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It would be a kind of miracle if you find some lug mount calipers which fit MINI steering knuckle. Even with brackets it's very hard since MINI steering knuckles have rather long lugs.
It's better to look at radial mount calipers with not excessive piston area (different limit for R56 and R53).
Some suitable Brembo calipers are:
- front Porsche 911 4 pot of different generations
- front Cayman/Boxster 4 pot
- FIAT 500/Punto Abarth
- Alfa Romeo MITO
- Renault Clio RS 3/ Megane RS 2
- Opel Corsa OPC
- Renault Megane RS 3
- BMW 135 6 pot
- Alfa Romeo Giulietta GTA
- Alfa Romeo 156/147 GTA 330x32
- Seat Leon Mk1/Peugeot 208/Citroen DS3 Racing
All these calipers have piston area equivalent to not more than 57mm diameter single piston.
All these calipers make sence only in conjunction with corresponding brake discs.
The Gen1 non JCW caliper piston is 48 mm (2.8 square inches) whereas the JCW and the Gen2 non JCW piston is 54 (3.5 square inches). The Gen2 JCW piston area is approximately 3.5 square inches. IMO as the Gen1 master cylinder has no issues with handling the 3.5 value of the single 54 mm piston with the 3.5 square inch surface area, it should not have an issue with the 4 piston Gen2 JCW design with the same piston area.
Porsche, BMW and the Fiat calipers should be available in the states but would think the others would be much harder to locate unless you were on the other side of the pond. Cooper_a, are you able to come up with any Brembo documents that have the part numbers? It appears the MINI/Cobalt calipers are a Family E type model.
I highly doubt Brembo or BMW made public any drawings for these OE Brembo brakes. It is the same that you cannot find any semblance of drawing on OE parts. You can find "drawings" for aftermarket kits as they are there for fitment checks for the potential sales.
You have to find a real life sample and do the hard work and measure trial and error. A junkyard is in the best position to do this without having to invest in the lottery.
I have found a Brembo info brochure that does explain the manner in that they code their calipers and rotors. The MINI and Cobalt calipers are from the Family E, Stage 2 group. Found a technical drawing and the upper portion of what they use for an example is really close to the MINI unit. I played around with the coding and when I inserted a caliper number, a got information on the Subaru units. LInk to the Brochure is below.
I also found some other GM forum threads as the Cobalt caliper gets used on allot of different models as a big brake kit. It surprises me that a MINI guy has not posted about the matter. One post appeared to narrow the hub bolt spacing down to 4.875 that is only an 1/8" off from the MINI 4.75. From the Family E drawing I found and when I insert it into my program that I used to create early drawings it appears the unit may require a bracket and if so, would not need to drill the existing hub out, but then when I overlay the Cobalt over the MINI caliper it appears to be very close to the same depth.
The kit comes tomorrow so either I will be all bummed out, or, like a kid with his hand in a candy jar.
Box arrived late today. The hub bolt spacing is 4 7/8", which is 1/8" wider than the MINI 4 3/4". To get them to line up would require that 1.5 mm be removed from each hole. I have some pictures below. The bigger issue is that when I got one installed but using the existing hub bolt holes, it was obvious a 13"/330mm rotor would work perfect. The pads extend out over the top of the rotor mock up by about 3/16" The problem is that nobody makes, that I can find, a 4x100 one piece rotor that big. Wilwood has two piece units at 12.88. . These calipers are wide and with the Enki wheels I have need some 4 mm offsets to clear the caliper. I could get up to a 1.1"/28 mm rotor to work with them.
So grab some more popcorn as this is a job in progress. I need to think about how I want to proceed.
The box that they come in.
The existing Gen1 JCW.R56 brake pad on top with the Cobalt Brembo Pad on the bottom.
The Cobalts are just over 10" long.
Had to cut about 1/4' ribbon on the heat shield away to get the calipers to mate up with the hub holes.
I mounted the caliper via the top hole so it is off center by approximately 1/8" The blue tape is what I used to hold my 11 mm wood pieces onto the existing 294 mm Gen1 JCW rotor.
I am anxiously waiting to see what your final cost is when you get these brakes working
Originally Posted by Whine not Walnuts
... it was obvious a 13"/330mm rotor would work perfect. The pads extend out over the top of the rotor mock up by about 3/16" The problem is that nobody makes, that I can find, a 4x100 one piece rotor that big.
...
it was obvious a 13"/330mm rotor would work perfect.
Great news!!! GP2 discs are not only 330mm, but also have 26mm width like CobaltSS discs have.
What about offset (axial compatibility of Cobalt calipers and MINI discs)?
As I see there are no steel bushings in the R53 steering knuckle lugs. It makes it easier to grind off 1,5 mm from the lugs. Some time I wanted to grind off the same 1,5-3mm to put R56JCW Brembos on 313-310mm discs. But I didn't want to deal with these bushings.
I had not checked out the GP2 rotors but thought they were 5 bolts like the Gen3. I have found postings on other forums where a 28mm rotor was used with 1mm each side of clearance. I am going to do a 13"/330mm mock up now so will be back later with some comments. Anybody know what the offset is on the GP2? To center I had to use a spacer washer, it was just a little too thick but could grind it down if there are thinner options.
On pricing, I have seen the Cobalts for around $175 on Amazon Prime. The pin kit that will do both sides is around $20. Amazon had/has EBC Reds for $18.00, yes $18. They do require a different caliper bolt and I have seen the size someplace else. I think the Banjo Bolt is different but I have seen them for around $8.00. I did a quick Centric search, The #121-34160 is just the regular rotor with no slots/holes and seeing them for around $30-40. Have not checked Rock. Around $500 total????????
The only 5 bolt wheel made for 2013 model year was the CM R60 and that was 5X120 IIRC.The ‘14 F56 and subsequent Gen 3’s have 5X112. GP2 is 4X100. Have no idea what a GP2 rotor costs. Sully might be able to help with that.
Below are the pictures from what I had this morning. The 4-bolt GP2 rotor would appear to have 2 mm or clearance to the caliper and about the same to the pin clips. The rotor would appear to be about 1 mm above the top of the pads so they would have full contact with the rotor. Now remember that the Gen2 JCW pad is 4 mm deeper then the Cobalt but neither are as large as the GP2/I35i pad.
I used a spark plug gauge that is 0.1" between the top of rotor and the inside of the caliper.
Rotor would extend beyond the top of the pads.
Distance been bottom caliper and rotor hub is 1". I have not figured out the hub size of the GP2 yet.
Last edited by Whine not Walnuts; 06-22-2018 at 08:01 AM.
TCE has spacers that you could use for properly locating the caliper when mounting it. These are provided as part of the kits that he sells and he also sells them separately.
I have found postings on other forums where a 28mm rotor was used with 1mm each side of clearance.
Great!!!
Then you have some interesting alternatives to GP2 discs!
Here are Brembo technical drawings:
Cooper S R56
GP2
Ferrari 360
Alfa Romeo Giulia
Aston Martin
The most interesting discs for Cobalt caliper are Ferrari discs. They are the lightest and have the best ventilation. Their downside is that they need the calipers to be moved a bit outwards because of their offset. This will require bigger wheel spacers.
Carrier bolt - GM 11570091 that is suppose to be a M12x1.75 x 43 mm.
Banjo bolt - GM # 24436543 or Dorman # 13940. This appears to be a M10x1.5 x 22.8 mm.
Pins & pad springs - Raybestos H5842A
Left Caliper - AC Delco (made in Italy) 172-2484
Right Caliper 172-2485
The Brembo # appears to be 20.A207.05 for left and .06 for right
When I measure my rotor, sorry I am a tape measure type guy, the distance from the brake surface to the outside of the hub is 7/8"/22.2 mm so when I add the 22 mm brake portion I get 44.2 mm whereas the tech info I see on the Gen2 316 rotor is 45.2. There is approximately 1/4"/6 mm between the back of the rotor and the heat shield. When I was thinking of a 1.25"/32 mm rotor I figured the heat shield would have to be removed and reworked. The bolts that hold it in place may also need to be ground down.
The caliper has a rotor slot of 1 1/8"/28.575 mm and from the slot edge to the outside of the caliper body it is 2 1/16"/52.38 mm. Need to be conscious of this relative to your rim outset.
Last edited by Whine not Walnuts; 06-22-2018 at 02:43 PM.
28.575 mm slot is too small for 28 mm rotor. The hubs may have some play and the rotors can touch the calipers. Could you check the slot of the caliper once again and measure the gap between the pads.
With the calipers right out the box and with EBC Reds in place, I get 1 1/8". The rotor slot appears to be just a little over that. I found a forum post where the guy said he was able to use 28 with a TEXTAR 92149803.
You can get screwed up really fast if you do not write down what you are looking for and what the part was to go into. Cobalt caliper, MINI rotor etc.
The amount of rotor face on the back side of the Gen2 GP is about 2 1/2" and the EBC Reds have a little over 2 1/8" of friction surface so when you add the little bit of rotor that sticks up above the pad, there is not much more than 1/4" of the rotor that is not being used. The Gen2 JCW has probably has another 1/8" of pad depth but all in all, this is a pretty good option. In order to use the Gen2 JCWs on the Gen2 GP rotor, you would have to make a bracket to kick the caliper out another 1/4" and knowing what the hub looks like that would be a real PIA.
I have the rest of the parts ordered now and may not have this all buttoned up for a couple of weeks. Hey I am retired and have some other retired type stuff I gotta do.
In order to use the Gen2 JCWs on the Gen2 GP rotor, you would have to make a bracket to kick the caliper out another 1/4" and knowing what the hub looks like that would be a real PIA.
It's not just PIA, it's impossible to make properly. To put JCW Brembos on 330 discs they have to be severely milled between the lugs, and it looks like a bad idea since they loose their rigidity. Another bad idea is to move the calipers to the top or to the bottom of the wheels using some weird brakets.
JCW Brembos don't need bigger diameter discs, they need wider discs. And with some manipulations they can fit 16" wheels with one-piece brake discs of the folowing sizes: 315-316x28mm, 316x32mm. And with two-piece custom brake discs up to 316x36mm monsters.
If to modify the mounting holes in the steering knukle lugs JCW Brembo calipers can be used with 310x28-36mm brake discs. JCW Brembo calipers have one great advantage - they are very tolerant towards the X-factor of the wheels.
With the calipers right out the box and with EBC Reds in place, I get 1 1/8". The rotor slot appears to be just a little over that. I found a forum post where the guy said he was able to use 28 with a TEXTAR 92149803.
Then it would be great to mate them with Ferrari discs.
Relative to shims and getting the caliper centered on the rotor, I have thought about hooking up my compressor. With the bolts loosened and by applying some pressure, the pistons will push the pads. As there are pistons on both sides this action should force the caliper to slide in or out on the loosened bolts and center itself.
Relative to shims and getting the caliper centered on the rotor, I have thought about hooking up my compressor. With the bolts loosened and by applying some pressure, the pistons will push the pads. As there are pistons on both sides this action should force the caliper to slide in or out on the loosened bolts and center itself.
Nice idea in theory, but not reality. This is how I remove the pistons from my Wilwoods. I fit a piece of wood that is just slightly smaller than the rotor slot. I learned that the pistons come out unevenly the first I tried this, but I used a smaller piece of wood. One piston came out, pushed the block all the way over to one side, the piston came out past the seal, and blew brake fluid all over me. Even with the tight fitting piece of wood, it gets pushed to one side or the other. There is just a slight difference in friction between pistons that will keep it from “centering ” the rotor.
06-20-2018, 07:26 AM
