Manual brakes
02-23-2014, 10:38 PM
#21
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Join Date: Dec 2011
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Here is what I got done today
Factory hole is 4.25:1 (75mm)
Middle hole is 5.4:1 (60mm)
Top hole is 6.4:1 (50mm)
The top hole is to high for the clevis to fit. Looks like 58mm is the most u can do.
Tapped the holes for the master so it can bolt in.
Installed w/homemade MC brace
Factory hole is 4.25:1 (75mm)
Middle hole is 5.4:1 (60mm)
Top hole is 6.4:1 (50mm)
The top hole is to high for the clevis to fit. Looks like 58mm is the most u can do.
Tapped the holes for the master so it can bolt in.
Installed w/homemade MC brace
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02-26-2014, 11:59 PM
#22
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Join Date: Dec 2011
Posts: 19
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The pedal is still more firm than I would like. It would be better if I had gotten the rear 4 pot Wilwoods as well.
I am currently working on replacing the master with a 13/16" bore over the current 7/8". What I was able to find was a 97-99 Honda Civic CX HB master. Has the same 80mm bolt width as the miata, only the hole on the center of the plate needs to be bigger.
It has 2 equal sizes outlets, so I will need to run a "T" fitting to split the fronts and already have a bias adjuster for the proportioning valve. On the plus side though, it has an inch shorter pushrod depth into the master, so I can now get the angle I need to run the 6.4:1 pedal ratio.
I am currently working on replacing the master with a 13/16" bore over the current 7/8". What I was able to find was a 97-99 Honda Civic CX HB master. Has the same 80mm bolt width as the miata, only the hole on the center of the plate needs to be bigger.
It has 2 equal sizes outlets, so I will need to run a "T" fitting to split the fronts and already have a bias adjuster for the proportioning valve. On the plus side though, it has an inch shorter pushrod depth into the master, so I can now get the angle I need to run the 6.4:1 pedal ratio.
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02-27-2014, 12:41 PM
#24
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Join Date: Dec 2011
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Got a change to install the new master cylinder and make the new lines. Still need to bleed it but the pushrod is able to fit nicely into the 6.4:1 ratio hole.
Last edited by 00MugenS2; 02-27-2014 at 10:46 PM.
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03-10-2014, 06:05 AM
#25
You dont get very much there either, better than nothing. Since the balance bar will put all the stroke to the empty circuit until that master bottoms then it pushes on the master with pressure still. If the balance bar is driver adjustable you can crank it over and be "fine" though. One other problem is if you dont have enough range of motion on the yolks that connect to the balance bar you can bend the **** out of the master rods. But you'd hopefully discover that issue when bleeding the brakes... like last year's WPI fsae team, that was an interesting call to get at 1am, "we broke the master cylinders do you know where the spares are..." 
Firstly, the balance bars require constant lubrication in order to remain smooth enough to adjust via the cable. Secondly, they are a pain to work on, as generally the pedal box must come out to get to the masters and that is a job that can take hours, especially if you have a roll cage with side intrusion bars in the way. Also can make a mess in the cabin with brake fluid, etc, and you will probably have to run remote reservoirs as there is no space in the cabin under the steering column for them.
Bleeding is difficult too. You either have to do fronts and rears at the same time (three person job), or use a vacuum or pressure bleeder to get it done.
But... if you end up with a well-matched system (you have to size the masters properly for your calipers), they work great. Dual masters saved my *** recently at a track day when I lost the front circuit. The rears didn't pull me up before the turn, but they washed off enough speed to keep me out of a wall.
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