90 with bad vibration
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Joined: Jan 2007
Posts: 90
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From: Cumberland Rhode Island
90 with bad vibration
There is a bad vibration that appears when the car gets up to around 50 MPH. There is also a pulsing action when the brakes are applied at that speed as well. I have jacked up the front end and checked for lose components which there was nothing obvious. The passengers side has a little side to side movement while the drivers side it tight. When I spin the rotors without the tires on, the passengers side spins freely while the drivers side had a warped rotor sound. It would not make a sound then in one area it would rub slightly on the brake pad and then go clear again. I went out and bought new rotors and pad thinking it was a warped rotor and still have the same issue. Is it possible the wheel bearing (hub) is warped? What is the best way to check them? What else can it be? I really do not want to spend 180.00 on a hub to find out that it was something else. I do have the J55 brakes.
thanks
thanks
Safety Car
Joined: Jan 2006
Posts: 3,566
Likes: 4
From: Mt Laurel NJ
St. Jude Donor '06-'07
There is a bad vibration that appears when the car gets up to around 50 MPH. There is also a pulsing action when the brakes are applied at that speed as well. I have jacked up the front end and checked for lose components which there was nothing obvious. The passengers side has a little side to side movement while the drivers side it tight. When I spin the rotors without the tires on, the passengers side spins freely while the drivers side had a warped rotor sound. It would not make a sound then in one area it would rub slightly on the brake pad and then go clear again. I went out and bought new rotors and pad thinking it was a warped rotor and still have the same issue. Is it possible the wheel bearing (hub) is warped? What is the best way to check them? What else can it be? I really do not want to spend 180.00 on a hub to find out that it was something else. I do have the J55 brakes.
thanks
thanks
As for the vibration, how many miles on your car? How do you use it? Do any Autocross? Usually if the bearings are bad (front or back) there will be play in the wheel. Remember, there should be basically no movement when you grab the tire at 3 and 6 and try to move it back and forth. If there is, it's new bearing time.
Read this thread, it should help save some $$$.
http://forums.corvetteforum.com/show....php?t=1392417
Good Luck,
Randy
Last edited by RandyJ75; Apr 5, 2008 at 11:22 PM.
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Joined: Jan 2007
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From: Cumberland Rhode Island
Randy,
I replaced the rotors and still have the same vibration and brake pulsing. With the new front rotor on, I still get that "warped rotor sound" from the drivers front which I know that rotor is not warpped as it only has 2 miles on it now. When I grab the front tires at 3 and 9 and rock it I get no movement and a very little back and forth when grabbed at 12 and 6. The car has just over 100K miles on it. I just got the car and know nothing about its past but would be driving it normaly no autocross or anything like that.
I replaced the rotors and still have the same vibration and brake pulsing. With the new front rotor on, I still get that "warped rotor sound" from the drivers front which I know that rotor is not warpped as it only has 2 miles on it now. When I grab the front tires at 3 and 9 and rock it I get no movement and a very little back and forth when grabbed at 12 and 6. The car has just over 100K miles on it. I just got the car and know nothing about its past but would be driving it normaly no autocross or anything like that.
Racer
Joined: Jun 2006
Posts: 408
Likes: 0
From: Elkton MD
Brake pulsing
Yes, a bent hub can give your symptom. Also crud on the hub that prevents the rotor from seating squarely.
So, clean the hub surface well and make sure there's nothing on the back of the new rotor. I use a 0.0001" resolution dial gauge to check the hub and rotor run out (axial - that is, parallel to the axis of rotation). At the perimeter of the rotor, you must get less than 0.004" axial movement but less than 0.001 movement is desirable and achievable. If you have more, check the run out (again axial) of the hub. The hub is smaller diameter than the rotor so it should have <0.003 or so run out. If the hub has excessive run out, replace it. If the hub is OK and the rotor is not, make sure the mating surfaces are clean. If they're spotless, replace the rotor or have it turned.
Really inexpensive (~$20) dial gauges are available from a some of the 'discount' tool stores and work quite well.
Good luck.
So, clean the hub surface well and make sure there's nothing on the back of the new rotor. I use a 0.0001" resolution dial gauge to check the hub and rotor run out (axial - that is, parallel to the axis of rotation). At the perimeter of the rotor, you must get less than 0.004" axial movement but less than 0.001 movement is desirable and achievable. If you have more, check the run out (again axial) of the hub. The hub is smaller diameter than the rotor so it should have <0.003 or so run out. If the hub has excessive run out, replace it. If the hub is OK and the rotor is not, make sure the mating surfaces are clean. If they're spotless, replace the rotor or have it turned.
Really inexpensive (~$20) dial gauges are available from a some of the 'discount' tool stores and work quite well.
Good luck.
Le Mans Master
Joined: Sep 2003
Posts: 5,874
Likes: 0
From: Littleton CO
Measurements of runout didn't turn up anything obvious, so I ended up replacing a bunch of stuff that was suspect - multiple wheel balances, all new bearings & shocks as well as the initial R&R of pads/rotors. I finally gave in and had my new rotors turned, and although they measured good (except for one figure that was "close enough"), they both made a hellacious clatter on the lathe at Midas.
It wasn't until I went to NAPA for a second pair (the first were not NAPA) of front rotors that my problem was 100% solved. Live & learn.
This might not address the cruising vibration, so you may have other things going on as well.
Melting Slicks
Joined: Apr 2003
Posts: 3,110
Likes: 6
From: Red Sox Nation! RI
I'd agree with all the above and a +1 for what JRP said. A friend who turns my rotors for me says they even turn most of the new ones they install, just to avoid comebacks.
I'd venture a guess that your wheel bearing would have to be pretty toasted to pulse during braking, but a bad bearing can give you a road vibration on the highway, too.
mypantera, I'm a couple exits down 295 from you. If you don't figure it out, feel free to drop me a message and I'll see if I can give you a hand if you'd like.
I'd venture a guess that your wheel bearing would have to be pretty toasted to pulse during braking, but a bad bearing can give you a road vibration on the highway, too.
mypantera, I'm a couple exits down 295 from you. If you don't figure it out, feel free to drop me a message and I'll see if I can give you a hand if you'd like.
Pro
Joined: Oct 2003
Posts: 506
Likes: 12
From: Savannah GA
If all else fails try swapping parts side to side, even though they are directional long enough for a short test will help eliminate stuff.
Runout will usually come along with slop or play in the steering. Loose wheel bearings up front do the same.
Vibrations like you are talking about come from halfshaft ujoints. My guess brake shudder and vibration is 2 problems.
Have the tires balanced on a Hunter GSP9700 road force balancer ( http://www.gsp9700.com/ look at there website) if the shake is comming from a tire and wheel that machine will show it in 2 minutes.
JS
Runout will usually come along with slop or play in the steering. Loose wheel bearings up front do the same.
Vibrations like you are talking about come from halfshaft ujoints. My guess brake shudder and vibration is 2 problems.
Have the tires balanced on a Hunter GSP9700 road force balancer ( http://www.gsp9700.com/ look at there website) if the shake is comming from a tire and wheel that machine will show it in 2 minutes.
JS
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