StopTech uneven pad wear

Michael Czeiszperger · **Joined:** Thu Apr 09, 2009 9:35 am **Posts:** 861

DickRasmussen wrote:

FYI: Fixed calipers means there are pistons on both sides of the rotor. Normal for race cars. Not normal for street cars for cost and packaging reasons.

Well, these must be fixed then as there are two large pistons on each side of the rotors that press the pad into the rotor.

MarcusMcRae · **Posted:** Wed Nov 23, 2011 1:06 pm

Michael Czeiszperger wrote:

DickRasmussen wrote:

FYI: Fixed calipers means there are pistons on both sides of the rotor. Normal for race cars. Not normal for street cars for cost and packaging reasons.

Well, these must be fixed then as there are two large pistons on each side of the rotors that press the pad into the rotor.

Hrrrmmm. We need pics.

Michael Czeiszperger · **Joined:** Thu Apr 09, 2009 9:35 am **Posts:** 861

MarcusMcRae wrote:

This is what a stop tech brake looks like.

You probably just have stop tech pads.

If you are getting that wacky of pad wear you should pull the caliper and rebluild it. The brass guide pin bushings might help also, but they require regular inspection and grease.

Those shiwn in the oucture are the calipers that are on my car, except mine are red. The receipt says StopTech MZ3 332mm Brake Kit. (They came with the car; I didn't buy them.)

MarcusMcRae · **Posted:** Wed Nov 23, 2011 1:16 pm

Those are fixed piston calipers. I would still take them to a shop that is experinced with them. If you live near raleigh give mark cooper a call at performance chassis. It's unusual for them to wear that unevenly.

DickRasmussen · **Posted:** Wed Nov 23, 2011 1:23 pm

1) Do you know for sure that the pads you took out were the same thickness when you bought the car or when you installed them? If not you may not have a problem.

2) If the inside pistons have trapped air they simply are not being used. "Proper bleeding" may be the solution . . . whatever that means.

3) The out side pads may be hanging up due to either pad/caliper interference or dead seals on the outside pistons preventing them from retracting slightly.

You can troubleshoot 2 and 3 with some easy street driving and using fingers to check temperatures on the calipers (don't touch the rotors unless your fingers are really tough). Drive a short distance and feel the outside piston area versus the inside piston area. Can you feel a difference? Repeat with some braking first. Significant brake drag or lack of braking on one side of the rotors may be obvious by the temperature differential. This assumes, of course, that the wheels and brake design give you any access.

Michael Czeiszperger · **Joined:** Thu Apr 09, 2009 9:35 am **Posts:** 861

MarcusMcRae wrote:

Those are fixed piston calipers. I would still take them to a shop that is experinced with them. If you live near raleigh give mark cooper a call at performance chassis. It's unusual for them to wear that unevenly.

Thanks, that's what I needed to know. More money to throw down the M3 pit!

This brake kit was installed by Bimmerworld so I didn't anticipate any issues. I hope these brakes don't require some regular maintenance that I wasn't doing other than checking pad depth.

MarcusMcRae · **Posted:** Wed Nov 23, 2011 2:04 pm

Michael Czeiszperger wrote:

MarcusMcRae wrote:

Those are fixed piston calipers. I would still take them to a shop that is experinced with them. If you live near raleigh give mark cooper a call at performance chassis. It's unusual for them to wear that unevenly.

Thanks, that's what I needed to know. More money to throw down the M3 pit!

This brake kit was installed by Bimmerworld so I didn't anticipate any issues. I hope these brakes don't require some regular maintenance that I wasn't doing other than checking pad depth.

They really shouldn't require anything special for normal street driving. The seals usually last a long time without any special maintenance.

Eric Stegmann · **Posted:** Thu Nov 24, 2011 11:19 pm

Plain grease does not work due to the extreme heat generated especially in racing situations. If the caliber "floats" I use a good coating of "No Seize" High Temp Lubricant on the slider pins regardless. It prevents corrosion in case the seals fail. As for the pads, the slide inserts between the caliber and brake pad need to be lubed and the backside of the caliber that they go back against. Before doing this, trial fit the pads. Now and then I have found that some pads needed some tweaking with a file on the "ears" for a good fit, even the high quality ones. Permatex has a Ultra Disc Brake Caliper Lube, It is a high temp synthetic lube that I use on the "ears" and backing of the pads to prevent sticking. If your Calibers are fixed and non floating, besides using the foe mentioned. First thing I would check is that you are using the correct brake fluid, another thing is that any air at all in the system will not let the pistons to retract even if the pedal feels good to you. Last off the top of my head, I do not recall if you have new calibers, ( I am not going back to look, seems when I do that with a reply, I get back to my response and it is gone! ) But if they are used, and you have been using them since they were new, might be time for a rebuild, pistons might have some corrosion as to they might not retract fully. Just my 2 cents worth. Hope you all had a good "Turkey" Day !

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