I remember someone(not on this site, but can’t remember where specifically) talking about some people fabricating their rear axle flange to setup a dual caliper setup for drifting for example. They briefly mention they would cut the axle flange and make some brackets on it to fit the two calipers. I was wondering if anyone knows anything about doing dual caliper setups on first gens? I would be doing it on an SA rear but shouldn’t be much different than a big bearing one but any information would be really helpful.

 

OK I will bite, even though I don’t see any point. If you wanted to do this you could easily do it, but you would want to start with a drum brake rear end housing instead of a disk brake housing.

Here is a picture of my first FC rear brake swap using an adapter bracket from the integrated caliper bracket on a disk brake rear end housing. It would be difficult to mount another caliper on the other side from the cast in bracket, and the flange on the disk brake housing uses 3 bolts instead of 4 in the drum brake housings.
This is my second version of FC caliper bracket. You can see that I used a drum brake rear end housing and made a flat plate to mount the caliper, it would be easy enough to make the bracket have another set of caliper mount holes on the opposite side. Then you would just have to make sure you used right and left calipers appropriately in each location. When doing the FC rear caliper swap you must run the right and left stamped calipers on the opposite side if you mount the calipers behind the axle FB style, on an FC the calipers are mounted in front of the axle. With a dual caliper setup, you would end up with one right hand and one left hand on each side, just make sure the bleeders are pointing up.

Another nice thing about using the drum brake rear end housing and flat caliper bracket is that you end up with a nice 3/8 thick bearing retainer in place of the crappy sheet metal part that comes standard on a disk brake rear end housing.
This is my latest setup using Wilwood calipers and rotors. You can see I have moved the caliper in front of the axle and mounted it horizontally, you can see how easy it would be to mount another caliper directly opposite this one behind the axle. Wilwood calipers have bleeders at both ends so they can be mounted however you want.

Obviously, these are all race car solutions with no provision for hand brakes, or any other street-oriented bits.

 

The other part of this is to work out which wheel sizes/offset will work to accommodate the calipers.

 

I have drum rears which from what you’ve done it seems like a good option. I was wondering what your dimensions for the brackets that you made for the calipers. Also what size wheels can you fit around the calipers. Also those are t2 calipers? If they are what was your decision for going with those over the na calipers? Did you just redrill the rotors for the 4 lug?

Just out of curiousity how much bigger are the wilwood calipers over the fc ones? From what i can tell it looks like you’ll probably need bigger wheels right.

 

I can share dimensions on my instillation, but I can’t guarantee that they will do you any good. my system was designed around my specific car and specific goals and issues. I am using FC rotors front and rear that I redrill to fit the stock 4X110 stud pattern.




One thing to notice is that the pilot diameter of the FC rear rotors is much larger than the FB axle flanges. On the first version I did we made laser cut rings that were welded to the axle flange, on the second version which is the one that uses the drum brake rear end housing I made a spacer that fits over the stock axle flange. It becomes a 12.12mm wheel spacer which is what is required to use the flat 3/8 thick caliper bracket. I had plenty of room for the spacer, but if you desired to run without the spacer behind the rotor you could offset the caliper mounting bracket by 12.12mm and mount the rotor directly on the axle flange.





As far as wheel clearance, any brake upgrade on an FB will probably require 15 inch wheels. Once you have the 15 inch wheels on the car you should never have to worry about the rear brakes clearing. The front with a much larger rotor and caliper becomes very tight and you do have to worry about clearance, but the rears are not a problem since you are pretty much limited to an 11 inch rotor.


I have tested this setup both with 15 x7 Koenig Rewinds, which are about the only game left in town for decent 4X110 wheels, and I have also run this setup with wheel adapters to use much wider 4X100 wheels with 245-15 tires. In either case you shouldn’t have any problem fitting pretty much anything you want in the rear.

 

Thank you this will help a lot. Also before I go any further are you good with me using your design as a ground work for mine with modification obviously to fit what I am trying to achieve with my car? If not and you want to figure out like compensation or something like that I’m more than happy to do so just let me know.

Also is this the oil seal what i circled below that then in turn sits against the bracket?

 

That part is a spacer that fits between the wheel bearing and the axle. It is required because you must have a large radius at that point on the axle or you will have stress issues, you can see that the spacer has a large chamfer to clear the axle radius. The oil seal is inboard from the sealed wheel bearing, so I didn’t bother modeling it since it doesn’t matter for the brake brackets.

The only good picture I have of a wheel bearing is one that was crashed. You can see the surface for the oil seal on the inboard side of the wheel bearing, and the thin sheet metal bearing retainer plate that Mazda used. This thin bearing retainer is known to cause problems when you run much larger and stickier tires and start creating more side loads on the bearings. Even when I was using the disk brake axle housing I made some ¼ inch thick bearing retainer plates to replace the thin stock parts.

You can also see in this picture the pilot ring welded onto the axle flange for the larger FC rotor. In hindsight I don’t think this is required, the rotor should be plenty accurately located by the studs.

 

I see in this one you have 3 studs on the rear retainer and in your cad it has 4 is this the first iteration you were talking about or is this something different?

Also are you okay with me using your cad design as a ground basis with modification to create mine on my car to fit what i want to do? If not if you want compensation or something we can figure it out just let me know?

 

That bearing retainer is to fit the 3 bolt flange on the end of a disk brake rear end housing from a GSL or GSL-SE. The 4 bolt design fits the flange on a drum brake rear end housing.

You can see that someone got cute and made the rear end flange in the shape of a rotor, well played to some Japanese designer.

Feel free to use my designs, I create stuff for what I need on my car, if anyone else can use it for what they need that is cool.