FYI, a rebuilt FD MC costs about $150, and $60 of that is a core charge and the plastic brake reservoir bottle is just expensive as the MC.

Ray should have one on hand ready to ship out.

 

its pretty simple to rebuild the m/c, its just a couple seals

 

On a related note, anyone know the bleeder size for the RB caliper? I'm a little to lazy today to go measure. I'd like to get a set of these:

http://www.speedbleeder.com/size.htm

To match the ones on the rear of the car.

-ch

 

I bought a rebuilt 929 master 2 weeks ago from Mazda Comp for $104. New it was $150 or 190. I forget exactly.

I've spoken with a few hard core track guys and they all recommend the slightly larger MC from the 929. Check out Crispy's site for one.

Hope that helps.

 

Interesting discussion. I was out at Laguna Seca this past Tuesday with Chris and had the same problem (mushy brakes). I suppose it could be just a coincidence that we both have the same problem after installing identical systems, but is seems unlikely. It does feel like air in the system though...

I was talking to a friend today who said that he had a similar problem with an old VW and eventually traced the problem to a bad wheel cylinder. He found it by individually capping each brake line then checking for pedal firmness until the problem went away. After replacing the defective wheels cylinder, he had no further problems. I may try this approach before shelling out the $$$s for a new MC.

RB has offered to replace the calipers, but I would like to do some further investigation before going that route just in case it's something else (or something I did wrong). They tell me that they are investigating on their end and I am hoping that they will find something in the design or manufacturing that could cause this.

BTW, since I trailered the car all of the way down to Laguna Seca, I was determined to get some miles in, in spite of the brake problems. After almost crashing the car a few times I figured out that if I pumped the pedal once before stomping the brakes, I could get them to work pretty well. So well in fact that I was able to get a nice tire howl out of the fronts coming into 5 at 100+. This could never have been accomplished with the stock brake setup. I was using the ET800s and have 245x40x17 Yok AD048s on the front (these tires suck, by the way). I think that if we can get the soft pedal resolved, this system might yield some impressive braking performance.

I'll attempt to spend some time diagnosing in the next day or so...

 

As requested, some pics of the RB setup behind the Fikses. You can't really tell from the pics, but there is plenty of clearance between the backside of the spokes and the frontside of the caliper. It's a bit tighter on the backside of the face where the mounting fasteners are located, they come within about 3-4mm of the brake line on the edge of the caliper.

 

Looking good Rich!

So are you having this brake pedal (possible air in the system) issue with your brakes?? I'm still couple of months away from installing these.

 

Thanks Phil. No problems at all. The pedal is very firm and the ET500s bite pretty damn good on the street.

Looking at those first two pics, I love the way the massive RB rotor fills up the space behind the wheels. I read on the RB site that the rotors are 2.3 pounds lighter than stock each, can't beat it

 

It could also be that the rotors are knocking the pads back, causing you to have to pump the pedal to get the pads to contact the rotors again. Just a though.

Nice Rich, here's mine. RE30s 18inch

 

The process is, bleed, go out somewhere where you can hit ABS, do it a few times, bleed again, rinse and repeat.

Technically I believe there is a way to get the ABS to open, but I believe I heard/read somewhere that it requires a special tool or something that we cannot get.

It should be noted that even when I have totally emptied the master cylinder (either on purpose or accidentally) and had to bench bleed it I haven't ever done anything but the above and my pedal is very solid. I usually do at least 500 pushes when I have to bench bleed it.

 

Call Malloy... and 929 MC is only just over $100 for a reman'd one.

 

Assuming that I have messed up my MC and need to replace/rebuild, I might just lean toward upgrading instead while I have it apart. Are there any modifications required to install the 929 MC? What year(s) fit the FD? Is there much of a difference in the volume of fluid being moved by the 929 vs. FD MC?

 

http://robrobinette.com/mastercylinder929.htm

 

Ok, I've got my 'revised, 2gen' kit on, and I'm definitely seeing the same. Approximately 1mm clearance on the outboard side, around 3mm on the inboard side (eyeballing - I can't get my digital caliper in there :P).

Car is '93 Touring.

I've got crappy cell phone pics, and can't get it off until I get back home later tonight.

Is this an issue? Would it being offset like that cause contact? I imagine it's just a matter of a revised bracket in either case.

 

Thanks for this info!

 

Glad to see I'm not going insane!

Technically speaking, if the wheel can turn freely once everything is torqued down (i.e., no significant drag) then it's not a show stopper. However:

1) As the pads wear, the inboard side will allow the pistons to overhang the bores/seals by a larger amount. This can lead to the pistons moving/vibrating in the bores under heavy braking
2) Depending on how much flex there is in the upright, there _may_ be contact issues
3) The obvious subtraction in style points for asymmetry on a precision-built brake kit is a real downer

In my case, these were academic as the offset actually caused the passenger's side wheel to bind when everything was torqued down, so I had to modify the bracket.

I talked with Warren and Steve said that the test fitting went well. They were worried that my car (a '94) might be different, but I assured them that the Mazda brakes were identical for all USDM production years. The fact that you're seeing the same on a '93 should put this to rest.

I'm going to call them on Monday and strongly suggest that they get another car and fit the revised kit. I think a 0.040" to 0.050" change in offset will be required.

If anyone else has installed the revised kit, please post here if you see this offset issue.

-ch

 

I thought there was only 2 main failures on a M/C, either its
- pissing out fluid all over, or
- it wont hold the pressure so the pedal will slowly sink to the floor (bypassing of the seals)
if while stopped the pedal can be hold pressure steady with a really heavy foot on it and absolutely no sinking then is there nothing wrong with the M/C..... am i missing something else?
curious what RB is looking into from their end......
Also, is the point of the 626 M/C is to shorten pedal travel, i think RB designed our system so we didnt have to go there........
pad knockback , excessive runout.......
are you using any pad backing plates? the RB site says only theirs to be used, i have none since they werent provided, front or rear.......

 

When I did the 929 MC swap many years ago and following Rob's notes; I had a problem with the banjo bolt facing the engine. The MC surface for that side was not flat enough and it leaked fluid. I had to get another normal brake line made for it.

 

You are correct, If the pedal pumps up and holds pressure there's air in the system. If the pedal slowly sinks to the firewall the master cylinder is nackered.

Paul


.

 

while this is correct, a better test is with light pressure

here is my write-up of the 929 m/c install

https://www.rx7club.com/suspension-wheels-tires-brakes-20/929-m-c-write-up-522474/

 

I only mounted the driver side. I probably won't bother with the passenger side, as that it's apparent that we'll need revised brackets.

Revised/2nd gen kit Notes:

With SSR GT2 18x10.5 +43, there is about 2" of clearance at the closest point to the caliper.

Where the 1st gen kit needed filing/milling on the mounting flange to provide clearance for rotor ring, there is roughly a full cm of clearance with an unaltered flange for the 2nd gen/revised kit.

With the exception of the slight offset of the caliper, it's a beautiful kit. Felt crummy putting the stock sized brakes back on.

I'll call Steve/Warren tomorrow to see what the options are.

 

I just inspected my calipers for offset and found that they were within acceptable limits. I included a picture of how I measured and my results were: .722" O / .734" I, on the drivers side and .694" O / .769" I, on the passengers side. It would be nice if the passengers side were a little closer to center, but I do not believe that this small offset requires machining. It is a bit alarming that there is such variation between installations. I'm assuming that the parts are run on a cnc machine at the factory, and as such the variation should not be more than a couple of thousands. Could it be that the FDs have that much variation from the factory?

 

The pedal pumps up firm for an instant then begins to sink to the floor. Guess this means that my MC is shot. Curious... it worked fine before I upgraded to the RB kit.

 

yeah sounds like the m/c is shot. the m/c must have been damaged during bleeding

 

Hyperion et al.

I am seeing the exact same thing on my early '93. The offset is a little worse on the passenger side, so much so that getting the outboard pad in is difficult. I'm so tired of waiting for these things that I'm going to run with it, maybe machine a few hundredths off sometime in the future.