Handbrake- has anyone tried this?

[The Veg]

Thinking about how useless our handbrakes usually are, I had an idea and wonder if anybody has tried this. Would it be any better to eliminate the tree and rods altogether and just run cable all the way to the calipers, as in more modern cars? I've seen more than one setup for this modern cars, either splitting the cable into two running directly to the calipers or using one variation or another of a centre-pull on a cable between two calipers.

Even if it works, I know that with the postage-stamp pads we've got it won't be a revolution in what the handbrake does, but the idea is to make them work at all, at least enough that parking in gear and carrying a chock aren't the only lines of defence against my car rolling away.

So has anybody tried it and was the result worth the effort?

[Slowtus]

As you say, with the swept area or lack of it...

I did convert one of my Plus 2s back in the day to hydraulic but it was no more efficient than the stock system though I suspect my choice of components was incorrect.

The 'drifters' seem to like them but again, swept area for them, our need is simpler here.

Edit, for 'swept' read contact.

Pad material and force applied as well - and other stuff I have long forgotten about

[mbell]

So switching to a cable system will remove any slop due to play in the tree/rods. But it won't address any slop play in the hand brake mechanism on the calipers. So whether it will improve depends on what is causing the issue with your car.

It is quite possible and not difficult to remove the slop from the tree/rods. The holes normally wear out of round, so a little weld/re-enforcement and drill can fix those. You can also easily make up adjustable rods that can help remove slack.

I've done this on my car and it seems to work ok without addressing the calipers. The adjustable rods cost me about $15 in parts per side and the tree was a hour or so of welding/drilling. Which is likely much quicker/easier than figuring out a new cable system. (Ignoring getting the tree out...)

[snowyelan]

The swept area isn't really relevant, nor are the pad sizes. The 3 primary changes you can make are to increase the pad distance from the axle (not really feasible due to the disc size), increase the pad CoF, or increase the clamping force.

Thinking about this further I wonder if a geometry change on the tree would help. From what I recall the tree rod arms are 90 degrees to the cable arm which results in a relatively linear travel ratio. Altering the angle could potentially change things so there is large travel/low force at the beginning of the motion which transitions to small travel/high force.

[Slowtus]

The swept area isn't really relevant, nor are the pad sizes.

So a 1mmx1mm pad will work?

[snowyelan]

Yes, as long as the materials used are strong enough not to yield*.

My point, which I have apparently failed to convey properly, is that the pad and rotor (swept area) size don't matter for holding capabilities. They are sized to balance lifespan (wear) heat dissipation, and cost. If better holding performance is required for the parking brake bigger pads won't help. A good example of this is with modern rear disc brakes that use an integrated small drum style emergency brake within the rotor. The diameter of the shoe assembly is in the 5-6" range and maybe an inch wide, but it is more than capable of locking up the tires. They can do this because the forces and material CoF have been optimised to work within the space confines. Likely the designer just upped the force and used a common friction material.

I'm suggesting that a geometry change to the tree could help to increase the clamping force, which will help with the brake holding capability. The tree has a limited amount of space to work in which I would need to explore.

* If you're going to use it as an emergency brake then their lifespan would be quite limited, probably to a distance measured in feet. As a pure parking brake 1mm x 1mm would be fine.

[elanman999]

Lots of good info above, here are some things that I have found useful.

The hand brake can be made to work OK as a parking brake but does need to be setup correctly.

Have you got the latest version of tree? The cable pull arm was longer and a sort of S shape, The pull rod arms may also be at a different angle.

The pull rods do not need to be adjustable but do need to be the correct length for the version of tree you are using. If having the rods adjustable is the only way to make them the correct length then fine. The rods MUST be straight, if new they should be.

You do not need that silly extra spring, that lots of people add to keep the calipers apart, you need the centralising strips to be fitted and adjusted correctly. And that is a total PITA to do but when correct it will be OK for many many miles.

Do check the discs for run out, the book says max of .004in (IIRC) but try to get to .003 or better. I shim them if needed. It means you can run the pads nearer to the disc without rubbing and it also helps with the foot brake.

Play in the system is not all bad, seized pivots etc are much much worse.
YMMV,
Cheers
John.

[HCA]

Has anyone ever considered the possibility of an electric handbrake?

[nmauduit]

Has anyone ever considered the possibility of an electric handbrake?

I'm sure there are such implementations out there, but if you are considering passing the TÜV or the French equivalent to maintain you legal access to corresponding public roads, you'll be reminded that the handbrake is coined "emergency brake" and that a change in operation principle would require a dedicated certification...

[andyelan]

Hi Everyone

Set up correctly, I have no problems at all with the standard set up

Regards
Andy

[ericbushby]

As Andy says above, I am satisfied with the handbrake as it is.
I bought the Sue Miller version of the cable which is two inches shorter than standard and the adjustable rods also from Sue. I stripped down, cleaned and lubricated everything.
The cable arm of the tree is approximately at right angle to the cable when engaging to provide maximum leverage.
I have not tested the handbrake on a slope because I have had no need to, as it just works!
Eric in Burnley
1967 S3SE DHC

[reb53]

Has anyone ever considered the possibility of an electric handbrake?

This could be a problem, especially with the Elans propensity for poor charging if you're still running a dynamo !

However, I agree with Andy above as I've never had a problem with it working ok.
Brazed up and reamed out the flogged out linkage holes about 30 years ago, as well as simply brass riveting some new friction material on. Also, sorry...., some springs to stop the rattle.
Haven't touched it since and it still manages its MOT fine.

Ralph.

[Quart Meg Miles]

As mbell describes, the tree holes all wear pear shaped.

In 1980, at 160,000 miles, I over-drilled all the holes in the T connections, without adding weld, and turned up some pins with about 0.001 inches clearance. After assembly I smothered it all in grease. I had previously done something similar at the rod end connections to the caliper levers, which are more accessible.

Since then, after 43 years and another 130,000 miles, it has worked perfectly on all inclines and could be used in an emergency. I have done nothing except maintain the pad clearance with the standard click mechanism, changed the pads when worn out and occasionally made sure the calipers were free. The handbrake pull and cable are the originals and the T is the original pattern.

[Andy8421]

You do not need that silly extra spring, that lots of people add to keep the calipers apart, you need the centralising strips to be fitted and adjusted correctly. And that is a total PITA to do but when correct it will be OK for many many miles.

John,

I think the 'silly extra spring' is usually added to reduce the rattle every time the car goes over a bump. That is certainly why I added it, and while it hasn't eliminated the rattle completely, it has certainly improved things.

[elanman999]

Andy,
Thanks for the explanation.
I find that if the centralising strips are “adjusted” so that they hold the pads off the disc and are under some tension then the pads and callipers are not loose enough to rattle.

Cheers
John.