I put new springs on my 69 Malibu all the way around and got it back to stock height. It drove fine. Then put air shocks in back to get another 1-2 inches up. With 30 psi in the shocks the rear is raised about 1/2 inch above the level with the old shocks and it drives fine, but any more pressure than that and I get a vibration between 35-45 mph. Does this indicate a problem somewhere in the drivetrain or have I just changed the angle of something enough to cause problems that are not going to go away no matter what (if I replace U joints is this likely to continue)?

Thanks for any ideas! Dave.

If it walks like a duck and it quacks like a duck it most likely is a duck. It seems that you have it down to the air in the bags: the question is this. Is the air causing the vibe to appear in a place that it has not been visible (the joints) or is the air itself enough to make a driveline that is in good mech shape vibrate due to the cumulative angles.

I think that you have changed the angle of the pinion enough to introduce a vibration. Most likely the additional helght is just enough to enter a range where the angles along the drive shaft are out of sync enough to cause the problem. It could be a U-Joint that was already bad but not yet displaying any problems till ya raise the rear and altered the running characteristics of the joint.

U-Joints are cheap. If the joints in your car appear OK when you remove them then you are only out what $25 / $30? Replace them and try the air at a stock height then at a raised height. You will know real quick.

I hate messin with jacked up rears for a lot of reason. For me ANY vibration is unacceptable and anything that adds vibrations has to be removed from the car right now. Cannot stand all the shaking and vibration.


Try the joints first they are cheap.

Dave,

I have had air shocks, air bags, and ladder bars on the back of my 69, and never a vibration. I've had the back up above the tires by two inches, and down over the tires by a good inch or more. Not once did I ever get a bad vib, so my guess is that something is not right in the rear, bushings, u-joints, or something is either bad or loose.

Fred.

The easiest thing to try is switching your wheels from front to back. Maybe you lost a weight. If the vibration changes after that, then more than likely you have a wheel/tire problem . Also check your tranny mount , see if it has sagged.

I'd check the bushings in all of the rear control arms. By loading differently, you may be stressing the bushings in a different manner. Worth a look.

I would take the air shocks off right after fixing the problem
air shocks tend to destroy the upper shock mount area there are many better ways to lift the rear of the car up without using air shocks
plus air shocks take away from the handling of the car

I never had an air shock destroy anything in the shock mounting areas or negetively affect the ride...might have been a little stiffer though?? What did you do to yours to make it damage the mount?


Tazz

Tazz,
Shock absorber mounts are not designed to support the weight of the vehicle, or any weight at all as far as that goes. If you use air shocks long enough, it will mess up the shock mounts .... BTDT.

In 1979 i bought a 72 Chevelle with factory air shocks(even had steel lines) I had 140,000 miles on it before I wrecked it. It was jacked up with N-50 tires like we did back then. There was no vibration problems and no shock mount problems. The chevelle I have now I bought in 1982. It has had Air shocks all this time, It had them when I bought it. It was my daily driver for years, and has had well over 2000 drag strip passes. I keep them on there because I drive the car to the track and need to haul a lot of supplies with me. then I can air down to race. I have never had a shock mount problem or a vibration. If you dont know the condition of your u-joints you should just change them anyway, its cheap insurance.

If the factory offered air shocks in the El camino as stock, they would not do so if it damaged the body shock supports as that is warranty work the factory would not want to have to cover. So no, air shocks do not destroy upper shock mounts.