Nothing left to do but brakes.
 

the current setup in the brakes department is a 929 master cylinder and hawk pads. I am not liking that I need to apply a ton of force to the brake petal to get the car to stop. The brakes don't need to be bleed. The petal is firm with no spongy feel but the amount of pressure I need to apply stinks. Is this from the 929 master cyclinder? If so then why do people do this mod? I thought it was pretty common thing to do.

Anyways I need to get this cleaned up. What are my options? Should I get new calipers? I am not going to track the car often so I feel like a big brake kit isn't worth the 2k for my application. Are there other things I could do to reduce the amount of petal pressure that's needed or just add some bite. My 335i stops way better. Shouldn't the fd be better? Or is the tech that much better these days?

The 929 master cylinder is the wrong thing to do without big brakes. You need to go back to the stock size which is 15/16" diameter instead of 1". The larger diameter MC was used when Mazda added larger brakes to the FD. The system needed less pressure since the caliper was further away from rotor center. Think of it like steering a boat, the larger the wheel, the easier it is to steer.

What silvertrd said is true, but think you may want to look at your pads first. Did you have them before you replaced your MC?

AFIK the 929 master is used for aftermarket big brakes because the piston size is larger but the size of the rotor doesn't have anything to do with it :scratch:

I also don't think 99 and later FDs with big rotors used the 929 master :scratch: Again the bore size is the same so no reason to change the MC.

I'd suggest checking the check valve, the booster may be leaking or you could have a small hole in one of the rubber hoses going to the booster etc...

As Tom suggest possibly the pads are glazed or not putting enough torque/bite on the rotors.

Mazda used a larger bore on the MC so they wouldn't have to redesign the calipers, so the bore size of the calipers is the same. If the caliper is at a larger distance away from the wheel center on the rotor, it has a mechanical advantage and requires less force to achieve the same clamping force? Does this make sense?

All the info you could want and more here;
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When the stock Master is used on a big brake kit, it is way too much clamping force. That is why people change their MC when they add a big brake kit.

The stock M/C will require less pedal effort (more boost per foot pressure) than the 929 M/C with the trade off that the pedal travel may be increased. If your brakes are otherwise stock then the stock M/C is likely the best match to your system.

As others have noted though check your pads first as it's way easier to change pads!

I read your post, and all I can think of is this :rofl:

https://www.rx7club.com/attachment.p...1&d=1459509842

Yeah the 929 master pushes more fluid and you control braking force more by pressure than by pedal throw. On track I prefer it as the added pressure on my foot seems to give me more feedback on grip. At least in my mind.
You should replace your pads with something that has good initial bite.

I am not sure what Hawk pads you have, but the hawk street pads absolutely suck. I had them on my car for a little while and took them off and sold them. I just did not like the feel and the poor braking capabilities of them.

I would try another brake pad.

Well that's bc I am idiot.

I had pettle first. Edited it to Petal. Still felt like something was wrong.

Lol

Well this was exactly what I was experiencing when i got my FD, and I was thinking something was wrong with the braking system, the pads shouldn't have been that bad. Then I changed to a BBK and everything has been fine since then.
Now this thread makes me wonder if I have 929 master cylinder installed.. Is there a way to visually distinguish the two master cylinders when already installed?

this is correct. the JDM FD'd all use the same master from 92-2002, big brakes or not. same guts as the US one. the RHD part has the lines on the opposite side.

+1, throw the hawk pads away, they are junk.

Peddle: to sell ones wares

Petal: a leaf, tree parts

Pedal: the thing hanging from the dashboard.

i know english is a crazy language, but just be glad we're not trying to speak latin

My fault. I assumed the 929 was made for the FD.

the 929 master comes from the 93-95 929.

these 929's were kind of ill fated, they came out right when the economy tanked, and were probably expensive so they didn't sell that well. they might have done better in 2015, as its got styling that is similar to the current Nissan range, or a whale.

under the skin, it was a DOHC 3.0 V6 making around 180hp. it had a couple neat things, like a solar panel in the moonroof to run the a/c on hot days. it also had a couple of not neat things they used a BMW like plastic water pump impeller, so like the BMW's they broke, and the overpressure from the overheat usually popped the radiator, so at the dealership we'd see these come in with a new radiator and hoses, and an engine with blown water seals.

they coupled this to a transmission that was shared with the Nissan Pathfinder and Mazda MPV, which failed early and often

couple the two together and the 929 is probably really rare now.

I don't know anything about math formulas but if I'm pushing fluid into a brake caliper with a bigger piston I need more fluid to keep the petal (oops pedal lol) from hitting the floor or to keep it high enough for a smooth comfortable heal toe.

I've driven track cars with big brakes and the stock master and there is not enough difference in clamping force to register a difference. Also in these old jalopies most give the brake a few taps before threshold braking to help with knockback and the pedal stays nice and high anyway :)

As far as rotor size goes a bigger rotor just heats up slower so if anything it's less sensitive than a smaller rotor. Of course if it's already hot you may want the big rotor :egrin:

While on the subject of FD and 929 MC's...I have noobish question

So Mazda eventually changed the brake booster to a smaller volume, on the later FD's, but kept the same MC from previous years.

I guess the reason was to "improve" pedal feel.

Now If I'm not mistaken, the smaller brake booster was also used on models with the larger brakes (314mm) (RZ/Spirit-R), right? But again, the same MC.

So If I were to use the smaller brake booster, larger 314mm brakes...which would be the preffered set-up? Stock MC or 929?

The fact that Mazda decided to decrease the brake booster volume, and leave the same MC, to improve the brake pedal "feel" confuses me just a bit. And I'm just wondering how adding the 929 MC to the smaller brake booster will affect brake pedal feel.

Or to ask it this way:

Larger brake booster + 929 MC vs. Smaller brake booster + 929 MC...and then both of these setups on stock vs larger brakes...

Don't confuse "larger brakes" as concerned with rotor diameter, versus "larger brakes" as concerned with larger caliper pistons. These items need to be quantified to get the whole picture.

I really doubt it's the 929 MC making your brakes hard to apply pressure. It won't do that. If anything it'll make it just apply sooner (less travel).

Something else is wrong. The booster/check valve hose is a good place to start. I had that hose come off at 120mph coming into T10 at VIR and all of a sudden you need to STAND on the brakes to get pressure. Scratch one pair of undees.

Or you may need a caliper rebuild or something. I doubt it's pads, from your description.

since we have the parts catalog for the JDM cars, we can go through it and this is the evolution for the Rx7.

the brake master is the same for every FD ever, the only difference is RHD/LHD, which way the lines face.

the booster is the same 92-95, again RHD/LHD are different, in the vacuum hose placement. they change the booster in 1996, and then it stays the same until the end, there is only the one, so it works with both the big and small brakes.

the front caliper pistons are different big brake vs small brake, they don't give measurements or anything

the rear calipers are the same, 92-02

Or maybe I am just used to newer technology and my 335i has amazing brakes? Serious question.

And enough with my poor spelling jokes.

I will check out those pads rich.

How could I test my break err brake booster?

i recently re-read the Rx8 book, and they mentioned something about using a master cylinder with a different curve, like the european cars.

they don't mention anything about that in the service highlights, but they do show the pedal ratio to be 2.8:1 vs like 5:1 for the FD...

Do you have an M-sport 335. They come with upgraded brakes. Just compare the size with your FD brakes. Now the BMW is bigger, but the brakes are that much better

The FSM explains checking your braking system. If you have the orginal vacuum lines, you may just want to replace them. Same goes for the brake lines upgraded to SS

There are probably many opinions on pads to be had