UpGrade to Dual cct Brakes

Hi All,

Just bagged a master servo with dual brake circuit. Hower one on my car is a single circuit servo. Anyone done this upgrade before, and if so can you give me brief upgrade on whats whats with it.

Ta!

M

sorry if i've miss-understood your question... but with dual circuit brakes one circuit is for the front and one for the back - make sure you get it the right way as often one set is weaker (can't remember which way round it is and i'm not awake enough to think it through)

So you need to take the front brakes, T'd together and connect to one circuit and same with rear...

Yu sure the 2 circuits aren't fnt lft & rr rt on one circuit and fnt rt & rr lft on the other?

The S3 book shows separate front and rear circuits, forward outlet on master to front brakes. There's supposed to be a warning switch in the brake lines which detects pressure differences between the two circuits but I suspect it just makes things more difficult to include it.

yes they are split front and rear but rear pipe on master cylinder works front brakes front pipe rear

the circuit failure switch is easy to fit as pipes from m/cyl go in either side at top and then come out either side at bottom (its shaped like H ) to go to rear or front circuit the wires go to dash light with bulb test switch integrated (they used same components in several B/Leyland vehicles eg sherpa ital etc ) . IIRC failure light is legal requirement for dual circuit brakes . HTSH
p.s. some m/cyl have switch (sensor) incorporated in m/cyl body.

tacr2man said:

the circuit failure switch is easy to fit as pipes from m/cyl go in either side at top and then come out either side at bottom (its shaped like H ) to go to rear or front circuit the wires go to dash light with bulb test switch integrated (they used same components in several B/Leyland vehicles eg sherpa ital etc ) . IIRC failure light is legal requirement for dual circuit brakes . HTSH
p.s. some m/cyl have switch (sensor) incorporated in m/cyl body.

Click to expand...

There was someone on here a few months back that had a mysterious light on his dash, I wonder if it was this.

jamesmartin said:

yes they are split front and rear but rear pipe on master cylinder works front brakes front pipe rear

Click to expand...

When you say "rear pipe" do you mean the one to the rear of the cylinder but the front of the vehicle? It sort of depends on what you mean by "rear".

This might help,the failure switch also has a shuttle valve in it which seals off the failed side of the system,

tacr2man said:

the circuit failure switch is easy to fit as pipes from m/cyl go in either side at top and then come out either side at bottom (its shaped like H ) to go to rear or front circuit the wires go to dash light with bulb test switch integrated (they used same components in several B/Leyland vehicles eg sherpa ital etc ) . IIRC failure light is legal requirement for dual circuit brakes . HTSH
p.s. some m/cyl have switch (sensor) incorporated in m/cyl body.

Click to expand...

You could probably argue that the shuttle valve and warning light isn't needed if retrofitting dual circuit brakes to an older vehicle. You certainly need one for an SVA (or whatever it is now) test and removing one from an existing system might be seen as reducing it's braking efficiency. Probably safest to fit one but I doubt an MOT inspector would notice and I can't see how one could be tested during an MOT.

Ahhhh - I have a servo that has come from a 1960's something or other.....

...Just spoken to the guy who owned it (my grandfather)...

"I upgraded the brakes to a servo in 1974 with a power assist. I cannot remember where it came from, but thats why it does not look original"

So what it has is a servo that looks like a LR item but larger and there is only 1 line coming from the servo to a manifold that powers both...

Thing is this, the brakes are actually pretty good, even by modern standard - enought to lock them up at 60mph and kiss windscreen by breating on them!, However i am a little scared about everything coming from 1 line i.e. if brakes lines, cylinders leak then everything is lost.....

so 2 question now are:

how good are normal LR servos?

is it worth upgrading considering i have wicked brakes now v's double death jepody running from 1 line.....?

Your thoughts please!!!!

Sounds like you might have the single circuit landy servo. I've got the non servo single circuit and I've not had a failure in 20 years. Mind you, I've got used to engine braking a lot 'cos the non servo brakes are not good....