Dual circuit brakes

T

the_tool_man

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Hi all:

I'm trying to source a dual-circuit brake master cylinder. Looking on the SAOCA forum, I found several recommending one from a 1978 Datsun F10 pickup, as it fits the mounting provision, and rod, and has the correct diameter piston (3/4"). I haven't been able to find any using the part numbers given (all sources at least two years old - everyone out of stock). When I search various sources using the above vehicle information, the images show a MC set up for remote reservoir, which isn't right. I've attached a photo of what I'm looking for.



Anyone sourced one recently?

TIA
John.
 
3/4" Dual Tandem Brake Master

the_tool_man said:
Hi all:

I'm trying to source a dual-circuit brake master cylinder. Looking on the SAOCA forum, I found several recommending one from a 1978 Datsun F10 pickup, as it fits the mounting provision, and rod, and has the correct diameter piston (3/4"). I haven't been able to find any using the part numbers given (all sources at least two years old - everyone out of stock). When I search various sources using the above vehicle information, the images show a MC set up for remote reservoir, which isn't right. I've attached a photo of what I'm looking for.



Anyone sourced one recently?

TIA
John.
Click to expand...

Got a couple new set-ups at the shop. How soon do you need it?
 
Well, the car's been disassembled for 20 years, so I guess it's not an emergency. :) I'm in parts-gathering mode on brakes and some other stuff after a long hiatus. When you say "setup" is it the Datsun unit or something else? Thanks.

Regards,
John.
 
3/4 Tandem Masters

the_tool_man said:
Well, the car's been disassembled for 20 years, so I guess it's not an emergency. :) I'm in parts-gathering mode on brakes and some other stuff after a long hiatus. When you say "setup" is it the Datsun unit or something else? Thanks.

Regards,
John.
Click to expand...

Hi John: I bought a bunch of the Suburu 3/4" when we could still get them. And yes, we can still get the repair kits if needed. The 3/4" bores deliver a more comfy pedal effort over the single 7/8" and still maintain ample fluid volumes. . . . .randy
 
If you are running stock calipers and drums then the Ford Courier/Mazda dual MC works quite well. I have them on two street Tigers.

bt
 
I thought the Datsun unit was 3/4" bore too. Am I wrong?

I plan to run stock discs up front for now. I will retrofit rear discs before putting it on the road (existing drums are a mess). Looking into Mazda RX7 rotors and calipers, if that matters (Wilwoods aren't in the budget). From what I read, the Datsun MC is good for either setup. Is this right?

I have no plans to fit a booster.

Thanks,
John.
 
3/4" bores are the key

the_tool_man said:
I thought the Datsun unit was 3/4" bore too. Am I wrong?

I plan to run stock discs up front for now. I will retrofit rear discs before putting it on the road (existing drums are a mess). Looking into Mazda RX7 rotors and calipers, if that matters (Wilwoods aren't in the budget). From what I read, the Datsun MC is good for either setup. Is this right?

I have no plans to fit a booster.

Thanks,
John.
Click to expand...

Regardless of which manufacturer you choose, the 3/4" bore is the prefered dimension. Some offer better pedal rod connection opportunities than others, so pay attention to installation snags. The only booster assisted 3/4" bore I'm aware of is a MK II in Georgia and the pedal effort is extremely easy as a result . . . . .
 
I have 4 piston rx7 turbo calipers with Nissan rotors up front and Mazda calipers with cougar rotors on the rear and with the f10 master gives me about 50/50 braking. I probably should add a valve but I haven't had any issues so far
 
In case anyone is interested, after five months of searching, I found an F10 M/C (3/4" bore) at this place for under $75 with shipping:

http://classicgarage.com/nidf10brmacy.html

Every other place I tried was out of stock, despite thier website saying they had them. I called and confirmed they had a couple. It arrived the other day, and appears to be the correct part. You still need reservoirs, which I got from Pegasus Racing, like everyone else does.

Regards,
John.
 
Hi All,
I am looking for a dual brake Master. I am in AUS and have an original RHD Tiger with lever accelerator linkages (not wire). I note that there are discussions re Subaru and Datsun brake master. Could you please be specific re the models before I exasperate the brake shop. Any advise greatly appreciated
 
steven said:
If the dual master is fitted, what is used for a booster?
Click to expand...
With dual circuit brakes no booster is possible unless it's a direct acting one physically bolted to the master cylinder. (think TR6 or late MGB) Aston Martin DB5's used 2 of the 7" Girling Mk2a units, so did some of the factory Tiger competition cars (mounted on the rear shelf behind the RH seat. The only other possibility I can think of would be something similar to a series 2 E-type which used a remote booster for a dual circuit system.. (Lockheed parts) It's been so long since I worked on it, I can't remember how it was plumbed

Wilwood makes a dual circuit master cylinder for use with their vented disc brake upgrade, but no booster is used. I recently removed one of these from a Mk2 in the shop as he wanted a more OE looking system underhood and wanted to retain the Girling booster.
 
Austin Healer said:
With dual circuit brakes no booster is possible unless it's a direct acting one physically bolted to the master cylinder. (think TR6 or late MGB) Aston Martin DB5's used 2 of the 7" Girling Mk2a units, so did some of the factory Tiger competition cars (mounted on the rear shelf behind the RH seat. The only other possibility I can think of would be something similar to a series 2 E-type which used a remote booster for a dual circuit system.. (Lockheed parts) It's been so long since I worked on it, I can't remember how it was plumbed

Wilwood makes a dual circuit master cylinder for use with their vented disc brake upgrade, but no booster is used. I recently removed one of these from a Mk2 in the shop as he wanted a more OE looking system underhood and wanted to retain the Girling booster.
Click to expand...
Starting in 1968 after ceasing production of the series Alpines and the Tiger, Sunbeam switched to a Lockheed system using a Lockheed dual brake master and a remote Lockheed booster mounted on the opposite side of the fire wall. This photo of my engine bay shows the set up on my 69 GT. They installed a valve with a sensor on the center of the fire wall behind the engine that turned on a light in
100_0254.JPG
the dash if pressure dropped on either the front or rear system. The brake lines from the master hook to this valve and then continue out the other side to the booster. You can see the two lines coming off the booster and going to the brakes.
 
Thank you for the super quick responses and apologies. I should have mentioned I am using a remote booster. It isn't Girling. Its local to AUS. 7 1/2" PBR VH40 specifically for disk/Drum. I now wish to go to dual circuit brakes as per my post.
 
oh sorry and one other thing. I have a friend who has a Mustang GT with remote mounted booster and dual circuit brakes so i would think that it is possible. Hopefully someone has done that with a Tiger.
 
Austin Healer said:
With dual circuit brakes no booster is possible unless it's a direct acting one physically bolted to the master cylinder. (think TR6 or late MGB) Aston Martin DB5's used 2 of the 7" Girling Mk2a units, so did some of the factory Tiger competition cars (mounted on the rear shelf behind the RH seat. The only other possibility I can think of would be something similar to a series 2 E-type which used a remote booster for a dual circuit system.. (Lockheed parts) It's been so long since I worked on it, I can't remember how it was plumbed
Click to expand...
I had assumed this but recently read of someone converting a car, Tiger I think, to dual circuit brakes and retaining the stock booster to work with just the front brakes. I can't seem to find where I read the account but it is an intriguing concept.
Obviously the front brakes do the majority of the stopping but would this create a possibly dangerous imbalance?
 
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Theorangetiger said:
I had assumed this but recently read of someone converting a car, Tiger, I think, to dual circuit brakes and retaining the stock booster to work with just the front brakes. I can't seem to find where I read the account but it is an intriguing concept.
Obviously the front brakes do the majority of the stopping but would this create a possibly dangerous imbalance?
Click to expand...
I have a vague memory of that as well... I believe I commented at the time that i thought it was just about the most dangerous thing to do with brakes I had ever heard of.
 
Austin Healer said:
I have a vague memory of that as well... I believe I commented at the time that i thought it was just about the most dangerous thing to do with brakes I had ever heard of.
Click to expand...
The lines I mentioned coming off the booster go to the two front wheels. No boost to the rear brakes.
 
65beam said:
The lines I mentioned coming off the booster go to the two front wheels. No boost to the rear brakes.
Click to expand...
As I said.... the only way to achieve power brakes in a dual circuit system (all 4 wheels) is by direct boosting a dual circuit master, or using 2 remote boosters (Aston Martin, rally spec Tiger). I have yet to come across a remote Dual circuit booster. By the way, the warning light on your dash is triggered by was Girling called a PWDA (pressure warning differential assembly) it has a sliding shuttle that cuts off fluid when there is a leak in one side. the sliding shuttle trips a switch mounted in the center
 
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