Has anyone rebuilt their GP2 front caliper pistons using RacingBrake.com's 135i kit?

 

I went with the cheaper rockauto aluminium pistons for my 135i but I have not needed them yet. So far all I've done is burned up the dust boots, the pistons are fine so I'm not touching them. I do run naca ducts off my splitter to the back of the hub for extra cooling.

are your pistons failing? Could you post pics? I wanna see what to watch for.

I may end up swapping to the blue 340mm brembo's used on the m235i/m240i and a few other cars with a track brake option, quick change pins are so much nicer than removing the caliper multiple times every time I go to the track.

 

I've got three pistons on the driver side that are toast and two on the passenger side. I've looked at the stop tech kit, but, I'm concerned that I'm going to have more issues if I go with aluminum. I'm thinking I should just go for stainless steel and be done with it. I'd love to hear from anyone that's tracked either the Stoptech pistons or Racingbrake.com's a bunch though. I'm also just trying to definitively confirm Racingbrake's kit will fit. I run DTC-60's and Motul too, in case anyone is curious. I'm also on track for HDPE about 14 days or so a year.

Yeah, having a quick change pin is awesome. I used to have Wilwood FSL calipers on a previous mini. They were so quick to change. I miss those brakes and wish I had just put them on this car.


Driver Inner

Driver Outer

 

If the kit is for a 135i then it should work fine cuz they're the same brakes, thank you for posting pictures. Have you considered running ducts? It's quite a difference in pad life and temperature on my cars I won't run without them it's just not worth it. My 135 is quite a bit heavier but I haven't had pistons fail at least not yet anyway. The worst track here in the southeast is CMP for brakes and I was there 3 days instructing last weekend and really didn't have any issues with the brakes pretty happy with them if only they had the quick change pins

 

I ran Sneed ducts on my last mini. They definitely helped. I wasn't impressed with the product quality at all though. The GP has some silly little "ducts" that channel air into the wheel well, directly in front of the tire.. pretty much worthless. I was hoping to not have to do ducts on the GP, because it'll definitely be a full custom job. But, I may end up going down that road. The Racingbrake guys are verifying their kit fitment for me. I suspect it'll be good to go. If it is, I'm going to go that route. I'll post some pics when it's done. I'll be at Roebling in a couple of weeks too. So I'll post with how they do.

 

I rebuilt GP2 brakes with the racing brake kit for 2x cars. One was a GP2 tarmac rally car. The other was a circuit racing R56 JCW with GP brakes. Both were dedicated race cars.

The kit all fitted and worked ok. Turned out to be very durable, never needed to touch them again, despite a lot of race time.

 

who is running the roebling event?

 

Thanks robbo Mcs! That is super helpful and exactly what I needed to hear. I'm pulling the trigger. Did you also have ducts run to the hubs, or no? If you don't mind me also asking; who's product were you using for wheel studs?

The Roebling event is put on by Just Track It. Awesome, awesome group of guys and the events are always top notch. Really can't say enough good things about them. Here's a link to their 2020 calendar. It'll give you an idea of their schedule, if you're interested: https://justtrackit.net/2020-events/

 

I dont connect directly to the hub, just point the duct at the back of the caliper / hub area.

I use apex studs, and their wheels

 

how many sessions does justtrackit give, and how many students they give to instructors ?

 

Their events are always either 5x 25 min. or 5x 20 min. sessions per day. I believe RR is usually 25 min. sessions and cost is $275 for 2 days. Pretty awesome deal. 1 student to 1 teacher. Novice drivers are with an instructor until the instructor signs off for them to move to Novice solo. JTi does a four run group format. Novice (Instructed and Solo), Inter.1, Inter.2 and then Advanced.

 

thanks, a lot of clubs give me two students and it's pretty hectic

 

I was running in some classes where modifications were very limited, so did not run with any after market brake cooling option. Used either Pagid RS29 pads or Carbotech RP2 on stock rotors. Both worked well, and were very durable.

 

Here is a thread you might be interested in about trying to put brake ducts into an R56. It is pretty much a no-go:
https://www.northamericanmotoring.co...or-r56lci.html

I have struggled mightily with this issue with my R56S. I did put a camera into the wheel well of my F56 with some yarn in the MINI brake ducts and found that at speed with the wheels straight they blow pretty much straight onto the caliper, which is a good thing. On my R56S I was was able to take advantage of this and have been able to channel some of that air stream into the base of the rotor vanes with some modifications to the dust shield. If you read through that thread I linked to, you will see the mods I made. It has helped a bit.

I am interested in what you are doing as the caliper piston construction in your brakes looks to be of same as what is on my F56 JCW and I am looking for options for replacing the pistons in those brakes. The disappointing part of all of this is why MINI decided to go this route in the design. It seems that this could be a safety issue.

 

they design for street not the track, that said with ducts my pistons have not cracked yet. You can easily run ducts on R56 the way most track cars are done, start cutting bumper, bumper support, splash guard and run the flexible hose. I started with hub adapters but found it was more effective to just point the hose at the hub & caliper area. I had the sneed brackets and threw them in the trash

 

this is what I did on the 135i, a little less cutting than the mini's I've done as the bumper has a nice spot for a NACA duct. Going to do this on a legacy GT next.

 

Thanks for all this helpful info guys! Really appreciate it.

Robbo, It's very helpful to hear these new pistons hold up well for you without additional duct work. I'm honestly trying to not have to mess with ducts right just this minute; maybe down the road. That's very cool to hear about your results with those pads as well. I love carbotechs. I ran Xp12's and 10's on my last mini. The GP2 came to me with a transferrable extended warranty. So I've been sticking with Hawks just because of the compatibility with OEM street pads. The warranty just ended though. Next set of rotors I probably will be going back to Carbotech. I've been thinking of giving DTC-70's a go though.

Hey Eddie. Good to hear from ya. It's been awhile. Thanks for sharing that thread link! Good lord, lots and lots of great info to digest! I'm going to read through it all later. I did see your dust shield mod though. Seems like a good and straight-forward approach. I did order the RacingBrake SS pistons. I'll post some pics of the process.

Thanks for sharing the pics too Mr. B. All of this has definitely gotten me thinking... I don't know though just how much more I'll go down the mod road with this car. I'm close to selling the GP and moving into an Exocet as a dedicated track car. That's ultimately where I see myself headed. I drive a work truck a lot these days so the GP has turned into somewhat of a garage queen, lol. I will be back though with questions fellas ;-) Thanks again guys.

 

Thanks...

When my MINI had stock brakes I ran the Carbotech XP10s with the stock pads and had no issues. In fact during a track day I switched from Yellow stuff pads to the XP10s with no problems. I know what Carbotech says, but I have not experienced any of it when I have switched to them from other brands. I know, just one data point, but I thought I would just mention it for consideration.

As for the Hawk DTC-70s... I have run the DTC-60s. For the right track, they are really good. They can take a lot of heat. However, they need heat to work correctly. They worked really well at Watkins Glen, which is a track that is really hard on brakes. At Palmer in Massachusetts, they didn’t get enough heat into them and they ate up a set of rotors in a 2 day event. I would expect the DTC-70s to be the same. Just be careful that if you do use them, that the track warrants their use.

 

xp12 do not last very long for me, I ran them once and switched to ST43-47. I've heard the dtc70 are not as hard on rotors as the 60's were but I have not ran 70s yet.

The biggest difference with ducts is pad/rotor life, double the pad/rotor life when running ducts. I've tested this by accident, had a cut duct on my R53 :( I was both impressed with the difference and angry as it cost me a set of pads...

 

Interesting about the DTC-70s. I wonder if they are more of an Endurance pad than the DTC-60?

I know a person who did these on his M2 BMW. The actual post with pictures is 3 or 4 post down on the page I linked to. These are similar to ones for the MINIs. They helped, but are likely not as good as something off the front of the car. For this person, part of the idea was to have something removable for driving his car on the street.

That thread also has talk about removing the dust shields. With the MINI brake ducts, there is too much air being blown onto the inside face of the rotor, which causes uneven cooling from the inside to the outside of the rotor. I broke a set of rotors because of that... Hence the modified shields I now have.

 

I bent the dust shields so they catch more air from the stock duct the E82 has, newer bmw/mini use basically the same duct that at least gets some fresh air into the wheel wheel.

I almost printed a set of those a-arm ducts, I cant see how they would be effective that area is a low pressure area even more so when you slap a big splitter on the front of the car like I did. With the legacy-gt we are going to try to sandwich some naca ducts between the bumper and the splitter like I did with the 135i. I always make my splitters so 4 bolts and it's off, minimal mods to the car so if I want to I can remove it for the street. I've caught my brakes on fire on mountain runs, now I just leave everything on the car

 

Hey Guys,

I just got around to doing the piston swap the other day. A friend gave me a hand with it. Neither of us had ever done caliper rebuilds. It took about 3 casual hours start to finish. It's really a very straight forward process. Here's a pic of the pistons that came out. Quite a few of them were in really rough shape. Notice how some of their heights aren't the same. One of the DTC-60 pads was chunked pretty bad. I spoke with a hawk rep for awhile about it. They're sending a new set my way. pretty cool. I talked to him a bit about running 70's too. The consensus is I'm going to hit the rotors with high temp paint and see what they're getting to. I'm seriously considering doing the dust shield mod down the road too. I'll be running the new 60's this weekend at RR though, without any other changes other than the new pistons. Looking forward to seeing how the car feels on track.

 

Ugh...
Those pistons are UGLY!

The new SS pistons look really good.

Any idea as to what that material is that the tops of the pistons are made of? Some people say it is some sort of plastic. But that doesn’t seem right. I had read/heard (don’t really remember which as it was a while back) that it was either a ceramic or sintered metal. Yours look to be more like a ceramic.

Any thoughts of sending pictures of those pistons to the NHTSA as being representative of a failure in the braking system and a potential safety hazard? BMW/MINI shouldn’t be putting those into cars...

Looking forward to hearing about how RR is with the brake rebuild.

And thanks for the post. This is the best I have seen that shows this problem. Now, if I could just find replacement pistons for my JCW caliper pistons...

 

The tips of them are ceramic. they do not fail on the street or even on the track. if you have ducting mine have not failed yet but I run pretty big 3-in naca ducts off my splitter

Nobody is going to make a successful claim because they work fine on the street.

 

I'd be most grateful to know what rotor temps you find with the paint. Do please tell when the time comes.

Cheers,

Charlie