What are the pros and cons of removing the brake servo? Its a sierra based robinhood disks front and rear...

And should I replace the enertia bias valve thing to a manually adjustable bias valve to make the full use of the rear brakes?

(I havnt done SVA yet!)

Thanks Guys

Dunc

Loose it. Needs a bit more effort on the pedal but you have better feel.

Depends how lazy you are feeling.

David

Locosts are pretty light. I'd say loose it. It takes a few minutes to get used to it but hey. The only time I'd have a servo is if the car was way heavy or if I was letting lots of people drive it who weren't used to non-servo'd cars (e.g. demonstrator). Then I might fit one to avoid people piling into the back of other cars @ traffic lights.

I work for a Tier 1 automotive supplier of braking systems and I have a servo on my car

As for the G-Valve (inertia bias valve thingy) dump it.

It has to be fitted at precisely the right angle to work properly and the angle for a Locost will be very different to the original Sierra installation angle. If you need a bias valve get an aftermarket one.

I would dump the Servo.

As for the Inertia valve. My Pinto powered MK Indy weights 605kg. It needed an Inertia valve to stop the rear wheels locking up b4 the front. (sva fail point).

I built the car without and on testing 2 days before sva i had to fit the sierra valve to fix the prob. You can fit the sierra valve on an adjustable mount which you can then tweek to suit.
My car has rear drums.

People have fitted adjustable valves and will be along to tell of things to be aware of if fitting such an item.

HTH

Nige

I used a Fiat Uno brake bias valve. New about 20quid.

It's adjustable by regulating the movement of the pin that sticks out the top. So the valve is mounted to the chassis and a bracket holds a threaded rod above it. The rod can be wound up or down to change the amount the valve pin is able to move up on braking.

I believe adrustables are a bit dubious for SVA as it needs to be locked for the test! So I left the threaded rod out for the test (as did Bob) and this passed (hey, it's not adjustable without the rod! ).

HTH,
James

No way is a servo needed on such a light car. They are only designed to compensate for the extra ton that most tin tops have to carry around.

quote:

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Originally posted by RazMan
They are only designed to compensate for the extra ton

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Servos are for girls!
Dave Andrew's web page has instructions for making an adjustable brake-bias
device (based on a Mini? one).

Definately no servo, my car is a portly 700kgs and the no servo'd cortina system is superb. A servo would make the brakes feel very on or off, but without you can even fel the road texture under heavy braking.

I have a fiat uno bias valve, but it is set to off all the time as it is not required with rear drums.

Using the non cast sierra MC, you can attach the MC directly to the sierra pedal box, saving a fortune and making the job really easy.

To tell the other side of the story - our first car has a servo fitted and it works really well with plenty of feel. The reason we fitted it was a very short brake pedal. The driver has relatively small feet, and to make it comfortable and floor mounted, it had to be short. Car 2 has no servo and a longer pedal. Both are very good on the brakes and have drums on the rear.

[Edited on 12/1/07 by Marcus]