khutchinson22

This is about the most obnoxious vibration I have ever tried to trace down and I have had about enough.

Repairs so far in no particular order;

Accumulators
Pulsation Dampener
Air Cell
Rear Tires
Brake Rotor Resurface x 4
Repair Wheel Imperfections x 4
Road Force Balance (3 times all around)
Transmission Mount

I'm sure there's others but seriously....WHAT THE **** ELSE COULD IT BE?!?

Here's the kicker....EVERY time the car is off the ground (could be a day or an hour) it drives smooth for a day or two and then it's back to the 70-90mph vibration.

What in the system would cause it to be smooth driving after being off the ground and then produce a vibration later? Bad/Leaky strut? There is no fluid ANYWHERE! Absolutely ZERO leaks. Is it possible that one or more struts could be leaking air and not fluid?

BlownV8

When my CL was having the exact same issues, it was the wheels. The system is very sensitive to any imperfections in the wheels/tires.

khutchinson22

The wheels have been repaired. Besides, if it were the wheels then why would it drive smooth after being off the ground for a while followed by the vibration returning? This makes NO sense to me at all.

gslse21b

The only time I've had freeway vibration like that was when the motor mounts were collapsed . 2 cl55s and 2 cl65s . Both 65s had them replaced twice in less than 20k miles

khutchinson22

But did the vibration clear up after the car had been in the air and then return? If this were motor mounts then the car in the air factor wouldn't change anything. This HAS to be suspension related.

castroadan

I would second the wheels. If you can get some spare wheels to try out and take it for a drive and see if it goes away.

khutchinson22

As stated in the original post the wheels have been repaired. They are within .0015. However, I would love to throw some factory ones on for a few days and see if that fixes it but I don't have access to any and to buy a used pair on the off chance that it solves the problem seems fleeting.

What everyone seems to be missing here is that THE VIBRATION STOPS AFTER THE CAR HAS BEEN OFF THE GROUND. Wheels, motor mounts, etc would not play into that scenario.

castroadan

I would still try to get some loaner wheels so you can cancel that out. I had a similar vibration on my other car and it turned out to be the wheels.

gslse21b

4 cars same symptoms . Same resolution .: mine were all unnoticeable until I was between 70-80 crusing on the freeway . Anything under 70 felt normal

RaceHorse

I am going to suggest checking the drive shaft, specifically the center where the U joint and carrier bearing are. When you have the car on a lift the rear will drop as the suspension sags. This will change the angle at the U joint. Maybe if there is a little play in the bearing or where the 2 halves of the shaft connect it may re-position itself for a bit until its placed under heavy load and then pushed backed into a warn vibrating position. The torque always loads up the one side based on the direction or rotation. Good luck.

khutchinson22

And under other circumstances I would check that but as mentioned I have already had the wheels repaired. Also, this still doesnt explain why it drives fine after its been on a lift and then returns days later.

khutchinson22

I will give this a shot. I already have the bearing. Going to order the rubber mount this week. In this case, would it make sense that these symptoms would only present when the rear of the car is lifted? To be clear, in your scenario, if i jack up just the front of the car and then let it down the vibration should remain. If it goes away then it would mean it is likely not drive shaft related and probably something else in the front end. I hope im being clear. This is a very strange problem sandwich.

khutchinson22

Before you cganged the wheels out did the vibration go away after the car was lifted only to return days later after being driven a couple times? If so, i will focus my attention on locaring a set of wheels.

Anyone in or near St Louis, MO wanna swap rims for a couple days?

RaceHorse

Just jacking up the front is not a bad idea in trying to rule out the location if it remains or goes away. I'm just guessing at it since wheel vibration from a bent wheel or bad tire should always be there at a certain speed, not come and go from one day to the next. If the vibration goes away from lifting the front I would consider an alignment if you already haven't done that.

Welwynnick

These cars are prone to strut top bush wear. If the bush becomes worn, it will collapse slightly, and go slack on rebound. When the weight is on the wheel, the compression bush will be loaded and everything is OK, but the rebound bush may have a gap.

Going slowly on smooth surfaces is no problem, but high speed or broken roads mean the damper is no longer controlling the wheel movement properly, and the unsprung mass can oscillate vertically at quite high frequency against the compliance of the tyre.

I haven't explained this very well, but its an endemic problem that few are aware of, and its dead easy to spot.

Jack up each corner in turn so the tire is just off the ground. Now shake the wheel up and down hard. It shouldn't move at all, but if the bush has worn, the whole wheel will move up and down freely by a fraction. If that's the case, the car will never drive right.

If it's a front strut bush, there's a cheap and easy fix I can tell you about. If it's a rear strut bush, I'm afraid you need to change the strut.

This may or may not be the solution, but its a common problem, and its easy to check for.

Edit: It might also be consistent with your wheels-off-ground observation.

Nick

khutchinson22

I had been meaning to mention that this needed to be done as well. I went ahead and fixed both front strut bushings last night and it made no difference.

slonar21

What kind of tires do you have?
Is it possible your tires aren't rated for the weight of the car and they get some kind of flat spot when stationary?

When my car gets out of storage I get that type of vibration for a day or two

khutchinson22

If that were the case it would be a constant vibration. This is not. It rides smooth for a couple of days after its been on a lift then the vibration returns again. Some days are also worse than others. For example, yesterday driving into work i had to really pay attention to feel it but on the way home it was really bad.

Dr Matt

Like slonar21 said, if the tires are flat spotting, it would be worse the longer it sits still on the tires, but not present after sitting on a lift. However, in my experience with tires that do that the vibration goes away after they run long enough to get warm, which may be more than 10 miles of cruising at or near highway speeds. My M&H drag radials did this on my Lightning after sitting for a while, but the traction was soooo worth it...

khutchinson22

If I jump on the highway and the vibration is there it stays there. Makes no difference how long I drive it. If I get on the highway and the vibration is feint it stays that way. The vibration is there more often than not.

I think I mentioned this already but I'll say it again. A road force balance was performed not long ago on a machine that had been calibrated the day prior. The tires and wheels are fine. That being said, I still want to put a set of stock wheels on for a few days and see what happens.

khutchinson22

Update:

Checked the wheel bearings and the fronts were pretty loose. Tightened those up and it seemed to improve the ride but the main vibration is still there. Almost like the bearings were part of it but not the actual cause.

Something strange I also noticed was that even though the car was on the rack the vibration did not temporarily go away this time like it usually does.

The vibration is also appearing in a broader range. Instead of happening between 80-95 its noticeable between 60-100.

Welwynnick

Obvious one I know, but are all the rotors sitting flat on the hubs?

Nick

khutchinson22

Yes, they should be. I pulled them to have them resurfaced and didn't notice any obstruction.

Welwynnick

When the wheels are off, when you spin the discs, is there a uniform friction resistance from the pads?

When the wheels are on and you spin them round, does the tyre tread move in and out at all?
Does the wheel rim move in and out at all? Especially the vulnerable inside rims?

Does the vibration change when you change gear, or is it just speed related?

Nick

khutchinson22

I will check both tomorrow.

Gear makes no difference. I've tried many combinations including gear and ride hight. Speed related only.