My life with 135i / BMW Performance Brakes

[3GFX]

DON'T DO IT

Now that I've saved you some time. Lets get into it!

After much reading on this forum and the E46 forum I decided a used set of 135i calipers (grey) / BMW Performance (gold) would be a reasonable upgrade for my Supercharged Non-M Z4. The brackets (epytec) were easy to come by and I could effectively run these calipers with the 345x28 rotors which was slick.

Let me start by saying for the road/show and the RARE track day, these guys are the ticket. Affordable compared to any other big brake option, easy to get parts for and they offer a look and feel that vastly improve over the stock setup. Do it. But read on to prepare yourself.

You see, the only time I spend on the road these days is going to the track. So for track days there is a lot to be desired.

I don't want to be long winded so I'll summarize issues that have come along with this set that you will need to way out from my experience. In no particular order.


1) Colour - These come grey on the 135i and usually yellow from heat. Be prepared to have to get them powder coated professionally. Don't paint if you're going to the track the paint will not hold up to the heat. Just don't expect them to look good at all after prolonged track/autox use.



2) Heat - The main cause of concern. From the factory the seals and piston on this brake setup have issues. Lots of cracking in the seals and such. You can google it, it's well known. The pistons are also a mishmash of materials such as phenolic to keep heat from getting into the fluid. Either way, once these heat up after multiple uses, be prepared to rebuild.

3) Pistons/Seals - Let me state that although fragile, the stock pistons and seals held up for over 10 track days (for me at least). While there are upgrades for pistons and seals, they are expensive and as I've found out can potentially not hold up either. I specifically purchased the high temp kit from Racing Brake .com. While the pistons held up ok so far the high temp blue seals failed almost immediately (and this was after I added cooling to my wheel well). The blue seals are highly sensitive to brake fluid and thus can fail prematurely. I asked for warranty but they essentially just offered me lower temp seals that held up better to the fluid. They offered it to me as the "goof proof" option. Hilarious since I had a BMW tech (a mechanic of over 10 years) who's very familiar with this caliper rebuild them for me. I wasn't expecting new seals for free, but I was expecting better customer service with a bit more tact. In this case I PARTICULARLY DON'T RECOMMEND RACING BRAKE.

June 2021


August 2021 (after two track days)


Update (25AUG21): After having my brakes most recently rebuilt by a reputable shop they agreed that Racing Brake was in error that the Motul 660 brake fluid I use would not affect the seals. They have simply said that the high heat seals also don't last. Professional advice was that for the extra money they provide little additional benefit over the stock seals.

4) Pads - While it is easy enough to grab 135i pads as a stock option, what I didn't factor in was the lack of a quick change (or back of brake) replacement design. If you're going to the track, it's worth getting a brake caliper that allows to you to "quick change" your pads without having to remove the whole caliper. What I will say is that if you can stomach the squeak, PAGID RSL/RS29 are the way to go over anything from HAWK this side of DTC. I'm trying EBC Blue shortly.

5) Rotors - Not so crucial, but there are limited options here. If you want 2-piece you're pretty much stuck with ECS tuning which is drilled and slotted. The stock M3CSL/Z4M rotor is just drilled. But if you're looking for a slotted only brake that's two piece...you're out of luck. Why would you want just slotted? To reduce heat cracking at the drilled points.

6) Balance - Not a biggie, but your brake pedal will be slightly more spongy than stock. Given the larger piston / fluid volume you should update your master cylinder for the brakes. Not necessary but worthwhile. I have not done it, just passing along knowledge.

Example Costs (CAD):
Used calipers, no paint and new rotors about $1,300-$1,600
New Calipers and new rotors about $1,900-$2,600
Rebuild Kit $400-750
Rebuild $150-300
Strip/Powder coat $300-600
Master Cylinder (installed) $750-$1,200

Facetious Big tip: Use your brakes less (don't actually but if you track/race you know what I mean)


Hope this helps....save up and get a better BBK