70 Mach Driveline vibration

[commonrail]

Anyone know how much clearance is allowable between the tailstock bushing of a Tremec 3550 ( or any gearbox) and the Yoke? Mine feels kind of sloppy, although I don't have hardly any miles on it! I'm certain I would have noticed this sloppiness during the build. All the parts were new, and now I'm worried about wearing out pieces or spitting out the driveshaft!
I rebuilt the rear axle ( tractionloc 3.70's), and it has new currie axles, bearings, you name it. I feel comfortable with the work there!
I'm chasing a rearend, or drive line vibration, and I could use some input from you guys! The vibration becomes noticeable at around 70, and at 75 or higher it feels critical!

 

[truck90278]

Have you balanced your driveshaft. Driveshafts out of balance will cause vibration

 

[commonrail]

The drive shaft was ballanced when it was built for the Tremec swap. I may remove it and have it checked though. I can see that weight was added at the aft end near the rear U-Joint. I would like to assume that it was done properly, but I am open to getting it re-ballanced.... anything else!
Anyone out there ever heard of a slightly bent rear axle housing causing this?

 

[TOM B]

I would check the book on the amount of play aloud in that bushing then would look at my tires and rims, I would have them balanced before the driveshaft again, some tire places do a real cheap and fast balance because it saves them time and money. I had a guy at pep boys put on 30 ounces on one spot till I told him to take them off and spin the tire, then he needed only 4 ounces.but he bitc*ed because he had to do it right.

 

[commonrail]

Tom,
Thanks, I had a reputable Goodyear store mount the tires on the rims. I'm running P.S. engineering 17s with goodyear F1s. I was standing next to the tire guy when he spun them. They were running straight and appear true. I don't recall more than 1/2 ounce added to any of the wheels. I will recheck them though, because I want to eliminate that from possible causes.

 

[MitchGT]

If your rim and tire combo are all the same size, you can swap front to back and see if you have the problem still. Also, how is your driveline angle? That could cause a speed related vibration, AND cause the yoke to wear out the tailshaft of the tranny....

 

[commonrail]

I will verify the driveline angle at the tailshaft yoke to shaft vs the pinion angle to shaft. I believe that both are pointed down slightly, but I will admit I can't put an exact figure to the angles. Do you, or anybody else know what the maximum allowable difference is between front vs rear driveline angles? Is there any reference articles available online, or published. I know there are standards for heavy Truck & Marine Driveshafts/Cardon shafts. I would like to put some SAE standard into checking this then if I make an adjustment(angles) I can put that issue to rest! Thanks for all your comments/patience.
OH about the tires, they are staggered width so they stay put! Quite certain they are O.K though.