JoelP
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| posted on 29/7/03 at 08:51 PM |
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Sierra master cylinder
Just a quickie. its a sierra 1.6 f plate by the way...
For sva you need seperate brake circuits for pairs of wheels, does that mean the master cylinder needs to have two 'barrels', or just
multiple outlets from one barrel/cylinder?
Also theres a device in the rear pipe that i thiink modifies the brake pressure to the rear brakes, does this have to go into the new one at the same
angle it came out at or will any position do?
thanx in advanx..!
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MK7
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| posted on 29/7/03 at 09:39 PM |
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MK supplied me with a complete brake pipe kit. In the kit there was no provision for a rear brake bias device so I'm assuming I won't need
one.
The MK kit is designed to work off the sierra master cylinder. Mine has 3 outlets, the one nearest the brake pedal goes to the rear where it is split
by way of a T piece to each rear drum.
At the front there is a pipe from each of the two remaining outlets, one to each front disk brake.
MK also supplied an in-line pressure switch which sits in the rear circuit and operates the brake lights when there is an increase in pressure, i.e.
when you apply the brakes.
Hope this helps.
Russell
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Dick Axtell
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| posted on 30/7/03 at 07:44 AM |
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quote:
Originally posted by JoelP
...does that mean the master cylinder needs to have two 'barrels', or just multiple outlets from one barrel/cylinder?
Also theres a device in the rear pipe that i thiink modifies the brake pressure to the rear brakes, does this have to go into the new one at the same
angle it came out at or will any position do?
Hi,
I used to work for Girling R&D. They produced the original brake system for the standard Sierra.
1: There are "two barrels" in the mcyl. They are merely in tandem, instead of being arranged in binocular fashion.
2: The device you are referring to is the 'G' valve, or decel-sensing rear brake pressure limiter. Please don't use this on ANY
kit-car. You'd be better off with the Mk2 Fiesta screw-in valve, for the rear circuit.
Lol
Work-in-Progress: Changed to Zetec + T9. Still trying!!
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Simon
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| posted on 30/7/03 at 08:26 AM |
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Dick,
"...to is the 'G' valve, or decel-sensing rear brake pressure limiter. Please don't use this on ANY kit-car."
Sorry to put you on the spot here but, why not?
Thanks
ATB
Simon
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James
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| posted on 30/7/03 at 09:39 AM |
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Russell,
I'm 99% sure you will need a bias valve for the SVA test (other MK builders have fitted one: Bob, Conrod Kid, Donut)- if not the brakes can lock
in the wrong order (though I can't remember which is the correct order- I'm pretty sure it's rears first then fronts a fraction
later) . Otherwise you are likely to spiiiiiin 
What you want is the bias valve from a Fiat Uno. It's adjustable with a screw in top. It'll need setting up but with any luck you can do
this in the test!
HTH,
James
P.S. Everything I've just said may well be bollox- I anticipate being corrected!
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Peteff
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| posted on 30/7/03 at 10:55 AM |
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The fronts do the work so they take most brake effort. The standard brakes don't need a valve as the master cylinder and the slave cylinder bore
take care of the brake pressure difference. The G valve doesn't come into effect until the nose of the car dives and the angle changes. In the
ideal world the brakes wouldn't lock at all, hence the invention of abs, to prevent loss of control. If you do need a pressure reduction to the
rear the Golf or Fiat valve has been recommended on here many times.
yours, Pete.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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Simon
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| posted on 30/7/03 at 11:07 AM |
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Pete,
That's good news then:-)
Cheers
Simon
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Jim
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| posted on 30/7/03 at 11:08 AM |
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We've SAV'd two Mk indy Blades and neither had a bias valve. The brakes passed the test very easily with approximately 66% braking effort
for the front wheels.
Recently taken car on track and locked wheels while braking too late for corner and the fronts locked but not the backs, which IMHO is correct because
if the backs lock wouldn't that cause a spin?
Cheers
Jim
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JoelP
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| posted on 30/7/03 at 12:37 PM |
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I think yr right, fronts first to lock. that what f1 cars do anyway....
thanx a lot for all the help fellas, that clears it up nicely! ta
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Dick Axtell
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| posted on 30/7/03 at 04:32 PM |
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'G' valve
quote:
Originally posted by Simon
"Please don't use this on ANY kit-car."
Sorry to put you on the spot here but, why not?
1: Judging from other builders comments, it seems that very few fully understand the implications behind these type of valves.
2: The installation angle is critical to the valve's correct operation.
3: How the hell can you ever test it effectively? (I got our Japanese associates to do this).
4: If you brake sharply, you'll beat the valve, and then you get full pressure at the rear brakes anyway.
5: Test results show that the cut-off pressure can vary widely, even under controlled conditions (re: 2 above).
6: The Fiesta screw-in valve is a more suitable (& lighter) piece of kit.
Check out the attached pic.
 
Rescued attachment Dicks.jpg
Work-in-Progress: Changed to Zetec + T9. Still trying!!
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