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Drive line vibration

7K views 15 replies 8 participants last post by  61Airstream 
#1 ·
Had my driveshaft balanced today. New yoke and bearings. I still have some vibration, if not more than before. Could the transmission tail shaft bushing be bad and not have any leaks or noticable play? Can this bushing be replaced without dropping the transmission?
I had the wheels balanced at the same time. I am assuming the wheels were done correctly. Is there a way to tell the difference between the wheel out of balance and the drive line?

Jim
 
#11 ·
A driveline vibration will be much faster than a vibration caused by a tire balance issue. You can usually feel a driveline vibration more through the floor boards, a tire through the seat or steering wheel.
 
#12 ·
Jim, it might also be associated with Pinion Angle. Mine was off, and adjusting it helped. Most of the Pinion angle issue I had was the Trans Mount was perished, and allowed the end of the trans to drop about 1/4". That was enough to throw off the pinon angles. BTW, the stock rear arms have enough play in them to create +/- 1* of pinion angle change. I didn't know that until I read it in the service manual.

From another site:
If there is vibration under acceleration, you need to add more downward pinion angle preload. If the opposite occurs, the vibrations tends to decrease or disappear under acceleration, you need to reduce the downward angle preload.

If the vibration steadily increases with driveshaft speed (either accelerating or decelerating) the symptom is primarily the result of a driveshaft imbalance or yoke runout. Sometimes this yoke runout problem can be improved by rotating the U-joint 180-degrees in the rear end differential yoke.

Driveshaft-related vibrations usually occur at roughly engine speed in high gear. Wheel/axle vibrations usually occur at 1/3 rd engine speed or driveshaft speed because of the differential gearing. To determining whether it is the output of the transmission or the pinion in the differential, change gears when the noise occurs and maintain speed. If the vibration/noise changes in frequency, the source is in the transmission or engine. If the frequency remains the same it is a driveline problem.



Another thing. I had my tires "Road Force" balanced. This method will find and bad spots in the wheel or tire, and suggest "spinning" the tire on the wheel to offset any variations. 2 of my 4 tires needed spinning.

Here's a good checklist for vibrations.
http://csgbenefits.org/camarovibration.pdf
 
#13 ·
Jim, it might also be associated with Pinion Angle. Mine was off, and adjusting it helped. Most of the Pinion angle issue I had was the Trans Mount was perished, and allowed the end of the trans to drop about 1/4". That was enough to throw off the pinon angles. BTW, the stock rear arms have enough play in them to create +/- 1* of pinion angle change. I didn't know that until I read it in the service manual.

From another site:
If there is vibration under acceleration, you need to add more downward pinion angle preload. If the opposite occurs, the vibrations tends to decrease or disappear under acceleration, you need to reduce the downward angle preload.

If the vibration steadily increases with driveshaft speed (either accelerating or decelerating) the symptom is primarily the result of a driveshaft imbalance or yoke runout. Sometimes this yoke runout problem can be improved by rotating the U-joint 180-degrees in the rear end differential yoke.

Driveshaft-related vibrations usually occur at roughly engine speed in high gear. Wheel/axle vibrations usually occur at 1/3 rd engine speed or driveshaft speed because of the differential gearing. To determining whether it is the output of the transmission or the pinion in the differential, change gears when the noise occurs and maintain speed. If the vibration/noise changes in frequency, the source is in the transmission or engine. If the frequency remains the same it is a driveline problem.



Another thing. I had my tires "Road Force" balanced. This method will find and bad spots in the wheel or tire, and suggest "spinning" the tire on the wheel to offset any variations. 2 of my 4 tires needed spinning.

Here's a good checklist for vibrations.
http://csgbenefits.org/camarovibration.pdf
 
#14 ·
Great information, Darbysan, thankyou. I may have more than one problem. I had some vibration before the drive shaft was balanced and I'm noticing it more now. I actually had it balanced twice at two different shops. The first shop balanced it fast and dirty. They spun it and just added a large weight at both ends. They didn't even grind off the original factory weight. In this condition, it was vibrating really badly and we added the hose clamps at the front to smooth it out somewhat. The second shop did a really nice job. They removed all the weights and checked the entired shaft for roundness. They found at least four places where the shaft was not true from the factory. They heated these humps with a torch and cooled them very quickly with water. They did all this while it was on the lathe. In one 12" section, they used a disk grinder as the shaft spun to smooth it out.
They were explaining to me that these shafts are not very true right out of the factory. You don't feel it when the car is new because all the bearings and bushing are so tight.

At any rate, i think I have a nice straight, well balanced drive shaft now. Since I don't notice the vibration much on acceleration i may have to reduce the downward pinion angle as you described.
However, I don't understand why I would feel more vibration after the driveshaft is balanced so well.
There doesn't seem to be any movement or play at the slip yoke. Do you think that the effect of wrong pinion angle would be more pronounced with the shaft balanced?

Jim
 
#15 ·
Shaft balance shouldn't have any affect on the pinion vibration. You can flip the driveshaft 180* at the pinion yoke- that sometimes helps. Also, make sure you are not over-tightening the yoke strap bolts. 15 Ft Lbs is the spec. Too tight, and the cups can restrict the bearings.
 
#16 ·
Shaft balance shouldn't have any affect on the pinion vibration. You can flip the driveshaft 180* at the pinion yoke- that sometimes helps. Also, make sure you are not over-tightening the yoke strap bolts. 15 Ft Lbs is the spec. Too tight, and the cups can restrict the bearings.
I wonder if the new unworn slip yoke is more sensitive to the incorrect pinion angle, where the old yoke was so worn the vibration wasn't as noticable?

Jim
 
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