ok just wanted to know would the 929 master cyl. make any diff. on a close to stock brake set up? i have brembo rotors and ceramic pads.

thanks
Robert

 

As far as i know, which isnt much, the larger amount of fluid the 929 can hold would be better for larger calipers that needed the extra fluid.

 

I have one and am using stock calipers. I love it. It's hard to push on, but I much prefer that to a soft pedal.

 

I just recently purchased the brake lines to the MC and the bracket. Im gonna fab up some custom lines so you dont have to bend your stock one. I also have a 929 MC that I need to put on but I'd rather not bend my stock line. I'll make a bunch and start selling them on here for cheap. Need to wait till school ends in a month before I have time to do it though.

 

With stock brake calipers the only difference you'll notice with the 929 master cylinder is a small decrease in the amount of brake travel needed to provide a certain level of braking force. Because the diameter of the 929 master cyclinder is 1/16" larger than the stock (1" vs 15/16") you get a about a 12% reduction in pedal travel.

I don't know if I'd bother with stock brakes. With aftermarket calipers that have larger pistons it sometimes helps keep the pedal travel from getting too long.

 

since you're losing pedal travel it would seem that it would be harder to regulate how much braking you want. is that accurate to say? my MC may be toast and wondering if i should try something else like the 929. stock brakes, hopefully some trackdays in the future.

 

Pedal travel will go down, pedal force required for the same amount of braking force will go up.

That means you'll have to push the pedal harder to get the car to stop.

 

No, it's not accurate. It is much easier to modulate something using pressure rather than distance. Once you start going to the track, you'll learn that smoothness in everything you do is the fast way. You can't squeeze on the brakes and go to full braking and then smoothly release at the end of braking when the pedal is moving a fricking inch and a half.

 

I have put in the 929 cyl and it is much better for me .Here is the difference in my install . I did not add any new lines nor did I re bend or re route any lines .I re machined the cylinder to fit in with the stock lines .I like the feel of the short stroke using pressure not distance to control the breaking effort . And yes the unit is polished and the vacuum booster is power coated and upside down so the vacuum line is hidden as all my lines are hidden . Good performance and good looks .

 

http://robrobinette.com/mastercylinder929.htm

Some good reading

 

best brake upgrade for the money imo....forget the "big brake" kits for $2k

from RRs old site:

Then we jumped on the other side of the fence: larger-than-stock pistons from the "big red" caliper (even more enormous caliper-from the front of a 993 turbo). We also increased the thickness of the MMC rotor from 1.1" to 1.25". Just barely fit behind the airy spokes of the big 17" TE37s. Around town, this set up was very nice. In fact, pedal travel was very close to stock. Braking force, on the other hand, was exceptional. However, on the track, while braking from high speed, weaknesses became apparent. It almost felt as if there was air in the system-it took two quick pumps to get the characteristically firm pedal it had when driven on the street. Repeated brake bleeding did not help.

Today, thanks to Mostly Mazda, a larger master cylinder from a '93 929 was installed. Stock bore is 15/16", 929 bore is 1". Doesn't sound like much of a difference, but it's significant. RESULTS: Firm, firm, firm pedal under any condition I can manage on the street. Ever drive a 911 turbo? Same feel. About one inch of free play, but then it stops. You modulate more with pressure and less with travel. The pedal lines up right next to the gas pedal (and the David B.'s pedal adapters, of course)-- making heel/toe footwork very easy. Braking is very, very strong. Braking also feels more "direct" and far less vague. You can even feel the holes in the rotor scrape against the pads. Very very fun. With RA-1 race rubber on, braking from high speed is absolutely incredible. Decelerates so hard that it repeatedly skips my stock CD player. It never skips otherwise. Looking forward to trying it out on the track with a prototype set of trick brake ducts that should be in next week. Should have a better idea of overall f/r balance. So far, I can find no fault. I'll update the list...

the soft initial pedal drives me nuts, the "two pump" thing is exactly what my car was doing, every time, and this upgrade fixes the problem

 

what year of 929 is it from?

 

This was probably caused by flex in the brake system that only came out under heavy loads while tracking the car. Usually insufficiently stiff caliper mounts. High load cornering can cause a flex and distortion that compresses the brake caliper pistons a little bit by pushing them again the rotor. Then when you straighten out there is a very small gap between the pads and the rotor. This can cause a soft pedal feel and require a longer strock of the master cylinder to fill the gap.

Personally I think the 929 master cycliner might help mask the problem but was not the solution, just wishful thinking.

 

Agreed. The excess caliper piston/brake pad gap can also be caused by vibration, which causes the brake pad to repeatedly rattle against and "hit" the piston, forcing it back in its bore. The vibration could be one that isn't readily noticeable by the driver, and could be cause by anything ranging from worn/rough discs to worn suspension bushings/bearings.

 

my bad... sorry.

 

wrong....

my car is not tracked and I do not "brake under excessively heavy loads"....the 929 mc FIXED the problem (soft pedal and "pump up")....and yes, I bled the brakes

I wish more people would just do this mod instead of randomly bashing it, we'd make a few more converts....driving the car is believing

 

I was refering to the example you quoted rather than your particular experience. I put a 929 master cylinder on my FD. It did just what I expected. A small reduction in the amount of pedal travel needed in order to achieve the same amount of braking force. I think it is a worthwhile modification. But not some kind of miracle brake problem cure.

Perhaps your original master cylinder was not in the best condition and replacing it with a new 929 master cylinder helped a lot.

 

"1993 Mazda 929 master cylinder part # HG31-43-400G (ABS version) - I got mine from Jeff Haas Mazda for $170 (that's a 25% discount for ordering from their 800 number: 800 233-2991). Pep boys wanted $214 for it. Mazda Competition Parts will sell it for $135 if you are a qualified racer. "

Quoted from: http://robrobinette.com/mastercylinder929.htm

 

i think a few of you need to meet up and drive eachothers cars to figure out what each of you like better. it seems that--unless you track your car--this mod is not requisite like a downpipe but more a mod of preference.
unless you are someone that feels the stock FD brakes are inadequate???

 

rather than make a NEW thread first, i decided to ask if any of you guys here know what it takes to install the 929 master cylinder on a Gen I Rx-7. is it a bolt-on affair? i already have stainless steel/Teflon lines and great synthetic fluid. i just want less pedal travel before i get response ...

thanks,
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