Brake shimmy
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Joined: Jul 2003
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From: Milton, Florida
Brake shimmy
I have a 1995 F-150 Eddie Bauer edition. I was a having a bad shimmy in the steering wheel when applying the brakes. So the rotors and pads were replaced in December 2004. In March 2005, the shimmy returned. I went back to the shop and they replaced the rotors, no charge. Now in June 2005, I have the shimmy again. It seems to happen when applying the brakes when going between 40 and 50 MPH. I have had no hard braking or driven through any deep water. Also the brakes have started pulling to the right. Any ideas?
Thanks,
David
Thanks,
David
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Joined: Jul 2005
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The brake shimmy is probably due to two problems, check your brake calipers for the front brakes. These probably need to be replaced. Second, check the rear brakes for wear, replace if necessary, adjust the rear brake and bleed the brake system.
Thread Starter
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New User
Joined: Jul 2003
Posts: 19
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From: Milton, Florida
I had the caliper checked and was told that it was OK and the rear brakes were good. Mechanic said the problem was probably due to after market brake rotors which tend to heat up quickly and warp. Guess I am going to have to spend some more money now. Thanks for the reply.
David
David
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Joined: Jun 2003
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From: Somewhere Saskatchewan
Quite often brake shimmy is caused by the driver or mechanic.
If the brakes are used heavily, as in repeated quick stops, heat will build up.
Then when you are sitting at a stop light the heat is directed to one area of the rotor. That is where the pads are clamped.
This excess heat will cause the rotor to develop hard spots.
Even thought the rotors are new they can be warped, right out of the box.
If the wheels aren't torqued properly the rotors can be warped which will cause the same response.
Check the rubber hoses to the calipers. After so many years they will collapse internally and cause the caliper to hold on longer than normal after the brakes are released.
Another area to look at is the apply rod that comes out of the booster to the master cylinder.
There are many different versions of a brake job, but leaving out any of the steps can lead to a problem, like premature pulsation (even on new rotors).
1. Use a name branded rotor - Raybestos, Wagner, Bendix, United, or AC Delco. Make sure you aren't getting the cheap line of ANY of those.
2. Make sure you remove any coating from the new rotors. A common coating from the old days is called cosmolene and it is thick. I haven't seen that for a while, but it takes some effort to get it off. If they just have a light coating of oil, use soapy water or as a last resort use brake cleaner.
2a. Open the bleeder screw before you push the caliper piston back in the housing. This ensures that you push any sediment out of the system rather than back up the line. You can always adjust the fluid level later.
3. Make sure the hub surface (where the studs are) is clean and free of rust scale.
4. Make sure your caliper hardware is both present and clean before installation. (including the caliper bolts)
5. Use a high quality brake lubricant on the caliper bolts and bushings, and anywhere the brake pads rub against the calipers. DO NOT use a petroleum-based grease or anti-sieze.
Okay, you got all the brakes and rotors replaced. Got the slides moving freely. Got the new rotors shining. Gotta put the wheels back on.
6. USE A TORQUE WRENCH ON THE LUG NUTS OR YOU CAN DISTORT THE ROTORS!! If you distort the rotors, then you will have a pulsation in a short time and get all pissed off again.
I'm sure others will add to this, but that is about as complete or in-depth as I wanna go right now. You're not done, though.
7. Remove the REAR wheels and drums.
8. Inspect for leakage from wheel cylinders.
9. Verify self-adjuster screw still turns
10. Verify no cracks in friction material (lining).
11. If that all checks out, stop for a minute and think about how the vehicle feels when you are stopping.
If you hit the brake pedal and the rear end squats or the rear brakes lock up easily, then this is the time to.
12. Replace the rear brake hardware kit.
13. Adjust the shoes for a very slight drag on drums.
14. Put the drums and wheels back on (refer to #6 above, because it can happen to drums too).
15. Get inside car and push brake pedal down a few times to set caliper piston travel.
16. Adjust brake fluid level if needed, but do not overfill.
Now you get to enjoy it. Take 'er for a ride and BE GENTLE. The very worst thing you can do on your first few rides is to push the brakes very hard. Don't "put them to the test" right away or you can burn all the resins out of your new pads. Uh, you did put new pads on, right?
If the brakes are used heavily, as in repeated quick stops, heat will build up.
Then when you are sitting at a stop light the heat is directed to one area of the rotor. That is where the pads are clamped.
This excess heat will cause the rotor to develop hard spots.
Even thought the rotors are new they can be warped, right out of the box.
If the wheels aren't torqued properly the rotors can be warped which will cause the same response.
Check the rubber hoses to the calipers. After so many years they will collapse internally and cause the caliper to hold on longer than normal after the brakes are released.
Another area to look at is the apply rod that comes out of the booster to the master cylinder.
There are many different versions of a brake job, but leaving out any of the steps can lead to a problem, like premature pulsation (even on new rotors).
1. Use a name branded rotor - Raybestos, Wagner, Bendix, United, or AC Delco. Make sure you aren't getting the cheap line of ANY of those.
2. Make sure you remove any coating from the new rotors. A common coating from the old days is called cosmolene and it is thick. I haven't seen that for a while, but it takes some effort to get it off. If they just have a light coating of oil, use soapy water or as a last resort use brake cleaner.
2a. Open the bleeder screw before you push the caliper piston back in the housing. This ensures that you push any sediment out of the system rather than back up the line. You can always adjust the fluid level later.
3. Make sure the hub surface (where the studs are) is clean and free of rust scale.
4. Make sure your caliper hardware is both present and clean before installation. (including the caliper bolts)
5. Use a high quality brake lubricant on the caliper bolts and bushings, and anywhere the brake pads rub against the calipers. DO NOT use a petroleum-based grease or anti-sieze.
Okay, you got all the brakes and rotors replaced. Got the slides moving freely. Got the new rotors shining. Gotta put the wheels back on.
6. USE A TORQUE WRENCH ON THE LUG NUTS OR YOU CAN DISTORT THE ROTORS!! If you distort the rotors, then you will have a pulsation in a short time and get all pissed off again.
I'm sure others will add to this, but that is about as complete or in-depth as I wanna go right now. You're not done, though.
7. Remove the REAR wheels and drums.
8. Inspect for leakage from wheel cylinders.
9. Verify self-adjuster screw still turns
10. Verify no cracks in friction material (lining).
11. If that all checks out, stop for a minute and think about how the vehicle feels when you are stopping.
If you hit the brake pedal and the rear end squats or the rear brakes lock up easily, then this is the time to.
12. Replace the rear brake hardware kit.
13. Adjust the shoes for a very slight drag on drums.
14. Put the drums and wheels back on (refer to #6 above, because it can happen to drums too).
15. Get inside car and push brake pedal down a few times to set caliper piston travel.
16. Adjust brake fluid level if needed, but do not overfill.
Now you get to enjoy it. Take 'er for a ride and BE GENTLE. The very worst thing you can do on your first few rides is to push the brakes very hard. Don't "put them to the test" right away or you can burn all the resins out of your new pads. Uh, you did put new pads on, right?
Last edited by stuart1; Jul 15, 2005 at 09:07 AM.
