help with driveline angles
06-09-2018, 08:36 PM
#1
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help with driveline angles ok guys i have a 78 camaro that i have swapped a 6.0/4l80e into. its lowered both in the front and back. i have a slight vibration. ive read quite a bit on angles but i keep getting confused on whether to add or subtract the angles so im hoping yall can help. so i measured the angles from the valley cover, the driveshaft and the pinion ujoint cap.
the transmission is 4.3 degrees tail down
the driveshaft is .4 degrees higher on the pinion side
the pinion is 1.4 degrees with the ujoint side of the rear end downward.
its leaf springs
what do yall recommend or is it good.
the transmission is 4.3 degrees tail down
the driveshaft is .4 degrees higher on the pinion side
the pinion is 1.4 degrees with the ujoint side of the rear end downward.
its leaf springs
what do yall recommend or is it good.
06-09-2018, 09:22 PM
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06-10-2018, 01:44 PM
#5
If the numbers you gave are accurate you have a 4.7 degree front operating angle and a 1 degree rear operating angle for your u joints. This will cause the vibration you are experiencing. Ideally, you want equal and opposite angles no greater than 3 degrees for u joints. If you have no room to raise the tail of the transmission significantly to improve your angles you may need to look into a CV joint driveshaft from somewhere like the driveshaft shop.
06-10-2018, 02:59 PM
#6
The “equal/opposite angle” guideline is for non-leaf spring suspensions - he has leafs. With leafs, the rearend winds up under acceleration - I think prevailing wisdom is to statically have the pinion a degree or 2 less “up” than the tranny is “down” so that when it lifts under acceleration, it’ll be close to equal/opposite dynamically.
06-10-2018, 08:08 PM
#7
Good call. My car being an A-body I don't automatically think of axle wrap on a leaf spring car. Either way, his angles need some work. Maybe some axle shims can get there with raising the trans, but there is some work to be done.
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06-11-2018, 06:22 PM
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ok so heres what im thinking, try to raise the trans a little, also gonna raise the car like 1 inch in the back which should put the driveshaft from sloping up from the front to sloping down from the front. then maybe pinion shim if i need. any thoughts on all that?
06-11-2018, 07:00 PM
#10
Aesthetically - do you WANT to raise the car 1" in the rear? I mean, '78 jacked up Camaro and we're gonna have a mullet joke in here shortly....
Seriously, unless the rear end of the car NEEDS to be raised, I'd focus on moving the tranny and shimming to change the pinion angle until you get the ujoint angles you need.
Seriously, unless the rear end of the car NEEDS to be raised, I'd focus on moving the tranny and shimming to change the pinion angle until you get the ujoint angles you need.
Last edited by Michael Yount; 06-11-2018 at 07:07 PM.
06-12-2018, 07:00 PM
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lol its almost to low right now so i can get away with up to an inch before i have to buy a wife beater and grow the mullet lol ill try to get the trans up as much as i can first i guess. hopefully i can do some pounding on the floor to allow me to come up some.
06-12-2018, 07:51 PM
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The transmission down angle should be equal to the rear axle up angle when referenced to a level plane. A couple degrees should not cause much problems. I bought a Johnson "magnetic protractor angle locator" at Menards and use it for many other uses besides this. Part # 53-004. I have Jeep with a 5.3 LS and Ford 8.8 axle with a very short drive shaft and I installed traction bars to stop axle wrap with the increased torque available. The transmission and axle degrees of angle are with in 1 degree as I can measure it on mine.