Metalwork-centralising strips-handbrake pads

[john.p.clegg]

Dear All

My MOT is overdue,just thought I'd check the handbrake pads,and yes,they are worn down,so the replacements dug out from the shed and decided to help the centralising strips,"set" (with gentle hammerwork) to keep the pads off the discs but it's been years since I did Metalwork at school,is it heat up to cherry red and leave to cool softens steel ,heat upto cherry red and quench to harden...?

John

with hard or soft centralising strips...

[andyhodg]

John

Heating to cherry red and quenching will harden the steel. The degree of hardness depends on the carbon content of the steel. If it is a high (relatively) carbon steel heating and quenching would leave it very brittle. If it is a spring steel it would be left brittle at this stage. The normal procedure would be to temper it after quenching.

To temper you clean the quenched item to leave bright steel showing, heat it gently watching the colour of the steel change, it will go from silver to light straw, to dark straw, light blue, dark blue and then black. I would suggest heating to a light - to mid blue (typical tempering for springs) and then allow to cool slowly.

I hope that is of some help.

Regards

Andy

[john.p.clegg]

Andy

Many thanks,I now have a working handbrake with hard centralising strips (better than soft?),I may as well wait till I can get over to Classicar Automotive and pick up four new ones...
Thanks
John

[billwill]

Hmmm, they might snap when the pads wear down, if you have hardened them. You needed to temper them not harden them.

I've never been sure about those things, whether they were deliberately designed from mild steel or not. On the face of it they ought to be spring steel.

Generally I just bend them out slightly whenever I change the handbrake pads.

[elansprint71]

John,
I have etched in my mind the iron/carbon equilibrium diagram but...... why not just fit a coil spring over the rod connecting the two calipers/pads to keep the pads off the disc- or am I barking up the wrong tree?

[john.p.clegg]

It's belt and braces time,I already have the springs fitted,one of the future jobs on my list is to shorten the handbrake cable so that it operates sooner..

John

[elansprint71]

John,
Having spent a couple of hours cursing the handbrake mech last night I've come to the conclusion that what is needed is a set of the adjustable-length rods mentioned in the Buckland Bible. This will allow the "tree" to start off from a better position and allow more of the cable to be pulled in. Also I think that getting rid of the clevis pins (which are a pissy fit in their holes) and fitting small bolts with nylocks will get rid of some of the lost motion in the design.

Looks like I've found a Winter project, now...... who stocks those rods?

[patrics]

Hi all,

These centralising strips were original made from cold rolled EN 2A and were fully annealed after forming.

The handbrake mechanism needs these strips so don?t throw them away but it is a good idea to fit a spring about the tie rod as well ? they are not doing the same job but the spring was fitted to all later designs.

The fundamental problem with the design is the wear in all the pivots ? unless this is sorted out the travel will always be long ? but obviously an out of spec cable isn?t going to help.

Elansprint71 you must have a great car if you have to find a winter project! I have started making new parts like the operating levers and still need to get a cost for the castings. I am in the middle of a complete rebuild so everything is a project.

Regards
Steve