Aftrer market master cylinder??
- Thread starter DaSuprawolf
- Start date
Boosted Supra said:
If the BBK is done correcty, then no, the stock M/C will be perfectly fine. I designed and built my BBK (wilwood 6pots on 13" rotors up front) and the peddle is actually stiffer then stock, also soon to have 12.75" and wilwood 4pots on the rear and the peddle will be the same or possibly better.
If the caliper piston area is to large for the application, then yes, you will need a bigger M/C bore. A properly designed BBK will usually have less piston area then the stock caliper and this why the peddle actually gets stiffer when properly done. Most people have the wrong idea about BBK's. The true reason for a BBK is heat management. If you can lock your wheels up above 70 to 80mph for a street car and about 90 on a track car, then you dont need a BBK, you need better tires. Now if you cant do it repeatedly, then you have a heat management issue and need a BBK. The most important thing to remember is that brakes dont stop your car, tires do. The biggest, badest brake kit in the world is not going to stop your car any better if your tires are shit...
Chris: Agreed 100%
There's a LOT of Math involved to do it right.......
I chose my callipers to suit the Mk3 Master and Proportioning valve and it's got great pedal feel and balance with no need for bandaids.
There's a LOT of Math involved to do it right.......
I chose my callipers to suit the Mk3 Master and Proportioning valve and it's got great pedal feel and balance with no need for bandaids.
Boosted Supra said:
LOL, I've killed many threads also:biglaugh: , as soon as I reply, nobody else says anything:icon_conf I boost my moral by telling myself that I had the best reply in the thread, so nobody needs to say anything else.
Anyways, I will be installing my Arz performance front kit and MKIV TT rear brakes in the next couple of weeks, I am hoping that my Master cylinder will be up to par, and that the system will still be balanced. Any inputs guys? A couple of pages down, someone did investigate the 4runner cylinder and found it to be almost a match, but he needed the 4runner reservoir as well, as our reservoir didnt fit the 4runner cylinder.
Watch this thread die now guys :icon_evil
Well I cant say for sure because of not knowing what piston size they are using on the front calipers. The Forged superlite's come with several different piston sizes. As for the rears, you'll be fine. The MKIV caliper has the same area IIRC. IIRC, they both (MKIII and MKIV) use 38mm pistons in the rear callipers. If they are not I dentical, I know that it is very close to the same (not enough to nesesitate a larger M/C).
EDIT: If you can find out what what piston superlites they (ARZ) are using, I can tell you exactly how it will work and what the ballance is, well sort of. I also need to know what the CF (Coefficient of Friction) of the pads that you are using (both front and rear) to be more exact with it, and even then without testing, you cant get 100% accuracy cause the pad CF is temp dependent, but it will give you a good enough idea to tell if there will be other things that need to be changed and or if the system will be happy.....
EDIT: If you can find out what what piston superlites they (ARZ) are using, I can tell you exactly how it will work and what the ballance is, well sort of. I also need to know what the CF (Coefficient of Friction) of the pads that you are using (both front and rear) to be more exact with it, and even then without testing, you cant get 100% accuracy cause the pad CF is temp dependent, but it will give you a good enough idea to tell if there will be other things that need to be changed and or if the system will be happy.....
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Boosted Supra said:
Don't know you, so your off the hook for now.
But that was a retarded comment about the stock cylinder sucking.
cjsupra90 said:
I only shortend your response for thread cleanliness. The brakes convert motion energy into heat energy.
:love: thanks
The reason I say the stock MS sucks is because I have to pump it at least once to get stiff pedal feel.
The reason I say the stock MS sucks is because I have to pump it at least once to get stiff pedal feel.
when was the last time you bled the brakes? how old is the fluid - what type of fluid are you using? Not all dot4's are created equal in temp handling or water absorbtion.
Boosted Supra said:
Your car needs service. A little study of Pascal's laws would help in understanding the mastercylinder, and why you don't need a great big one.
Nick M said:
Back from the dead
Well, with the Jim King BBK pedal stiffness is only noticeable after at least one pump on the brake pedal. I spoke to Jim King about that and he mentioned something about a 1 or 2psi bleeder valve?
I spoke to others and upgrading the stock MS to something slighter bigger would get rid of this problem I have.
cjsupra90 said:
CJ,
Could you apply your formula to the following combination and give my a general idea of the bias while running the stock master cylinder and proportioning valve?
Front, 1.75x4 piston Wilwood Superlite Calipers, BP-10 pads.
Rear, 1.38x4 piston Wilwood Dynalite Calipers, BP-10 pads.
cjsupra90 said:
Sorry about that. I was on my way out and in a hurry. Anyways,
Fronts are 13"x1.25". Rears are 12.8"x.81".
Thanks,
Steve
Supra7MG here are some numbers for you.
All numbers are calculated using an assumed 400psi M/C outlet pressure. (This is a typical pressure for normal light to medium stops and also happens to be roughly where the stock proportioning valve starts to take over)
Stock brakes are as follows:
Bias
F = 71%
R = 29%
Brake torque
F = 429.2 lb/ft
R = 170.4 il/ft
Upgraded brake setup listed would be as follows
Bias
F = 62.3%
R = 37.7%
Brake torque
F = 814.9 lb/ft
R = 494.2 lb/ft
Piston areas
Stock piston area is
F = 4.381 in/sq
R = 1.757 in/sq
Upgraded setup is
F = 4.810 in/sq
R = 2.969 in/sq
___________________________________________
There are two problems with this setup. One is that the piston area especialy the rear was increase quite a bit. The other is that there is a bit to much rear bias with this set up. I would not exceed a 65/35 bias ratio for MKIII's that have been lowered and are running staggered tire size. For stock setup (i.e. stock ride height and equal size tires front and rear), I wouldn't exceed 68/32 bias ratio.
Having said all that, my seguestions would be to upgrade to the 4runner M/C and use a smaller piston rear caliper. A rear caliper with 1.25" pistons would be better here. It would bring your bias ratio to 66.6/33.4 front to rear and the new piston area would be 2.454 in/sq
IMHO, the uptimum setup would be the same rotor sizes as listed (13" and 12.8") and same pads but front calipers that had 1.625" pistons and rears that had 1.125" pistons. This would brind your front piston area down to 4.14 in/sq and the rear to 1.988 in/sq. This setup would be perfect for the stock M/C, would bring you to and exact 68/32 bias ratio, would generate 702.7lb/ft of torque in the front and 330.8 lb/ft in the rear. So for the same peddle pressure, you would get about 65% more brake torque overall and probably have an ever so slighty stiffer peddle.
All numbers are calculated using an assumed 400psi M/C outlet pressure. (This is a typical pressure for normal light to medium stops and also happens to be roughly where the stock proportioning valve starts to take over)
Stock brakes are as follows:
Bias
F = 71%
R = 29%
Brake torque
F = 429.2 lb/ft
R = 170.4 il/ft
Upgraded brake setup listed would be as follows
Bias
F = 62.3%
R = 37.7%
Brake torque
F = 814.9 lb/ft
R = 494.2 lb/ft
Piston areas
Stock piston area is
F = 4.381 in/sq
R = 1.757 in/sq
Upgraded setup is
F = 4.810 in/sq
R = 2.969 in/sq
___________________________________________
There are two problems with this setup. One is that the piston area especialy the rear was increase quite a bit. The other is that there is a bit to much rear bias with this set up. I would not exceed a 65/35 bias ratio for MKIII's that have been lowered and are running staggered tire size. For stock setup (i.e. stock ride height and equal size tires front and rear), I wouldn't exceed 68/32 bias ratio.
Having said all that, my seguestions would be to upgrade to the 4runner M/C and use a smaller piston rear caliper. A rear caliper with 1.25" pistons would be better here. It would bring your bias ratio to 66.6/33.4 front to rear and the new piston area would be 2.454 in/sq
IMHO, the uptimum setup would be the same rotor sizes as listed (13" and 12.8") and same pads but front calipers that had 1.625" pistons and rears that had 1.125" pistons. This would brind your front piston area down to 4.14 in/sq and the rear to 1.988 in/sq. This setup would be perfect for the stock M/C, would bring you to and exact 68/32 bias ratio, would generate 702.7lb/ft of torque in the front and 330.8 lb/ft in the rear. So for the same peddle pressure, you would get about 65% more brake torque overall and probably have an ever so slighty stiffer peddle.
Remember, these numbers are not exact cause of non constant veriables. The calculations are pretty close though and are more then suffiecent for street use.
Thanks CJ. Very impressive also. I think that everything that you have said makes perfect sense. Trouble is that this setup is on my car right now. I have not driven it yet as I have been away a lot for work the past two years and I made a lot of changes on the car. I'm away right now and when I return I plan to finish the custom work in the rear hatch area and will then be able to drive the car. I did a full Sparco upgrade and traded the rear seat for an Autopower 4 point in order to run 5 point harnesses. I do run a staggered tire setup, 235x45x17 front and 275x40x17 rear. I went with the Wilwood setup for a number of reasons, cost figured into the equation. I used the piston sizes that were available and seemed to best suit my needs. I was ready to ante up for the "Mystery Master Cylinder back in November but the seller kind of rubbed me the wrong way and did not return my PM. Back then I started a thread on Supraforums that went on for a long time and was quite informative until a few of the self proclaimed Elitist's trashed it. I haven't been back there since. A few of the contributers to this thread were there and I am confident that they felt the same as I do about where it went. Sorry to vent. I feel that I have two options to reel in my bias if I feel that there is a problem. Installing an adjustable proportioning valve or possibly going with a less aggressive rear pad. Also consider that the Superlite pad has substantially more surface area than the rear Dynalite pad. What do you think?
And thanks again
And thanks again
yeah, you can install a an adjustable proportioning valve or start playing with pad compond to adjust the bias. The surface area of the pad has almost no effect the bias. Yes you are covering more area, but the pressure will be reduced. Remember, PRESSURE = FORCE/AREA... So if the calliper is generating lets say 1000psi of clamping force and you have say 5 sq/in of pad. The pressure that the pad is gernerating against the rotor is 1000/5=200psi, now up the pad area to 6 sq/in and you get 1000/6=166.6psi. So as the area increases, the pressure drops, but you still have the 1000psi of clamping force the caliper was generating to begin with. This is why pad area is not accounted for when calculating brake torque.