I plan to be the April 22nd day at Pacific.

I haven’t had much brake issues since I pioneered the use of the Mini Cooper kit and started using Cobalt Friction XR2 pads but now for sure I will not have a problem.

The most recent upgrade to the brakes was swapping to a 929 1” master cylinder. What a huge improvement in feel that was. Next brake upgrade will be swapping out the rear calipers to ones with bigger pistons from a late gen M2 with the bigger sport brakes. Should allow me to adjust the willwood bias valve to something other than full rear I think.

Bob

I'm hoping to make that 22nd alfa day. Depends on my vacation schedule. I know my wife and I are doing some traveling in April, just not sure of the dates.

I thought you were using the Wilwood Civic kit in the rear? Not happy with the bite from those? Ditched those and went back to the stock caliper for the E-brake feature?

I'll look at that 929 MC. Even with stock brakes I've always thought the pedal was a little mushy.

I've got a set of the Mini Cooper Dynapro's like yours to go on the front along with RX7 rears with brackets that allow for a vented 11" rotor in back. Trying to decide on the right combination of calipers and discs for my usage though. Removing some of the shims I could use those big dynapro's on the front with an 11" rotor and keep with the stock rears. My Kosei's would fit fine that way where the Dynapro's with the 11.75 rotor is too big for them without a big shim.

Stainless steel lines would help with that mushy pedal Casey, mine's certainly not mushy, and it's the only difference in our systems beyond your Corroded rotor setup.

I have stock calipers in the rear the rotor and hat I’m using in the rear is from a wilwood Drag race kit for a Civic. They are 11.44” diameter. The non vented steel rotors that wildwood sells suck though, So I had custom rear rotors made out of cast Iron from Coleman Racing.

Which Kosi wheels do you have? I have used the older Kosi K1’s with no spacers and they fit fine. Probably the tightest fit of the wheels I have tried but they fit.

The RX7 rear caliper is a better match I think because of piston diameter. It should correct the two far forward bias nature of the stock system. But I have also discovered the Stock rear calipers from a big brake NB have the same piston diameter as the RX7 calipers and will fit on the earlier NA/NB caliper brackets so it is an easy swap for me.

Bob

Let us know how that turns out Bob... Would be interesting to see if you can improve on your current system.

My Kosei's are K1's also. I'm still working on the brake system. Haven't fiddled with spacing yet. As they were set up when I got them they just barely touched. I'm working on shimming them differently but I'm slow and lazy and haven't spent much time on it yet. It's a daily driver so I have to make sure it stays drivable while I'm screwing with it.

Let me say a BIG THANK YOU for your great write up on the brakes. That page has been favorited for about a year now. Just now actually doing something with it.

You have ABS?!? Plus those stainless lines I have look a lot prettier on my shelf than hidden and dirty under the car. :facepalm:

I'm thinking the mushy has more to do with difficulty bleeding the brakes with the ABS system. Pretty common problem/headache.

I think my K1's are 38 offset did they make them with more offset or something? the only way mine would hit is if I put balancing tape weights in the wrong spot.

Same offset as mine. Like I said, it may be fiddling with the spacers. These calipers might be shimmed out just a touch too far on the radial bolts.

You need to do a 80's computer programming montage where you do all sorts of crazy computer modeling to an upbeat sountrack

Bob: got any write up on 929 MC ? I've been to parts stores a few time, never could get the right parts. my brakes has always been mushy.

I better start clean up my car for MRLS. Bob is bringing his monster !!

Some info buried in this thread. Pictures about post #36

Some interesting brake information (tech!) - Page 2 - MX-5 Miata Forum

Basically you need a booster from a later model Miata that came with the bigger sport brakes, a 1” 929 Master cylinder, and you need to redo some hard lines by the Master cylinder. I haven’t figured out the difference between the ABS and non ABS 929 MC it might be that one has 2 front brake ports in it like my stock miata one did. The 929 one I used only had 1 outlet for front brakes and 1 outlet for rear brakes and I had to add a T to the front brakes. A 10mmX1 tap with a modified tip can be used to change an SAE 3/8" inverted flare T into a metric inverted flare T. dosnt seem to be any metric T's avalable and this is much esyer to do than flaring new hard lines.

Bob