duel brakes

[Piero franchi]

Hi guys

What's the advantages off duel cercite brakes if any

And can this system be fitted with a servo




Many thanks

[herald948]

The dual-circuit braking system simply provides a bit of a "fallback" should a leak develop in a pipe or wheel cylinder on one corner of the car, leaving you with some braking ability. As to a servo, I believe they can be fitted (and were, on late US-spec. GT6 Mk3 models), but they will only function on the front brakes (most all Triumph dual-circuit brake systems were split front and rear).

[nang]

What are you driving?
Tony

[thescrapman]

As Andy says, entirely a safety thing, if you get a leak you only get 2 out of 4 brakes fail.

Triumphs split front / rear, but as you are in a position to install piping to a better design, then you can go diagonal corners, then with the handbrake you only loose 1 out of 4 brakes.

Does make servo assisting a bit more difficult, but you could use 2 servos.

Or just not have a servo, it isn't needed normally.

Cheers

Colin

p.s. if you wanted to be really clever, get 4-pot front calipers and have them fed by 2 separate circuits, that way should have even greater safety margin.

[Alex]

When I had my saloon mot'd this year I was told that my handbrake needed to be better than a modern due to the single circuit brakes.......cant remember what the percentage difference was now though...

[Sheepy]

Or if you really want a servo, what about searching modern small cars for a suitable dual circuit servo and fit that.
I'm sure people have done this.  :)

We had a small iveco truck in work the other day, and the servo was perfect, good style/position, dual circuit, but only problem it was a bit too big, dammmm

Cheers
Shaun

[WIMPUS]

4058 wrote:

Or if you really want a servo, what about searching modern small cars for a suitable dual circuit servo and fit that.
I'm sure people have done this.  :)

We had a small iveco truck in work the other day, and the servo was perfect, good style/position, dual circuit, but only problem it was a bit too big, dammmm

Cheers
Shaun

hi, I know somebody that's fit a honda jazz (small box car) brake servo on his spitfire '77 !

[junkuser]

"p.s. if you wanted to be really clever, get 4-pot front calipers and have them fed by 2 separate circuits, that way should have even greater safety margin."  Colin

The much criticised Lada Niva had this setup.  One circuit did two front pots only and the other the rest.

[JohnD]

If you have dual master cylinders, operated by a bar that compresses them both, then the position of the brake pedal on the bar determines the balance between front and rear brakes.  That position can be adjustable, even in motion, by a suitable linkage, although that's illegal for club motorsport.
A proportioning valve in the rear circuit can do a similar, though more crude, job.  Ford vans used to have a weight sensitive valve to decrease rear braking force if the van was heavy-loaded.

John

PS Alex, your MoT man is talking borrocks.  The parking brake need be no more than half as efficient as the hydraulic brakes.  See: http://www.motuk.co.uk/manual_3100.htm

[nang]

The reason I asked what car, Aussie and N Z  2500's and I understand LHD models were fitted with tandem cylinders and a booster bolted to it.
They're still available.
Tony.

[Nick Moore]

The saloon boosters were bolted to the master cylinders on the bulkhead. I don't think there's room on a Spit / GT6 bulkhead to mount one, more's the pity.

I'm restoring a 1972 US-spec GT6, which had dual circuit brakes. I'm planning to do as Triumph did - add a remote booster to the front circuit and choose the rear cylinders to retain some rear wheel braking. There isn't a lot of room under a GT6 bonnet for two remote boosters!

[rotoflex]

The interesting thing about the intention of the dual circuit brakes versus observed behavior is that there is so infrequently a leak in the system downstream of the master cylinder: I think I have two original wheel cylinders still on the car!

On the other hand, the brake master cylinder seems to go pfut every other year or so, and when that happens, the dual hydraulic circuits avail you nothing.  It's right hand to the handbrake, and nothing else.

The dual circuit scheme's most frequent announcement of itself is the shuttle in the brake PDWA getting de-centralized while bleeding the brakes and driving you crazy trying to get it re-centralized so that the light will go off.

[ferny]

I'm certain that the Acclaim's dual circuit brakes are diagonal, they also use a servo. I think it uses a  proportioning valve do do it. I'll check the workshop manual later.

[bob dunn]

i asked my son about duel brakes he said why would you stick a sword into the back wheel!