Didn't realize you were still on leafs. Have you considered changing to a 3" aluminum driveshaft? The larger aluminum shaft will absorb some vibrations that a small dia steel may amplfy.

I can't imagine that they're still even available - even in a wrecking yard out in the middle of Wyoming...


HAHAHAHAHAHAHAHAHA

I'm running a 3.5" steel shaft from Inland Empire. This last shim change move the vibration up in on the mph chart, 65-70 isn't bad at all, 75 mph and the mirrors fuzzing out, 85 mph and the mirror is oscillating fuzz...... :D

Upside is it improved..........what's bugging me is I've used this setting. Either I didn't get a wedge positioned on a pin properly and missed that when torquing the u-bolts even though I've visually inspected every time (keep in mind on my back not on a lift) or maybe I've got a moving target. :headscratch:

I think John Deere still uses them on a limited basis.........:guns:

Had a friend that had the same problem one time and his bolts were slowly backing out of his ring gear. Not saying that is your problem, just relaying another possibility.

I have also seen a car have that problem where the axles were changed and no one noticed it had a ford register instead of a chevy. When the wheels were bolted up they were not perfectly centered and it did the same as your car.

Stuff like what is going on will make you crazy. Good luck

This vibration (not a GOOD vibration - Beach Boys) felt "centered" in the car - so I understand Siegs chasing the driveline settings.

The rest of the car felt planted and smooth. It's really a "nice old car". I don't mean that as a slam - rather it's a description of a car that hasn't been Pro Toured in our usual rotisserieed / body off $250K build... I've owned several of these, and this is a nice one.


I've felt driveline angle issues, and when it was the pinion setting - the vibration felt "rear" and sounded "rear". It was also usually MUCH more pronounced than what Sieg is dealing with.


This felt more "harmonic" to me. I think it's the too short (and perhaps unbalanced) driveline "orbiting"... and it may have already ruined the output shaft bearing - or at least - being in the process of doing that. The output shaft is already unsupported for a pretty good distance... then you hang a driveline on it.

I'm still sticking with imbalanced drive shaft.

the other thing it COULD be is the trans itself, we have had a car in here with an old t56 LS1 type, it would only vibrate in 5th and 6th, customer had the trans rebuilt and said it was MUCH better. seems a lot of the drive shaft over speed could be the cause??
Scott why are you using a 3.5" steel shaft? seems a bit over kill. and even if it is .083 wall DOM it will be really heavy. my 1000 hp drag car only uses a 3" steel shaft. on the cars that we have used aluminum shafts in the issue does not seem to be as apparent.

Well..... you know what ASSume means. :lolhit:

Ruined bearing...........NOOOOOOOO! I hear you but I don't want too! Besides I'm not in the mood. :D

It well could be, though the feeling through the shifter has not changed. Sounds like that shaft needs to go to the local shop and be checked for balance first, then lengthened and balanced for the proper rpm range.

Blake - This shaft was supplied with the Hurst Drivelines kit. The trans is a T56 Mag, close ratio.

I'll check the local shops pricing on aluminum as it sounds like to be buttery smooth aluminum is the way to go in OD trans applications.

I took a brief break............just so you gentlemen know I respect your input:

http://photos.smugmug.com/photos/i-D...DdZzHrB-XL.jpg

http://photos.smugmug.com/photos/i-s...sdgBWtd-X2.jpg

I was glad to see the amount of yoke over the shaft, but another .5" wouldn't hurt. The photo distorts the measurement the actual coverage is 3-1/8"

Is that enough in your opinion?

If so re-balancing would be a lot cheaper than building a new shaft to gain a half inch. :D

Some times it's not about how much you put in --- it's about how much you leave hanging out. <oh if you could see the grin right now!>


I might add to this thought -- that Amy would certainly understand you're asking her to get a second full time job - so that you could get a new shaft.