Classic/Antique Car Repair/RR vibration
QUESTION: Hi, own a 79 RR, had 42,000 on it when purchased, several problems but the most pressing is a serious vibration at or around 55 mph, has to be coming from the rear of the car. Drive shaft rebuilt and balanced, half shafts rebuilt, new tires and balanced twice, all to no avail. Still shakes.
Any ideas, Im out of them....
ANSWER: Hi George:
A few things that could cause such vibration.
1. Wheel Bearings, but they would be noisy as well.
2. Hydraulic Leveling System Bearings, but vibration usually occurs when there is a load in the back (e.g. back seat or trunk).
3. A bent wheel/rim would cause this even if the tires are balanced, but a good tire guy should have checked your rims first.
I once had a problem with front-end vibration and took the car to two difference places to have the tires check and balanced. The second place balance them twice. The car still would vibrate at 55 mph. I called a old mechanic friend of minds and explain the problem. He said "your tires are not balanced". I told him "Yes they are. I have it done 3 times by two different shops. He explain how some shop equipment is faulty and the technicians don't pay close attention to the computer read-out and where its telling you to "EXACTLY" put the weights.
He suggested I try someone he knew that really knows what he is doing at Discount Tire. I took the car there. They computer balanced the tires again and told me the balance was way off. I suggested the idiots that balance it before him didn't know what they was doing. His response to be was "Did you take it to a tire place" I said, no. His response to that was, "when all you do is tires for a living, you tend to do it right or you are out of business".
Long story, but everybody with a balancing machine, can't balance tires...
---------- FOLLOW-UP ----------
QUESTION: I going to take your suggestion and do the tire balance the third time and cross my fingers.
You #2 suggestion interest me. This vibration is much worse with passengers in the back.
Could you explain in more detail about how the hydraulic leveling system could cause the 55 mph vib. One of my other problems is a clicking from the right rear leveler, I replace the sw and now back doing the same clicking... now wondering if the vibration and clicking are part of the same problem.
Absolutely. Forgot to mention, one of the signs of hydraulic bearings problem is the clicking sound from the driver-side rear. This is where they are located. Have a Rolls mechanic either clean the bearings real good or replace them. Often they just need a good cleaning. Especially if the vehicle have not been used a lot.
As the weight in the car changes with passengers, luggage, etc. These bearings may click once ever so lightly as the hydraulic system kicks in to adjust the car height. If you are hearing loud clicking constantly, these bearings are either dirty or worn. Vibration from this system tends to happen when climbing a hill or accelerating with passengers in the rear or front. The weight of the car is not correct and the whole car vibrates. If you don't feel any vibration in the steering wheel, I believe your tires are balanced and your problem is here.