Sunday, April 08, 2007

Brake Master Cylinder upgrade

R32 GT-R N1 (V-spec version) BM50 Brake Master Cylinder

OK so a lot of you would already be aware that I'm running the front and rear Brembo calipers (with DBA4000 slotted rotors) from an R33 GT-R on Sillbeer (couple of pics here). Unfortunately the model of Silvia I've used as a base rolled out of the Nissan factory without ABS. Now this wouldn't seem like such a problem, but then I need to be able to fill these massive calipers (in comparison to the stock) ones with decent pressure and the stock Silvia brake master cylinder (BMC) just would not be up to the task with a resulting deep pedal. The other problem being that non-ABS cars need three ports on the BMC, 1 for the rear circuit and two for the front circuit. In the Nissan line up there's little choice in the larger sized BMC's available.

So the hunt was on for a larger BMC. Now there's quite a number of articles from the USA that says that their Z32 300ZX NA version did come up with a 1" (BM50) and 1 1/16" (BM55) BMC, and has been used successfully on their S13 240SX cars with larger caliper that was the first direction I took. After looking at a number of the photos of this setup, it finally clicked that this just wouldn't work...they drive on the left hand side of the the ports on the BMC are on the wrong side. This was backed up by the fact that Nissan Australia couldn't find anything in their parts database for an Australia equivalent. Back to the drawing board.

After a couple of weeks, another light blinked on at the end of the tunnel. I recalled that the R32 GT-R N1 came from the factory without ABS fitted. Now the N1 came in two basic versions. The first was based on the standard GT-R, and the second as I understand it was based on the V-spec and V-spec II versions, which used the same Brembo calipers as the R33 GT-R (which I'm using). Next was to find some pics of it...and after a bit of search on the Yahoo Japan auctions, I found some and this confirmed the existance of a 1" BM50 brake master cylinder with 3 ports on it. Yay. Now it was just a matter of finding the Nissan part number. Part of the clue came from these photos with some of the part number stamped onto the end of the BMC body. The other bits came from the Nissan Fast software.

- Screen capture of GT-R Brake Master Cylinders

Relavent Translations:
(5) #46010-05U01 | *RB26DETT.GT-R.17 | Tokico 1" N1 Specification
(6) #46010-05U21 | *RB26DETT.GT-R.17 | Nabco 1" N1 Specification

After confirming that there were two numbers matching my requirements, a call to Northside Nissan in Perth confirmed their availability - which was affirmative ex-Japan. Pricing was reasonable at around $530 retail and about $450 trade. When we ordered, it wasn't sure which item of the above two would come in, but in the end we go the Tokico unit (46010-05U01). Here's the pics below of the brake master cylinder now all hooked up.

R32 GT-R N1 Brake Master Cylinder Pics:
- Part number on front
- Outside view - BM50 | Nissan | Tokico
- Outside view closeup
- 3-ports overhead shot

So for all those doing big brake conversions on your Nissan Silvia or Skylines which didn't have ABS, or you're wanting to remove the ABS, then this would seem to be the solution. Of course there's the subject of brake bias that is still to be tested, but that's all par for the course.


PS> Thanks to some of the boys in the Japan sub forum on Skylines Australia for your Japanese-to-English translation help.


At 6:13 PM, Anonymous Anonymous said...

ajwpHi Brendan,

How did the Brake master cylinder go? Was the brake bias weird? Did you have to change the brake booster or did it bolt straight onto the S13 one?

I only ask because i've got a soft brake pedal in my s13 after i installed R33 GTS-T calipers.

cafc_86 (


At 7:55 AM, Blogger Brendan Underwood said...

BMC went well, good solid brake pedal. Not too solid though so you can do good progressive braking. Bias is pretty good too.

If you've gone the R33 GTS-t calipers, then I have known people to use an R33 BMC as well with great success. Shouldn't be as expensive and will be easier to find than the R32 GT-R N1. It should be a bolt on affair too like my one was.


At 1:55 PM, Blogger Josh said...

Hey mate,

As per the above question. I have recently installed 6 piston greddy brakes on the front and 4 piston greddy brakes on the rear. I have standard BMC and booster. I have just purchased the same BMC as you and want to know if it is necessary to upgrade the booster as well? I'm not sure if the r33 gtst boosters fit, do you know?



Josh @ j o s h m a r t y n . com

At 2:51 PM, Blogger Brendan Underwood said...

I have used the original S13 booster, along with the BMC in question.

Not too sure about the R33GTSt boosters though.


At 6:08 PM, Anonymous adam welcome said...

hey bro ive got an R31 aussie which i have fitted an r33 BMC + Booster and now my pedal is rock hard! and my back brakes have locked up to the point that when driven 10km the rear disc become so hott that the paint from the Pads begins to flake off and start a fire! ah fuck any clues mate??? or any help to guide me in the right direction lol

At 7:03 PM, Blogger Brendan Underwood said...

Hi Adam

Afraid I can't help you. Did you match the BMC to the calipers? If not then that would be where I'd be starting. Unless you're using an R33 BMC from say an NA R33 which I think from memory only came with single piston floating calipers, you really should be using twin-pots out the back and 4-pots at the front as per what would have been originally with that BMC/Booster combo.



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