nick baker
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| posted on 4/2/05 at 12:23 PM |
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Hydraulic Handbrake + Mechanical Parking Brake
A few questions....
1. Hydraulic handbrakes won't pass the SVA will they? 
2. Mechanical handbrakes... Is it ok for them to work on the front wheels?
3. Has anyone yet coupled hydraulic handbrake in tandem with the clutch for autotesting purposes? (lock rear wheels and dis-engage clutch
simutaniously and visa-versa)
time for more coffee I think...
N 
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flak monkey
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| posted on 4/2/05 at 12:34 PM |
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I can answer #1... a hydraulic handbrake will NOT pass sva AFAIK
Sera
http://www.motosera.com
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David Jenkins
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| posted on 4/2/05 at 12:51 PM |
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I can answer #2 (indirectly)... the Citroen BX had its handbrake on the front wheels - they had an extra device (disc or drum, not sure which) to do
the job.
I remember being entertained by a boy racer trying to do handbrake turns in a BX, and failing...
David
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nick baker
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| posted on 4/2/05 at 12:51 PM |
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doesn't surprise me
leaks etc.... bummer. (not even if I promised to carry chocks with me?? LOL)
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alfasudsprint
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| posted on 4/2/05 at 12:52 PM |
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Alfa sud series had inboard front discs with handbrake too. Guess ok for SVA... Pain in the rear to work on!
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DaveFJ
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| posted on 4/2/05 at 01:05 PM |
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Land rovers used to have the parking brake on the main rear drive shaft (may still - dunno)
Dave
"In Support of Help the Heroes" - Always
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DarrenW
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| posted on 4/2/05 at 03:15 PM |
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Im sure that ive seen a new development that incorporates a mechanical and hydraulic handbrake in one unit. It would have been in one of the Ford mags
or motoring news.
AFAIK the issue with hydraulic handbrake for road is
a. You cant lock them on for parking,
b. the SVA requires a handbrake on that does not rely on the main hydraulic system, hence mechanical. Maybe something to do with fail safe in case
problem on hydraulic circuit.
Its worth reading the manual carefully, its quite detailed.
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britishtrident
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| posted on 4/2/05 at 03:49 PM |
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If a handbrake operates on the front wheels it must operate the brake lights.
[Edited on 4/2/05 by britishtrident]
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David Jenkins
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| posted on 4/2/05 at 03:55 PM |
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It didn't on my Citroen BX...
DJ
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britishtrident
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| posted on 4/2/05 at 05:19 PM |
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quote:
Originally posted by David Jenkins
It didn't on my Citroen BX...
DJ
Road Traffic act/construction and use requirement --- applies any brake working on front wheels.
[Edited on 4/2/05 by britishtrident]
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NigeEss
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| posted on 4/2/05 at 05:40 PM |
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There is a big problem with the front handbrake setup.
As your front brakes cool and contract the handbrake can lose grip. Need I state the result ?
Some folk may remember this being an issue shortly after the Citroen Xantia was launched and
I actually know some one who came out to find his across the road in a neighbours hedge.
And if you consider how hot a 7's brakes get, after all, what do we build them for ????
Land Rovers still have theirs on the back of the gearbox, known as a Transmission Brake and allows all four wheels to be held.
Time is an illusion. Lunchtime doubly so.................Douglas Adams.
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NigeEss
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| posted on 4/2/05 at 05:44 PM |
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ps
I knew of a rally car with a hydraulic handbrake and the mechanical one was a screwdriver stuck in the prop UJ through a hole in the tunnel .
Passed the MOT ( 5 or 6 years ago now )but doubt very much if it'd pass the SVA !!
Time is an illusion. Lunchtime doubly so.................Douglas Adams.
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flak monkey
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| posted on 4/2/05 at 05:47 PM |
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quote:
Originally posted by Nige_S
ps
I knew of a rally car with a hydraulic handbrake and the mechanical one was a screwdriver stuck in the prop UJ through a hole in the tunnel .
Passed the MOT ( 5 or 6 years ago now )but doubt very much if it'd pass the SVA !!
There are exceptions for rally cars (not sure about the screwdriver  ). They are allowed hydraulic hand brakes. AFAIK they are not SVA'd but
they do have to have an MOT. Ergo a hydraulic handbrake should pass MOT but not SVA... Could be wrong though.
David
Sera
http://www.motosera.com
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David Jenkins
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| posted on 4/2/05 at 05:51 PM |
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quote:
Originally posted by Nige_S
There is a big problem with the front handbrake setup.
As your front brakes cool and contract the handbrake can lose grip. Need I state the result ?
In my BX the handbrake device was separate from the conventional brakes, so wouldn't have got hot in normal use. Maybe they'd changed
things for the Xantia!
David
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NigeEss
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| posted on 4/2/05 at 06:55 PM |
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re BX separate mech
Still operates on the same (hot) disc though doesn't it ?
Time is an illusion. Lunchtime doubly so.................Douglas Adams.
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JoelP
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| posted on 4/2/05 at 07:12 PM |
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i tried handbraking my zantia round several corners before i worked out what was going wrong! much head scratching at the time... 
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nick baker
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| posted on 4/2/05 at 07:59 PM |
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Thanks for the input guys.
Given that I have the ability to include a spring of some sort into the system (to maintaing cable tension, I may yet have an "under the
dash" parking brake that operates on the front disks.
Hydraulic handbrakes's a must though.. never had one... and rather fancy the idea.
Cheers,
N
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David Jenkins
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| posted on 4/2/05 at 09:53 PM |
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quote:
Originally posted by Nige_S
re BX separate mech
Still operates on the same (hot) disc though doesn't it ?
I humbly take it all back!
I found my old BX Haynes manual in the garage this evening - as you say, it's a separate mechanism on the same disc. Doesn't have a brake
light switch, though...
DJ
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britishtrident
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| posted on 5/2/05 at 09:10 AM |
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Hydraulic parking brtakes\aren't allowed under the Construction and Use regs. Traffic police are quite well up this aspect of the law due the
misuse of line locks by the cruising fraternity of nutters.
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Bob C
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| posted on 5/2/05 at 03:33 PM |
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My kid bro's rallyt avenger had a hydraulic handbrake & started its misbehaviour by knocking down one of mum's trees, but moved up to
disappearing from outside a off license with expensive consequences...
I used to own an alfa 1750 (twin cam wet liner engine ended up in my elan) This had discs at the back but the handbrake was on a drum hidden in the
middle of the disc! IIRC the volvo (245?) estate had the same double back brake system.
Bob C
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britishtrident
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| posted on 5/2/05 at 04:29 PM |
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quote:
Originally posted by Bob C
My kid bro's rallyt avenger had a hydraulic handbrake & started its misbehaviour by knocking down one of mum's trees, but moved up to
disappearing from outside a off license with expensive consequences...
I used to own an alfa 1750 (twin cam wet liner engine ended up in my elan) This had discs at the back but the handbrake was on a drum hidden in the
middle of the disc! IIRC the volvo (245?) estate had the same double back brake system.
Bob C
As did he Saab 99 /90/900 -- used cast iron brake shoes worked a treat.
[Edited on 5/2/05 by britishtrident]
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Marcus
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| posted on 5/2/05 at 05:36 PM |
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There are no special rules regarding rally car handbrakes. AND they do need MOT to compete. Most use a hydraulic cylinder acting on the original lever
with the ratchet mechanism turned round (so you have to press button in to lock it). They also need cables, although most run them slack. A few
competitors have been caught out by this.
Marcus
Marcus
Because kits are for girls!!
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NS Dev
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| posted on 6/2/05 at 09:49 AM |
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Marcus, that's EXACTLY what we've done in the past on rally cars. The secret is to make the cable just tight enough that it appears to be
doing the work!!! We just drilled the pad backplates and threaded the inner cable through and put a nipple on the end! The cable then squeezed the
pads together a bit. Once set up the hydraulics did the work and the cable looked like it did! With the ratchet reversed, the job was a goodun and we
never had another scrutineering problem. None of that is to say it will pass SVA! I certainly wouldn't try it. Get it through the test with some
Sierra rear handbrake calipers on and then change it afterwards!
The thing to bear in mind is that you are not necessarily after a hydraulic handbrake, just one powerful enough to lock the wheels. The solution I
used on my RWD Pug 205 was subaru 4x4 pickup front calipers on the rear. These have a front handbrake, and being a pickup, are pretty big calipers. I
just used the mechanical handbrake, this had no bother locking the wheels!!
Andy Burton's rally car used an interesting setup, he had a pushbike brake lever on the top of the hydraulic handbrake lever, which was linked
to the actuator for a clutch mechanism (someone told me it was a tractor PTO clutch which is entrirely possible with Andy!!) on the rear diff. This
disconnected the drive to the rear of the car at the same time as locking the wheels with the handbrake, but still kept the drive to the front of the
(4wd) car, thus making forestry hairpins very fast indeed!!
I also know of a rally car that used the "screwdriver in the UJ technique"!!! Definitely NOT an MOT pass!!!
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DarrenW
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| posted on 7/2/05 at 10:58 AM |
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I looked through the Ford mags at the weekend. Prepfab do a kit to add cables to a hydraulic handbrake set-up.
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