Ever since I went from a torque tube to open driveshaft on my 37 Buick it's had a vibration at 1800rpm and up in high gear. The pinion angle is down 1 1/2 degrees and the pinion yoke is less than 1/2 degree offset to the right---all well within specs. Driveshaft is straight and balanced, re-done twice to make sure. Different pinion yoke and slip joint at the front. Bushing in tailhousing replaced. Went to strobe it and my pricey variable speed strobe light is missing---probably loaned it out. The $20 party/DJ lights only go to about 500rpm so are useless. Put the car on the drive on rack with the accessory axle jacks so one can be raised with the weight still on the suspension which is necessary for some tests. For a strobe I hooked a good bright timing light on to a plug wire of my Ranger which had it's nose run under the rack so the wires would reach. The Buick has a throttle so set the rpm's at 1800 in high gear and had one of the guys bring the Ranger rpm's up till the driveshaft seemed to be nearly standing still. The front yoke was wiggling in the new bushing so pulled tailhousing and found the output shaft is bent. Mystery solved FINALLY.
Glad you found the problem for that, the little vibrations always bug the crab out of me. The Buick should run really nice now. Charles
Fixed It ! Doesn't that kinda stuff drive you crazy finding it ? . I appreciate your sharing the step by step diagnosis too , many will be able to learn yet another new thing from this . How the heck did an internal tranny out put shaft get bent ?! . Or is it some weird Q.C. issue . I'm sitting here slurping coffee and gazing out the window at my 1970 Honda CT90K2 Moto I saved from the bowels of an older Honda Dealer , it's been giving me fits sorting out the strange, weired and hidden electrical gremlins but is very nice indeed to hop astride it @ 0-Dark:30 and roar across two towns to the Coffee House knowing it'll make it there no hassles and nearly 200 miles per gallon @ 49 MPH (radar trap on the way) .
Nate, Chalk the bent shaft up to some DohDoh (not to mention names) getting a junkyard tranny with a broken tailhousing and just sticking another housing on it. One would THINK that with the tailhousing snapped in a wreck that it might be a good idea to check the shaft.
Evan, it is good for us tyros to see that even the experts can forget something once in a while. Glad you finally found the problem.
