Hi all,
I've got some serious brake shudder. I can't figure it out which rotor/caliper is causing it. Any ideas on how to narrow it down. I've replaced all the pads and rotors - no change. Should I start re-building the calipers?
thanks

Some things I would do to shake down the shake.

Check for grease on pads or leakage onto the disk.

Take a micrometer if you have one. Measure the thickness in several places around in the middle where the pads run.

A dial indicator will check for run out and reflect any change the micrometer shows. It also will detect if you have wheel bearing play. It’s probably the one best method. You are only allowed a couple thousandths of an inch or you will start feeling your symptom. Run out of .007 to .010 is really bad.

Look at both spindles under the dust caps. Compare the distance from the end of the hubs to the end of the spindles with a scale. Just in case the bearings are not seated all the way on. The axle nut may need adjustment if this has happen or not. A rotor with run out can work on the spindle bearing adjustment if not done correctly or vice a versa.

If you are confident the calipers are tight and bearings are fitted up and jelly tight.

Look at the ball joints or bushings loose in the control arms. Although I think you would already notice looseness in maintaining your steering direction though.

Depending upon severity a bad ball joint usually shows up as shudder. Just as you come to a stop and sometimes while turning slightly it may come and go.

Brakes/bearings are at higher speeds and shake the hood or front end if really bad. Feels like you may have run over a bunch of rabbits. An unknown fact for me though, just my imagination at work.

I use this method under a car lift with an adjustable screw foot jack. You can use this method.

Raise the wheel just off the ground. Have someone try to tilt the wheel up and down from underneath with a 2x4 or with a fulcrum. Check out the three control points for play while loaded and unloaded.
There is a specification for ball joint allowable play before repair.
Bushings are impossible to describe and again your alignment should be drifting.

Hope this helps.
Phil

The advice you have received about brakes, tie rods, lug nuts and ball joints are totally valid. That being said, no one has mentioned tires... a tire on the front of the car with a torn/slipped belt can feel fine at cruise but shake your fillings out under braking.

The easiest test for this would be to rotate the tires front to back, if the problem gets better, you have the answer.

jorrell
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92 245 299.3K miles, IPD'd to the hilt, 06 XC70, 00 Eclipse custom Turbo setup...currently taking names and kicking reputations!

Knowing you replaced the rotors, I figure you made sure the mating surface on the hub was clean and smooth. Raise each wheel and grab the tire. Shake it. Investigate any play in suspension ball joints, tie rods, and especially the wheel bearings.

Then, the easy stuff past, pull the pads and be sure all 4 pistons in each caliper are free to move, and the pads do not bind in their ways.
--
Art Benstein near Baltimore

It's always darkest before dawn. So if you're going to steal your neighbor's newspaper, that's the time to do it.

FYI - Bad ball joints made my 240 feel like it had warped rotors.
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95 855 GLT Sportwagon, 90 244 DL 300k

Thanks Art. I'll check it out. Didn't think of the ball-joints and tie-rods.

If it turns out to be a stuck piston - would recommend I buy one of those rebuild kits from FCP - or should I just get a new caliper?

I love all your input. Thanks

If it turns out to be a stuck piston - would recommend I buy one of those rebuild kits from FCP - or should I just get a new caliper?

Don't know what I would recommend to you. Pros and cons to both approaches are:

Rebuild can be a very messy and time-consuming task. You might find yourself unable to complete it. One busted bleeder screw can send you to the store for a reman caliper. When I rebuild one, it isn't the one on my car, but a good-looking one from the pick'n'pull. That's the way it was, anyway, these days they're all pretty nasty by now.

No such thing as "new" so you're getting someone else's rebuild when you replace the whole caliper -- often not so well done. Look them over on the counter for things like mis-matched halves, buggered valve and pipe seats or threads, or poorly fitting universal-style dust boots. Have to admit, I never needed to return one to FCP.

In doing it yourself, you know exactly how it has been done, right or wrong. That is education in the least, and satisfaction at best. The kits only provide seals and dust boots, but you know the parts are correct for the Girling.


--
Art Benstein near Baltimore

A Local Area Network in Australia is the LAN down under.

Hi,


I had tires put on my 1977 264 GL. There was major shudder after the service. The lugnuts were not overtightened, just tightened unevenly. Re-tightening the lugnuts solved the problem.


Goatman

Thanks. I'll check it. I hope its that easy

my steering rack leaks a bit... when it gets too low I get shudders under braking. Bringing the reservoir back up to a healthy state gets rid of it. just a thought.

hmmm. Interesting. Thanks

Wow, such great replys to the problem. I had a front end shake problem when the brakes were applied. It turned out to be a twofold issue for me. The first part of my "shake n brake" problem was the fact that a "professional" mechanic removed my vented rotors and matched calipers and replaced them with solid rotors and matching calipers. The problem with that was the fact that my particular Volvo had the corona mags with the air-dam. I was supposed to have the vented rotors and matching calipers. The "pros" took em off during a brake job without telling me. The second part of the problem was related to way overheated solid rotors - they warped. I sure hope you're problem isn't anything like that. I got all my parts back, but only after I threatened to call the cops. Now I do most if not all my own work - I have such bad luck with "professional" mechanics. If it were me, I'd rebuild the calipers - carefully - At least that way I'd know what it was done right....slow, but right.