Mystery Vibes

[scott soucy]

I'm still getting a vibration at 50 to 65 mph (at 65 the t-case shifter starts to rattle). I've had three new driveshafts on the truck, new trans mounts, new rear output bearing on the 203 t-case, and tires rebalanced. The vibe is not a constant type, but more like the kind that vibrate and fade away over and over again. If anyone has any ideas on what could possibly be causing this let me know, I could use the info right about now.

 

[lectric80]

Couple of possibilities I have seen:

1. Try rotating the driveshaft at the rear yoke 180*. Sometimes drivelines just like to be in a certain position to stay balanced. Doesn't make much sense, but I have seen it happen.
2. Check the tires very carefully for any chunking of the tread. I just replaced a two month old tire that had a small <1/2" chunk of one lug missing in the center of the tire. To look at it you wouldn't think it would do anything, but my vibration left with the new tire. Like I said, it was a very small chunk and wasn't really noticeable.

 

[Thunder]

The 50-65 vibration is very common in lifted Blazers. Have you checked your U joint angles? May need to shim the rear or drop the Tcase.

Also as said above it could be a tire balance problem.

 

[isaac]

shim your axle or get a cv shaft.

 

[scott soucy]

I forgot to add that, the new driveshafts have all been cv. The pinion angle is within a couple degrees of shaft angle. I think I may have discovered the problem. It seems the t-case is missing the shims that go between the speedo gear and output bearing, I wont know until I get some, and installed. Thanks for the replies.