Recap: I am temporarily running my GT-6 (Spit bodied, 2.5L) with a Spit 4.11
diff. I had severe driveline vibration from about 60 mph up after replacing
u-joints. Numerous responses from the list suggested that I have the drive
(prop) shaft rebalanced. I really did not want to since I will be upgrading
the diff with something else (probably a 2nd gen. RX7 diff as used in GRM's
Ro-Spit project) in the foreseeable future and I would definitely need to have
the custom driveshaft balanced at that time. Well I went ahead and had the
shaft rebalanced and it greatly reduced the problem. Yesterday I had to attend
a meeting at a supplier on the other side of town and got up to near 80 mph with
only a very slight vibration - I could not get to 65 mhp before.
Thanks to all that suggested the rebalance. FWIW, the driveline shop tech
mentioned to me that the balance machine mfg'er - Bear (sp) - says that anytime
that u-joints are replaced that there is enough potential imbalance/variance in
u-joints to cause a vibration.
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