I thought I recalled seeing larger diameter FD brake rotors are a straight swap to FC's (with 5 lug/4piston brake suspensions), and just require an adapter plate to relocate the caliper. Is this so, and does anyone know if such a thing is sold commercially? I looked at Racing Beat, MazdaTrix, RX7.com, and a couple other sites and didn't see anything. Google and the RX7club search engine both gave a pile of useless search results. RHDJapan has some to allow FD calipers to be used at the rear, but that would be going the wrong way; like pretty much all FC's, I already have too much rear brake bias, which I've tried for years to deal with by using more aggressive pads at the front.
I can't put in an adjustable proportioning valve in my class, but I can do a big brake kit. The front calipers and pads are the same between FDs and FCs with the four pot brakes (GXL, GTUs/Sport, Turbos), but the FD has a larger diameter rotor, effectively delivering more leverage and so more brake for the front. My understanding is FD rotors are a swap on, and I don't want or need a lot more brake, just trying to balance the front/rear brake proportioning by upping the stopping power at the front. Maybe I'm wrong about the FD front rotors even being a swap on?

 

Theoretically I'd think nearly any brake setup would be swappable so long as it uses the same bolt pattern with the hub. At least in the 240 world (new to RX7's so you'll have to pardon me) if you had a 5 lug hub, you could bring over STi or Mitsu Evo brakes (calipers and all) with just an adapter to mount the caliper where it needed to be.

I see no reason why a FD rotor given it has a 5.114 bolt hub rotor couldn't just fit right in place, leaving you with "mounting" for the caliper. Course, given that you may indeed want to look at the Brembos from a STi or Evo for more front bias? Chances are you can find them for less than a pricey aftermarket equivalent.

 

I'm looking low buck here - I already have the FD calipers in effect, and they're very good brakes, since they're the same as the FC ones, I'm just looking for a larger diameter rotor to clamp them on, as that would give greater mechanical advantage, and should help with the excess rear brake bias of the FC. I know a couple FD guys in Calgary, maybe I can see if someone has a used up rotor I can borrow to mock this up, see if it's feasible to create the needed adapter.

 

FC Mandeville Brakes

 

Greg, I've got plenty of spare fd brake parts. Let me know what you want. If all you need is a rotor for mock up I'll pull one from the metal bin.

 

I had come across the Mandeville brakes after posting initially; same idea as I'm after.

Neal - you were someone I was thinking of hitting up to see about a junk rotor to try mocking something up I'll be happy to lighten your scrap metal bin.

I am beginning to wonder if I dreamed up that someone had already tried this before. At least maybe not tried successfully.

 

I have fd rotors on my 91 complete bolt on =) no problems

 

So did you fab your own caliper adapters? Pics?

 

Well, I finally got around to trying out the FD rotor fd_neal flipped me last year - it is not a feasible swap. The FC hub is ~144mm in diameter, while the inner diameter of the hat portion of the FD rotor is 140mm. I could possibly have the hubs machined down by a couple mm radius, but then I'd still have to find a way to fasten the caliper a mere 1/4" further out (half the FD rotor's greater diameter), but in the same plane. Doesn't seem likely that can work, save by welding new ears onto the hub carrier and tapping new holes. If I had a machine shop available to do it myself, this might make some sense, but not if I have to pay someone else to do the work.

 

Alpha 7 might have himself confused, maybe he has fd calipers not rotors.
Are fd calipers direct bolt on?

 

FD calipers ARE a direct bolt on affair. I've done two FD caliper swaps to FCs with single piston calipers.

 

but obviously using FC calipers correct?

 

Using FC rotors, brake pads, and brake lines (in the case of a swap to a single piston FC, the FC3s turbo hard lines are needed, they go in between the caliper and the rubber brake line).

 

now im wondering if I should have spaced out ( ronin kit ) a set of FD calipers for my FC instead