Lotus Elan

Park brake springs???

PostPost by: nomad » Wed Jan 13, 2016 7:03 pm

Should I replace the little L shaped springs that keep the parking brake pads centralized? The originals don't all match and I'm wondering if brake heat may have taken the temper out and if the new ones are of equal quality??
What say the experts? :D

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PostPost by: mbell » Wed Jan 13, 2016 8:29 pm

I just bent them back. I believe they are meant to deform as the pads wear and then be re-adjusted when new pad are fitted.
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PostPost by: nomad » Thu Jan 14, 2016 12:19 am

mbell wrote:I just bent them back. I believe they are meant to deform as the pads wear and then be re-adjusted when new pad are fitted.


Hmmm, I would think that a spring would be appropriate for that application. I haven't tried bending them but now that you mentioned it I imagine there is probably just enough spring back in them to give the necessary clearance.

Thanks
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PostPost by: gus » Thu Jan 14, 2016 1:39 pm

A spring would be appropriate, but that is not what we got. They are soft, bend them back to keep the pads against the caliper. With the brake adjusted correctly they do work, and with these tabs doing their job they do not wear quickly so while the parking brake is weak, it is there
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PostPost by: billwill » Thu Jan 14, 2016 2:45 pm

mbell wrote:I just bent them back. I believe they are meant to deform as the pads wear and then be re-adjusted when new pad are fitted.



Agreed.

You can also assist them by putting a cylindrical coil spring on the threaded rod that has the adjusting nut. Arrange it to push the pads apart.
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PostPost by: TroonSprint » Thu Jan 14, 2016 5:07 pm

the parking brake is weak
Not on my Sprint it isn't. It holds really well with only a light pull on the handle. Much better than on my MGB.
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PostPost by: nomad » Thu Jan 14, 2016 6:47 pm

billwill wrote:
mbell wrote:I just bent them back. I believe they are meant to deform as the pads wear and then be re-adjusted when new pad are fitted.



Agreed.

You can also assist them by putting a cylindrical coil spring on the threaded rod that has the adjusting nut. Arrange it to push the pads apart.


Bill, the adjuster has a coil spring fitted from the factory to push the pad's apart. Are you saying that should be upgraded??

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PostPost by: Maulden7 » Thu Jan 14, 2016 7:11 pm

billwill wrote:



mbell wrote:
I just bent them back. I believe they are meant to deform as the pads wear and then be re-adjusted when new pad are fitted.


Agreed.

You can also assist them by putting a cylindrical coil spring on the threaded rod that has the adjusting nut. Arrange it to push the pads apart.

Bill, the adjuster has a coil spring fitted from the factory to push the pad's apart. Are you saying that should be upgraded??

Kurt


Are you sure Kurt? I've never seen this & there's nothing shown in the Lotus Parts Manual?

However, the suggestion that there should be one is very valid & I did this many years ago. I found that the suspension spring from a small remote controlled car did the job perfectly!
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PostPost by: stugilmour » Thu Jan 14, 2016 7:16 pm

Kurt, this thread is pretty helpful with some good pics. i think the spring in question is shown in an Alex Black post on the second page? Maybe your car has them already, but don't think they are stock.

Also note the post by [email protected] on the second page. Replacing the bushing pieces he mentioned was the secret to get my brake to work. I made something up by grinding the corners off a small hex nut.

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

HTH

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PostPost by: mbell » Thu Jan 14, 2016 7:22 pm

From the factory they didn't have a coil spring over the rod/adjuster, this is a common addition/mod.

Such a spring doesn't actually directly push the pads away from the disc/rotor as the pads aren't rigidly fasten to the arms that the additional spring works on, the pads are hooked over the arms pivot but not fasten to the arm. The additional springs do spread the arms when the brake is released and therefore insure the arms are not apply pressure to the pads (presuming correct adjustment). This means the standard spring only then needs to push the pads away and not the combination of the pad + arms.
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PostPost by: nomad » Thu Jan 14, 2016 8:22 pm

Wow, I didn't think there were so many nuances to the parking brake. I thank you all and will attempt to digest it tonight.
My calipers definitely have springs on the adjusting bolts and I will have to give them a good look but I believe they are rather fancy with a varying diameter. Small to big and then back to small. Looks like making up a new compensater tree might be a good idea as well.

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PostPost by: john.p.clegg » Thu Jan 14, 2016 8:45 pm

Kurt
You can upgrade to the later handbrake "tree" which helps with the parking brake ,dimensions have been posted ( years ago )...

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PostPost by: 7skypilot » Thu Jan 14, 2016 10:51 pm

The coil springs certainly help to keep the pads from lightly kissing the disc, and prevent the consequent uneven wear. Adjustable rods also help in setting the park brake correctly (Susan Miller). It's also worth checking the cable is the correct length.

When everything is adjusted correctly it works OK and will hold the car on a steep slope. The unsolvable problem is that the lever really doesn't give the sort of leverage we're used to on a more modern car (and the fact that I can't reach it with harness tightened!). To rely on it in an emergency would be exciting...

My park brake (1970 S4) has been just fine for the last four years and, yes, it is used outside the annual 'MoT' test. There is minimal wear of the pads (which are pricey to replace; less costly to reline).
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PostPost by: billwill » Thu Jan 14, 2016 11:59 pm

nomad wrote:
billwill wrote:
mbell wrote:I just bent them back. I believe they are meant to deform as the pads wear and then be re-adjusted when new pad are fitted.



Agreed.

You can also assist them by putting a cylindrical coil spring on the threaded rod that has the adjusting nut. Arrange it to push the pads apart.


Bill, the adjuster has a coil spring fitted from the factory to push the pad's apart. Are you saying that should be upgraded??

Kurt



Nope. They were not on my car when I got it, so I fitted my own as it seemed a logical thing to do.

I do not know if mine were removed by the first owner or whether earlier (or some) cars never had them.

They are not shown on the parts diagram:
http://www.lotuselan.net/wiki/JC_-_Brakes_-_Rear
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PostPost by: nomad » Fri Jan 15, 2016 2:51 pm

The Springs on my adjuster bolts seem very "factory" folk's.

I got to thinking and looking over the whole assembly and I'm not very impressed by the design. As I see it there is no way to keep the compensater tree from flopping to one side or another and forcing one pad or another against the disc. Similarly, they need adjustable rod's as SM offer's. I wish I had noticed this while I was welding on the chassis. One could fit something to the frame to solidly locate the compensater lever when in the released position so that with adjustable rod's the pads would stay off the disc's. Of course this wouldn't take into account the changing geometry as the wheels move through their arc but could be adjusted for normal running.

On second thought, that wouldn't work either....wouldn't account for one wheel moving more than the other. Really would need something to centralize the assembly at the brake disc. As is just the weight of the lever arm and cable is going to bias the wear. If I still had a drawing board I could perhaps come up with a compromise but I guess its a matter of living with the design for now.


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