Help Please

[NewGuy]

I recall reading a post awhile back about a member with a LT4 who had a vibration in the rear running gear of the car and he described how he replaced everything but the real problem was something simple.

I am in the same boat: It is after the transmission, have balanced all the half shafts and drive shafts, new u-joints, everything in great condition, no unusual wear in the wheel bearing assemblies which are tight with no freeplay.

New tires (25 miles) switched front wheels to back to exclude an out of round wheel.

This vibration occurs at 71 mph to about 80. No matter what gear or rpm. Put it in neutral and coast, the vibration increases so that seems to indicate a drive line problem that is kept partially down by having a load on it. 100% sure it is speed related.

Anyone recall the post I am looking for?

Thanks in advance

 

[vettl83]

Sounds like a problem I had in the 84 a few years ago. It seemed normal under a load but would howl under coast. It turned out to be a worn out yoke on the pinion shaft. Replacing the yoke, bearings, and pinion seal solved the problem. The bearings were ok but as long as I was in there up to my elbows they got replaced too. Great time for a gear change too if your so inclined. 84 CF 91 ZR-1

 

[oldace84]

Is it recommended to replace these.....my '84 has 87K on it....what do you think????????
thanks
tony