Dual circuit brakes

[ktwhite]

I recently converted to front Wilwood disc kit and Courier dual master. Rear are stock drum. Works really good. Leg pressure is really good. Had issue with front brakes dragging after release. Removed factory residual valve for fronts behind large nut on master and all good. Stops great. Converting a Nissan style incase I want to do Wilwoods in rear. 4 discs all around need a slightly larger master. Wheel cylinders are smaller than the amount of piston space. Don’t see a need but I am a just to do it guy.

 

[ktwhite]

Forgot to mention I did do a little turn down on the mushroom head of the pushrod and ball milled a little off the piston in master where the mushroom head contacts. Wanted a slight amount of play to ensure rod is not pushing on master in relaxed position.

 

[Austin Healer]

I recently converted to front Wilwood disc kit and Courier dual master. Rear are stock drum. Works really good. Leg pressure is really good. Had issue with front brakes dragging after release. Removed factory residual valve for fronts behind large nut on master and all good. Stops great. Converting a Nissan style incase I want to do Wilwoods in rear. 4 discs all around need a slightly larger master. Wheel cylinders are smaller than the amount of piston space. Don’t see a need but I am a just to do it guy.

The cars are so light that a booster really isn't something that is really required. I've driven Tigers with, and without a booster and never really thought there was a huge difference...

 

[Austin Healer]

Forgot to mention I did do a little turn down on the mushroom head of the pushrod and ball milled a little off the piston in master where the mushroom head contacts. Wanted a slight amount of play to ensure rod is not pushing on master in relaxed position.

yes, you have to have a little free play or the pressure cannot bleed off and the brakes will eventually lock "on"

 

[65beam]

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

The Lockheed set up used on Sunbeams works quite well. It is a dual master and there doesn't seem to be a need for boosting the rear brakes. These cars are not a Tiger or Alpine so Rootes engineers designed the braking system to fit the car and to pass U.S regulations. The cars are a comfortable cruiser that stop really well.

 

[65beam]

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

The Sunbeam parts book used the description of" pressure failure warning switch " which means the same as what you said. This switch was only on cars sold in the U.S. and Canada. Cars sold elsewhere used a single circuit master with the booster on both front and rear wheels. The rear wheel cylinders of no booster were a different part number from the ones used on cars that had the booster to the rear wheels. I have new cylinders for the U.S cars but not for the others so I haven't been able to find the size of the two cylinders. They must be different sizes. Sunbeam changed to a different size rear cylinder on the series 3 Alpine when they started using the booster.

 

[Tigerbill]

I am going to go the two remote booster route….one front, one rear….

 

[pfreen]

I am going to go the two remote booster route….one front, one rear….

That's what my Lotus Europa has, which was stock. The Girling boosters were replaced with Lockheed booster 20 years ago and I have never had a problem.

 

[CobraTiger]

Thanks for all the advice. I really do not want to plumb in the front brakes only to the booster and having driven my Tiger un-boosted, I prefer it with the booster. So will stick with the original Master, albeit stainless re sleeved with stainless piston. I may change that position about the booster once my car is back on the road, as I have upgraded the brakes using the Brembo conversion from a Peugeot

 

[Tigerbill]

Every time I drive my “unboosted” ‘39 Jaguar SS100, the braking effort required confirms why my Tiger is getting boosted in order to make full use of it’s dual circuit four wheel discs…my right leg isn’t as powerful as it once was
Go fast and gotta slow fast too!

 

[Forrest39]

I recently converted to front Wilwood disc kit and Courier dual master. Rear are stock drum. Works really good. Leg pressure is really good. Had issue with front brakes dragging after release. Removed factory residual valve for fronts behind large nut on master and all good. Stops great. Converting a Nissan style incase I want to do Wilwoods in rear. 4 discs all around need a slightly larger master. Wheel cylinders are smaller than the amount of piston space. Don’t see a need but I am a just to do it guy.

I finally installed the Courier MC. I also installed a Wilwood proportioning valve as I will soon be fitting a Dale’s front end with 11.75” brake rotors. I sure wish I would have read this post about removing the residual brake valve from the front circuit. I finally got to the same solution, but I wasted a bunch of time and effort matching the mushroom bolt and piston thinking that I was not unporting to the reservoir. In any case, I’m happy with the install and have reasonable brakes now. I just wanted to second the importance of removing the residual valve from the front brake circuit of the MC.
-Kevin

 

[Hoghead]

I recently converted to front Wilwood disc kit and Courier dual master. Rear are stock drum. Works really good. Leg pressure is really good. Had issue with front brakes dragging after release. Removed factory residual valve for fronts behind large nut on master and all good.

Can you explain more about this residual pressure valve on the Courier MC ?
I understand what it is, but unaware that the Courier MC had one

 

[Forrest39]

Can you explain more about this residual pressure valve on the Courier MC ?
I understand what it is, but unaware that the Courier MC had one

Can you explain more about this residual pressure valve on the Courier MC ?
I understand what it is, but unaware that the Courier MC had one

Sure! Two are installed. There’s a 21mm gland nut at each exit port where the banjo fitting connects to. Removing this nut reveals a spring and diaphragm. The idea is geared towards drum brakes so that the shoes don’t fully retract. Good idea for drums - not so much for a disc brake application that has very little movement. I left the forward one installed as it goes to the rear drum brakes. I will remove it when I get around to installing rear disc brakes. I discovered the existence of the valves by looking up an expanded diagram.

 

[Forrest39]

Here’s the picture that clued me in…

 

[Hoghead]

Interesting that there is a check valve on both front and rear lines, and the Courier must have had front drums
One would expect that a rear drum car would use a 2 psi or so residual pressure valve in the rear, and I have used an in-line Wildood valve on my stock MC for that very reason

Thanks for the tip

 

[66TigerMK1A]

It took me about a minute to find this one... I think I came across it before actually

https://www.s-v-c.co.uk/products/dualservo-dual-remote-servo#pic6