the sometimes squeak when the rust. my best guess.
good luck.

 

[clarkjr]

The u-joints/driveshaft can cause a vibration even if you cannot physically feel play in the shaft. I would recommend replacing the u-joints and have the driveshaft balanced (heavy-duty truck repair shops often offer this service). After a gear change, the d/s spins so much faster than it did before and often a vibration will show up right away.

Another potential cause is too much neg. pinion angle. You did not state if you had adjustable control arms but if so, try adding a degree of two more pinion angle into it (postitive, not neg).

 

[wrathchild]

The u-joints/driveshaft can cause a vibration even if you cannot physically feel play in the shaft. I would recommend replacing the u-joints and have the driveshaft balanced (heavy-duty truck repair shops often offer this service). After a gear change, the d/s spins so much faster than it did before and often a vibration will show up right away.

Another potential cause is too much neg. pinion angle. You did not state if you had adjustable control arms but if so, try adding a degree of two more pinion angle into it (postitive, not neg).

The driveshaft is an aluminum unit. I have stock control arms. This just started all of a sudden and got worse. It wasnt directly after the gear change. It was a few months after.

I talked to a local trans/rearend and he told me that my problem is going to be either in the tailshaft bearing or the ujoints.

I also asked just out of curiousity, how much to rebuild my tranny if i bought the parts. He said if i buy the parts he would tear down, clean and rebuild the tranny for $60.