I have recently put new tires (Michelin Pilot Sports' PS2) on my '01 coupe (30,000 mi) but it has an oscillating vibration at 65-70 mph. The tires have been rechecked by a very reputable mechanic. Has anyone else had a similar problem? Your help would be very much appreciated!
Thanks,

 

Get the tires and wheels checked on a Hunter 9700 road force balancer.

 

I had similar issues with my brand new PS2s.

The tech at the shop that I use was able to get my wheels/tires balanced on a Hunter 9700 (which checks for wheel force variation caused by things like out-of-round tires or bent wheels).

However, he had to break the beads on all 4 of my wheels/tires, reposition the tires on each wheel (matching the high spot of the tire with the low spot of the wheel or something like that ), temporarily overinflating each tire to 90 PSI (yes, 90 PSI ), and then backing the pressure down to 30 PSI.

The overinflating thing is wild (especially since the sidewalls are stamped 50 PSI max or something like that) but apparently this is common practice among experienced tire installers to help stretch the new rubber (especially along the bead where it can bind and cause balance issues) and get the tire to mate up against the rim properly

Larry

 

The two posts above contain the answer!!

 

Been there, still there and done that- Wheels & Tires (GSD3) new, rotated on rim per Hunter 9700Road Forced Balance three times, Hub Centric Rings installed, Four Wheel Alignment, issue still there on smooth roads. Not so noticeable on California roads as I'm to busy dodging the pot holes and ground swells. Going to go back to stock 03 wheels on my 98. Drove some other 03 vet and his did basically the same thing on the smooth road but not as bad. FWIW the weights on my rears were placed in the center line which did help. The fronts are on the inner edge and behind the spokes (motorsports). The friends weights are behind the spokes also and I'm told by tire tech that the best way to get a true balance and forego dynamic problems is by placing the weights on the outer edge and inner edge.
Personally, I'm fed up with the issue and wish someone had an answer the worked.

 

The old saying "You don't know until you are aware" holds true. My friend had never noticed the vibration in his Corvette with 45,000 miles and now does only after it was pointed out to him. Add another to chasing the rhythmic oscillating vibrating ghost.

 

When they road force balanced your tires - did they find any variance the last two times? If they didn't - the drive shaft coupler might be causing your vibration.

 

Get this done:

Brakes - Brake Rotor Lateral Runout Correction

File In Section: 05 - Brakes

Bulletin No.: 01~05-23-001A

Date: March, 2003

INFORMATION

Subject:
Brake Align(R) System for Brake Rotor Lateral Runout Correction

Models:
2003 and Prior Passenger Cars

This bulletin is being revised to add model years. Please discard Corporate Bulletin Number 01-05-23-001 (Section 05 - Brakes).

This bulletin is being issued to update General Motors position on correcting brake rotor lateral runout (Refer to Corporate Bulletin Number 00-05-22-002B for additional brake rotor service procedures).

Important: Certain conditions may apply to individual vehicles regarding specific repairs. Refer to those specific repairs in applicable service bulletins. Make sure other possible sources of brake pulsation, such as ABS pedal feedback, have been addressed before checking rotor runout.

Anytime a new or refinished rotor is installed on a vehicle, the rotor must have .050 mm (.002 in) or less of lateral runout. This specification is important to prevent comebacks for brake pulsation. Until now, the only acceptable methods to correct brake rotor runout were to index or replace the rotor or to refinish the rotor using an on-vehicle brake lathe.

GM has approved a new technology for the correction of lateral runout on new or refinished rotors. This new method is called Brake Align(R) It will allow the technician to meet the .050 mm (.002 in) or less requirement for lateral runout by installing a specially selected, tapered correction plate between the rotor and the hub. The Brake Align(R) Correction system does NOT require the use of an on-vehicle brake lathe to correct for lateral runout.

* We believe this source and their products to be reliable There may be additional manufacturers of such products. General Motors does not endorse, indicate any preference for or assume any responsibility for the products from this firm or for any such items which may be available from other sources.

The Brake Align(R) Starter Kit will include an ample supply of Correction Plates, in various correction sizes, that will cover most current GM passenger car applications It will also include a Brake Align(R) tool kit containing a dial indicator and retaining washers along with other useful tools.

Service Procedure

Follow all the procedures referred to in Corporate Bulletin Number 00-05-22-002B. Dealers who have purchased the Brake Align(R) Starter Kit may use the following simplified runout correction procedure:

1. The existing rotors must first be machined on an approved, well-maintained bench lathe to guarantee smooth, flat and parallel surfaces. Should the rotors require replacement, please note that this is not necessary to machine new rotors.

2. Make sure all the mating surfaces of the rotor and the hub are clean, using the J 42450-A Wheel Hub Cleaning Kit. Mount the new or refinished rotor onto the vehicle hub onto the vehicle hub using the retaining washers provided in the kit. Do not reinstall the caliper or wheel at this time.

3. Tighten all the wheel nuts to the proper specification, using J 39544 Torque Socket or the equivalent.

4. Fasten the dial indicator to the steering knuckle so that the indicator needle contacts the rotor friction surface approximately 12.7 mm (1/2 in) from the rotor's outer edge.

5. Rotate the rotor and observe the total runout.

6. Index the rotor on the hub to achieve the lowest amount of lateral runout. This will require removal and reassembly of the rotor until the lowest total lateral runout reading is obtained. If this reading is .050 mm (.002 in) or less, the assembled rotor is within specification The brake system may be reassembled.

7. If total lateral runout is greater than .050 mm (.002 in), proceed with determining the correct Brake Align(R) Correction as follows:

^ Rotate the rotor to locate the lowest dial indicator reading and set the dial to zero.

^ Rotate the rotor to determine and locate the highest amount of lateral runout.


8. Remove the rotor.

9. Select the appropriate Brake Align(R) Runout Correction Plate for this vehicle.

Important: Never attempt to stack two or more Correction Plates together on one hub.

Never attempt to re-use a previously installed Correction Plate.

10. Following the Brake Align(R) procedures and diagram, install the Correction Plate onto the vehicle between the hub and the rotor. The V-notch in the Correction Plate is to be installed and aligned with the noted location of the "high spot" on the vehicle hub and marked wheel stud.

11. Install the rotor onto the vehicle with the Correction Plate placed between the hub and the rotor. Be sure to install the rotor onto the hub in the same location as identified in Step 7.

12. The rotor should then be secured onto the hub and tightened to the proper specificating. The rotor should be dial indicated once more to assure that the rotor is now within specification.

The brake system is now ready for the remaining service and assembly. Once the caliper has been installed, check to ensure that the rotor rotates freely.


Parts Information

Road force balance won't help if your Hub and Rotor assembly is out of tolerance. I had my wheels and tires Road Force balanced and still had issues. Did this lateral run out check and found out my driver's side rotor and wheel hub was out 14/1000ths of an inch, way out of tolerance. Turned out the Hub was damaged (Bent) by the previous owner. Replaced the Hub assembly, now it's at 2/1000ths of an inch and I have no vibration issues at any speed. If you're barely out of tolerance, shim the rotor using the process delineated above to get within tolerance.

Good luck,

 

Had a rythmic Vibration in my '98 coupe, the Hunter found both rims on the left side were out of round at the inside edge. Replaced the rims and had them rebalanced on the 9700, rode Perfect!!

I just put new rims and tires on my "new" '99 coupe...had the same damn vibration, but not as bad. Took the entire set to another shop and the mechanic found the balance out on all 4 wheel assemblies!!!
Now she rides like the Luke Skywalker Speeder!!

The Hunter 9700 with an experienced mechanic is worth its weight in gold!

 

Thanks for the info- Have done the 9700 Hunter and there were changes each time. FWIW I do not get any pulsating upon brake application and I would suspect the rotors as the cause if I did. Can they be bad and you would still not feel it upon braking?

 

Thought of that too, in test drives with Chev. Dealer, when placed in (N) it should go away and it did not, nor does it change on slight acceleration or decel.
Thanks-

 

In my case, I didn't really notice pulsating during braking and was shocked to see how far out of tolerance the latteral run out actually was. Just another check you can do. The runout gauge can be 'borrrowed' from your local Auto parts store for free (Advanced Auto) or a nominal rental fee. Only takes about 15 minutes a wheel. I have a low profile jack and can get the tire off the ground using a puck on the rail without having to do the ramp/jack stand thing.

IMHO, if your rotating assemblies (Rotor/Hub) are within tolerance, then you know it's probably alignment, wheel, or balancing issue. These are always hard to track down. I'd work from the inside out on your rotating assemblies => Steering Knuckle assembly (Is it loose, are the ball joints good), Rear assembly (Is it loose, drive shafts OK?), Hub/Rotor assemblies (Are they within rotational latteral runout tolerances, are they mechnically OK?) , Wheels/Tires (Are they balanced correctly, are the wheels round or out of round, tires out of round?), Alignment (is it within spec, did it hold settings from the last time?). If those all come up OK, then do you have any frame or other mechanical damage? Other than that, I'm out of suggestions. Best of luck.

 

Thanks, will check into the rotor as have done wheel bearings-OK, wheel balance-OK, wheel assembly-OK, alignment done-OK, front assembly checked by Cheverolet garage= OK (23,000 mile on 98), Tires are new GSD3s and checked and rechecked and turned on wheel per 9700 Hunter-OK,
Thanks again-

Steve