Identifying and Correcting Disc Brake Judder

Ive been having this problem since Ive owned the car but has become increasingly annoying. When I step on the brake pedal travelling over like 20mph the front vibrates violently. I have changed the brake rotors, brake pads, and tires. I also had an alignment done on the car. The car will not stop shaking has anyone else expirienced this problem?

Are you sure it's the front end? Can you see the steering wheel move as you feel the vibration?

I had that at one time. It would occur the most at downhill speeds (around 50mph) during braking. It was a warped rotor.

Have you changed the rotors in the rear also? If it does it when braking, it's brake related.

wow man dont know what to tell u except MAYBE the rotors u got are ALREADy shot or Maybe Struts IDK that wouldnt only be during braking

AA - Yes the steering wheel shakes when the brakes are applied.

98Riv98 - I was thinking about doing that KYB swap but I cant really justify spend my entire paycheck on a pair of struts.

When you changed your pads, did it look like they had even ware on the pads. If it's uneven ware you may caliper issues in addition to the warped rotors.

They looked like they were wearing evenly. I cant imagine how expensive calipers would be to replace. Could it be that the A-Arm bushings are bad? There seemed to be some play when pulled from side to side when I had the wheels off.

I'm thinking tie-rod ends could cause this, but they'd have to be really bad. Inspect them as well as upper/lower ball joints. Still sounds like rotors, but if you're sure they're straight...

Did the problem get better at all when you changed the rotors, or did everything stay exactly the same?

Did you also do your rear brakes AND rear rotors?

A minor shimmy from the rear seems to really shake the whole car.

The problem didnt get fixed the last time I changed the brake rotors.

Bad rear rotors can indeed shake the whole car, but they shouldn't make the steering wheel pull left/right in your hand. Mine were about as bad as they get, and that's the way I could tell.

Do you have aftermarket rims with hub-centric rings?

No stock rims.

theres also inner tie rod ends..that reside inside the rack...an are made of a nylon material... PITA to change....along with the LCA busshings...there are no upper ball joints...jack the front end up..an see if theres any movement vertically..and horizontally in the wheel....

Is there any better than OEM product on the market for a our LCA bushings? There is horizontal movement from the LCA.

i dont think so...no poly or anything... i just did stockers...i did my whole front suspension....an while braking the whole lower Control arm would flex ..causing a *clunk*

Well it seems as if the alignment I just had done on the car kinda sorta fixed the problem. The vibration during braking is now just a light shudder. Deffinately more comfortable to drive. Alot smoother.

Since I bought my Riviera in mid '03, I've managed to change the rotors 5 or 6 times, I can't remember which. The reason for replacement: brake judder (shimmy). On average, I can get a pair of front rotors to last between 30-35k miles before they start vibrating beyond acceptable limits.

Why was this happening? My first thought was poor rotor design and/or iron quality. I figured the cheaper, solid Chinese replacement rotors I used were warping over time. The solution? Maybe try a drilled set from eBay. Result: the judder came back right on schedule. Next I tried a quality set of (EBC) slotted rotors with the F-Body caliper upgrade. Result: judder came back again.

During the quest for ideal rotors, I tried various pad compounds as well, including metallic, ceramic, and composite blends. I found no real answer to the judder problem here, but I did find a noticeable difference in how they performed. Metallics are noisy, ceramics are clean & quiet, and the premium composite blends (ferro-carbon) seem to offer the best stopping power.

But in researching I found that warping doesn't just happen. The cause is usually the uneven distribution of pad compound, created by a combination of factors including installation, driving habits, and choice of pad compound. This uneven pad disposition can lead to hot spots on the rotor, which can then lead to warping over time. See StopTech's info here: http://www.stoptech.com/tech_info/faqs.shtml#25

So maybe the pads had more to do with things than I thought. I'm still not sure, but I'm working on it. Currently I'm running a club/autocross pad that's pretty noisy and dusty, making it barely acceptable for street use, but it's more abrasive when operating cold, so in theory the discs will be "cleaned" during start-up. This will wear the rotors down over time, but if it keeps the pad compound more evenly distributed, maybe they won't warp. I will see.

One thing I found rather interesting is the install instructions that come with most better quality rotors. Here's what came written on the box of my new Royalty rotors. Following this procedure is required for their lifetime warranty to be effective:

1) Remove old rotor.

2) Carefully clean rotor mount and hub to ensure they are free from rust & scale.

3) Check brake caliper position for full retention ability.

4) Disassemble all caliper slider mechanisms, remove all scale and rust, smooth file or sand as necessary to provide smooth surface on slider faces.

5) Apply small amount of high melting point grease sparingly to sliders. Reassemble caliper.

6) Fit new brake pads. Failure to fit new pads invalidates warranty and will cause high spots on rotor. Rotor will overheat and vehicle may suffer loss of brake in early driving miles. Do not install caliper at this time.

7) Install new rotor and secure with two wheel nuts finger tight and inspect rotor for run-out (before fitting wheels). If run-out exceeds .003" remove rotor, rotate rotor one bolt hole and repeat. If run-out still exceeds .003" there is a run-out fault on the vehicle which must be rectified before proceeding. Obtain On-Car Brake Lathe and skim rotor to bring within tolerance or use tapered shims to correct. Run-out in excess of this figure will cause "brake judder vibration". This is not a warrantable condition.

8) When satisfactory run-out is obtained, remount brake caliper with pads, mount wheel nuts, then finger tighten.

9) IMPORTANT: Tighten wheel nuts with vehicle hand brace or torque wrench using gradually increasing torque figures and tighten wheel nuts diagonally. The common fault when installing new rotors is to tighten with air gun to torque figures way above what is required. This pulls the rotor surface to one side, creates significant run-out, will cause disc thickness variations, and eventually brake judder.

10) Check brake fluid level and pump brakes to bring up pressure. Follow vehicle manufacturer instructions in all respects in addition to the above guidelines.

Get all of that? Seems more complicated than how I've always installed rotors (clean the hub and slap them on), but I complied and did each of these steps. Seems the Royalty Rotor company is more concerned with judder than I am! The EBC rotors came with similar instructions. Most interesting I thought is step 7, the part about measuring run out. For this step I moved my bench vice down on the floor next to the rotor (car is on jack stands), clamped a dial caliper with depth probe touching the portion of the rotor furthest away. Spinning the rotor by hand, I could see the variance in run-out. It took partial 3 rotations of the new rotor, but I finally got it perfect: