Driveline vib, driveline angle measurements inside, help! I'm trying to track down a driveline vibration that occurs at highway speed, usually 65mph+ and gets worse as you go faster. I just checked all driveline angles with a magnetic angle finder and have the following info: Transmission angle: 3.5 deg downward Pinion angle: 1 deg upwards Driveshaft angle: 1 deg sloping downward from trans to rear pinion. I am running a 4l80e trans with holley crossmember and a poly mount. 4th gen rear with a brand new custom steel balanced driveshaft. Do these angles look ok? The holley crossmember has adjustment in the torque arm that will change pinion angle if needed. Any help would be great! |
Re: Driveline vib, driveline angle measurements inside, help! No, not really OK... Ideally you want the trans and the pinion at the same angle. I.e. if you drew a straight line through each, the lines would be parallel. Yours are not. If you can raise the front end of the torque arm, that's the direction the pinion needs to go. About 2½° or so. Maybe just a bit less, ½° maybe, so that when engine torque does what it does, which is to raise the pinion slightly, they're parallel when powered. |
Re: Driveline vib, driveline angle measurements inside, help! Thanks! Will try to get it adjusted tomorrow. Could I also shim the trans bracket to reduce the downward angle to match the 1 deg upward angle of the pinion?? Just looking for a few options. |
Re: Driveline vib, driveline angle measurements inside, help! You could try that; I guess it would depend on how much tunnel clearance you have. I doubt it would be as effective as adjusting the rear's angle though. Try the correct, designed-in approach first. |
Re: Driveline vib, driveline angle measurements inside, help!
Originally Posted by sofakingdom
(Post 6279455)
You could try that; I guess it would depend on how much tunnel clearance you have. I doubt it would be as effective as adjusting the rear's angle though. Try the correct, designed-in approach first. |
Re: Driveline vib, driveline angle measurements inside, help! adjusted the mount to its max setting and ended up with the following angles: Transmission angle: 3.5 deg downward Pinion angle: 2 deg upwards So i gained one degree by adjusting my torque arm mounting position on the crossmember. Took the car for a quick spin and it felt better, but will have to get some highway miles logged to really tell. Getting an alignment tomorrow, may try to put some miles on after I get it back. |
Re: Driveline vib, driveline angle measurements inside, help!
Originally Posted by sofakingdom
(Post 6279365)
No, not really OK... Ideally you want the trans and the pinion at the same angle. I.e. if you drew a straight line through each, the lines would be parallel. Yours are not. If you can raise the front end of the torque arm, that's the direction the pinion needs to go. About 2½° or so. Maybe just a bit less, ½° maybe, so that when engine torque does what it does, which is to raise the pinion slightly, they're parallel when powered. |
Re: Driveline vib, driveline angle measurements inside, help! trans is angled toward the ground, the driveshaft is almost level and the rear points up All of that of course, with the car sitting on a level surface, with the suspension at normal ride height... doing this on ramps with somebody about your size sitting in the driver's seat, somebody else about your SO's size in the pass seat, and a full tank of gas, is a great way to get that part right. |
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