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      08-10-2011, 01:11 AM   #317
KNS Brakes
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Drives: Torch Red
Join Date: Aug 2011
Location: Cary NC

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Quote:
Originally Posted by BMWbab1 View Post
It sounds like a lot of you are having serious problems with the 135i brakes. I too have been having a ton of problems which I think are all related to the lack of cooling/airflow to the brakes. Anyway, after a weekend at VIR and running HT-10 pads for the first time I noticed that the dust boots/seals around the brake pistons were starting to crack. First of all do I need to replace them or will the brake be ok without them. Second, is there an easy way to replace these if so where can I order the boots/seals or do I have to do a caliper rebuild? I really appreciate any help you can give me on this subject as the only reason I bought this car was to attend a few DE's a year and as of right now it looks like I might not be able to continue with these events due to the brake issues! P.S. I will be adding ducting to the brakes if I make it to another event.

Brian

Take a picture and take it to your dealer. "I went to a driving school similar to that which BMW puts on at VIR" (They were unloading a zillion of them after you all left the last time out there)

Rotor efficiency is not the answer to cooler pads/calipers. 2 piece rotors can last longer and may block some heat from the hubs/bearings. I still have high pad wear and my calipers look horrid. (C5Z06)

And shims may help the piston/boot - but the pads and rotors will get hotter. The heat has to go somewhere.

You can get some improvement from 2 piece rotors - we have been there/done that on STi's - but if a brake component is currently wearing fast due to heat i.e. piston crowns cracking in a few events or rotors cracking fast or high pad wear or whatever - more efficient rotors are unlikely to solve it. They MIGHT help a bit - again what we have seen is better ROTOR life and I expect that is due to both improved materials and better efficiency. (A completely new topic)

That suggests that this is a design flaw and BMW is likely pretty livid w/ Brembo. There simple yet damn good brakes are a hallmark.

Who else uses Brembo ceramic crowned pistons? That is one thing I didn't research.
If not - BMW has the choice of - flipping off a few race guys/track guys versus replacing a zillion expensive calipers (on street cars that likely have no risk but ....they read this thread!).

Pretty piss poor by Brembo btw - that name is plastered on the STi brakes as well and while Subaru didn't go for the ceramic topped pistons the STi calipers are far from a race caliper.

In STi land if they track a lot I tell them - sell the Brembo's to a WRX guy while the gold paint is still nice and glossy. Once you track it they lose half the value.

Brian is pretty fast on street tires and he told me his piston crowns are not looking good so that should help out the data pool here.

Brembo makes a competitive race product - but the OEM stuff seems to be lacking.

STi/EVO - terrible noise issues w/ any sort of moderately aggressive pad. Subaru changed the knuckle/bolting arrangement in both 05 and 06 to try and help it.

Camaro - same - enough fro GM to add giant ROLLER SKATES to the pads - hilarious

Older CTS-V/Mustang - no info - but uses the same pad shape as STi/EVO.

Newer CTS-V/GTR - this is the new 'Brembo' caliper - no real info yet but the multi depth pad shapes gets to be a pia. And enough w/ the damn drilled rotors...really?

If the Stoptech ST60 pistons fit right then it's probably the way to go for most. I did email ST - they are going to make the 1-series piston. I am not sure what the diff is between that and the ST60 pistons. Timing not available.

-Ken