What a larger bore master REALLY MEANS is that you'll MAKE LESS PRESSURE per pound of pressure exerted on the pedal (given equal pedal ratios)... and have a harder pedal feel vs. the 7/8" master.

Some people prefer a harder pedal. :D

The amount of movement at the pistons in the bore at the caliper would only back fluid up into the reservoir of the M/C, because it would arrive there (back flow) prior to having anything to do with the piston/stroke etc of the M/C. It's an open chamber without engagement of the stroke of the piston.

Can't fix the KB issue via the M/C. You're going to have to fix the flex / root causation.

Just a PS...

The very reason that under floor mounted M/C's REQUIRE residual valves to be installed is for the reason I stated above... the simple laws of gravity will allow the fluid to flow back into the M/C reservoir and overflow it without them!

10# valves for drum brakes

2# valves for discs

I still wonder if these valves wouldn't "help" (not cure) the KB issues on the discs you guys are using. If it's okay to drive around in a hot rod with under floor M/C using them (2#'s) it can't be an issue... Right? So maybe the 2# valves would make it a little better? Anyone?

It doesn't fix the knockback, it simply covers it up. There is a reason factory cars come with power brakes. It's not all pedal effort. A 2# residual valve didn't help mine. It's still in there. 10 pounds makes me nervous.

We have tried the 2 pound and 10 pound residual pressure valves on other cars with knock back issues and it did not work.

My last 7 cars have had this problem....
Tri Trip
Red Witch
Thrasher
Mule
Camaro X
Jackass
Red Devil (The knock back is good on this car but it is still new)

I'm very close to going to a full floater to solve all this problems.

Knock Back
Oil leaking tube ends

But it induces some problems of ABS sensors, park brake system, wheels, cost and complexity

I have gotten used to left foot braking to pump up the brakes going down the straights. :rolleyes:

The standard tapered roller bearing Ford big bearing seems to have about .020" - .050" end play after track use. This is what causes knock back of opposed piston calipers (4 piston).

I'm going to work on a better design to help fix the problem.

Stielow

Have you tried shimming the race out to put more pre load on the bearing? I've got some .010 shims coming right now. I'm going to measure the rotating torque before and after if and when I install them.

Mark- The bearing issue has eveybody looking for a solution.. I got two things I am working on that might help..

Working on designing a housing end that will use angular contact call bearings & doubling them up with a beefed up bearing retainer.. In theory it should have about .001 to .002 end play...

Have a meeting next week with Kenny Sapper from Speedway Engineering.. Working on getting a Street/Race floater built.. The parking brake will be challenge.. rotor adapter is easy.. can even float the rotor..

I spoke with Kenny last week
 

about building me a floater as well. I am going to for go the parking brake as mine does not work worth a crap now.

Cris, would a single piston parking brake from Brembo help simplify the issue of putting one on a full floater?

Matt

Just a note on the inner axle seals. DO NOT USE THEM! I went through several manufacturers of them when I raced circle track. In every case oil would get past the seal and fill up the right axle tube and trap the oil there. This then starves the center section for lube. Luckily it never bit me, but several people lost several gear sets until this was figured out. They were used in our case not to solve a leak as we used full floaters. We needed to keep the lube from leaving the gear set and traveling up the tube and starving the bearings. In the end it actually magnified the problem over time. I will never use them again!

I put a single disc parking brake on my Ford 9" --- bolts onto the yoke -- has a hand brake style lever - it's own disc (tiny) -- it's a PARKING BRAKE not an "emergency brake".


http://www.tsmmfg.com/Pinion_Mounted_Parking_Brakes.htm


Mark -- Good info on the residual valves not working. I didn't think they would because that's not really their job... but thought maybe it might help.



Gonzo -- Can I tell ya sumthin.... :rofl: