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Brake pull off springs

Submitted by robert_haslam on Fri, 03/02/2017
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Commando

I was watching James May putting a Honda Monkey Bike together in The Reassembler last week and I was struck by how much trouble he had fitting the drum brake shoe pull off springs.

I have also encountered the same problem with both the removal and replacing of my Commando springs, as I am sure have so many other owners.

Not wanting to go through the same struggle when I stripped my brakes last summer, I applied some thought to the problem and came up with the following solution which is quick, pain free and cheap.

The 2 photos pretty well show all you need to know.

The use of a G-cramp enables the process to be performed unaided.

The cramp will keep the brake hard 'on' with the springs fully extended. Armed with a total of about 10 fairly thick washers per spring, push them between the coils from opposite sides, (to keep the springs straight), until it is fairly full. Then, remove the cramp and the springs will be held stretched sufficiently to simply lift them off. Leave the washers in-situ until reassembling, then put the springs back over the shoe hooks and remove the washers with pliers.

For the rear brake, a similar technique can be used for the removal of the cam end spring, then it is necessary to extend the non-cam spring by levering the brake shoes apart enough to push washers into it.

Bob Haslam, 1971 Fastback

Attachments brake%20spring%201.JPG brake-spring-2-jpg

Submitted by les_howard on Fri, 03/02/2017

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Nice tip Bob. It is an old one but worth showing as there are many that would not have known about this so and will be a very valuable tip for them. The only reason I don't generally use this method is that whenever I strip the brake drums I clean everything up, yes even the springs with a rotary brush, then take them to be zinc plated or 2x packed in a nice silver colour.....Ha Ha......ONLY JOKING....Wink but yes I do clean them up..... Sometimes you can fit the springs to the shoes and then lever the brake shoes from a vertical position to a horizontal position over the pivots and cams (probably not so easy with the 2LS brake) but the spacer method you show is very good.. I like James May, I wonder how he would get on with Henry Cole.

Les

Submitted by robert_haslam on Fri, 03/02/2017

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Hi Les, yes, I had a feeling that I was re-inventing the wheel!

It is also possible to fit the washers to the springs after polishing (!). Mount a screwdriver pointing upwards in the end of a bench vice and slip the spring over it. Then, using another longish screwdriver, or suitable rod, pass it through the free end of the spring and arrange a fulcrum at the base of the vice and heave away to stretch the spring. Then insert the washers. (Probably requires a third hand).

Cheers, Bob

Submitted by david_evans on Fri, 03/02/2017

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I see from your second photo that you have fitted the slippers over the cam end of the shoes. You don't need those slippers where the shoe has the steel slipper incorporated. That is why your springs are so hard to fit. Bet the whole lot doesn't fit inside the drum.

Submitted by peter_denham on Mon, 06/02/2017

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Submitted by barry_carson on Mon, 06/02/2017

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Hello Robert . good idea that, those spring lugs on the shoes don't take much stick before they snap off as i found out . i would have to stick a notice on the outside of the brake plate reminding me to remove them all else that could be interesting Baz

Submitted by richard_woolnough on Mon, 06/02/2017

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in my ignorance, when you say 'slippers' do you mean the inserts between the shoe and cam, if so how do they come to be here, are the shoes replacements and the 'slippers' off the originals?, 'tis so confusing sigh, kind regards

Submitted by robert_haslam on Tue, 07/02/2017

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Hello David.

You would lose your money, the shoes fit into the drum with plenty of room to spare. I seem to remember that the reason I added the extra slippers was to enable me to get the brake arm into the most efficient position, which is at 90 degrees, to the cable when the brake is on. The same holds true for the short 'top' arm which should be at 90 degrees to the pull rod. As there are only 2 alternative positions for fitting both arms to the cam spindles, only coarse adjustment is available. I must have been lucky with the gauge of steel I used, as it has done the trick and I have got both arms at 90 degrees operated.

However, your observation did give me food for thought. Had I compromised brake perfomance by adding the extra slippers? If the relationship between the cam rotation and it's effective lift is non linear it may have a 'sweet spot' that I could be missing. I am using an 'earlier' part of the cam, i.e. a smaller rotation than normal to operate the brake.

Since the photo was taken, I have added the stiffening kit. This provides 2 new cams so I have the old ones available. I made up a simple test rig and found that the relationship is linear from about 5 degrees of cam rotation to about 58 degrees, 0 degrees being the flat of the cam. Therefore, there is a great deal of latitude. I am reassured!

I did once see Henry Cole looking at a spanner whilst someone else was using it.

Richard, yes you are right, hope my explanation makes their existence clear - they're one offs.

Regards, Bob

Submitted by david_evans on Tue, 07/02/2017

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Fair enough Bob, you have obviously put a great deal of thought into the front brake. Someone on the accessnorton forum, quite recently had fitted new rear brake shoes that would not fit in the drum, because he had the original slippers AND the incorporated slippers. the reason was that the Shoes from RGM have the slippers incorporated but the original ones (riveted I guess) have them separate. Embarassed

 


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