929 MC modification
 

my MC died last week on X-mas day. So i figured what the hell i'll just order a 929 MC and do all my brake mods at the same time. so i switch everything... but i only have about 1" or so of brake pedal travel, and no braking whatsoever.

So i removed the MC, adjusted the brake booster actuating rod all the way in, then adjusted the brake pedal adjust all the way out. i did this because it seemed like it took alot of force to get the MC on in the first place.

i have had the MC on and off like 40 times, everytime, i re-bleed the front brakes at the calipers etc. still the same thing... i am at the point where i think it would help to pull the MC off and space it away from the brake booster...(thinking that the piston in the MC is all the way in already)

My car is a 1988 T II with ABS, Stainless steel lines and Hawk HPS pads... BUT i had the problem before and after the line and pad swap, so that is not the problem. what have you guys done to make yours work? what do you percieve my problem to be. I have owned and maintained RX-7's for years, so i know how they work, i must be forgeting something stupid, OR the fact that this is my first ABS car might have something to do with it..


Any insight would be greatly appreciated!

Thanks in advance

I thought the 929 mod could only be done on 3rd Gens. I know that the ABS system is slightly different from SIV and SV RX-7s. I wouldn't be surprised if it was drastically different to the 3rd Gens as well.

Anyways Chuck, whatever happened to you? Do you still have that GTUs? PM me on the forum as my ZachSpazz name on AOL is dead.

The 929 master works on the FC. Had mine on for about 6 months now. You need to check ALL the brake line fittings. If you have air getting in the system, the system will not bleed and the pedal will go all the way to the floor.

I'm wondering... the 929 master is a larger diamater, and gives a stiffer pedal feel. However, because of the way hydraulics work, doesn't having a larger master cyl mean that for a given pedal pressure, you are getting less squeezing pressure on the caliper side? Because the force ratio is a function of master diameter and slave diameter... for example a hydraulic jack for lifting your car works this way, you pump a teeeeny little cylender, and it boosts the big one.

yeah but that is the problem,the pedal isn't going to the floor, and all the fittings are tight...

I am going to try to re-bleed tomorrow,,,

if you come up with anything else, please let me know!

crack one bleeder screws, fill the reservoir and take an airhose and gently pressure the reservoir with the small hole in the cap. See if it'll bleed some of the air out.

that's a clever idea with the air hose. I got a speedbleeder screw for the clutch... much easier than cranking it on and off while someone pumps the pedal...

Sounds like the master wasn't bench bled?&nbsp Almost guarantee there's air in the system.&nbsp It doesn't matter if the pedal hits the floor - this'll happen when there's a lot of air.&nbsp If there is a tiny bit of air, it's enough buffer to prevent good braking but still keep the brake pedal off the floor.



-Ted

no front brakes....
 

after hearing what a few of you said i moved the MC and bench bled it yet again. It really helped, i have really killer rear brakes, but no front brakes now...

Also i have very very little pedal travel... could this just be something i need to adjust?

There is no air in the system, i bled every wheel twice..

this is driving me nuts, any insight will, as always be greatly appreciated...