Suspension Travel effect on hand brake rods?

[mbell]

Hi,

So I am in the process of re-fitting the brakes to my +2. Rear calipers are back on and both sets of pads installed. On connecting the handbrake rods I found that they were too short and basically pre-engaged the handbrake to connect them, even with the cable disconnected at the tree. The hand brake appears to be working fine but I?d much prefer to be able to adjust the pad positions with the no tension in the system.

It crossed my mind that this might be because the car is currently on stands and there is some droop in the suspension. This could be causing the tightness in the rods. So adjusting it while on the stands ins?t a good idea because at normal suspension travel the rods will be under less tension.

Do other people have the same tightness in the rods?

Do people think suspension travel will have the effect of slightly applying the handbrake?

Thanks,

Mark

[patrics]

Hello Mark
You are correct that when the suspension move up and down then the parking brake would apply but..
The hand brake tree moves freely from side to side so composites for this but if both move up or down at the same time then the brakes would apply

Regards
Steve

[oldelanman]

if both move up or down at the same time then the brakes would apply

Is that right ?
I would have thought that the hubs and therefore the brake calipers are furthest from the centre line of the car when the wishbones are horizontal - normal ride height - movement up or down from there will move them inboard slightly, pushing on the rods, the compensator will rotate and just add a bit of slack to the handbrake cable. Happy to be proved wrong though.

[jimj]

"Do people think suspension travel will have the effect of slightly applying the handbrake?"

No. The arc of travel, such as it is, is constant.
Jim

[patrics]

Hi Roger,
Thinking about it but not 100% sure.
As both wheels move up together then rods get pushed towards centre so pushing inboard pads on and if both wheel move down then outboard pad will be pulled on?

If as in cornering one wheel goes up and the other down then the tree moves side ways and compensates.

If the tree rotates then isn't applying?

Still thinking about it...

Regards
Steve

[oldelanman]

Hi Steve,
As it travels in an arc, I think the hub will always move inboard as the wishbone moves either up or down from the horizontal (normal ride height position) so the rods will always be pushed towards the compensator, never pulled. However, provided the compensator is completely free to move, I don't think there will ever be any movement of caliper brake levers and therefore no braking. Random applications of the park brake would not be a desirable feature

Regarding Mark's original question about the rods appearing to be too short, I believe this is because of wear and/or bending of the lever stops over time. Adjustable rods are available from the usual suspects to overcome this condition...... or you could simply gently "adjust" the stops.

[patrics]

Hi Roger

I think my point is that they have different centers - the hand brake rods are 4 to 5 inches above the suspension pivot point so scribe different arcs thus are pulled if both wheel drop together.


Mark, just in case - but the short arm goes to the right side of the car and long one to left side.

Regards
Steve

[oldelanman]

Good point Steve. My head really really hurts now

[patrics]

Took a while to put into words correctly what I was thinking!

Mark, just a general point but the tree should pivot in two ways
1. On the screw thead when handbrake is applied
2. Move freely from side to side on the tree too chassis fixing

Regards
Steve

[Quart Meg Miles]

Hi Roger

I think my point is that they have different centers - the hand brake rods are 4 to 5 inches above the suspension pivot point so scribe different arcs thus are pulled if both wheel drop together.

Regards
Steve

The T is also above the inner wishbone pivot so the rods will stay fairly parallel. However, as with steering rack alignment, it is a matter of keeping all suspension links in line with a common intercept and the strut complicates that by leaning the hub outwards as the wheel descends and inwards when it rises as well as moving the effective pivot point around. I think the rods, in total, are longer than the two wishbones so the arcs may not be optimum though are probably as good as possible given other constraints.

Perhaps, Mark, you could jack the wheel up and tell us how much the alignment changes.

[mbell]

Thanks everyone. It's all the different arc's here that are confusing me.

I had a look at the stops on the hand brake. With just the two connecting rod and handbrake cable disconnected, the right hand side sits nicely on the travel limiter but the left hand side is significantly of the limiter.

Left side limiter.

This side is also missing the bush the bolt goes through which allows a little more length to the rod. So it looks like I need to adjust the travel limiter or get/make some longer rods. Adjustment seems like the cheaper option but looks like it might need more adjustment than I'd like.

Currently the car is on jack stands under the hubs so jacking it hub to see effect on handle/rods quite as easy as it sounds. It does mean that the suspension is only slightly drooped, hasn't settle done from jacking it up. I should do some more testing to see the effects of suspension travel on this, either by taking it of the jack stand or by doing something to compress. Will have to see if I get time to do this. Currently need to source some new brake lines for caliper to flex hose as all the ones available over the counter here have double male ends.

[gus]

Suspension travel is simply not an issue. Adjust the brake at whatever point you see fit and it will work. The biggest problem with the parking brake is that it needs to run the pads very, very close to the disk to function. If the small metal clips are not adjusted correctly to hold the pads against the caliper they will wear quickly. Adjusted correctly the pads will last decades and work as well as they were designed to [which is not saying much]

If you are having problems adjusting the brake, it is not geometry related.

[elansprint71]

I've been messing about with Elan handbrakes for some little while now (about 40 years actually) and it makes my head hurt too.
So; what I have found is: if you adjust the handbrake with the suspension on full droop, when you lower the car drive away, the handbrake will be binding, so draw your own conclusions.
I have no experience of the +2, by the way.

Susan Miller sells rods which are adjustable for length.

[stugilmour]

Kind of with Pete on the suspension position while adjusting. I ran the Plus 2 up on ramp blocks to do the adjustment, and it finally worked out well.

Followed the other tips, including bending the tabs to the correct shape, adding a spring to keep the pads off of the rotor (might not be needed but added them anyway), and making up a replacement bush piece in the hole at the end of the operating lever (was missing from mine; see Jeff's post on second page of link below. I think this was the main issue with mine). Didn't end up needing the adjustable rods.

This thread has a ton of info and pics I found helpful. Brake still working fine two years later, and has endured the odd take-off with the brake set, which can't be terribly helpful. Will have to check things out back there tomorrow before storing the car for the winter.

lotus-suspension-f42/elan-parking-brakes-can-they-made-work-t25716.html

HTH

Stu