I am going to use a pressure switch in the brake line for my brake lights, but is there an SVA requirement that, with front/rear split braking system, either front or rear must be able to switch the lights on, or am I ok just putting the switch in the rear line?

Technically by the old Construction & Use/Road Traffic Acts it should be in the front line but the reg seems largely forgotten now buried by euro harmoised type approval requirements.

I put mine in the front as my loom had wires for a switch on the foot pedal there.

Mine is in the front as well

Mines in the back as thats where the brake lights are,SVA didnt seem to have problems with it and i had spare wires run to the rear for future work anyway.
Rescued attachment MK Indy build pics 077.jpg

you could have a switch in both lines connetced to the brake lights, but also to 'exclusive OR' logic circuit to work a brake faliure light on the dash board.

Ours was in the back brake line...

Mine is on the front line, but again, only beacause the wiring loom put it there

Bit of history -- front brakes only became popular after WW1 before about 1926 cars usually had a hand brake which operated band brakes on the rear wheel and if you were lucky a foot operated transmission brake. Transmission brakes tend to be rather difficult to control ----- any one who has driven a car of this period will know that a foot operated transmission brake is not for the faint hearted so most stopping was done more sedately using the hand brake. When front brakes were introduced they either operated only on the front wheels or on both the front and transmission brakes. For obvious stopping distance reasons when brake lights were fitted they were required to be connected so that they operated inconjunction with any brake the operates on the front wheels (this included handbrakes such as on the old Commer/Dodge PB that operated on the front wheels).

This is one of the reasons why cars with a diagonal split hydraulic system always either have a mechanical type switch operating on the pedal or two pressure switches wired in parallel (found on some VW Caddy models).

With a front/rear split system the strict definition is that a hydraulic type switch should be plumbed into the front circuit but SVA testers don't seem to know this and in practice it makes little or no difference anyway



[Edited on 13/3/05 by britishtrident]

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Originally posted by clbarclay
you could have a switch in both lines connetced to the brake lights, but also to 'exclusive OR' logic circuit to work a brake faliure light on the dash board.

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Unless i misread the SVA manual a light indicating of brake failure on hydraulic systems is requirement.

section 16.4
4 d.

not as long as there is a light warning of fluid loss in either circuit and it is a split circuit braking system.

Is this pressure switch a requirement then or can it be a pedal operated switch?

No, don't worry, a pedal operated switch is fine, but as the brake lights will be switched directly, and I like the simple and minimal approach, I want to use a 4 way tee piece at the rear of the car to split the lines to the two rear calipers and have the switch for the rear lights mounted on it too, and incorporate it into the rear loom on it's way to the lights.

Mine is in the rear brakes simply because it was the most convenient place to put it . That way I only need use two tee joints near the master cylinders - one from the front m/c to the front calipers and one from the rear m/c to brake switch and long brake line to the rear of the car (which then splits on another tee to the rear calipers.

Could u not use a 4 way piece for this and put the switch where the split is for either side?

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Originally posted by Danozeman
Could u not use a 4 way piece for this and put the switch where the split is for either side?

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