tegwin
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| posted on 11/1/07 at 01:41 PM |
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To keep or loose the brake servo?
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
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flak monkey
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| posted on 11/1/07 at 01:42 PM |
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Loose it. Needs a bit more effort on the pedal but you have better feel.
Depends how lazy you are feeling.
David
Sera
http://www.motosera.com
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BenB
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| posted on 11/1/07 at 02:13 PM |
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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.
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JAG
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| posted on 11/1/07 at 03:40 PM |
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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.
Justin
Who is this super hero? Sarge? ...No.
Rosemary, the telephone operator? ...No.
Penry, the mild-mannered janitor? ...Could be!
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cryoman1965
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| posted on 11/1/07 at 04:09 PM |
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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
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James
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| posted on 11/1/07 at 04:30 PM |
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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
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"The fight is won or lost far away from witnesses, behind the lines, in the gym and out there on the road, long before I dance under those lights."
- Muhammad Ali
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RazMan
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| posted on 11/1/07 at 05:24 PM |
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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.
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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Catpuss
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| posted on 11/1/07 at 06:20 PM |
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quote:
Originally posted by RazMan
They are only designed to compensate for the extra ton
As in "Its a sierra based robinhood " :-)
Robinhoods take the servo as standard (at least the 2B) IIRC. I don't see why you couldn't start with it and junk it later.
If you are building a 2B, why not. The website (if still there) used to show one with servo.
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jack trolley
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| posted on 11/1/07 at 06:31 PM |
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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).
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Mark Allanson
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| posted on 11/1/07 at 09:31 PM |
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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.
If you can keep you head, whilst all others around you are losing theirs, you are not fully aware of the situation
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Marcus
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| posted on 12/1/07 at 09:03 AM |
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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]
Marcus
Because kits are for girls!!
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