I bring this up as I think a lot of people are following this thread just because this is a low cost BBK. And I think it is a great thread because of the effort you have put into doing this. I just want to point out to any novice drivers who may be thinking that this could be a great setup for the track, that this may not be the case or that they need to do some upgrades such as cooling to the brakes and/or some really high temp brake fluid (there are some that are pushing 680 deg vs 550-600, which is more common https://www.lelandwest.com/brake-flu...ow=1&SF=5&ST=2).

 

I did not drill, I filed them out with a rotary drill. If you have time and tools including a drill press you may be able to:

1.) Remove the knuckle from the car.
2.) Weld the existing hole shut.
3.) Tack weld a 3 mm round blank onto the rotor side of the knuckle.
4.) Using the drill press, make new 12 mm holes in the knuckle that are 4 7/8" centers and are back into the wheel center by 1/6".
5.) Remount the knuckle and mount the caliper.

I do not have a welder but I have also thought about laying a bead to help infill the area that I used the special made washer to help infill. I would then use the rotary file to "round" the hole up.

This is a low budget option. Of course it is much easier to just dip into your pocket and spend more money on kits that already have brackets, shims etc, OR, just buy the Gen2 JCW brakes/rotors and bolt them up.

 

Agree 100%. Thread has gotten pretty long so I have not kept count on how many times I said this is a Track Wannabee big brake option.

There are some very talented people here with mechanical abilities that may be able to point out issues that my feeble old brain has not foreseen. I have; 1.) Taken a caliper from a Chevy, 2.) Used a rotor from a Gen2 MINI that is eleven years newer in design than then the first Gen1s, twelve if you consider the Euro models, 3.) Enlarged the original knuckle hub by filing it and 4.) Performed all the work without a drill press or a measuring caliper. I do not plan on running the car at Le Mans or any other track. I am an individual that has cut coil springs, loosened my oil filter cap with a vice grip via the wheel well, used straight out of the bottle Simple Green on my engine bay and painted my chrome trim black. I am cheap and will crawl around my car using every curse word in the book attempting to perform tasks that those in their right mind would only do on a full blown car lift. Eighty-Five foot pounds of torque is a good amount as one must push the wrench pretty good to achieve. I filed the holes so that the outer edge of the knuckle was not impacted and with that amount of torque along with some threadlock, I cannot envision the caliper bouncing around so that the filed hole is enlarged thereby weakening the knuckle to the point that the entire thing is going to blow apart. I am not going to be concerned that I do not have stainless steel pistons or additional cooling ducts.

That is me and I can only point out that if anybody attempts this modification they fully consider all the issues and if they decide to do so, they do so at their own risk.

 

I thought welding on a casting wasn’t a good idea as it can leave strong and weak spots depending on how and where the welding anneals the casting. Maybe grinding/rotary filing the hole is the best option in this case.

 

14.75 is pretty close! Might work, 949racing wheels are made to fit over big brakes, they fit over stuff that most will not

that cobalt had brembos on it, but it would not matter if he had brembos or the regular caliper, the fluid boiled and he killed a couple sets of autozone pads

I have a mig welder if you want to plug the gap on the brackets, with cast parts you have to heat them up first before you weld

 

The curvature of the caliper is not the same as the my wheel but at the tightest spot I have is just over 3/16" of an inch. I took and moved the wheel weights out 1/4" so that they would not make the 3/16" even less. The offset could be increased more so it comes down to how much time you want to spend.

On the gap, if one took a 12 mm rod or bolt and a file . . . . . . . .

Hey think about Andy in Shawshank

 

I went to a U-Pick yard and got a used knuckle/spindle/carrier. I have been thinking about either a bracket or a better washer to address the area that is filed out. A bracket could be made that would bolt to the knuckle but that is for another day and post. For a better washer I picked up some $0.62 electrical JB covers and got my roper punch out. When you torque the caliper bolts the washers do want to rotate. The top bolt has a perpendicular ledge on the knuckle so you can kick off that to keep the washer from spinning. For the bottom bolt need to have two different type washers as the passenger side wants to rotate out away from the center while the driver side rotates down toward the center when tightening.

Stay tuned . . . . .


I use the Roper punch to outline the piece I want. I have made the tab/finger longer than what you can do with a regular washer as the plate has no holes to compensate for.




You can see how the upper bolt hole has something for the washer to kick off of so that it will not rotate.


On the passenger side can bend a portion down into the area that is open for the ball joint. On the driver side I will have to make some tabs that will bend over the curved bolt carrier. You can see how the tab extends down into the bolt hole and "infills" some of what was filed out.


The tab is much longer and extends over the smooth portion of the bolt and over part of the threads.

 

lkq? I have not had any luck finding any other yards that let me dig around

 

Yes LKQ but the car I got the part off is now gone. They also have a warehouse down the street that you can order parts that they bring in on shuttles.

 

how do you order parts to get them shipped there? I kinda like digging around though, they had an r53 with an engine/trans in it in greensboro, if I had helping hands I would have pulled it out

 

http://www.lkqcorp.com/en-us/

Raleigh is a major call center for them. The guy I talked to has a friend up in Jersey that has like 60 different Minis. On the u-pick yards I think they let the gophers like us remove the interiors, plastic trim etc and then when the car is picked over pretty good they send it off to the scrap yard.

 

I know there has to be some out there that pull this thread up and between the Cayman calipers and my ISO fabrication tolerances just sit back and either shake their heads or laugh their butts off.

 

measure it out, design it in one of the free cad programs like tinkercad, I can 3d print them for you, then once it's good get them cnc'ed, I have a contact in raleigh that can do one off parts I'm not sure what the cost is though

 

So lets address wheels.

I have said in previous posts that anything less than 15" inside wheel dimension has to be carefully checked. I have that 15" and I clear by more than a 1/4" on the end of the caliper where it centers over the rotor. The bigger issue is how the spokes of the wheel are formed. The GP2 rotor has a face 1.5 mm thicker than the 22 mm rotor that will push the wheel out. My wheels have a 42 mm offset so I tried a 3 mm wheel spacer first. This 3 mm and the 1.5 mm rotor thickness was closer than I cared to venture so I went with another 2 mm by using a 5 mm wheel spacer. With the 5 mm spacer, I have around 3/16"/4,5 mm clearance.

This amount pushed my wheel out by just over 1/4". I have coilovers with a 1" drop but have not driven the car hard to see if there is any rubbing against the outside fender well. My camber is within factory specs so I can go a little more negative that would help any rubbing. The GP1 camber is about -1.5 according to posts that Way made relative to his car. I do have adjustable camber plates so this can be accomplished quite easily.

 

I have a feeling that wheel selection will be limited because of the size of the calipers. Same thing applies to the F series BBK. There are a couple of threads dealing just with wheels that’ll clear them.

I really like what you’re doing with your big brake project. I don’t, and will never own an R53 or another R56 but it’s still interesting to follow the progress of your project. Looks like the only major problem is making the oblong hole in the knuckle round again. If you could design a half sleeve with an integrated spacer that would solve that particular problem and lock the calipers securely in place. Only problem would be the CAD and CNCing of the parts. That likely would not be cheap and would change your inexpensive project to just another BBK.

Look forward to seeing the final results next time I see you.

 

I would consider another way. To relocate the existing caliper lugs' steel inserts instead of relocation of the knuckle holes. Of course if the caliper lugs have enough material to keep strength. For R56 it's more atractive than for R53 because of the steel bushings inside the R56 knuckles.

 

IMO this is not a major issue. First, the caliper is going to maintain the bolts in a 4 7/8" spacing. I am going with the thought that Brembo has an enormous safety factor on the strength of the caliper connection points. Next the clockwise force of the wheel is going to force the bottom bolt into wheel center, something it cannot do as the bolt is up against the knuckle material. The force associated with braking in reverse is significantly less and I am going on the premise that the 85 foot pounds of torque is sufficient to withstand the counterclockwise force associated with reverse braking. The top bolt is the main point of interest and the only way it can move into the oblong portion is in a downward movement and we are back to the caliper maintaining the bolt spacing. So the question is whether a continued braking force will either compress the metal of the knuckle or cause it to fatigue to the point that the bolt can displace knuckle material. This leads back to the washer tab that the bolt would have to compress and I see neither scenario occurring. It would be logical to assume that adhesion between the rubber tire and the road surface would not allow a force of this magnitude to be transferred.

If the force to compress or fatigue existed it would be logical to assume that the OEM knuckle would reflect oblongated holes after prolonged use. Anybody know if such an example exists?

 

and, no I am not an engineer but I also do not think I am talking out of my butt.

 

I am sitting here looking out on a lake that is 10 minutes from the Tail of the Dragon. No MINI just a Seadoo that was towed with our SUV.

The issue with the oblong holes would be an issue if the MINI Gen2 JCW Brembo was placed on a Cobalt as this would be putting a 4 3/4" bolt spaced caliper in a knuckle/carrier made for a 4 7/8" unit. The JCW Brembo could move up and down without proper shims. With the Cobalt Brembo the opposite exists and I never really thought of expressing the issue in this manner.

I thought I read someplace where the GP2/135i calipers had to have the Gen1 knuckle/carrier reworked by 2 mm. It is logical to me that a larger caliper would have a wider bolt spacing.

 

Here is a thread on the GP2/135i caliper retrofit. The guy talks about 1 mm but it may be that it was 1/16" that is 1.5 mm. I found another thread where the guy said he used a dremel to enlarge the hole but did not mention how much.

https://www.northamericanmotoring.co...in-here-3.html

 

I finished up my oblong hole shims and put them on the car. There is not rotation with the manner that I made them, something that was not the case the fender washers that I used earlier.


Driver side on left and passenger side on right. The top units are basically mirror images whereas the bottoms are different to compensate for the opposite rotation from left to right side.


Passenger side caliper with the special hole shims in place. Not the easiest position to take pictures in. On the bottom unit you should be able to see the tab that is bent into the area where the ball joint goes. The ball joints can be replaced without having to remove the caliper bolts.

 

How is pedal feel and drivability?

 

Have not done any spirited runs yet. The pedal does seem to move more than with the single piston but from what I have read that is normal for the system. In years past I normally would open up the bleeder to push the pistons back but with these calipers the pistons move very easy with the bleeder closed.

One would think that with the big (for a MINI) 330 mm rotor that is also 26 mm in lieu of 22 along with bigger pads the heat mitigation should be better.

I will probably be taking a trip over to Winston Salem to talk with a shop about a roll bar I have been thinking about. The shop is on the road to Mt Airy and there are some great runs up there. My friend has the Gen2 JCW Brembos and he said his peddle was different as well but now is just used to them.

 

hard dog? I had him make the bar for my track car

 

Yes Hard Dog.