View Full Version : Brake decelleration valve

David Horsnell
13-09-03, 08:13 AM
I've recently road tested my Sumo and found the brakes very spongy and the rears are not at all effective.

I've fitted a decelleration valve from a Sierra (rest of running gear is Granada) but cannot remember which way round to connect the valve to the front and rear pipes.

The valve is mounted at the correct angle to the horizontal with the narrow end facing forwards.

Should the rear brake pipe outlet be fitted to the narrow end of the valve or the fatter end ?

All help very gratefully received, when you all get back from Donnington !!!!


Mike H
13-09-03, 08:18 PM

Steve's web site has a picy....http://www.softstar.co.uk/cobra/may.htm that may help you.

I have a valve fitted from a Granada and have fitted it similarly.


David Horsnell
13-09-03, 08:29 PM
Thanks, from the picture it would appear that the pipe thats comes out of the decelleration valve at the front(the small diameter end) goes to the rear brake pipes.

This is what I have since thought should happen, sadly not the way I've plumbed it in at the moment.

Thanks for your help, better to change now than after it's failed the SVA.

Another job for tomorrow, after Donnington.



Keith S
14-09-03, 10:31 AM
i recently completed my Sumo Mk3 RV8 with granada running gear and did not need to use one of these valves. I asked Tony Holmes about whether it was necessary to have one and he said that you only need this if you use Sierra running gear. The brakes on my car are very good and it passed both the MOT and the SVA first time.
If your brakes are spongy then you must have air in them. Are the caliper pistons moving freely?. If theese are Ok and you have fitted new discs and pads (as I did) they will take a fair bit of bedding in.
Good luck.

15-09-03, 09:54 AM

I'd agree with you. I have Sierra running gear on mine and my brakes are very firm, but without the decelarting valve fitted, the rear brakes would lock up before the front's almost every time. With it fitted, the fronts lock first time every time.

Tony B

Paul B
17-09-03, 12:49 PM
Ironically, I found just the opposite. I have the Sierra running gear and was told by Tony that the decelartion valve was un-necessary.

It passed the SVA and MOT first time.

Which is correct ???? Don't know.