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Master cylinder sizes and capacity


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#1 plox

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Posted 27 September 2016 - 8:24 PM

Hi guys

My bc5 has just failed cert on a few things, master cylinder "capacity" is one of them. The issue is the pedal is half down before it actually starts braking and near the bottom of the range when it's hard/locked up.
The certifiers issue/thought is that my master cylinder doesn't have enough capacity to displace enough fluid when the brake pads wear more.

Running v7 wrx 4 pot fronts and 2 pot rears
Upon inspection my car has a 1 1/6 master cylinder according to the casting. ABS, 2 ports.

From what I have read here a few of you have upgraded, what size did you upgrade to? From the Nasioc 1 1/6 is the largest factory bore?
Are there different capacity (longer) cylinders?

I'm going to try bleeding the brakes again but the certifier agreed it didn't feel like they needed bleeding, just that it need to displace a lot of fluid before starting to brake.

#2 Leufkax

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Posted 27 September 2016 - 10:24 PM

My BG GTB runs 4 pots very nicely, good firm pedal. Maybe look into a master and booster from one of those

#3 DRFVDR

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Posted 27 September 2016 - 10:53 PM

As most japanese vehicles run brake gear from only a few manufacturers I would look at other makes as well, as long as the bolt holes are the same every thing else can be mixed and matched.best bet would be to see what Nissan has
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#4 plox

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Posted 28 September 2016 - 12:50 AM

My BG GTB runs 4 pots very nicely, good firm pedal. Maybe look into a master and booster from one of those

Would you be able to take a photo of the booster? and let me know if there is a size on the cylinder and if so what is says?

A mate has checked his partners v7 wrx (factory 4/2 pot model) and no size on the cylinder, nor on my gdf sti

#5 plox

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Posted 28 September 2016 - 12:53 AM

As most japanese vehicles run brake gear from only a few manufacturers I would look at other makes as well, as long as the bolt holes are the same every thing else can be mixed and matched.best bet would be to see what Nissan has

Good to know, thanks

Will check a mates r32 & r33 and see what they have.

#6 Reuben

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Posted 28 September 2016 - 11:31 AM

Maybe it's just fucked... Those masters are good to run brembo's... So maybe just try another master and see if it's any different.

Maybe also upgrade the booster to BH or GD turbo. They are bigger.
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<Shale>: Blighter doesn't really have an accelerator pedal, it's more just a loudness pedal. You can change volume, but you won't go any faster.


<mjlqtown>: (Southern US accent) I'v excised the demon! This car is now clear!


<Reuben>: I feel like when you stomp the throttle in Blighter, it's like you've startled an old man!

#7 plox

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Posted 29 September 2016 - 7:53 PM

I'm thinking it's an issue with my car/cylinder so will give it a bleed and see if we can find anything strange. Then look at replacing bits.

#8 5th injector

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Posted 30 September 2016 - 7:00 PM

I'm running 4 pots on a standard bc5 master no problem. id look at the master and booster. but most prob the master i reckon.

#9 DCVR

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Posted 01 October 2016 - 6:30 AM

Your master has been upgraded already by the looks of it. My factory 89 RS one was 1" not 1 1/16"

You're running the same master that I converted to and I have no problems running 4 pots and 2 pots on the rear. I also run the factory RS booster

There's a little bit of play at the top of the pedal before it bites hard.

I'm going to upgrade the booster to a V7 sti because I'm going to Brembos all round

Swap out the master for starters. Bench bleed it before installation
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#10 DCVR

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Posted 04 October 2016 - 2:19 AM

I did notice at pickapart though that some BF's were running the 1 1/16" MC
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#11 Leufkax

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Posted 04 October 2016 - 2:26 AM

I think that may be more to do with having ABS than anything else

#12 plox

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Posted 04 October 2016 - 9:23 PM

I'm fairly sure mine would be factory because the rest of the car was pretty factory when I got, who knows though.

Yea reading online it could be an issue with the abs pump. Need to give it a bleed then test it. Have a v7 n/a "wrx" here that I'm paddock bashing then wrecking so hopefully the abs pump matches if that's what it needs.

#13 Reuben

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Posted 05 October 2016 - 10:57 AM

First gen ABS pumps are unique to the model. There's actually two types if I recall correctly, and they need to match their ABS computer under the drivers seat. So no, sadly the V7 ABS unit won't work.

And those non turb V7 WRX's are neat cars, factory badged btw, they are the continuation of the Hx20, SRX line of imprezas.
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<Shale>: Blighter doesn't really have an accelerator pedal, it's more just a loudness pedal. You can change volume, but you won't go any faster.


<mjlqtown>: (Southern US accent) I'v excised the demon! This car is now clear!


<Reuben>: I feel like when you stomp the throttle in Blighter, it's like you've startled an old man!

#14 plox

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Posted 05 October 2016 - 6:34 PM

First gen ABS pumps are unique to the model. There's actually two types if I recall correctly, and they need to match their ABS computer under the drivers seat. So no, sadly the V7 ABS unit won't work.

And those non turb V7 WRX's are neat cars, factory badged btw, they are the continuation of the Hx20, SRX line of imprezas.

Dammit, I knew selling my other shell cheap was going to bite me in the ass

Yea it's de-regod and had a bunch of parts stolen otherwise other would be an alright car.

#15 plox

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Posted 18 October 2016 - 12:51 AM

Gave it another bleed and still had the issue. Pulled the master cylinder and have a new one on the way, will install and see how it goes.
Fingers crossed otherwise ABS pump is the next place to look.

#16 Reuben

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Posted 18 October 2016 - 11:02 PM

I hate clutch and brake hydraulics... Fucking poxy jobs...

Hope it bloody works!!!
Posted Image


<Shale>: Blighter doesn't really have an accelerator pedal, it's more just a loudness pedal. You can change volume, but you won't go any faster.


<mjlqtown>: (Southern US accent) I'v excised the demon! This car is now clear!


<Reuben>: I feel like when you stomp the throttle in Blighter, it's like you've startled an old man!

#17 plox

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Posted 20 October 2016 - 10:56 PM

New MC in, bugger all change... fuck it :angry:

Going to bleed the abs pump separately, then try clamp off each brake line and see if we can find one that causes more play than the others.




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