as some of you may have read i have just failed my sva on the first attempt. the main problem i had was with the brake deceleration valve. this is the valve that i thought was just a pressure reduction valve for the rear wheels. but apparently it isnt! it works on inersia and has to be facing fore and aft at the same angle as that in a sierra to work properly. it works by the fact a ball bearing inside moves foward as you decelerate ,allowing fluid past it to the rear brakes.
but in good tiger tradition i had followed the book! so now have to go to a scrappy and see what angle the sierra one sits at to keep mr sva happy. by the way bloke at norwich is very helpful and seems like a nice bloke . if anybody has a sierra sitting on the drive and could save me a scrappy trip could you tell me what sort of angle the valve sits at i would much appreciate it. and i hope having read this i can save you the same trouble as ive had but not to worry ill get there in the end

I suspect the angle of dangle for a lightweight like a Locost will be different from what is required for the much heavier Sierra.

There was a thread on this quite recently and I'm pretty sure the concensus was to throw the bloody thing away.

Others will confirm or ridicule what I've just said no doubt

as jonti says, that is what was recommended by members whose opinions i respect. fiat bias valve is the usual recommendation, and some have said it isnt needed on all cars.

i personally wont be using one because i have a drum brake rear end and my weight is maybe even mostly on the back wheels. time will tell though...

If you want to fit it then the attached photo may help

John
Rescued attachment brake valve.jpg

Well done JohnN, good pic! I can got about modifying mine now, i have only just fitted the damn thing!

how will mr sva know that its fitted at the correct angle, this will effect the safe operation of the brakes, so surely you will need some evidence (upon request) that it is fitted in the manner to make it function correctly, surely it cann't be a case of any angle will do, some body correct me!!!

It works on the suspension dive in the Sierra which you do not get with a locost type car. What brakes are fitted to the car? The system works without the valve in most cars or use the fiat or volky one as others do.

ive got the standard cortina front end and rear sierra drums from a 2LTR estate .mastercylinder is from same sierra and all new pipework from tiger.so the general concensus seems to be towards the fiat or vw .is that just a straight reduction valve then? and is there any particular model best suited to get one from? and thank for your help on the subject ( i was ignorant and blissful !)

quote:

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Originally posted by Peteff
It works on the suspension dive in the Sierra which you do not get with a locost type car. What brakes are fitted to the car? The system works without the valve in most cars or use the fiat or volky one as others do.

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If the valve works on enertia, when they test the brakes on a rolling road, the valve shouldn't work since the car is stationary. I phoned Tiger and they said it doesn't make any difference what direction the valve is mounted as long as the angle is about right. To me this seems to make sense !!??!!
Rescued attachment DSCF0004.JPG

First off, makes sense to me... if the valve relies on intertia during decelleration then the valve must be orientated correctly to work.

secondly, a lot of people have binned the sierra valve and fitted one off a fiat Uno. this is adjustable and seems to be a better solution.

Finally.... A PINK CHASSIS !!! that's just wrong !

but seriously - any chance of a pile of piccies in your archive.? all sources of information are extreemly helpful and you seem to have done a few things differently from your photo.... What is the steering column from? why the ally bulkhead ? etc etc

Cheers

Dave

On page 217 of Sierra Haynes manual, it shows the deceleration valve with an installation angle 'A'. I've measured this angle with a protractor and it is exactly 25 degrees.
It will have to line-up fore and aft in order for it to work!
I'm fitting the ST/Luego type pedal box with seperate master cylinders for front/rear brake circuits to my Avon c/w bias bar. I'm unsure if I need to incorporate the deceleration valve into this set-up. What have others done? (Northy etc?)

Cheers,
Andy.

Another thing worth mentioning is make sure you put the pipes in the right way round. The pipe from the m/c needs to go in the back (fat end) and the pipe to the brakes come out the front (thin end). Guess who made that mistake first time




Hope this pic from John Ferguson's Cat helps...

Cheers,
James

[Edited on 13/9/04 by supercat]

Right guys,

If you fit the Sierra device as per "the Book" and SVA at Beverly, YOU WILL FAIL!!! You have been warned. I didn't fail on this, that is what the SVA inspector that Pat (Avoneer) told us.
I think he said if it was fitted as per the Sierra it would pass.
This cam about by him passing a car that had it fitted as per "the Book", that car was involved in an accident, and he had the accident investigators asking lots of questions!! Since then, they don't pass, no questions asked.

He told me he phoned Jim, told him what I just told you, and Jim aggreed and said they were aware of this problem, and it had ben altered in the new book (allegadly Don't sue me!). I'm not sure if it was altered or not.

I think this message will have been passed onto other test centres, as the SVA inspector got backup from head office over the whole thing.

Hope that has answered your questions.

Cheers

quote:

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Originally posted by andrew.carwithen
I'm fitting the ST/Luego type pedal box with seperate master cylinders for front/rear brake circuits to my Avon c/w bias bar. I'm unsure if I need to incorporate the deceleration valve into this set-up. What have others done? (Northy etc?)

Cheers,
Andy.

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