Master Cylinder Question R32/33

[AzzurrA]

just checked mine... it says BM44... this is on a non-abs Series II R32 GTS-t

[discopotato03]

Hmm , so looks like R32GTST's get the 15/16 bore master cylinder .

Some more possibilities , these Nissans have 25.4mm (1") master cylinders .

Maxima 5/90 on 3L , Pathfinder D21 VG30E 4x4 10/92 - 11/95 , Pathfinder R50 V6 4x4 11/95-00 .

Patrol Y60 (GQ series) had both the 1" and 1 1/16 BMC .

Going to have to look through wreckers or pester some poor parts person .

Cheers A .

[discopotato03]

I had a dig through Pick and Pay Less today and mainly found out what doesn't have what I need . Just about all the larger heavier cars like 280ZX's , Z31 300Z , 300C's use some form of BM44 15/16 bore master cylinders .

The only useful thing I did find was a D21 Navara (5/87) with a Nabco BM50 1" cylinder , perfect except it had no proportioning valve . It also only had 1 front and 1 rear hydraulic line outlet so would need a "T" for the front and some kind of external rear line pressure limiting valve ie like JDM R30's and Bluebirds had .

They had no Y60 (GQ) Patrols or later D50 Pathfinders to look at .

Cheers A .

[Duncan]

Maxima 5/90 on 3L , Pathfinder D21 VG30E 4x4 10/92 - 11/95 , Pathfinder R50 V6 4x4 11/95-00 .

Patrol Y60 (GQ series) had both the 1" and 1 1/16 BMC .

Interesting....this means you have a good chance finding something local. PBR make local master cylinders for early D21s. Not sure where the lines come out though?

[discopotato03]

The kindest thing anyone ever did to an Australian built Nissan was to throw all PBR/Girlock hydraulics as far away as possible . Irks me to say it but local content brake components are rubish compared to JDM bits .

Rally fraternity hate PBR/Girlock cylinders because they are built to a price not to a standard .

Thanks anyway cheers A .

[sav man]

how much diference will putting a R33 GT-R master cylinder onto an non-Brembo R32 GT-R do? I just put Porsche calipers on the front, and now the pedal is longer than I like.

[VSPEC32]

discopotato03, I'd like to wade in on this discussion. I'm currently looking for a solution for my S13 Silvia I'm building that now has a set of R33 GT-R Brembo's fitted:

Pics

http://www.sillbeer.com/2007/01/and-now-wh...ew-hotness.html

Now I also saw the article on the US site where they had used a Z32 300ZX Brembo brake upgrade and went for the 1 1/16" non-ABS BMC. Unfortunately like you I've realised they're only in LHD guise (UGH!!!!).

So if anyone can help in identifying if Nissan (ie. Nabco/Tokico) make a 1 1/16" non-ABS BMC for RHD situations from a car with a similar weight distribution as a Skyline/Silvia, please speak up...otherwise a 1" might have to do. Part numbers would be very helpful too.

Cheers

Brendan

[VSPEC32]

Just a thought, but according to most specifications around the web, the R32 GT-R N1 versions had the ABS removed to reduce weight, would that then point towards the possibility of them having a 3 port brake master cylinder in the larger BM57 size?

Anyone?

Edited March 8, 2007 by VSPEC32

[sav man]

R33 N1 has ABS, R32 didn't.

[Roy]

Dayam aye, why is the R33 one smaller? You'd think less travel, more force would be better (except when you lock them up too easily)

Just remember to think about the correct meaning of the words you are using....and never forget these two equations.

Pressure (P) = Force (F) / Area (A) .................... Eqn (1)

Friction = uN (Normal force N) .................... Eqn (2)

A few things impact on the general setup...but we can neglect pedal ratio as we are using all this different gear on the same car (Assumed).

So you put a smaller master cylinder in your car. That means you have less area of piston. So making the denominator smaller does not affect the numerator. So that is using a smaller master cylinder doesnt directly affect the force...it affects the pressure. It increases the pressure in the brake lines.

Now that is related to the caliper and pistons/pads as its the pressure in the brake lines that apply a normal force to the pad onto the rotor.

So there are two types of friction, static and kinetec. Now whilst static friciton is higher then kinetic, we dont want to be locking brakes. As that means we have less grip with the road as a locked tyre is modelled as kinetic friction. (remember thats the lower of friction values...bad if we are tryign to stop a car) So remember a rolling tyres grip level is modelled by static friction, ie no relative slip between the two surfaces.

So not wanting to lock a tyre, we must ensure the pad is moving relative to the rotor. ie Kinetic friction.

Now we only want enough force that brings the pad and rotors to the brink of lock up. If we lock up we lose tyre grip with the road.

So remembering that P = F/A. You havent changed your calipers, so the Area of pitons is the same. Having increase the pressure in the lines means that F=PA. A is constant, so the more pressure we have the more force we have.

So that all said, this all assumes the same pedal effort all the way back at Eqn 1. So you apply a 10kg load onto the brake pedal with a smaller master cylinder you will be closer to locking up the brakes with a smaller master cylinder then you would a larger master cylinder. If you have bigger pistons in your caliper and combine that with a smaller master cylinder then you will again have brakes that lock up too easily.

So if you increase the piston size in your calipers, then its not a bad idea to increase the diameter in your BMC. It helps not to have a hair trigger brake pad ready to lock your rotor as soon as you look at the brake pedal. Looking at Nissan it seems they have done the same thing.

Now take this with a grain of salt, but i have driven an R32 GTSt with Brembos it stopped realy nicely. Loved how it stopped. I have driven an R33 GTSt with Brembos and i jumped on the pedal and instantly locked them all up and crashed into witches hats. Now i dont know what pads and tyres were like, and the R33 was on a slippery skid pan...but its something that is in the back of my mind.

So why did Nissan drop the BMC size on the R33. I dont know. But if ppl can tell me the coeffecient of friciton of the R32 and R33 std pads...i suspect they dropped the BMC size as they reduced the friction in the pad used as the car had bigger rotors and would handle the heat better then an R32. Lower temp pads normally means lower friction coeffecient.

The GTRs which would have had more performance orientated pads woudl have had a higher u level meaning that a pedal offering more modulation / travel would be desirable.

[VSPEC32]

Just a thought, but according to most specifications around the web, the R32 GT-R N1 versions had the ABS removed to reduce weight, would that then point towards the possibility of them having a 3 port brake master cylinder in the larger BM57 size?

Has anyone got any solid information on this?

[sav man]

Has anyone got any solid information on this?

Our Targa car is a genuine R33 N1, it has ABS. I'm pretty sure i've heard duncan taling about the R32 N1 ATTESSA unit, as it's ABS functions are deleted, so R32 N1 (and Nismo) have no ABS.

[VSPEC32]

Thanks, now if I could just get confirmation, even some pics and part numbers I'd be set.

[Duncan]

sorry I can't confirm part numbers for non-abs 32....I would need a N1 vin #. If anyone has one pm me and I will look it up.

[Cubes]

Better late than never.

Late 1992 R32 GTST Non-ABS Master Cyl.

Excellent pedal feel. Almost too easy to lock all 4 wheels but that comes down to the pad that I run.

Hasn't had a flush for 1yr. :S

Only markings I can see on it are:

BM-44

NAB00

I had a mate with a Late 1992 GTS4 check his he said it says..

Japan Nissan Tokico BM50

[VSPEC32]

Hey Cubes

Did the mate with the GTS4 have ABS on his car?

Cheers

Brendan

[CEF11E]

Just had a look at mine

car was originally an 1993 R32 GTS and it has a Tokico BM38.

pedal feel is good with the crappy single piston callipers but i am going to have to upgrade it now that gtr32 calipers and 324mm rotors are going on or I am guessing the pedal would hit the floor before lockup

[Cubes]

Yes Abs.

Hey Cubes

Did the mate with the GTS4 have ABS on his car?

Cheers

Brendan

[VSPEC32]

DOH!!!

That does it, I give up!!

[VSPEC32]

OK, still trying to track down information on the brake master cylinder from an R32 GT-R N1 (BNR32 N1) - I did manage to find a Chassis number...would that help anyone in tracking it down?

R32 GT-R V-SPEC N1 > KBNR32RBFS ZN

R32 GT-R V-SPEC II N1 > KBNR32RBFS8 ZN

Cheers

Brendan

Edited March 15, 2007 by VSPEC32