R1 Concepts Big Brake Kit Review

[uberschnell]

I've always had fascination with Big Brake Kits. On my 335i which has a good stock set up I went with a full Rotora 6/4 set up for track use. Ended up not being too impressed with them. Then I fell in love with the bulldog looking 135i and I thought I would be set, great car with stock BBK! Well, quickly found out those brakes were not up to task when it came to serious track time. So I decided to upgrade to the real thing, Brembo GT!

Well, time has come to retire my ride from track duty and focus instead on a fun weekend canyon carver. I came across the R1 Concept BBK offerings. It's been out for a little bit but I could not find too many reviews on the kit. R1 is mostly known for rotors, pads and lines with a fairly solid rep. I've wanted to go front and back and frankly the Brembo GT is so damn expensive. Plus I wanted to go for cross drilled bling. A no-no for track but ok for street.

So I ended up trying out the Front kit to see how it fairs.

I went with the 8 pot, 355 mm front. I upgraded to Stainless pistons and knock-back springs, and full float 2-piece cross drilled rotors.

R1 BBK's are built to order to I went with Yellow calipers and black rotor hats. They color selection is pretty large and the price is the same so that can make it a little hard to pick the right set up for your car.

I ordered these straight from R1, so no special deals or anything, just an honest review of what they offer. I'll post up how the install goes and once I get some miles on them a long term review.

For starters, here is my BMW N54 experience, all but the R1 with track time.

335i - Stock with upgraded pads and fluid
335i - Rotora 6/4 full BBK
135i - Stock brakes
135i - Brembo GT front, ECS Slotted rotors rear, EBC Yellows rear
135i - R1 Concept 355 BBK front, EBC Red rear, R1 Concept Cross Drilled rotors rear

First, a photo of what's being replaced.

[uberschnell]

got the R1 in the mail, box weighs a ton. First look, pretty high quality. The calipers are clearly CNC. They are forged, but they are two piece unlike the mono-block GT. Size wise, the disk on the R1 is slightly wider then the disk on the Brembo set up. Also, the Brembo GT caliper is slightly larger then the R1. Brembo is superior quality, but these hold up well.

The rotors appear pretty high quality, with the holes drilled in between the vanes at an even space. The holes are nicely beveled at the end to avoid shard angles.

Fit and Finish I give it an A- (Brembo gets and A+)

[uberschnell]

Package came with all necessary accessories. Hardware look good. The kit comes with R1 Brake lines which look the part. Here is where I found the first "issue". Stock lines include two rubber grommets to secure the line, the R1 lines only had one. The Brembo lines came with two, like oem. Brembo lines are made by Goodridge, so you know they are top quality. Will have to see how the R1 lines do in the long run.

[questionable]

Pm sent regarding Brembo Gt's

[uberschnell]

Here is a photo of the SS pistons up close. It's a cheap upgrade from the aluminum and well worth it. (Brembo, of course, are already SS)

Without getting into the specifics comparing stock vs R1, piston's are 36mm, 32mm, 30mm, and 28mm. I suspect this will move the brake bias forward, but not by a tremendous amount with the stock 135i rear calipers.

As you can see on the Brembo brakes, the pistons are much beefier. In fact, I'm not even sure where the dust shields are on the R1 brakes. It's clear the Brembo would probably be better suited to track duty, but the reality is I am comparing $3800 BBK to a much more reasonably priced alternative, so something has to give.

[uberschnell]

Install

So the real test is to see how well these are engineered for a specific car. I mounted everything up without lock-tight or torque specs. One thing that had me worried was the fact that they packed like 30 spacer/shims with the package. I was not crazy about the idea of having to shim these to fit.

Upon installing the pads I breathed a sigh of relief. Everything seems to have been designed to specs. The spacing on the bottom and top of the pads are right on, and the caliper was centered. The only issue I ran into was the right caliper had about a 1/2 mm less space on the inside pad then the outside pad to the rotor. There was not too much wiggle room for the pads to fit and that could be a function of the pad size. Either was was not a problem. Should function fine.

Overall fitment, B+

[Dmak]

Nice looking brakes. I guess you will test it out on track too? Let us know how it is !!

[CRYA]

Price on this kit? Did you ever get the M3 seats installed? Just curious how that all worked out. Couldn't find your build thread.

[uberschnell]

Got them on and tool them for a quick drive. So far so good. I'll bed them in and put some miles on and report back on bias and overall performance.

One thin for sure, they look huge behind an 18" wheel

[houtan]

And updates? How much did these cost?

[davidwarren]

What is the pad selection like for these? Can you get PFC pads?

[uberschnell]

Originally Posted by houtan

And updates? How much did these cost?

I absolutely love these brakes. They are working flawlessly.

Originally Posted by davidwarren

What is the pad selection like for these? Can you get PFC pads?

My understanding anything you can use on Stoptech ST6. I have to admit, I am really happy with the R1 pads included (I went with Street). Great, consistent bite, even when cold. Zero noise. I haven't taken it to the track but for street driving and weekend canyon carving these pads have worked perfectly.

[houtan]

thanks for the update. are you planning on doing the rear as well?

[r1concepts]

Originally Posted by uberschnell

I absolutely love these brakes. They are working flawlessly.


My understanding anything you can use on Stoptech ST6. I have to admit, I am really happy with the R1 pads included (I went with Street). Great, consistent bite, even when cold. Zero noise. I haven't taken it to the track but for street driving and weekend canyon carving these pads have worked perfectly.

Glad to hear the BBK is performing well on your vehicle! We appreciate you choosing R1 Concepts

[uberschnell]

Originally Posted by houtan

thanks for the update. are you planning on doing the rear as well?

I've been focused on finishing up my widebody conversion, but yes, at some point

[houtan]

Originally Posted by r1concepts

Glad to hear the BBK is performing well on your vehicle! We appreciate you choosing R1 Concepts

Can you please confirm what pads are compatible with your caliper? Also, how much does the front and rear bbk cost?

[r1concepts]

Originally Posted by houtan

Can you please confirm what pads are compatible with your caliper? Also, how much does the front and rear bbk cost?

Depending on which calipers you decide to go with, the Stoptech, Hawk, and Posi Quiet brake pads are compatible with our BBK. PM sent!

[HP Autosport]

Doesn't look like the rotors are full floating, can you confirm?

[r1concepts]

Originally Posted by HP Autosport

Doesn't look like the rotors are full floating, can you confirm?

Our rotors come standard fixed 2-piece for the daily driver and we offer full floating rotors as well for anyone that tracks their vehicle at an additional cost. This is what uberschnell has on his BBK for his 1 series.

[HP Autosport]

Originally Posted by r1concepts

Our rotors come standard fixed 2-piece for the daily driver and we offer full floating rotors as well for anyone that tracks their vehicle at an additional cost. This is what uberschnell has on his BBK for his 1 series.

Thank you for the clarification. It's good to know there is the option to choose full floating over the standard setup.

[fe1rx]

Originally Posted by uberschnell

Without getting into the specifics comparing stock vs R1, piston's are 36mm, 32mm, 30mm, and 28mm. I suspect this will move the brake bias forward, but not by a tremendous amount with the stock 135i rear calipers.

OE front caliper pistons are 36 mm, 32 mm and 28 mm for a total piston area per side of 2438 sq mm.

R1 total piston area per side is 3145 sq mm.

Other factors affecting brake bias are pad friction coefficient (if different compounds are used front and back), and the effective radius (which is likely increased slightly with the R1).

OE brake bias assuming the same pad material front and rear is 65% Front / 35% rear.

R1 brake bias assuming the same pad material front and rear will be something like 71% Front / 29% rear. This will likely have a detrimental effect on stopping distance. Engineered big brake solutions make a point of not changing brake bias without good reason.

[WhatsADSM]

Originally Posted by fe1rx

OE front caliper pistons are 36 mm, 32 mm and 28 mm for a total piston area per side of 2438 sq mm.

R1 total piston area per side is 3145 sq mm.

Other factors affecting brake bias are pad friction coefficient (if different compounds are used front and back), and the effective radius (which is likely increased slightly with the R1).

OE brake bias assuming the same pad material front and rear is 65% Front / 35% rear.

R1 brake bias assuming the same pad material front and rear will be something like 71% Front / 29% rear. This will likely have a detrimental effect on stopping distance. Engineered big brake solutions make a point of not changing brake bias without good reason.

OP:

I had to double check the piston area calculations on this and I agree. This most certainly moves brake bias considerably more forward (I show about 71.5% / 28.5% bias assuming the quoted 65/35 ratio was the correct stock number). Moving the ratio forward a little bit usually isn't a bad thing for a modified car but you may likely find that it is too far forward like this and as mentioned will probably increase overall stopping distance. If it gets to be too great you may have to tweak your compound selections front to rear to compensate (not ideal but will help), I believe the carbotech XP series compounds are available in that pad shape and have varying mu values (friction coefficient).

Another thought is that it is possible that R1 concepts designed this kit assuming that you would use their rear BBK with it which would likely shift the bias ratio closer to stock. Only issue with that is overall volume of caliper to master cylinder would be affected and would be decreased pedal feel and potentially the need to use too much pedal travel. Which means you might then need an upgraded master cylinder as well.

In any case it's always nice to have more brake options out there so I am happy to hear there is another product out there for the chassis. Thanks for the thorough review with all the pictures and the comparison to the high dollar brembo GT kit.