The 3000 Forum

Dual circuit brakes

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bbh Andy S
Clitheroe, Lancashire, UK   GBR
My plan from the start of my rebuild of my 1961 BT7 tri-carb, has been to incorporate dual circuit brakes.

I started with a plan to keep drums on the rear, upgrade the front (BJ8 disks / Girling type 16 callipers) and support each by a servo (2:1 rear, 3:1 front) with 2 x 7/8" master cylinders pushed from a balanced bar equiped pedal box.

As time has progressed, I am re-considering the servo bit (some of the rally cars and Sebring race cars had a similar master cylinder / servo set-up, I am led to believe), but do I really need a servo? and can I make things a bit simpler by omitting these.

Thus any feedback on the following would be really helpful :

Servo v non servo on a road car?

If non-servo, any experience with choice of master cylinder size for front and rear, remembering they will be operating on separate circuits.?

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hipo528 Avatar
hipo528 larry ingram
easley, SC, USA   USA
i have somewhat the same dual circuit on my healey as you are planning....but i used a dual circuit wilwood master cylinder and an adjustable proportioning valve for the rear drum brakes. i use four piston calipers on the front. the wilwood master cylinder bolts into the original healey location without modification other than the pushrod. and, the proportioning valve is small and easy to mount. the master cylinder has built-in reservoirs for each circuit. of course brake lines will change to accommodate the new setup.

Jack T Avatar
Greensburg, PA, USA   USA
Back when I was in my 20s I thought the Healey brakes were fine without a servo. Of course that was back in the day when your typical Amurrican car had drums all around. When I got my BT7 back on the road last year I was shocked at how much effort it took to bring the car to a stop. I installed a servo and am glad I did, although I have yet to upgrade the M/C. I once lost the boost from the servo on my 1966 E-Type (4-wheel discs) and the brakes went from very good to practically non-existent. I don't think you will regret installing a servo.

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