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I like Boost
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Discussion Starter · #1 ·
I just bought a BBK set up for my car, z32 calipers. Now I hear a lot of people saying that the stock master cylinder doesnt cut it for this brake upgrade, you get a mushy low pedal.

Now I can only assume that the fact that there is 4 pistons in the z32 caliper they use more fluid, that of which the master cylinder cannot deliver. I've heard of people using MK3 masters to "help" with this problem, but it doesnt seem to compleatly solve it.

So what have you guys done? I was thinking of getting like a willwood master off jegs and making a bracket to make it fit, but then, what am I looking at if I want to buy an aftermarket "universal" type master?

I want the stiffest pedal possible obviously.

have braided lines already to go with the swap.
 

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Supra since '86
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Master cylinder bore diameter.

MK1: 7/8"
MK2: 15/16"
MK3: 1"
MK4: 1"

Z32: 1 1/16"

F=PA. If 50psi of pressure is needed to be applied to the caliper then the following forces need to be applied to each master cylinder in order to get that 50psi.

MK1: 30.1lbs
MK2: 34.5lbs
MK3: 39.3lbs
MK4: 39.3lbs

Z32: 44.3lbs

If the mechanical advantage of the brake pedal is 4:1 the following force will be required by the driver on the pedal.

MK1: 7.5lbs
MK2: 8.6lbs
MK3: 9.8lbs
MK4: 9.8lbs

Z32: 11.1lbs

Caliper piston diameter.

MK1: 2.12" x1
MK2: 2.245" x1
MK3: 2.37" x1
MK4: ?" x4

Z32: 1.591" x4

F=PA. If 50psi of pressure is to be applied to the caliper then the following forces will be applied to the disc through the pads.

MK1: 176.4lbs
MK2: 197.8lbs
MK3: 220.5lbs
MK4: ?lbs

Z32: 397.4lbs

Let's say 10lbs of force was applied to the brake pedal with each master cylinder in conjunction with Z32 calipers. The force on each disc would be as follows.

MK1 master cylinder and Z32 caliper: 236.4lbs
MK2 master cylinder and Z32 caliper: 205.6lbs
MK3 master cylinder and Z32 caliper: 180.7lbs
MK4 master cylinder and Z32 caliper: ?lbs

Z32 master cylinder and Z32 caliper: 159.8lbs

You are correct by saying there will be more volume required. Low pedal and I think it is the flow, the change of volume over a certain period of time that is important. I won't go into the math as it's too late...

Bryan (83restomod) is running Z32 calipers he would know best.
 

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can't you also adjust the brake booster rod to regulate the pedal travel to lockup factor? that also determins how far you need to push the pedal and probably with how much force. if the pedal still has a soft feel after swaping to an mkIII M/C then someone should try to adjust the rod and see if that helps.
 

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I like Boost
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Discussion Starter · #4 ·

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Supra since '86
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Some members are running MK3 master cylinders.

I like the 4 Runner master cylinder as it is the same bore as the Z32 master cylinder (1 1/16"), a Toyota part and the 4 Runner also uses 4 piston calipers. Hopefully next week if I get the parts I'll try an affordable rear BBK. Which the extra 1/16" bore will help with.

How does it feel Billy?
 

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Solo1Supra has an mkIII M/C installed. good news on the 4runner M/C, looks like that's the logical answer. i hope you get the rear brakes figured out rsdeo, i've been very interested in your findings.
 

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Billy please do elaborate on which 4runner master to use. I just looked around on rock auto and just picking random year I noticed they used a few diff ones and couldn't find one with the 1 1\16 bore.
 

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Supra since '86
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TOYOTA 4RUNNER SR5 (1994-1995)
'94-'95 W/ABS


Also

TOYOTA PICKUP (1994-1995)
TOYOTA PICKUP DLX (1994-1995)
TOYOTA PICKUP SR5 (1994-1995)
TOYOTA T100 (1995-1998)
TOYOTA T100 DLX (1995)
TOYOTA T100 DLX EXC (1995)
TOYOTA T100 ONE-TON DLX (1995)
TOYOTA T100 SR5 (1995-1997)


Item#:TS 112710 Bore 1 1/16"
Item#:TS 112711 Bore 1 1/16"

Napa and Rock Auto parts numbers.


Rear brakes, just need to get parts and find time to see if my thoughts work out.
 

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Billy, whats up with the comment on the booster swap? I've been running around with the mk3 booster and master cylinder since I finished my swap and my brakes feel awesome. Still on the stock calipers but I'll be going z32 all the way around at some point.

FYI, the z32 TT originally came with 1.0inch brake masters, the 1 1/16th was a mid model change, can't remember what year it kicked in. The point being, the mk3 master cylinder should work just fine. Again though, it does come down to what you run in the rear as well. I'll be on z32 calipers all the way around so I'm not worried about it but I will probably add an adjustable rear bias valve to get it just perfect. I may have to drill out the stock bias block limiter for the rear if I need more bias back there.
 

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Not to Hijack the tread, but I've heard the 4runner booster can also be fitted and is of a smaller diameter. Anyone as more informations on that?

It would solve my mushy brake pedal feel with Wilwood caliper and the head cover clearance on the V8!

Thanks
 

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I ran the mk3 booster because it was skinnier and made more room in the engine bay where I wanted it, it is alot larger in diameter but not enough to significantly complicate removing the clutch master.
 

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From what I've seen the Z32 master cylinder started out as a bore of 1 1/16" and switched around '92 to 1" bore. Going from 1" bore to 1 1/16" bore means 11.6% more effort on the pedal for equal braking force.

I guess it all depends how strong your leg is...

I just realized that the Toyota trucks all have rear drums. This might be an issue if those master cylinders are used with rear discs. Disc brakes require more pressure and flow than drums. Will the different proportion valves handle this properly for us?
 

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First one to rockauto wins...

BECK/ARNLEY Part # 0729028
ABS
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How does it feel Billy? (in reference to the 4runner master cylinder)
Hard-ass pedal, solid as a rock. (I like to put some effort to my braking) I'm running the 1-1/16th 4-runner MC, Q45 front calipers on mpv rotors, stock rears, braking is extremely balanced, with the fronts slightly stronger than the rears (allowing you to carry some braking into the corner, rather than locking up the rears upon steering input, which I find suits my driving style).

Billy, whats up with the comment on the booster swap? I've been running around with the mk3 booster and master cylinder since I finished my swap and my brakes feel awesome. Still on the stock calipers but I'll be going z32 all the way around at some point.
Oh my god 1-million overboosted holey moley! Put it in... rolled down to my street's stopsign, touched the brakes *SCREECH* almost threw myself through the windshield, locked them up. Holy shit! Nearly un-driveable, so totally overboosted... If yours is good, you have a weak mk3 booster. I do not suggest it to anyone, especially if you get a new one. Likely to wreck and die...

--billyM
 

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Z32 calipers, MPV rotors, SS lines, stock mk2 master and booster and i have a nice hard pedal that is slightly lower (could be in my head as i never measured it) pedal but if u didnt know, you couldnt tell.


next inline is rear Z32 calipers so we can have all 4 aluminum....
 

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the brake pedal height is adjustable btw.

Weird Billy, but then again the rest of your system is hardly factory and I'm still on stock calipers. It is a used booster I put in too, but it was in nice shape, a little over 100,000miles on it and it wasn't filled with brake fluid. I noticed the brakes locking up faster afterwards, or being more responsive if you will, but I also went to the 1inch MC and stainless lines at the same time so its debatable whats doing what. But I'm very happy with the feel and performance right now, no complaints.

Also, extremely grippy performance street pads can cause the issues you had too. Maybe a strong booster doesn't work so well with your pad choice. I'm on PBR Deluxes, they're ceramic and much grippier then stock but not crazy at all. Love em, no dust, they barely wear down and they've survived several track days and countless autoxes now.
 

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Also, extremely grippy performance street pads can cause the issues you had too. Maybe a strong booster doesn't work so well with your pad choice. I'm on PBR Deluxes, they're ceramic and much grippier then stock but not crazy at all. Love em, no dust, they barely wear down and they've survived several track days and countless autoxes now.
+1 on those pads. I've had them on my car for a couple years and they're really good for a stock set-up.
 

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they're good for any setup that mostly sees street use. You can get them in almost any application.
 
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