135i Racing Brake Piston Upgrade

[yandy]

If you track your car, then do this! No driving impressions yet, but you'll see from the pictures just how bad my stock pistons were. I let them get way beyond what they should, mostly due to laziness and I was getting away with it. But last time out, I ruined a set of pads from uneven wear, due to the deterioration of the pistons.

Took about 6 hours with pad replacement.

Links to what I purchased:

FRONT KIT
REAR KIT

Process:

No information on how to uninstall/install brake lines and calipers, there's plenty of that in this site or e90 sections.

1) Get car up on jack-stands (all four wheels at the same time preferred).
2) remove brake line from caliper
3) remove caliper from hub
4) remove pads from caliper
5) use compressed air (90 psi) or so through the same whole brake line plugs into. This ejects the pistons. I used carpenter clamps to hold the other pistons in place while ejecting one at a time and replacing. Otherwise only the closest piston to the air will eject.
6) remove dust seal/boot
7) remove pressure/oil seal
8) install new pressure/oil seal
9) place new dust boot/seal onto new piston neck (there's a slot that it falls into)
10) Install new piston with dust boot at the same time, and make sure boot falls into caliper slot.
11) repeat steps 5-10 for each piston (best to do one at a time)
12) install pads
13) install caliper to hub
14) install brake line
15) re-fill/bleed brake fluid system
16) blah blah, you get it.

Car still on jackstands, because almost through the process I forgot that I ran out of brake fluid.. [dumb move]

Packaging

Nothing fancy, but well put together and prepped. Each set of pistons and seals had their own sub-compartment within the bag.

overall packaging


Seals and Boots


Pistons


Install

This is what the front caliper looks like with beat up stock pistons

Picture 1

Picture 2


Side by side comparison of new stainless-steel piston and stock one. No idea how I was breaking like this, all of them were this bad or worse.



Compressed air through pictured slot to eject pistons. Make sure to put about 1" to 1 1/2" inches of cardboard infront of the piston you're ejecting, it comes out rather quickly and with force.



Removing the dust boot, use any thin flat-head screwdriver, or something to fit in and pull up.



To remove the pressure seal, use the same tool and essentially place it behind the seal, and pull out. Once there's enough of the seal out of the slot, remove with fingers ore pliers.

Install the new seal into the same slot, kinda of a pain, tedious, not hard.



Here's the new piston with the dust-boot/seal attached, this goes into the caliper together. Then, the boot fits into the same slot as the one removed earlier.



Once done, it should look something like this.




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Here's what the six pistons from the driver side front caliper looked like.



No pictures from the rear, they weren't nearly as bad, but still should be done. The process is the same, just less work, only one piston on each side of the caliper, bigger piston, whole and easier to work with.

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If you decide to do this, do at your own risk.

[MLSavage]

I was already planning on doing this. They should have come from BMW with this 'mod' done.

While we have the caliper off the car, can anyone explain what the 'legs' of the caliper do? The 2 bolted on extensions at the respective ends on the outside of the car.

[Focusedintntions]

Nice write up Yandy! I've had mine in for a while now and I love em. I have the fronts only though, but I've found that there is much better pedal feel. Did you also get the larger front rotors with the bracket??

MLSavage, the bolted extentions are there for vibration control. I took mine off and haven't experience any difference. Takes a bit more than 1lb of unsprung weight off the car.

[yandy]

Originally Posted by Focusedintntions

Nice write up Yandy! I've had mine in for a while now and I love em. I have the fronts only though, but I've found that there is much better pedal feel. Did you also get the larger front rotors with the bracket??

MLSavage, the bolted extentions are there for vibration control. I took mine off and haven't experience any difference. Takes a bit more than 1lb of unsprung weight off the car.

The rotors are in the plans, but with everything I've done recently, funds are starting to be limited.. lol, but soon.

[r0nd3L]

Nice work! Is it the pictures or were your stock pistons really crumbling away LOL?

[MLSavage]

Originally Posted by Focusedintntions

Nice write up Yandy! I've had mine in for a while now and I love em. I have the fronts only though, but I've found that there is much better pedal feel. Did you also get the larger front rotors with the bracket??

MLSavage, the bolted extentions are there for vibration control. I took mine off and haven't experience any difference. Takes a bit more than 1lb of unsprung weight off the car.

Did you fill the holes with anything? I see 2 reasons why you would: 1. Cosmetic (applies to both, really) and 2. To protect the inner threads from junk getting in them in case you wanted to reinstall the vibration dampers.

[Focusedintntions]

Originally Posted by MLSavage

Did you fill the holes with anything? I see 2 reasons why you would: 1. Cosmetic (applies to both, really) and 2. To protect the inner threads from junk getting in them in case you wanted to reinstall the vibration dampers.

Just left the holes open. If they get filled up i'm sure they can't be cleaned out with some compressed air and water hehe. Cosmetic wise....you can't see them once the wheels are on unless you're really trying to look for it. Nobody really even noticed i took them off out of my friends that really know my car either.

[yandy]

Originally Posted by r0nd3L

Nice work! Is it the pictures or were your stock pistons really crumbling away LOL?

Heh, they actually look better in pictures. My stock pistons were really bad!

[yandy]

finally got my RBF 660 in and the mid stainless-steel lines. I had done the others, but never the "mids", now I know why. What a pain in the ass those things are in this car, but got them done anyways.

Just bedded my new RP2 Carbotech pads, didn't crash, car stops fine, so I think it's good for now.. lol

I'll post up more/impression as I drive around with them.

[timhatimay]

Wow, those look awesome. I've been considering doing this upgrade next time I change pads/rotors. I didn't know RB made a kit though. What made you choose theirs over the ones originally discovered here:

http://www.1addicts.com/forums/showthread.php?t=441050

Looks really nice, you will have to keep us posted on the performance. Those brittle stock pistons have got to go!

Tim

[andrey_gta]

I think its cost.
The stop tech link you refer to has sub total of $510.00 vs RB $475.20

[BrokenVert]

I have a full pad and rotor job coming up and I'm seriously debating doing this.

Nice writeup

[timhatimay]

Originally Posted by andrey_gta

I think its cost.
The stop tech link you refer to has sub total of $510.00 vs RB $475.20

In the scheme of a brake upgrade, I wouldn't change my mind based on $40. Also, there are several differences in the two types. The stop tech pistons are aluminum and flat on the front. According to the RB site, theirs are stainless steel and they have visible ridges on the front. Truth be told, after the cracked rotors I saw here, I'm skeptical on the RB parts, even though it looks very high quality.

Either way, with a piston upgrade and some quality pads and fluid, it looks like you could make a very good improvement to the stock brakes!

Tim

[yandy]

Originally Posted by BrokenVert

I have a full pad and rotor job coming up and I'm seriously debating doing this.

Nice writeup

thanks, you should def look into it.

Originally Posted by timhatimay

In the scheme of a brake upgrade, I wouldn't change my mind based on $40. Also, there are several differences in the two types. The stop tech pistons are aluminum and flat on the front. According to the RB site, theirs are stainless steel and they have visible ridges on the front. Truth be told, after the cracked rotors I saw here, I'm skeptical on the RB parts, even though it looks very high quality.

Either way, with a piston upgrade and some quality pads and fluid, it looks like you could make a very good improvement to the stock brakes!

Tim

It was the steel vs aluminum that steered me in that direction, not exactly the price.

[turbowolfe]

Got the RB upgraded pistons too, as well as the larger front rotors... Will be put on in a couple of weeks when I get back into town. Can't wait.

Yandy, how are you liking the Carbotech's?

[Focusedintntions]

Originally Posted by turbowolfe

Got the RB upgraded pistons too, as well as the larger front rotors... Will be put on in a couple of weeks when I get back into town. Can't wait.

Yandy, how are you liking the Carbotech's?

You're going to love that combo. I just did a full weekend at the track with that kit (3rd weekend of tracking) and so far everything is holding up great. The rotors still look really good. My calipers are a solid gold from the heat but no issues inside