Dual circuit master cylinder

[138]

Will any other Holden (or any brand for that matter) dual circuit master cylinder (for drums) bolt up to my existing firewall mount?

[Harv]

Not sure if any are a direct bolt up, but the Gemini booster is pretty common. It is small enough in diameter to clear the bonnet hinges, which can foul with larger booster/master combinations. The earlier Gemini boosters are used, which have a horizontal bolt pattern (later Geminis used an angle mount). The booster is mated up to an XA/B/C &*#@ master cylinder, which is dual circuit (PBR part number P6258a). The master cylinder pushrod has to be extended slightly so that it protrudes 1.5mm from the booster face (in order to provide appropriate booster pre-load). The booster mounting bracket mounts neatly to the firewall, though some holes have to be enlarged/drilled.

There are some photos of the setup on my build thread from memory (http://www.fbekholden.com/forum/viewtop ... 3&start=60).

Cheers,
Harv

[Errol62]

CRS used to supply an adaptor to bolt up HQ drum brake dual circuit master cylinder to FE - HR. This gives you unboosted dual circuit brakes. Harvs solution will give you boosted dual circuit to suit disc or disc/drum with compatible slave and proportioning hardware. May also work with drum/drum combo.


Sent from my iPhone using Tapatalk

[Harv]

CRS used to supply an adaptor to bolt up HQ drum brake dual circuit master cylinder to FE - HR.

Interesting... hadn't seen that one before. CRS now advertise an adaptor for HQ master to EJ/EH: http://www.rodshop.com.au/holden/fb-ek/ ... aptor.html. They list it on the FE/FC, FB/EK and EJ/EH pages... wonder if it fits FB/EKs too?

Cheers,
Harv

[Errol62]

Same master from factory so should do. I'm planning to fit one and boost the front circuit only then run standard EJ rear hardware and HR discs front. The booster will be hidden under the rear cargo (van) with the battery. One day!


Sent from my iPhone using Tapatalk

[gpi]

CRS used to supply an adaptor to bolt up HQ drum brake dual circuit master cylinder to FE - HR.

Interesting... hadn't seen that one before. CRS now advertise an adaptor for HQ master to EJ/EH: http://www.rodshop.com.au/holden/fb-ek/ ... aptor.html. They list it on the FE/FC, FB/EK and EJ/EH pages... wonder if it fits FB/EKs too?

Cheers,
Harv

doesnt fit fb ek due to the bumps in the firewall. i milled it down to fit.
might cast a few considering its nothing like how i originally bought it.

[Errol62]

How about some photos? I'll probably be keen to get one if you go ahead.
Cheers
Clay


Sent from my iPhone using Tapatalk

[Trev]

I bolted a HG dual circuit directly to my firewall, had to enlarge the hole and flatten the pressings but it went on no problem.
Then used a remote booster.


Sent from my iPhone using Tapatalk

[Errol62]

Boosting front circuit only I assume Trev. Drum front compatible cylinders on rear?


Sent from my iPad using Tapatalk

[Trev]

I had a HR disc front end sorry Errol I should have said.
Yes front boosted only.


Sent from my iPhone using Tapatalk

[Errol62]

That is what I plan doing. Worked okay Trev?


Sent from my iPhone using Tapatalk

[Trev]

I used that for about 10 years then started having trouble with front brakes locking up so I went to a fully boosted system.
Ended up being as simple as a blocked flexible hose in the rear end. So didn't need to change after all.


Sent from my iPhone using Tapatalk

[Errol62]

Cheers Trev
Good to know.


Sent from my iPhone using Tapatalk

[Mick]

I've used the method trev described a few times except i leave drum brake compatible set up on rear, the last time it had to be brake checked for engineering the guy said they were fantastic and wanted to know what the set up was so he could use it if need be

[Errol62]

Cheers Mick
Good way to keep the engine bay uncluttered if you can hide the remote booster some where. I'm thinking to put booster behind the seat in the van together with the battery. Means some extra plumbing but reduces understeer and keeps engine bay tidy.
Anyway sorry to hijack your topic 138.
Cheers
Clay


Sent from my iPad using Tapatalk