T56 driveline vibration
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From: NH
T56 driveline vibration I took my Camaro for it's first ride with the LS1 and T56 installed. Just 4 miles to calibrate my Autometer speedo. I get a lot of vibration from the tailshaft of the T56. Seems to be under all load conditions, like part throttle, cruise, etc. I checked pinion angles because the T56 had to be lowered about 1.25 inches (compared to the Th400). The angle from the front u-joint bearing cap to the top of the driveshaft is 4.5 degrees. The angle at the 9" rearend from the u-joint bearing cap to the bottom of the driveshaft is 10 degerees. I read that these angles should be within .5 degrees of each other. My 9" was installed many years ago, but I had it installed with drag racing in mind and it was set at -4 degrees. (4 degrees pointing down towards the ground). So, how can I fix it? I read on another post about those 2 degree shims from CE or Moroso and I had used them before, but do they sell them in 4 degree increments? What did you guys do? Suggestions please.
On The Tree
Joined: Nov 2001
Posts: 157
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From: Orlando, FL
Re: T56 driveline vibration you're on it. The driveline to yoke angle on the rear end should be equal to the angle on the transmission so that the pinion shaft and transmission tailshaft are parallel to each other. You didn't tell us what kind of rear suspension you've got ... so I'll assume leaf spring. The Moroso angle shims you mention are the way to go to fix your problem short of moving the leaf pads on the housing. Use two shims per side ... that will be 4 degrees. You might want to consider tack-welding them together so they don't move around as much.
Now with all that said, 4.5 degrees (1 to 2 degrees is ideal) is still a lot of angle, just about the end of what most u-joints are designed to handle without vibration. So even if you get the rear end fixed up, you may still have some vibration at higher driveline speeds. You'll have to try it and see.
Good luck,
John Parsons
Now with all that said, 4.5 degrees (1 to 2 degrees is ideal) is still a lot of angle, just about the end of what most u-joints are designed to handle without vibration. So even if you get the rear end fixed up, you may still have some vibration at higher driveline speeds. You'll have to try it and see.
Good luck,
John Parsons
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From: NH
Re: T56 driveline vibration John,
What I do not understand is that if I measure the angle at the T56 yoke end from the top of the ujoint bearing cap to the top of the driveshaft I get 4.5 degrees, if I measure from below I get around 1 or 2 degrees. Shouldn't they be the same?
What I do not understand is that if I measure the angle at the T56 yoke end from the top of the ujoint bearing cap to the top of the driveshaft I get 4.5 degrees, if I measure from below I get around 1 or 2 degrees. Shouldn't they be the same?
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From: NH
Re: T56 driveline vibration Alright, I still have vibration at part throttle cruising. I now have 6 degree shims made to my spec. This creates a 2 degree working angle at the rear end. The pinion points 2 degrees up and the driveshaft is 4 degrees down. At the tranny end, I again have the 4 degrees driveshaft and about 6 degrees on the tranny. So, they cancel. This didn't help at all. I still have some misalignment side to side. I have not measured it but what should it be? The tranny doesn't fit exactly in the center of the tunnel anymore and the 9 inch rear end pinion is off center to the same side. Maybe this is the problem? 
Re: T56 driveline vibration Side to side misalignment is not that critical. Although you want it to be alligned in a similar way. If you were to look at the car straight from the top or bottom, is the pinion shaft parallel to the output shaft of the transmission?
Andrew
Andrew
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From: NH
Re: T56 driveline vibration I would say it is close. I know the pinion is straight in the car with the leaf spring mounting. As for the tranny...when I loosen the bolt on the mount it moves a little to the pass side mainly because of the interference with the driver's exhaust manifold and the steering box. But, for the most part the shifter comes through the stock tunnel with a little modification to the pass side. I imagine the motor mounts do not allow this to twist side to side very much.
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Teching In
Joined: Jan 2003
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From: Baton Rouge LA
Re: T56 driveline vibration This was addressed recently on the Chevytalk board. I found out a lot due to the discussion, besides there are several links to tech articles in the post.
http://www.chevytalk.org/threads/sho...&fpart=all
http://www.chevytalk.org/threads/sho...&fpart=all
Staging Lane
Joined: Jan 2003
Posts: 57
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From: NJ
Re: T56 driveline vibration As far as I know side to side misalignment makes no diffrence, I read that somewhere. But your Engine might not paralel to the center of the car due to manifold clearence problem.
I had the same problem when I put my motor in the car and engine did not looked centered so I had to gring the manifold and put O2 sensor on the egzost and now engine is centered and there is enough clearence manifold to steering box. By the way i used S&P motor mount adapters and have iroc steering box.
Good luck
I had the same problem when I put my motor in the car and engine did not looked centered so I had to gring the manifold and put O2 sensor on the egzost and now engine is centered and there is enough clearence manifold to steering box. By the way i used S&P motor mount adapters and have iroc steering box.
Good luck
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From: NH
Re: T56 driveline vibration Yeah, I already ground it down and redrilled the 3 hole pattern and relocated the O2 sensor. So, there is still some minor misalignment side to side but it looks straight.
Re: T56 driveline vibration What's the full history of the driveline (shaft)? Did you use the same one & shorten it for the T56? Who put the u-joints in? They might be too tight.
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From: NH
Re: T56 driveline vibration I used the same one. It didn't require shortening. Just by luck. The u-joints where replaced with new ones to mate the T56 yoke to my shaft. The whole thing was done by a local driveshaft shop who I have used in the past. They installed new joints and balanced it.
