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Discussion Starter #1 (Edited)
I thought I would bring this great info over to the SR20DEForum since there is no info like this in the 240SX section here and Asad from FA did such a great job explaining this over there so he gets all the credit for this: Here is a link to see Asad's Thread on this:

Enjoy:
http://forums.freshalloy.com/ubbthr...page=0&view=collapsed&sb=11&o=&fpart=all&vc=1

Different brake setup bias on a 240SX:

Stock 240sx non-ABS front brakes (CL22VB):
- Single piston sliding caliper
- 54.0mm piston diameter
- 252mm diameter rotor
- 45mm wide pad ('width' is the radial dimension of the pad, following the terminology in the FSM)
- effective rotor diameter: 252-45 = 207
- effective piston area: 54^2 x 2 (<-sliding caliper) = 5832
- brake torque = 1207224

Stock 240sx rear brakes (CL9H):
- Single piston sliding caliper
- 34mm piston diameter
- 258mm diameter rotor
- 40mm wide pad
- effective rotor diameter: 218
- effective piston area: 34^2 x 2 = 2312
- brake torque = 504016

Front brake bias = 1207224 / (1207224 + 504016) = 70.5%
Rear brake bias = 29.5%

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300ZX front brakes (OPF25VA) with Z33 rotors (OBP27VA):
- Four piston fixed caliper
- 40.45 piston diaeter
- 324mm diameter rotor
- 50mm wide pad
- effective rotor diameter: 324-50 = 274
- effective piston area: 40.45^2 x 4 (fixed caliper) = 6545
- brake torque = 1793330

300ZX rear brakes (OPZ11V):
- Two piston fixed caliper
- 38.1mm diameter piston
- 297mm diameter rotor
- 36.5mm wide pad
- effective rotor diameter: 297-36.5 = 260.5mm
- effective piston area: 38.1^2 x 2 = 2903
- brake torque = 756231.5

front brake bias = 1793330 / (1793330 + 756231.5) = 70.3%
rear brake bias = 29.7%

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Q45 front brakes (CL26VF):
- Two piston sliding caliper
- 42.8 piston diameter
- 280mm diameter rotor
- 56mm wide pad
- effective rotor diameter: 280-56 = 224
- effective piston area: 42.8^2 x 2 (sliding caliper) = 7327.36
- brake torque = 1641328.64

Q45 rear brakes (AD11B):
- Single piston sliding caliper
- 38.2mm diameter piston
- 292mm diameter rotor
- 33.9mm wide pad
- effective rotor diameter: 292-33.9 = 258.1mm
- effective piston area: 38.2^2 x 2 = 2918.48
- brake torque = 753259.688

front brake bias = 1641328.64 / (1641328.64 + 753259.688) = 68.5%
rear brake bias = 31.5%

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300ZX front brakes (OPF25VA):
- Four piston fixed caliper
- 40.45 piston diameter
- 280mm diameter rotor
- 50mm wide pad
- effective rotor diameter: 280-50 = 230
- effective piston area: 40.45^2 x 4 (fixed caliper) = 6545
- brake torque = 1505350

300ZX rear brakes (OPZ11V):
- Two piston fixed caliper
- 38.1mm diameter piston
- 297mm diameter rotor
- 36.5mm wide pad
- effective rotor diameter: 297-36.5 = 260.5mm
- effective piston area: 38.1^2 x 2 = 2903
- brake torque = 756231.5

front brake bias = 1505350 / (1505350 + 756231.5) = 66.5%
rear brake bias = 33.5%
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JDM 180SX front brakes (UNKNOWN):
- Single piston sliding caliper
- 57.2mm piston diameter
- 280mm diameter rotor
- 45.3mm wide pad ('width' is the radial dimension of the pad, following the terminology in the FSM)
- effective rotor diameter: 280-45.3 = 234.7
- effective piston area: 57.2^2 x 2 (<-sliding caliper) = 6543.68
- brake torque = 1535801.696
 

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Discussion Starter #2
Now this makes sense why I was able to lock up my Q45 setup but not my Z32 setup atleast not as easily and the only big differnce was 2% more front brake bias for the Q45 setup, wow what a difference just 2% makes, but on a side note with Z32 it feels like im coming to a stop quicker I guess im used to being able to lock it up at will.
 

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Discussion Starter #3 (Edited)
Just some new info to add to this thread:

1988 z31 Turbo and NA uses a 15/16 BMC with a split point of 427psi.

Examples:

91 - 94 S13 240SX (all)
7/8" BMC
Split Point – 569psi
Reducing Ratio - 0.4
If you have 1000 psi of line pressure, the fronts get 1000 psi, the rears get 569psi + (1000psi -569psi) * 0.4 = 741psi.
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Z31 300Z Non-Turbo
Part# 46010-06F00 (07/83 - 09/85) TOKICO
Part# 46010-21P00 (09/86 - 00/00) TOKICO***
Part# 46010-56L20 (07/83 - 09/85) NABCO***
Part# 46010-04P00 (09/85 - 09/86) TOKICO
Part# 46010-04P20 (09/85 - 09/86) NABCO
15/16" BMC
Split Point – 569psi
Reducing Ratio - 0.4
If you have 1000 psi of line pressure, the fronts get 1000 psi, the rears get 569psi + (1000psi -569psi) * 0.4 = 741psi. same as stock
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90 Z32 300ZX
15/16" w/o ABS Aust. BMC
17/16" w/ABS Aust./Euro BMC
Split Point – 498psi
Reducing Ratio - 0.4
If you have 1000 psi of line pressure, the fronts get 1000 psi, the rears get 498psi + (1000psi -498psi) * 0.4 = 698psi. 42psi less than stock
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Z31 300Z Turbo
Part# 46010-22F00 (07/83 - 09/86) TOKICO
Part# 46010-22F20 (07/83 - 09/85) NABCO
Part# 46010-56L20 (07/83 - 09/85) NABCO***
Part# 46010-18F20 (09/85 - 09/86) NABCO
Part# 46010-21P00 (09/86 - 00/00) TOKICO***
15/16" BMC
Split Point – 498psi
Reducing Ratio - 0.4
If you have 1000 psi of line pressure, the fronts get 1000 psi, the rears get 498psi + (1000psi -498psi) * 0.4 = 699psi. 42psi less than stock
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Z31 300Z Turbo and NA
Part# 46010-21P00 (09/86 - 00/00) TOKICO***
15/16" BMC
Split Point - 427psi
Reducing Ratio - 0.4
If you have 1000 psi of line pressure, the fronts get 1000 psi, the rears get 427psi + (1000psi -427psi) * 0.4 = 656psi. 85psi less than stock
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94 - 95 - 96 Z32 300ZX
1" BMC
Split Point – 356psi
Reducing Ratio - 0.4
If you have 1000 psi of line pressure, the fronts get 1000 psi, the rears get 356psi + (1000psi -356psi) * 0.4 = 614psi. 127psi less than stock
 
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