Brake Master Cylinder Size

[LotusGTR]

OK, I'm in Australia and I've come all the way over to your forum in the hope to gain some clarity on the size of a stock standard unmolested BMC on a 1990
R32 GTR. Choose from 15/16", 1", 17/16".

Please only reply if you know 100% for sure. There is no size indicated on the casting.

Thank you all.

[LotusGTR]

Anyone? Heeeeeelp.

[V1H]

yours should be marked with one of the following BM

BM33 = 13/16
BM38 = 7/8
BM44 = 15/16
BM50 = 1"
BM57 = 1 1/16

bm57 is the r32 brembo & r33 gtr one, should also be same for r34 gtr, think bm44 is the r32 gtr sumitomo one, will check later.

hth

[LotusGTR]

Thanks for that. I've got BM50 on the side of mine and if you're corect it'll be a 1". Be interesting to see what yours says.

Cheers for your help.

[V1H]

yep, same as yours, a BM50.

[LotusGTR]

Great. I'll assume you have an R32 GTR. Mine has no size indicated on the casting, does yours? Can I ask where you got the above info?

I've snooped areound a good Nissan dealer here and it seems the 1" is the std item, the 17/16" is for the GTR V-Spec R32s and R33s i.e. OEM Brembo equiped cars and the 15/16" is a 3 outlet unit for the N1 which did not have ABS (although I beleive it could be optioned). Seems strange that the N1 has a smaller BMC but perhaps that suits the non ABS set up better.

Does this match up with what you know to be true?

Cheers.

[lightspeed]

My info was that N1 is 1", R32 std is 15/16" and Brembo cars 1 1/16".

[V1H]

S15 brakes

corresponds with other info on web, but then again they might have used the same source, however, think it is correct as some bmc are marked with both BM# and size.

BM44 = 15/16 = 23.8
BM50 = 1" = 25.4
BM57 = 1 1/16 = 26.9

and from this:

Brake Rotor / Caliper information

--------------------------------------------------------------------------------

R32 GTST
Master Cylinder diam (mm) - 25.4 area 506.71mm^2Front Caliper Piston(diam x qty) - 40.4 ×4 = 5127.58mm^2
Front rotors (diam x thk) - 280×30
Rear Caliper Piston(diam x qty) - 38.18×2 = 2289.78mm^2 ratio FR = 2.239
Rear Rotors (diam x thk) - 297×18
total 7417.36 brake to master ratio 14.63


R33 GTST
Master Cylinder diam (mm) - 23.8 444.88mm^2Front Caliper Piston(diam x qty) - 40.4 ×4 = 5127.58mm^2
Front rotors (diam x thk) - 296×30
Rear Caliper Piston(diam x qty) - 38.18×2 = 2289.78mm^2 ratio FR = 2.239
Rear Rotors (diam x thk) - 297×18
Total area 7417.36mm^2 brake to master ratio 16.67

R32 GTR (Non V-Spec,)
Master Cylinder diam (mm) - 25.4
Front Caliper Piston(diam x qty) - 40.4 ×4
Front rotors (diam x thk) - 296×32
Rear Caliper Piston(diam x qty) - 38.18×2
Rear Rotors (diam x thk) - 297×18

R32 GTR V-Spec / R33 / 34 GTR with Brembos
Master Cylinder diam (mm) - 26.9 568.32mm^2Front Caliper Piston(diam x qty) - (44+3Cool×2 ... leading pistons smaller then trailing 5309.29mm^2
Front rotors (diam x thk) - 324×30
Rear Caliper Piston(diam x qty) - 40×2 2513.27mm^2 ratio FR = 2.1125
Rear Rotors (diam x thk) - 300×22
total 7822.56 brake to master ratio 13.76

This is the ratio of master piston movement to overall brake pad movement
R32/GTR calliper ratio 15.43
R33/GTR calliper ratio 17.58


So there isn’t much difference between the Brembos and the std Nissan R32/33 GTST calipers and R32 GTR callipers


Oh...and an old favourite that seems to be a good practical test of what the theory suggests....

Car & Driver did a test a few years ago ...Test Car was a WRX (US Spec which only uses two piston sliding caliper, not as good as Nissan 4 spot or later Model WRX 4 pots)

So tested kits were, std car, std car with upgraded pads and fluid, Brembo F50 Kit, Brembo Lotus Kit (Similar to as fitted to GTRs, 44/38mm pistons), Stoptech it and Prodrive Kit (Alcon)

Stopping Distances 70mph - 0 , 3 Stop
Brembo F50;_____________ 185 / 183 (Average / Best)
Brembo Lotus; ______________ 200 / 196
Prodrive; __________________ 198 / 194
StopTech;__________________ 187 / 186
Stock; ____________________ 205 / 196
Stck with pads and fluid; ____187 / 184

The above figures are all in feet, one stop difference between pad and fluid upgrade to crappy sliding caliper brake setup and massive Brembos is 1 ft...lol 30cms And over 3 stops the average is 2 ft...lol 60cms

So you can see the one stop max of the upgraded pads and fluid is damn good when you consider the $$$ to % difference.


Stopping Distances 100mph - 0 , 25 Stop
Brembo F50; _____________ 299 / 288 (Average / Best)
Brembo Lotus; ______________305 / 294
Prodrive; __________________ 308 / 295
StopTech;__________________ 297 / 290
Stock;_____________________ 340/317
Stck with pads and fluid;_____316/299

Not the world of difference you would be led to believe by the "you need 6pot caliper 343mm rotor crowd."


Specs of the kits:
Rotor Weight (pounds) Size in inches (diam / thk)
Brembo F50;.................15.8......................... .13.1 / 1.3
Brembo Lotus;..............12.9.......................... 12.9 / 1.1
Prodrive;......................16.5............... ............13.0 / 1.1
StopTech;...................13.9.................. ........12.9 / 1.1
Stock;.................. ......14.2..........................11.6 / 0.9


Caliper Weight , Piston Size, (mm)
Brembo F50;..........8.6 pounds...........40 / 44, Leading / Trailing
Brembo Lotus;.......6.8.......................36 / 40
Prodrive;...............9.1..................... 34.9 / 41.3
StopTech;.............9.3.....................36 / 40
Stock;.................10.8.................. .43 / 43


...and COST!!!
Brembo F50;.......................US$2,995
Brembo Lotus;.....................US$2,595
Prodrive;.............................US$1,999
StopTech;...........................US$1,695
Stock with pads & fluid;....... US$130

R32 GTST
Front rotors (diam x thk) - 280×30

R32 GTR (Non V-Spec,)
Front rotors (diam x thk) - 296×32

R33 GTST
Front rotors (diam x thk) - 296×30 Different caliper to R32 GTR but same disc diameter.

R32 GTR V-Spec / R33 / 34 GTR with Brembos
Front rotors (diam x thk) - 324×30

R34 GTT
Front rotors (diam x thk) - 310x30

The calipers that suit larger diameter discs have longer mounting legs to space the caliper out further.

quote from: Brake Rotor / Caliper information - GTRCanada - Canada's premier skyline enthusiasts club

[LotusGTR]

Originally Posted by lightspeed

My info was that N1 is 1", R32 std is 15/16" and Brembo cars 1 1/16".

I have heard this too but this contradicts the other posts on here. I suspect us Aussies are getting our info from the same places you are as the contradiction we've got here was what I was trying to solve.

Where are you getting your info from?

[LotusGTR]

Thanks for all the info. So has anyone seen a BM50 with 1" in the casting? Or has anyone got a way of 1000% validating this? Tis confusing.

Originally Posted by V1H

S15 brakes

corresponds with other info on web, but then again they might have used the same source, however, think it is correct as some bmc are marked with both BM# and size.

BM44 = 15/16 = 23.8
BM50 = 1" = 25.4
BM57 = 1 1/16 = 26.9

and from this:

Brake Rotor / Caliper information

--------------------------------------------------------------------------------

R32 GTST
Master Cylinder diam (mm) - 25.4 area 506.71mm^2Front Caliper Piston(diam x qty) - 40.4 ×4 = 5127.58mm^2
Front rotors (diam x thk) - 280×30
Rear Caliper Piston(diam x qty) - 38.18×2 = 2289.78mm^2 ratio FR = 2.239
Rear Rotors (diam x thk) - 297×18
total 7417.36 brake to master ratio 14.63


R33 GTST
Master Cylinder diam (mm) - 23.8 444.88mm^2Front Caliper Piston(diam x qty) - 40.4 ×4 = 5127.58mm^2
Front rotors (diam x thk) - 296×30
Rear Caliper Piston(diam x qty) - 38.18×2 = 2289.78mm^2 ratio FR = 2.239
Rear Rotors (diam x thk) - 297×18
Total area 7417.36mm^2 brake to master ratio 16.67

R32 GTR (Non V-Spec,)
Master Cylinder diam (mm) - 25.4
Front Caliper Piston(diam x qty) - 40.4 ×4
Front rotors (diam x thk) - 296×32
Rear Caliper Piston(diam x qty) - 38.18×2
Rear Rotors (diam x thk) - 297×18

R32 GTR V-Spec / R33 / 34 GTR with Brembos
Master Cylinder diam (mm) - 26.9 568.32mm^2Front Caliper Piston(diam x qty) - (44+3Cool×2 ... leading pistons smaller then trailing 5309.29mm^2
Front rotors (diam x thk) - 324×30
Rear Caliper Piston(diam x qty) - 40×2 2513.27mm^2 ratio FR = 2.1125
Rear Rotors (diam x thk) - 300×22
total 7822.56 brake to master ratio 13.76

This is the ratio of master piston movement to overall brake pad movement
R32/GTR calliper ratio 15.43
R33/GTR calliper ratio 17.58


So there isn’t much difference between the Brembos and the std Nissan R32/33 GTST calipers and R32 GTR callipers


Oh...and an old favourite that seems to be a good practical test of what the theory suggests....

Car & Driver did a test a few years ago ...Test Car was a WRX (US Spec which only uses two piston sliding caliper, not as good as Nissan 4 spot or later Model WRX 4 pots)

So tested kits were, std car, std car with upgraded pads and fluid, Brembo F50 Kit, Brembo Lotus Kit (Similar to as fitted to GTRs, 44/38mm pistons), Stoptech it and Prodrive Kit (Alcon)

Stopping Distances 70mph - 0 , 3 Stop
Brembo F50;_____________ 185 / 183 (Average / Best)
Brembo Lotus; ______________ 200 / 196
Prodrive; __________________ 198 / 194
StopTech;__________________ 187 / 186
Stock; ____________________ 205 / 196
Stck with pads and fluid; ____187 / 184

The above figures are all in feet, one stop difference between pad and fluid upgrade to crappy sliding caliper brake setup and massive Brembos is 1 ft...lol 30cms And over 3 stops the average is 2 ft...lol 60cms

So you can see the one stop max of the upgraded pads and fluid is damn good when you consider the $$$ to % difference.


Stopping Distances 100mph - 0 , 25 Stop
Brembo F50; _____________ 299 / 288 (Average / Best)
Brembo Lotus; ______________305 / 294
Prodrive; __________________ 308 / 295
StopTech;__________________ 297 / 290
Stock;_____________________ 340/317
Stck with pads and fluid;_____316/299

Not the world of difference you would be led to believe by the "you need 6pot caliper 343mm rotor crowd."


Specs of the kits:
Rotor Weight (pounds) Size in inches (diam / thk)
Brembo F50;.................15.8......................... .13.1 / 1.3
Brembo Lotus;..............12.9.......................... 12.9 / 1.1
Prodrive;......................16.5............... ............13.0 / 1.1
StopTech;...................13.9.................. ........12.9 / 1.1
Stock;.................. ......14.2..........................11.6 / 0.9


Caliper Weight , Piston Size, (mm)
Brembo F50;..........8.6 pounds...........40 / 44, Leading / Trailing
Brembo Lotus;.......6.8.......................36 / 40
Prodrive;...............9.1..................... 34.9 / 41.3
StopTech;.............9.3.....................36 / 40
Stock;.................10.8.................. .43 / 43


...and COST!!!
Brembo F50;.......................US$2,995
Brembo Lotus;.....................US$2,595
Prodrive;.............................US$1,999
StopTech;...........................US$1,695
Stock with pads & fluid;....... US$130

R32 GTST
Front rotors (diam x thk) - 280×30

R32 GTR (Non V-Spec,)
Front rotors (diam x thk) - 296×32

R33 GTST
Front rotors (diam x thk) - 296×30 Different caliper to R32 GTR but same disc diameter.

R32 GTR V-Spec / R33 / 34 GTR with Brembos
Front rotors (diam x thk) - 324×30

R34 GTT
Front rotors (diam x thk) - 310x30

The calipers that suit larger diameter discs have longer mounting legs to space the caliper out further.

quote from: Brake Rotor / Caliper information - GTRCanada - Canada's premier skyline enthusiasts club

[heller44]

My car has a BM50 master cylinder, with 1" on the casing. Not N1, not brembo, full abs, sumitomo, in need of work brakes.

[V1H]

you're thinking too much, i've got a 32gtr with bm50, and even with stainless lines, brake stopper and uprated pads, the pedal had a long travel with not much bite, now uprated to bm57 from an r33gtr and the pedal travel is less with more feel and easier to modulate. This was with a bbk and the bm57 was needed(will work without but much better with) to fill up the extra capacity of the bbk.

re: the bm50 rating, can't 1000% validate that but can validate a bm57 marked with 1 1/16.

[LotusGTR]

Originally Posted by V1H

you're thinking too much, i've got a 32gtr with bm50, and even with stainless lines, brake stopper and uprated pads, the pedal had a long travel with not much bite, now uprated to bm57 from an r33gtr and the pedal travel is less with more feel and easier to modulate. This was with a bbk and the bm57 was needed(will work without but much better with) to fill up the extra capacity of the bbk.

re: the bm50 rating, can't 1000% validate that but can validate a bm57 marked with 1 1/16.

Thanks. Really that is the answer I'm looking for. bbk? What this is?

[LotusGTR]

Originally Posted by LotusGTR

Thanks. Really that is the answer I'm looking for. bbk? What this is?

Shute. Big brake kit of course.

[ISai]

Hi everybody, I'm from Russia
I need your help. Does enybody know an original part number of Master Brake Cylinder Tokico BM57. This is original cylinder for R32 GT-R V-Spec, R33/34 GT-R with Brembo brakes. If there are different brake cylinders on these cars, tell me please all part numbers. I need this for my Nissan 180SX.
Sorry for my English.