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MG MGB Technical - Single OR Dual Circuit Brakes?

I am doing a ground up restoration on my '65 B that obviously has a single circuit braking system. My understanding is that they went to dual circuit in'68.

I have been advised to upgrade the brakes to a dual system (non-servo) for safety reasons. It looks to me like the pedal may be different and that the stop switch is in a different place. If I do this mod. I would want to keep the appearance as close to original as possible.

I would really appreciated some advice and comments from anybody who has considered or done this conversion and whether it is worth while?
Julian Wooldridge

Nothing wrong with a well maintained single ciruit system with a good hand brake. However it is fairly easy to convert your car. The brake light switch should be a pressure switch in-line so no change required. Replace the master cylinder and plumb the rear brakes to the rear of the M/C and the fronts to the front.
Leland Bradley

What Leland says is true, but you will have to plug the outlet to the rear brakes on the existing tee, which may be too obvious to mention. If you use silicon fluid you might want to consider using the later type brake light switch which is located on the pedal box cover, since I understand that the pressure switch tends to be sensitive (i.e. it fails) to silicone fluid use. Check the archives on that.
If you are sensitive to looks, then of course the later MC looks a lot different than the original too.
Andrew Blackley

If you feel that a single circuit brake ist too unsafe for you, why dont you simply buy a car with dual circuits instead of bastardizing an honest old sports car? Say, a 69 B? It also has a safety dash but unfortunately still no airbags :-)
The car doesn´t stop better with the dual system, there are just more parts to break!

I know because I own a 64 MGB and never had trouble stopping it.
joern

Andrew,
You're right. I started to write about repiping my 64 race car using a modified brake failure switch to route the pipes from the M/Cs to one fitting and then out to the brakes. Decided it was to complicated and missed a step.
Leland Bradley

Well maintained single circuit brakes are no problem and some say are better than the later 2 circuit system-so just keep your eye on the fluid level in the reservoir and obviously question any severe fluid loss in same.Don't worry single cct brakes are very reliable.(got a 65MGB)
ADRIAN

Joern, entschuldigen sie bitte, das stimmt nicht!

My MGBGT had single circuit brakes. One day while tooling down a boulevard at about 55mph I made a quick left hand turn across the boulevard, but had to stop for oncomming traffic. When I hit the brakes, a seal in one of the rear wheel cylinders let loose and the pedal slammed to the floor without even a hint of braking.

I can tell you that there was absolutely NO time to reach down and find and then grab and pull the emergency brake. The only thing I could do was crank the wheel hard right and head up over the curb of the center strip.

To this day, 20 years later, I have a habit of reaching down to feel for the hand brake frequently to make sure it's accessable.

Julian,
You are not bastardizing a car if the changes you make can be reversed and if the change is in the spirit of the period and the car. I already have a dual circuit non-servo unit for installation into my MGA.


Fred Horstmeyer
Fred Horstmeyer

Much appreciated Gents. Great feedback. I think I am going to stay with a well maintained single circuit system.
Julian Wooldridge

This thread was discussed between 14/05/2002 and 17/05/2002

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.