bass
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| posted on 28/4/02 at 06:17 PM |
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hand brake
can i use a hydraulic hand brake , and will it pass the test?
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stephen_gusterson
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| posted on 28/4/02 at 07:34 PM |
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quote:
can i use a hydraulic hand brake , and will it pass the test?
Im too lasy to wade through my (legal) sva copy, but im pretty sure its
NO.
ATB
Steve
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theconrodkid
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| posted on 29/4/02 at 05:30 PM |
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the answer is no ,next question please 
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bass
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| posted on 1/5/02 at 07:37 PM |
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next question to conrodkid, on which page in the sva book does it say i cant use a hydro. hand brake?
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bob
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| posted on 1/5/02 at 08:38 PM |
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Bass
After a little reading of the manual.
It doesnt say yes or no,but it does say it must be controled independant of the service brake.
So i presume this means you would need a seperate master cylinder of which the fluid reservoir must be accessible.
Then there would be another warning light for fluid level.
Seems like a lot of hard work when the cable version will do,but i suppose it depends on the braking system you want to use.
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Dunc
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| posted on 2/5/02 at 08:46 AM |
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Bob is correct but why would you want to use a hydraulic handbrake, what benefits would it have over the cable. Better feel? Hmmm.
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David Jenkins
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| posted on 2/5/02 at 10:33 AM |
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quote:
Bob is correct but why would you want to use a hydraulic handbrake, what benefits would it have over the cable. Better feel? Hmmm.
Easier installation? Possibly...
I thought the reason why hydraulic handbrakes aren't used outside of competition cars was the risk that pressure would be lost over a period of time
(past the seals, easing of flexible pipes, etc) and you might find your car rolling down the road after parking overnight!
This is not a concern in race/rally saloons, nor are "easing" flexible pipes on an ordinary car's main brakes (you just push harder).
As Bob said, you would have to have a totally separate hydraulic fluid supply, as the SVA manual does say that every car must have a completely
independant secondary braking system (in case the main one fails). Yanking on the handbrake at speed isn't funny, but it may be the only option if
the main brakes have gone!
No matter what it says in the SVA manual, if the examiner considers something to be unsafe then you will fail - unfair perhaps, but true.
David
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theconrodkid
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| posted on 2/5/02 at 01:13 PM |
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Re Bass,s reply read construction and use.
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eccles
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| posted on 2/5/02 at 06:02 PM |
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Is this the bit you mean?
"using a control which is independent of the service brake, and capable once applied of being maintained in the 'on' position solely by a
mechanical means."
Alan
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theconrodkid
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 posted on 2/5/02 at 06:35 PM |
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You got it mate!
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bass
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| posted on 2/5/02 at 08:16 PM |
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how can it be com. independant if i use the same shoes/drums as main b/system? thats the control of the h/brake, not how it works.
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Dunc
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| posted on 2/5/02 at 09:11 PM |
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Where do you stop? Do you go to the wheel and the tyre as well we use your theory, even the vehicles that have both pads and shoes at the rear use the
same rotor, wheel and tyre. The SVA talks about the mechanical means of applying the brakes, if you look at the drum shoe setup or even the disc setup
for dual brakes you will notice that they operate independantly of each other. The slave cylinder at the top pushes against a solid bit at the base of
the shoes and the handbrake works against the cable, normally at the bottom, and an auto adjusting bar 2/3rds the way up.
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bob
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| posted on 2/5/02 at 10:06 PM |
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Old jags (XJ6/12) have a completely seperate handbrake caliper on the inboard discs,but thats the only car i can think of.
BASS,do you have a preference to hydro handbrake for a reason?
Looks like it could be hard work,but it is a thought.
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bass
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| posted on 2/5/02 at 10:33 PM |
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bob , it would simple to put a m/cylender in the line to work the h/brake.
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bass
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| posted on 2/5/02 at 11:02 PM |
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to bob , so did rover2000,3500, mk 2 jags and fords
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bass
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| posted on 2/5/02 at 11:12 PM |
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austin A 35 had a hand and foot brake that worked of the same circuit
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eccles
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| posted on 3/5/02 at 05:54 AM |
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So did the Austin 7. And it had friction dampers. Those were the days. I can remember when .....
Alan
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bob
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| posted on 3/5/02 at 07:01 AM |
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I think the hydro hand brake is a good idea but,the problem is the wording of the manual.
The mechanism that operates the hand brake must be seperate from the service brake.
I think this means you cant put a m/c in line,and must run a seperate system.
In the end the best way around this is to contact your local SVA test centre,as we are only summising.
I think i'll stick with a cable and keep it simple 
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Dunc
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| posted on 3/5/02 at 08:41 AM |
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You can't have another master cylinder in the line without affecting foot brake performance. You would need a non return valve which defeats the
purpose and a solution would over complicate the idea.
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bob
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| posted on 3/5/02 at 08:48 AM |
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Dunc
You hit the nail right on the head there mate.
Keep it simple,and cheap to maintain
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JohnFol
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| posted on 3/5/02 at 09:07 AM |
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Can someone explain something to me. On a std Ford rear hub, the foot brake pressure is transfered via fluid to a wheel cylinder (that expands to push
shoes blah blah .. )
The hand brake uses a cable and leaver to push the shoe.
If you use fluid transfer in place of cable, how do you actuate the leaver behind the shoe?
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Dunc
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| posted on 3/5/02 at 09:31 AM |
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You wouldn't use the lever at all, you would have a another wheel cylinder at the bottom instead for use by the handbrake only. When the hanbrake is
off though the bottom of the shoes would need to act against a solid bar like on standard so that the foot brake won't feel spongy at best or non
existant at worst. This would be because if you just had it acting on the handbrake wheel cylinder, applying the footbrake would force the fluid up
the handbrake line, through the hole in the master cylinder and into the resevoir. A bit like when your changing you brake pads and you force the
cylinder back into the caliper with a g clamp and the fluid that you topped up last week starts to wee out of the top of the lid.
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JohnFol
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| posted on 3/5/02 at 09:53 AM |
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So in theory you could have one top and bottom operated by the foot brake to give better braking, at the expense of pedal travel .. .
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Dunc
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| posted on 3/5/02 at 11:21 AM |
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In theory yes, but in theory you can also balance a cube on one corner on top of a ball that's sitting on the point of a pyramid. But pedal travel
doesn't have to suffer as a result if you use 2 smaller diameter wheel cylinders and or a larger diameter master cylinder. You might have noticed
when driving a drum rear car that if you pull the handbrake on just before you brake the pedal feels firmer with less travel. That would be similar to
what you're asking but where would you put the handbrake?
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bass
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| posted on 3/5/02 at 08:29 PM |
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no you havent got it. you put the m/c in line like they do when they convert to invalid cars. the f/brake pressure goes through the h/brake m/c, no
tank or one way valves.
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