Lotus Elan

Re engineering the handbrake

PostPost by: jono » Thu Mar 12, 2009 11:22 am

Short of the Spyder centre mounted handbrake has anyone though of a way to improve the handbrake operation?

I have the bodyshell off my Spyder chassis + 2 and now I can see everything I can see how naff that handbrake tree mechanism is. My Caterham had, in some ways, a similar chassis and layout and used a modern (Rover I think) handbrake cable which was split into a single loop at the back and actuated by a pulley mounted on the underside of the central chassis spine controlled via a single wire from an underdash mounted handbrake. It seemed to work quite well when properly adjusted.

I was thinking of a lever on the passenger side of the tunnel and mounted through to one of the rails on the Spyder spaceframe and opertaing the brake by this means using modern spiral sleeved cables.

Has anyone pursued this or other options or have any other suggestions?

I believe in improving the car wherever possible with sympathetic and reversible mods and the handbrake seems to be one area which deserves some thought.
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PostPost by: jimj » Thu Mar 12, 2009 12:35 pm

Coincidentally, this very day I`ve been looking for a localish scrap yard that racks up spares so I can go and look at various handbrake levers. I reckon a thin one will just squeeze down the side of the seat and bolt to the flange on the chassis, the cable routing through the backbone of the chassis to the tree, halving the length of cable. I think this would improve the leverage and be reachable wearing static seat belts.
I had 4 Elans in the 60s/70s and never used the handbrake but it is inconvenient and my wife is loathe to drive the Elan for this very reason.
Maybe a twin cable sytem via pulleys direct to the calipers would be even better. Cliveyboy, owsaboutit?
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PostPost by: Frank Howard » Thu Mar 12, 2009 4:00 pm

jimj wrote:I reckon a thin one will just squeeze down the side of the seat and bolt to the flange on the chassis

As I recall, someone on this list installed a Jaguar handbrake lever because it was thin. Even included a picture of it.
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PostPost by: jeff jackson » Thu Mar 12, 2009 7:11 pm

One thing I love about my plus 2 is the wide transmission tunnel, and the lack of handbrake on top of it. I like the Sypder Zetec conversion, but one thing I don't like is the big fat escort handbrake.
I Have thought about an alternative many times, and I have seen a really short stubby handbrake lever as fitted to TVR's.
Maybe this could be a better alternative?
Personally I don't have a problem with the umbrella Handbrake, although my wife seems incapable of operating it, " because it's on the wrong side"
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PostPost by: jono » Fri Mar 13, 2009 9:33 am

The MGB or sprite lever seems to be the obvious choice, especially the early chrome version, as this is a side mounted lever (tunnel on driver side).

I think I will obtain one of these and see what can be done.

It would be nice to come up with an improvement to the original design which also 'looks right'. I agree that the Spyder version does not look right and also clutters up the nice tunnel top.
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PostPost by: john.p.clegg » Fri Mar 13, 2009 11:54 am

Could not one of our Geometrists have a look at the design and suggest lengthning/shortening levers,positioning arcs at tangents etc etc

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PostPost by: gerrym » Fri Mar 13, 2009 12:37 pm

There's a couple of different aspects to the re-engineering tthat need to be considered:-

The original Lotus system uses straight pull lever (no mechanical advantage), with mechanical advantage gained via the handbrake tree and the operating levers on the calipers themselves. The handbrake tree is very light and probably only good for the maximum straight linear pull that a strong man (or a strong Elan scuttle) can generate.

The Spyder system uses Ford handbrake calipers and cables all the way to the calipers. There is no handbrake tree. Mechanical advantage is gained through the handbrake lever and the Ford calipers

A hybrid system (centrally mounted lever) would have some mechanical advantage at the lever, some at the tree and some at the calipers. For the system to work overall, the amount of cable pull at the handbrake lever would need to be compatible with the tree, plus the forces generated by the handbrake lever might be greater than the tree could handle (consider the offset between input "lever arm" on the tree and the two "output" arms for the actuating rods).

Regards

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PostPost by: Frank Howard » Fri Mar 13, 2009 2:01 pm

Or you could eliminate Spinich from your diet before you set the handbrake. :wink:
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PostPost by: Matt » Thu Mar 19, 2009 7:18 pm

When I restored my +2 I re-made the handbrake tree out of stainless steel and it's link rods I added three extra springs one on each caliper adjuster and the other on the tree itself, I also used copper bushes between the tree and chassis and spaced the nut out so I could remove it in the future.
After five years I have done alot of miles in the car and have had no problems with the handbrake, I haven't even need to adjust them up for the MOT
Hope this Helps

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PostPost by: jimj » Mon Mar 23, 2009 11:07 am

Well, I`ve done it. I bought a slimish neat conventional handbrake lever from ebay and removed the extraneous bracketry etc. There was still no way it would fit down the side of the seat so a bit of 1" angle and it bolted through the floor to the chassis flange just ahead of the seat where the chassis splays. I needed to make up some spacers for between the body floor and the chassis to avoid crushing the fibreglass. I can now just reach it though positioning it so tight up against the transmission tunnel so it`s not in the way makes it awkward to grasp.
The next problem was that the quadrant on such a lever only pulls the cable a short distance compared with the amount of movement required to rotate the handbrake tree. I contrived a bracket about 4" long which bolts to the differential torque rod stud, suitably angled so as to not foul the chassis. The cable from the hand brake lever attaches low down on the bracket and another cable from the handbrake tree, with an adjustable swage, attaches to the top of the bracket thereby gearing up the movement.
This was all done on an S3 Elan threading the cable through the chassis backbone as normal, but I imagine it would work just as well on a +2.
I`ve left the original handbrake and cable, taped to the wishbone, in place so the whole thing can be easily reversed leaving just 3 holes in the floor under the carpet. It actually took a lot longer to do than it sounds, with much measuring and head scratching, but it works brilliantly.
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PostPost by: Jas » Tue Mar 24, 2009 8:27 am

Here is a picture of Mopho's Jaguar E-type handbrake.
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PostPost by: gerrym » Tue Mar 24, 2009 10:21 am

Re Jim's post and handbrake system incorporating E-Type lever.

If I understand it correctly the system is now:-

1/ handbrake lever = High mechanical advantage & low travel.

2/ crank system to reduce mechanical advantage and increase travel

3/ handbrake tree to increase mechanical advantage (& decrease travel)

4/ caliper levers to increase mechanical advantage (& decrease travel)

The above looks a bit tortuous to say the least, losses must be high.

If using a high gain (mechanical advantage) handbrake lever, why not do away with the additional crank lever and handbrake tree and have twin cables (outer terminating on spine of chassis behind differential housing) directly from handbrake lever to caliper levers??

Regards

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PostPost by: jimj » Tue Mar 24, 2009 4:31 pm

Yes Gerry, I was tempted along just those lines should "my" system prove too Heath Robinson but it seems to work well and is easily reversible. Not that I`m thinking of ever selling but..................
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PostPost by: grahammay2 » Sat Mar 28, 2009 5:54 pm

My other car is a S-type Jag it has an electronic hand brake, press a button for on or off, also a touch on the accelerator releases it. How this works I do not know, can a similar system be introduced to classic cars replacing the dreadfull original under dash lever. Has anyone got answers?

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