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View Full Version : Brake vibration problem: help needed for diagnosys



snowbird
07-12-2007, 03:15 PM
I bought the second set of brake last year after the stockers started wobbling a bit and pads were at ~ 60% wear in front ==> ~28000 miles.
I don't consider myself hard on brakes.

I bought a complete EBC front and rear disks, red pads, SS lines kit and went for install in June 06 with a complete bleed/fluid change. Unfortunatly, I had to make a high speed braking cycle on the highway at the end of last year summer. The front disks started wobbling very little, were manageable until last month when they degraded very fast. I changed (only) the front ones for Powerslot ones as the EBC replacement were B.O. for an expected long time. Thats about 3 weeks ago.

The problem:

Those new ones are starting to wobble a very tiny bit (at least appear to, from what I feel in the steering) while they have only 400 hundreds or so miles. The front disks surface look brand new and the color look even everywhere. I know I've been babying those new one so there might be something else:

Jamming caliper: ? they were looking normal in action when we installed the disks and never stopped the car from idling itself away when letting off the brake when stopped. But: the old disk were pretty blued when taken off.

Bent spindle ? Maybe, don't know. But: The car steer straight, turn right, like to fly to 80-90, no visible problem or vibes off the brakes or from tire wear. One person told me an alignment would tell (bent spindle), another one not.

Rear disks being ready for change ? (They are the EBC ones from last year and got about 13-14 000 miles at the most) Can we feel some vibes in the steering when the rear discs are shot ? I never did before and the disks surface look very nice.

Any other possible reason that I don't know of ?

Thanks for any comment as I don't feel confident on how to start the search and correct procedure for this one. :confused:

Blackened300a
07-12-2007, 03:22 PM
You would be surprised what vibration's you feel when a balance weight flies off the rim.
Had it happen twice and I felt a vibration at around 65MPH. Drove me nuts til I had the wheels re-balanced.
I also had a vibration after installing my 4.10's. The rear rotor was frozen on and I had to beat it off which when I re-installed everything caused a vibration while driving but went away when I stepped on the brakes.
I painted the calipers on my old car and a drop of paint got in between the caliper surface and the back of the pad. That gave me a 2 week headache til I found it.
It may be something simple
Good Luck

Richy04
07-12-2007, 04:04 PM
Forget reading to much into it, the bent spindle etc..

If the problem is during braking only and increases with the amount of pedal you put into it or get worse when they are hot.. Suspect Warped rotors.. Even the touted best, most expensive rotors will warp if they are not made of the proper material and heat treated.. Been there, done that.

If the problem is present all of the time (while regular driving/no brakes), then a wheel weight or tire/rim etc.. problem might be the issue..


99% of the time its the fronts which warp and mostly the right over the left, do you feel the shimmy thru the steering wheel when braking, then suspect rotors? Dont bang your head over it, replace the rotors and pads and call it a day.. I have good luck with NAPA rotors and Raybestos/Bendix pads, forget all of the hocus pocus crossdrilled slotted rotor, most of them arent treated so they arent worth two cents..

vegasmarauder
07-12-2007, 04:27 PM
If you have more that 30K miles on it, and are using slotted/drilled rotors and are still warping them I would suspect the caliper mounting hardware is getting loose. This causes the caliper to slightly deflect when hard braking, changing the load points on the face of the pad against the rotor and ending up with localized overheating which will warp even new rotors. When I change pads I change all the mounting hardware. It's relatively cheap and eliminates the side to side pull when hard braking. Out here in the desert in the summer, the heat tears up the hardware kits.

I have also found that if you do a really hard stop and warp the rotor, it will re-warp quickly after a re-surfacing. It's OK on mom's car, but if you are on and off the brakes hard, they will quickly re-warp, so I opt for new ones. Pricey, but keeps down the annoyance factor...

snowbird
07-12-2007, 05:32 PM
So far, thanks for the comments. The calipers hardware, I'll get into it.

When the EBC set went bad, I started to look 3-4 weeks for EBC replacement and they were B.O. everywhere. The set on the car wobbled very badly and was getting worse everyday. I finally called quit on the EBC and went Powerslot. I have no difficulties thinking that with the couple of weeks of vibrations, the fixing hardware had been damaged by heat and vibes.

Richy04
07-12-2007, 07:01 PM
Your problem is not hardware related in my opinion.

You just keep buying high priced garbage which was no better than the stock stuff you took off..

Anyway in response to the hardware issue, When you apply the brakes, the calipers self level to the rotor surface as there are rubber bushings which allow for this. If the wear was even on the sets of rotors that you removed prior, thats not your problem.. If they (hardware and bushings) were worn they would clunk when backing or applying the brakes..

All of the touted brands are junk unless they are nitrogen dipped or heat treated and then surfaced.. This is what makes good rotors expensive.. Brembo does this, thats what makes them Brembos and thats why they arent 99 bucks a rotor..

Another fallacy is that slotted or drilled rotors stop better. Not true, they just cool faster. In fact they reduces braking surface area, which is lost and unrecoverable surface area.

If they are not treated, the metal around where the slots or drill holes are harder than the general surface metal causing uneven wear. Most are not treated by the way... Unless you spend..

Most of the stuff out there looks cool thru the wheel but its just bling. Power slots, Stillen etc.. They are dealers in garbage if its drilled or slotted (or both) unless they are heat treated, this aligns the grain of the metal and the final cut trues everything up. Its your money, spend it how you like..

If EBC's and powerslots didnt work, you just saved a whole lotta people who are paying attention a whole bundle..

I did notice a vender selling high end rotors here, he walks the prospective buyer thru the process of how the rotors are manufactured. They are very expensive, and if all of that was followed by the manufacturer, they are worth the money, especially if you drive hard.

Drilling holes or making slots in rotors doesnt make a company experts in braking components, its the followup work to them which will judge how well they will serve you..

Remember the movie Tommy Boy? All Mr. Zalinski wanted was the Callahan name, not the fine product..

Richy04
07-12-2007, 08:46 PM
Looky Looky,

A quote from Powerstop...


IMPORTANT REMINDER: Slotted, drilled or dimpled rotors offered as OEM replacements should not be considered appropriate for high-speed track use.
While grooved, drilled and slotted rotors offer an enhanced appearance ( I think they mean.. BLING!! ) and add some resistance to the boundary layer of gasses that can build up between the pad and rotor, they are not designed to withstand the extreme temperatures that are produced on the racetrack. If they are used on the track, it is very important that the rotors be carefully inspected and should not be driven on if even minor signs of deterioration are seen. Note, too, that if any products are used on the track they are not warrantable.

:rolleyes:>>>>>>Cyrogenic Versions of this rotor are available as well!! <<<<<<:rolleyes:

darkvader
07-13-2007, 03:15 PM
so what the best rotor for your buck, because iam considering purchacing ebc,baer decela rotors,brembo or reybestos. Which one of these are high in quality and worth the crazy prices that are offered.

MENINBLK
07-13-2007, 05:09 PM
Have you checked the torque on your lug nuts ?
If they are torqued uneven, your rotors can warp.

Just retorquing your lugs can sometimes take out the smallest shimmy.

Stranger in the Black Sedan
07-13-2007, 11:50 PM
This car seems to be particularly hard on rotors because, in my opinion, the car is underbraked from the factory. There are a whole lot of cars that weigh 1000 lbs less than this car, or more, and have just as large or larger rotors. I am only expecting 15-20k tops out of genuine OE brake parts and that's all I'm getting.