RacingBrake 4 piston fixed caliper install tease...

[The HACK]

And oh what a tease it is.

Put all the OE components and the RB components on my crappy bathroom scale and got the following numbers:

OEM rear rotor: 15.5 lbs
RB rear rotor: 14.5 lbs

The impressive part? Put the OEM caliper with pads and bracket up on the scale, and put the RB caliepr with pads and bracket up on the scale and got this:

OEM caliper, bracket, and pads: 15 lbs
RB caliper, bracket, and pads: 11 lbs

The front rotors are a slightly different story, with the OEM rotor coming in 1 lbs lighter.

OEM front rotor: 19 lbs
RB front rotor: 20 lbs

The rear rotors went on without a hitch.



You can see about 1/4" of the bottom of the pad and backing plate shaved off to prevent interference with the rotor fasteners.



Here are some comparison shots of the OE caliper vs. RB caliper.







Despite the extreme wide angles of the phone camera lens, the RB caliper is only wider by orders of millimeters.

The way the bracket and caliper is set up, you only need to trim the dust shield by a minimum amount. You can see where the trim marks are on the following.



Caliper bracket installed. The instruction calls for 40-50 ft-lbs but BMW's TIS calls for 81 ft-lbs. I compromised and did 50 ft-lbs with red LocTite. BMW's caliper brackets are iron and the RB brackets are aluminum, which stretches easier so I don't think torquing it to 81 ft-lbs would be smart.



Here's the caliper as installed on OEM rotor.



Unfortunately I had to stop there. Need to work out some issues with RB first before I proceed further.

[Kgolf31]

Issues? That doesn't sound good.

Looks nice though.

[Finnegan]

Subscribed

[3002 tii]

Issue, guessing you have to shave down the steering knuckle?

[The HACK]

Calipers touching the inside barrels of both 18" wheels. Problem not correctable with spacers. Need to figure out what to do, as in I'm not going to run 19" wheels period, nor am I willing to try other wheels to see if they fit. I've been told 18" RAC wheels fit, but I need them to at least fit the OEM wheels.

Otherwise they fit very nicely. VERY nicely. Caliper to spoke clearance is shockingly good for a fixed caliper. Caliper to barrel clearance is the problem here.

[Gt4]

Maybe you can bring the bracket to a machine shop and remove some material on the brackets were the calipers is fixed? Calipers will be closer to the rotors hat but it seems like there is some space.

[i2ichal2dZ4M]

APEX ARC-7 should clear, if not volks te37?

[3002 tii]

Originally Posted by The HACK

Calipers touching the inside barrels of both 18" wheels. Problem not correctable with spacers. Need to figure out what to do, as in I'm not going to run 19" wheels period, nor am I willing to try other wheels to see if they fit. I've been told 18" RAC wheels fit, but I need them to at least fit the OEM wheels.

Otherwise they fit very nicely. VERY nicely. Caliper to spoke clearance is shockingly good for a fixed caliper. Caliper to barrel clearance is the problem here.

Originally Posted by i2ichal2dZ4M

APEX ARC-7 should clear, if not volks te37?

You mean ARC-8 or EC7 but either way buying new wheels should not be the answer, if manufacturer stated clearance would be fine with 18's. Plus seeing how a spacer wouldn't resolve the issue, I think it's a diameter issue, not spoke/width which is why Hack said he didn't want to go to 19's.

[i2ichal2dZ4M]

Originally Posted by DSC_OFF

You mean ARC-8 or EC7 but either way buying new wheels should not be the answer, if manufacturer stated clearance would be fine with 18's. Plus seeing how a spacer wouldn't resolve the issue, I think it's a diameter issue, not spoke/width which is why Hack said he didn't want to go to 19's.

Thats true if they stated that it fit OEM 18" wheels, but not always the case if they only specified 18" wheels though. My buddy has 380mm Brembro BBK and they will clear TE37,but he originally had ARC-8 and had to switch over to TE37 because of barrel clearance issues. He is now considering trading his 380mm kit down to a 350mm kit so he can rock ARC-8 again. Either way, good luck getting the issue resolved!! patiently awaiting reviews!

[DRedman45]

RB had TONS of issues with their kits they made for the mk6 gti's, when I still had mine...a good friend bought it and fought it for months before he gave up and bought stoptechs

[The HACK]

It takes guinea pigs like me to discover these fitment issues so they can fix it for the rest of their customer(s). Especially with big brake caliper fitment it's hard to get right. The shaving/machining caliper bracket might work, I just need the whole caliper to move in by about 1/8".

[Beedub]

Originally Posted by DRedman45

RB had TONS of issues with their kits they made for the mk6 gti's, when I still had mine...a good friend bought it and fought it for months before he gave up and bought stoptechs

ive read about a serious amount of issues also.... mostly with the balance tubes.... and leaks!!

[DRedman45]

Originally Posted by Beedub

ive read about a serious amount of issues also.... mostly with the balance tubes.... and leaks!!

There have been tons, fitment is the easiest to correct...but there has been almost no help from rb in my buddy's case

[The HACK]

Originally Posted by DRedman45

There have been tons, fitment is the easiest to correct...but there has been almost no help from rb in my buddy's case

I've read through some of those complaints, and while I'm not going to pretend I know RB well enough to defend anything they do, I am going to point out that if you're in this (automotive aftermarket) industry long enough, you're going to have your share of unhappy customers.

I'm going to see if the fitment issue is something that can be resolved relatively easily, and if it's something RB will implement on their Caliper Upgrade line-up. Obviously, if we can't make it work for my specific needs, I'll need to return the kit relatively unmolested.

At least I still have matching rotors front and rear.

[DRedman45]

My only concern is that it was awful service afterwards across everyone that bought the kit, and hasn't been corrected yet...I have heard good things about there oem replacement 2-piece rotors, and would definitely consider them...until I have a bad experience I would try and hold off judgement, but it's pretty tough

[The HACK]

Oh believe you me, if I share just a small sample of the customer complaints I hear through the grapevines in regards to most of the major automotive aftermarket companies, none of you will EVER want to buy anything from this industry ever again.

In the end, I think it'll be to everyone's benefit to hear both the good AND the bad and decide for themselves. So far, based on my cursory examination of the kit, it appears to be well built except for the fitment issue. If RB will address the fitment issue and I get it on the car before Auto Club Speedway, I'll report back, good or bad.

[The HACK]

Ran some "numbers" on the piston area comparison between the two. OE MZ4 Coupe front caliper should be a 60mm piston diameter, while the RB uses 2 different sizes, 44mm for the leading piston and 38mm for the trailing piston as measured with a tape measure by me.

Based on that, the MZ4 Coupe's single piston area on one caliper is:

2,827 mm^2

While the RB piston area is:

2,655 mm^2

The 6% smaller piston area should lead to a moderately stiffer brake pedal.

[The HACK]

So after showing RB the caliper and where it rubs, it's been deemed too many variables will have to align for this kit to fit MY car. And for me, I'm not willing to run the car with spacers up front nor go with larger 19" wheels, or take a chance on other 18" wheels in the hopes that the barrel is thinner...

For now, I've abandoned the project. Those of you using other aftermarket wheels like Apex which may have better barrel clearance, feel free to give it a shot. I told RB that the calipers would address a very minor issue with the brakes that I am more than willing to live with, and if we have to make various changes to the system to try and get it to fit my car specifically, well, they're just chasing a wild goose just make it fit MY particular case, and who's to say that it won't have other fitment issues with other people's cars...

Anyway, just from what I see, it's a well put together kit. Maybe if they have plans in the future to make the caliper smaller in a future batch, then we'll talk again. For the time being, fitment appears to be an issue. For me.

[Beedub]

Originally Posted by The HACK

So after showing RB the caliper and where it rubs, it's been deemed too many variables will have to align for this kit to fit MY car. And for me, I'm not willing to run the car with spacers up front nor go with larger 19" wheels, or take a chance on other 18" wheels in the hopes that the barrel is thinner...

For now, I've abandoned the project. Those of you using other aftermarket wheels like Apex which may have better barrel clearance, feel free to give it a shot. I told RB that the calipers would address a very minor issue with the brakes that I am more than willing to live with, and if we have to make various changes to the system to try and get it to fit my car specifically, well, they're just chasing a wild goose just make it fit MY particular case, and who's to say that it won't have other fitment issues with other people's cars...

Anyway, just from what I see, it's a well put together kit. Maybe if they have plans in the future to make the caliper smaller in a future batch, then we'll talk again. For the time being, fitment appears to be an issue. For me.

Annoyingly my ap 6 pots have the same issue, they don't even fit the csl rim without heavy spacing which put me off, but by this time I'd purchased them. They are however beyond words at stopping....

Good luck on your quest.

[Finnegan]

Thanks for the detailed information Hack.

Caliper to spoke clearance should be a piece of cake with the EC-7s, but barrel clearance is another thing. If I decide to move forward with trying this solution, I'm going to see if they can provide a template--cut that out in cardboard--and then test to see if it has barrel clearance.

[JCz04Bimmer]

This is marginally off-topic, my apologies.

I have the front rotors... love 'em. And I would definitely run the rears as well but I have no interest in dealing with shaving down pads (and the RB compounds are not appealing to me).

BUT! After doing some research, it seems that PFC rotors are likely victims of the same hub hardware clearance issues and they have developed a pad shape (7855) that addresses the problem.

Take a look:

(7855; For PFC Rotors)


(548; For OEM Rotors)


Looks like they should work, yes? Same shape, just 5mm shorter just as requested by the RB folks.

[The HACK]

Originally Posted by JCz04Bimmer

This is marginally off-topic, my apologies.

I have the front rotors... love 'em. And I would definitely run the rears as well but I have no interest in dealing with shaving down pads (and the RB compounds are not appealing to me).

BUT! After doing some research, it seems that PFC rotors are likely victims of the same hub hardware clearance issues and they have developed a pad shape (7855) that addresses the problem.

Take a look:

(7855; For PFC Rotors)


(548; For OEM Rotors)


Looks like they should work, yes? Same shape, just 5mm shorter just as requested by the RB folks.

Yes, I'm in the same boat, and I also love PFC pads except they're expensive. I may ditch DTC-60s and run PFC-08s exclusively with RB rotors for now.