Drive Shaft Angles

[Greg SmileZ]

I slipped in my test fit 350 block and my T-56 transmission into my '77. I checked the difference between the trans angle and rearend, it is 4 degrees. I am using the JTR engine mounts and will build the trans mount after I determine where to mount it. I can drop the rear of the trans to make the difference less than 4 degrees. Can anyone tell me what the desired difference should be?

[SpeedRacer]

Pete has some great information on driveshaft angle on his site http://tidalwave.net/~pparaska/ check it out.

[DennisK]

I was told by a customer of mine, a driveshaft shop, to shoot for 5 degrees. He said that too straight(close to 0 deg) would cause vibration. If that is correct, you should be OK.

[pparaska]

Woah there. Sure, straight (0 degrees) is not good, but pretty hard to obtain with the Z's layout.

 

Check my site's writeup on u-joint angles, http://members.home.net/pparaska/drivelinemods.htm . A 4 degree _DIFFERENCE_ in u-joint angles is way too much. Either angle being 5 degrees by them selves is also too much.

 

The front and rear u-joint angles for a V8Z (with a 20inch-ish driveshaft) should be 4 degrees or preferably less. Yes, one degree can make a difference. Ever ridden/driven in a V8Z or other powerful car that had driveline vibration under full torque? Very loud, Very rough, and unsafe. The u-joints will have much shorter life it the angles are too large or too far from each other (should be within 1 degree front and rear). There's a link on my site and this one to a very good write up by street rod builders on these issues.

 

There are two issues with u-joint angles:

 

1) The actual angle between the driveshaft centerline and the transmission out put shaft or differential pinion gear.

 

and

 

2) The difference between the front and rear u-joint angles. It should be no more than 1 degree, preferably zero.

 

I hate to be the party pooper, but I'd find a way to get the angles within 1 degree of each other and 4 degrees or less, if possible.

 

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Pete Paraska - 73 540Z - Marathon Z Project - pparaska@home.com">pparaska@home.com -

[DennisK]

I agree with Pete on all. It seems to me from all subjects that these are really starting points and fine tuning is needed for individual cars/setup. If memory serves, Mikelly has no vibration problems, and is using soild diff, and urethane engine/trans mounts, which JTR says will transmit noise/vibes. Mike, what angles are you running? Needless to say, my guy never worked on a Z V8, his was a general statement.

[Mikelly]

Mine is right at 3 degrees on either end. I did have some issues when I first installed the motor and trans, but made the JTR recommended mods to the mustach bar bushings and have had no adverse vibrations since.

 

Mike

 

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"I will not be a spectator in the sport of life!"

mjk

[John Scott]

I thought 0 degrees is what to shoot for. As long as the trans and diff. are on different planes the u joints will wear well. A straight shot from trans to rear is a no-no. The Z will have two offsets in relation to the diff centerline. First the engine is biased to the passenger side, and second the trans. is somewhat higher than the diff. I have a zero degree diff, but my engine is set so low this is easy to do. (Having your oil pan hanging out for any road hazard isn't the the best solution here. Probably better for lowering the C.G. and a good argument for a dry sump system) I've had some minor "mystery" vibrations I feel better urethane mounts would cure. The stock rear diff. mount seems sloppy to me, and with the power of some conversions, I think the solid mount is the way to go. The JTR fix with cable is a good recommendation, but the solid mount, noise or not will be the way I'll go.