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unequal length handbrake cables
blakep82 - 12/10/09 at 10:41 AM

for various reasons, i need a handbrake system with 2 seperate cables. one will need to be about twice the length of the other.

am i going to come across problems with one stretching more than the other, and unbalanced braking efficiency etc? difficult to adjust etc?

I've got a rover handbrake lever with a compensator and fitment for 2 cables. the lever will go to the right of the seat, so the right rear wheel is only about 1.5m away, but the left rear is about 3m (1.5m across the back of the cab, and them 1.5m to the back axle)

or should i make them the same length and find a really long way round to route the 'short' one? i'd prefer to keep it neat and have them go direct to where they're going if posible


Mr Whippy - 12/10/09 at 10:49 AM

You could loop the cable that would be shorter round a pulley to increase the length. Pulleys are quite common in production cars and like you say it’s quite likely their will be an imbalance in the rear brakes when applied. Though tbh aren’t you meant to be stopped anyway before applying the handbrake?

Alternatively you could drill a hole further down on the handbrake link so the longer cable is pulled further than the short one to compensate for the extra stretching. Just how much this is I don't know.

I'd love to see why you have one cable longer than the other, are you doing something weird?

[Edited on 12/10/09 by Mr Whippy]


tegwin - 12/10/09 at 10:49 AM

Cant see an issue having two different length cables...

If each one has a sepperate threaded adjuster on the end you could re-tention them to get the best balance


Mr Whippy - 12/10/09 at 10:57 AM

Looking at the back end of your car, it just looks like a standard live axle, why is this needing something so different to a cortina handbrake setup etc?


blakep82 - 12/10/09 at 11:02 AM

Description
Description


a very rough diagram.

whats the cortina set up? isn't that one cable with the handbrake in the middle?

its not a standard axle, but yes it is a live axle. its got sierra calipers. the back end of the truck is very long. i did buy a astra estate cable, and even that wasn't long enough for half of it to reach the back (but thats a single cable setup too)


Mr Whippy - 12/10/09 at 11:13 AM

if you used cables round pulleys you could do something like this? Rescued attachment 7handbrake.jpg
Rescued attachment 7handbrake.jpg


blakep82 - 12/10/09 at 11:24 AM

hmm, yeah, could sort out something like that. i see you put all the pulleys in there, but if the cables all go through an inner cable they won't be needed will they? just need to secure it to the chassis, and theres plenty of tubes running around there


nitram38 - 12/10/09 at 11:31 AM

Simple solution is to run a single cable from the handbrake to a yoke/pully which connects to the two equal length cables.
That way, all forces are equal.
MOT's will check for handbrake imbalance and cause a fail if you don't get this right!


Mr Whippy - 12/10/09 at 11:47 AM

quote:
Originally posted by blakep82
hmm, yeah, could sort out something like that. i see you put all the pulleys in there, but if the cables all go through an inner cable they won't be needed will they? just need to secure it to the chassis, and theres plenty of tubes running around there


no there's no inner cable, you have two separate cables, the pulley next to the handbrake is a double one. Its all rather like trailer brakes, have a look on the web for the parts they use and you'll see heaps of fittings you could adapt.


kj - 12/10/09 at 12:41 PM

What about a morris marina or ital cable set up like the diagram, or i have a pair of inner allegro cables i could let you have. Rescued attachment handbrak.JPG
Rescued attachment handbrak.JPG


Mr Whippy - 12/10/09 at 01:30 PM

^ cool


britishtrident - 12/10/09 at 03:22 PM

Use a Morris Ital hanbrake cable complete -- no alterations required but you might need to rotate the brake back plates and re-drill them to clear your panhard rod or watts linkage.


britishtrident - 12/10/09 at 07:48 PM

I should also add the Ital/late Marina doesn't need anything fancy fittings made up --on the Ital it was just held to the axle with a single cable tie.

We used them as straight replacements for the Escort cable -- used to chuck away the solid pull rod and the horrid rubber flap hinge thingy. Doing this mod did wonders for the handbrake efficiency on one wheel on the MK1/MK2 Escort which was a very common MOT failure on these cars.


Ninehigh - 12/10/09 at 09:44 PM

Why not have the handbrake in the middle where it should be?


blakep82 - 13/10/09 at 12:12 AM

can't do the ital/marina thing as the calipers are off a sierra, and the way they're mounted the cables need to pull forward (photos tomorrow) thanks for the offer though KJ

BT, its disc brakes on the rear, so no back plates for rotating or re-drilling

ninehigh, there are no chassis tubes on the top of the tunnel, and the tunnel is just 0.5mm sheet steel. so not stong enough. so it'll be bolted to the floor


I'll get some photos tomorrow that will hopefully explain it better.

though, if i've got long enough adjusters, i can't see that the difference in stretch in the cables will be more than about say 5mm?


you can maybe see in this photo why the tunnel can't have the lever mounted to it

[Edited on 13/10/09 by blakep82]


blakep82 - 14/10/09 at 12:27 PM

ok, heres a photo of the calipers
Description
Description


and you see it has to pull to the front of the car.

as tegwin says tho, as long as i've got really long adjusters, it shouldn't be a problem