Update on my 70 SS driveline bug: I pulled the driveshaft and took it over to a friend's company - Raven Engineering - in Oxford, MI. These guys make balancing machines - like $350,000 machines that are purchased by driveshaft manufacturers to balance THEIR driveshafts. Raven also balances all the driveshafts for NASCAR on behalf of American Axle & Manufacturing. To make a long story short, my driveshaft was out of balance. They corrected it and I put the thing back in and most of the vibration is gone. I think there is still some minor problem with the way the pinion flange was installed but Raven says it's a simple fix. However, I also learned that as you spin a driveshaft up to NASCAR speed (7000 RPM) the quality of the shaft and fittings becomes apparent. While my driveshaft is as good as you'll see on a street car, you could visibly observe the shaft begin to flex as the RPMs built up. This is due to weak materials (in a relative sense - no street driven driveshaft is likely to EVER spin 7k so why overbuild it. Also, if you saw a NASCAR driveshaft you'd see what I mean - they are ROBUST). Also, spinning it through 6000 and letting it back down caused the balance point to actually shift 180 degrees through the shaft! It was amazing but these guys say is it common and normal. Anyway, it was a facinating exercise to watch.
Moral of the story: if you need a driveshaft build or balanced, call Andy Abraham at Raven Engineering. These guys are no-bs experts and dyed in the wool gearheads. Also learned that you never use zerk fitting u-joints - they are cheap and poorly machined. Use OEM u-joints or, for $40 a copy, go all the way to NASCAR style (great big suckers - look like they'd take 1000 HP all day long). In any case, I've learned a lot about driveshafts and I've never seen anyone with the sohpistication and capabilities that these guys have.
<<application/ms-tnef>>
