weird shudder

[Hambo-180]

folks,
i've got a weird shudder coming from the front, only happens above 70mph and gets more noticeable the higher the speed.
I've had the wheels balanced, swapped round etc etc but no joy, its not the brake discs as they are new.
It feels like a flat spot on a bearing or something.
Any ideas? Couple of folk have mentioned drive shaft but how do i get it checked?
Your thoughts would be appreciated.....

[peterzs]

Did it start after the new disks were fitted???

You have to clear all the rust and muck off the mating surfaces of the disks.

Not a flat spotted wheel where you have fallen into a pot hole. Know you said they have been swapped around but did you do fronts to back????

Have the wheels balanced on the car???

Have no idea really just things I would check to eliminate, before getting into the drive shafts, which I wouldnt know what end to look at!!!!

Best of luck with it, hope you solve the prob.

[Ritchy]

just because they are new discs doesnt mean they arent warped mate, does it get woorse when touching the brake?
you can get on car balancing where the whole driveline effectivly gets balanced, my work has a balancer but youd be better going to a tyre place that has one tbh,

[Hambo-180]

thanks lads, the brakes were cleaned etc before the new dics were fitted, wheels have been swapped back to front, side to side, corner to opposite corner and balanced within an inch of their lives!!!!
Ritchy, it doesnt get worse when braking and nothing through the pedal. Sounds like the on car balancing would be an idea, is it expensive? Do you know any tyre places off hand that has the equipment? How much would your place charge? (sounds like 20 questions here!!)

[Ritchy]

Clydebank tyre centre might have one, not sure though, and ours hasnt been calibrated in years so id think about going somewhere else first lol

[Hambo-180]

thanks Ritchy appreciate it....

[BUCKYDEVIL]

Have you had the tracking looked at or Track rod ends ?
Jack car up at front and see if there's any excessive play either side.

[zsserbia]

Here's what I found on another forum, on the exact shudder above 70 mph and I quote:

"Whatever you do, please find a new tire dealer. If they won't adjust tires that are defective, they give the rest of us a bad name. Both excessive lateral and radial runout are justifiable reasons for adjustments. Naturally, the higher quality level tire you buy, the more they are inspected by the manufacturers, or so they try to tell us. In fact, that is one of the main reasons why they charge more for the premium tires. Michelin, a FRENCH manufacturer, is the only one that still hand inspects every tire and it shows in their prices. Also, they own BF Goodrich and Uniroyal, however, they are inspected like all the other brands, with X-ray machines. It is hard to beat the eye of a well trained inspector, though.
I can't help but think that if you were dealing with a first class establishment they would be willing to check your tires closely. Certainly turning the tires 90 degrees on the rim, at a time, can sometimes eliminate excessive runout and balance problems, but if the tire is truly out of plumb, you probably can never get it completely out. Also, if the car manufacturer reccomends a certain speed rating for your car, V or H generally, don't try to run a lesser tire and expect good performance.
Vehicles from Europe seem to have certain expectations of quality designed in them where tires are concerned. Volvo, Audi and Mercedes Benz seem to demand tighter standards because the sensitivity built into their front [and rear] suspensions will pickup any out of plumb and send it to the steering and suspension and create sensations of rapid vibrations. It helps to dismount the tires and check the runout of the wheel as well. Also, the offset of the wheels must be close to the spec or it can put extra stress on the steering geometry sometimes more than the amount it will stand without balking.
Good luck."

I'm no expert, maybe he thought 180 degrees, but Ritchy may know about this runout of the tires... All I know it's present and I've experienced it on some tires on some other cars. Thing he says about michelin may be true. When I first bought my ZS it had firestones tz200 on the front, looked as new but they had shudder/runout at exactly 37 mph. As said, balancing could not cure it. I had almost dead michelin pilot sports at the back but at least they were so quiet.

Here's another quote:

"Drive the vehicle at exactly 6-7 mph on a perfectly smooth road (I realize the difficulty here........).

Look for your head to bob ever so slightly in response to the rotation of the tires. The frequency will be 1.5 cycles per second. If you sense this, then the tires and/or the tire wheel combo is out of round. All the balancing in the world won't cure it. The tires must be rotated on the wheels to minimize it. However, the typical runout of most of the tires today is just not acceptable on a M/B (mercedes/benz). It's highly sensitive to runout of the tires..........a condition that is totally ignored by the tire dealers.

My suspicion is that most BF Goodrich won't meet the runout requirements of a M/B.

Good luck. I've had to eat some tires in the past due to this condition. The dealer won't take them back on warranty."

Hope this helps m8. Cheers

[Hambo-180]

Here's what I found on another forum, on the exact shudder above 70 mph and I quote:

"Whatever you do, please find a new tire dealer. If they won't adjust tires that are defective, they give the rest of us a bad name. Both excessive lateral and radial runout are justifiable reasons for adjustments. Naturally, the higher quality level tire you buy, the more they are inspected by the manufacturers, or so they try to tell us. In fact, that is one of the main reasons why they charge more for the premium tires. Michelin, a FRENCH manufacturer, is the only one that still hand inspects every tire and it shows in their prices. Also, they own BF Goodrich and Uniroyal, however, they are inspected like all the other brands, with X-ray machines. It is hard to beat the eye of a well trained inspector, though.
I can't help but think that if you were dealing with a first class establishment they would be willing to check your tires closely. Certainly turning the tires 90 degrees on the rim, at a time, can sometimes eliminate excessive runout and balance problems, but if the tire is truly out of plumb, you probably can never get it completely out. Also, if the car manufacturer reccomends a certain speed rating for your car, V or H generally, don't try to run a lesser tire and expect good performance.
Vehicles from Europe seem to have certain expectations of quality designed in them where tires are concerned. Volvo, Audi and Mercedes Benz seem to demand tighter standards because the sensitivity built into their front [and rear] suspensions will pickup any out of plumb and send it to the steering and suspension and create sensations of rapid vibrations. It helps to dismount the tires and check the runout of the wheel as well. Also, the offset of the wheels must be close to the spec or it can put extra stress on the steering geometry sometimes more than the amount it will stand without balking.
Good luck."

I'm no expert, maybe he thought 180 degrees, but Ritchy may know about this runout of the tires... All I know it's present and I've experienced it on some tires on some other cars. Thing he says about michelin may be true. When I first bought my ZS it had firestones tz200 on the front, looked as new but they had shudder/runout at exactly 37 mph. As said, balancing could not cure it. I had almost dead michelin pilot sports at the back but at least they were so quiet.

Here's another quote:

"Drive the vehicle at exactly 6-7 mph on a perfectly smooth road (I realize the difficulty here........).

Look for your head to bob ever so slightly in response to the rotation of the tires. The frequency will be 1.5 cycles per second. If you sense this, then the tires and/or the tire wheel combo is out of round. All the balancing in the world won't cure it. The tires must be rotated on the wheels to minimize it. However, the typical runout of most of the tires today is just not acceptable on a M/B (mercedes/benz). It's highly sensitive to runout of the tires..........a condition that is totally ignored by the tire dealers.

My suspicion is that most BF Goodrich won't meet the runout requirements of a M/B.

Good luck. I've had to eat some tires in the past due to this condition. The dealer won't take them back on warranty."

Hope this helps m8. Cheers

interesting read, thanks mate!