Bad vibration when braking not rotors

Tiny
DENNIS KUBIN
  • MEMBER
  • 2001 CHEVROLET CAVALIER
  • 2.2L
  • 4 CYL
  • 2WD
  • MANUAL
  • 200,000 MILES
I have a terrible vibration when I apply the brakes that is felt more in the whole car and pedal, but not really in the steering wheel. As typically you would think front rotors (rear are drums), as it had some wear, I replaced the front rotors and pads maybe a year ago, but the vibration did not go away. Yes, this has been going on some time.

My next thought was to replace the rear drums and shoes, although this did not help (replaced with brake parts kit). The emergency brake setup appears to be functioning and releasing, so I do not think it is the cause of it. I feel that it is still somehow related to the rear brakes, or something attached to them, as when I pull up on the emergency brake while driving, I basically get the exact same vibration that I feel when I apply the brakes with my foot.

As this car has now 200,000 miles on it, and a lot of the components are still original. I then began to replace items that may somehow lead to a vibration, and figured with that many miles it could not hurt, and was still cheaper than taking it to a garage.

Here is what I have done to try and fix this:
Front rotors and pads
Both front ABS speed sensors
Rear drums/shoes/brake parts kit
All (4) Struts and new strut mounts
Both front control arms w/ ball joints
Front engine torque strut
Wheel alignment
Tire rotation
Windshield wipers, washer fluid, air freshener…….

Of note, the ABS has always kicked on fairly easily, too soon in my opinion, although it may be slightly better after having replaced some of the components, but by no means perfect.
I did order some rear control arm bushings that attach at the pivot point, but as I could not remove them, I left them in, yet they appeared to be alright and not loose. I welcome any advice that you may be able to give me.

Thanks, Dennis
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Friday, March 17th, 2017 AT 5:57 AM

8 Replies

Tiny
HMAC300
  • EXPERT
Have your struts checked for being weak/leaking etc? Or maybe a wheel bearing. Also, check motor mounts and transmission mount that can be setting it off as well as control arm bushings.
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Friday, March 17th, 2017 AT 6:40 AM
Tiny
DENNIS KUBIN
  • MEMBER
As mentioned, I replaced a lot of that already, but I have not looked to see if there is a manual transmission mount that may be worn. I have not replaced the wheel bearings as they seem to pass the "grab and wiggle" test, but could they still be loose?
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Friday, March 17th, 2017 AT 6:48 AM
Tiny
PATENTED_REPAIR_PRO
  • EXPERT
Since applying the parking brake re-creates the same vibration, it may be because of a loose rear axle component. Usually I check those just by prying on the rear axle and attached bushings with a large prybar.
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Friday, March 17th, 2017 AT 7:56 AM
Tiny
CARADIODOC
  • EXPERT
The perfect clue is that you can cause the symptom with the parking brake. The issue has to be with the brake drums. Start by measuring lateral run out with a dial indicator, on the outer lip of the wheel. I wouldn't want to see more than perhaps 0.030" run out. If you do, that wheel could be bent, but you'd hae other or different symptoms. Rather, I'd expect to find the drum is warped or not seated squarely on the hub. Remove the drum, then measure run out on the outer edge of the hub. That should be close to 0.00".

Next, look for rust or scale, or some other debris that became impacted between the hub and drum. Most commonly that happens when do-it-yourselfers reinstall a drum after throwing a set of new shoes on. There are one or three access holes in the hub. Water gets in there and forms circles of rust on the back side of the drums. If that rust isn't cleaned off, especially when machining a drum, it can get caught between the hub and drum. The drum and the wheel will wobble.

Don't be fooled that a new drum can't be out-of-round. That is more common than for an old drum that has been on the car for years. Mount the drum backward on a brake lathe, then measure out-of-round with the dial indicator. One potential clue to severe out-of-round is there may be uneven color around the entire friction surface.
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Friday, March 17th, 2017 AT 6:05 PM
Tiny
DENNIS KUBIN
  • MEMBER
I had the vibration both after new drums, and after having good drums machined. How exactly do I go about measuring wheel and drum run out? Also, in case this adds additional information that may help steer you in steer me in the right direction, I do recall that a couple of years ago I did have extreme difficulty installing the drums after replacing the brake shoes. I am not sure what happened, perhaps the brake adjuster was not completely turned out, but sadly I do recall beating on the drum with a hammer to get it to fit over the shoes. Could I have bent something that is now causing vibration issues when braking, but not felt otherwise when driving?
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Monday, March 27th, 2017 AT 11:06 AM
Tiny
HMAC300
  • EXPERT
You need a dial indicator that moves to.100" to mount someplace near wheel and check against hub to see if any runout, a drum would more than likely need to be mounted to a machine.
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Monday, March 27th, 2017 AT 12:00 PM
Tiny
DENNIS KUBIN
  • MEMBER
Thanks! I'll take a look at that tonight.
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Monday, March 27th, 2017 AT 12:33 PM
Tiny
CARADIODOC
  • EXPERT
New drums can be out-of-round, either from rough handling at the parts store, or if they're Chinese. There's nothing wrong with Chinese parts, but when we make parts out of cast iron, we set them aside for 90 days to "age" before they get their final machining. The Chinese cast 'em, pack 'em, and ship 'em, then they age on your car. Warping after a few months is very common, but a light machining is all that's needed to solve the problem permanently. When people demand new rotors under warranty, the new ones are just as likely to do the same thing.

You might find a dial indicator at an auto parts store that rents or borrows tools, otherwise, Harbor Freight Tools has an inexpensive one that works just fine. You'll need a heavy metal base or a magnetic base and something to attach it to. I don't know if those come with it.
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Monday, March 27th, 2017 AT 4:47 PM

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