Brake bodges

[plj]

New linings, bushes and springs had arrived before Xmas so to try and achieve my target of road worthiness by "drive it day" I stripped the o/s/f brake. Found an interesting modification to the operating cam but doubt it was manufactured by Mr Morris, the disturbing thing is that with the bodge the operating lever is about 90 degrees but without it, it goes over centre. Two questions, are such mods common and acceptable? Can the brass/bronze slippers on the end of the shoes be replaced, if so does anyone know of a stockist? Are the dimensions of parts such as the operating cam available to check for wear? Yeah I know that's more than two questions but I'm on a roll, I have seen suggestions that brake shoes should be shimmed to the shoes, does anyone do this?? Having checked the diameter of my drums there is very little wear and no signs of scoring or skimming.
Any suggestions appreciated.

Regards,

Philip

[Ian Grace]

Philip,

Great photos - thanks. I have never seen a shim wrapped around the brake cam like this, but I have seen lots of shoes with extra material added to the steel caps on the brake shoes themselves.

I am very surprised to see the cam (and lever) at such an angle in your lower picture, which would seem to indiacte that either the drum has been skimmed waaaay oversize, or the linings are badly worn. As you have confirmed that the drums are standard 8", then the problem has to be the lining thickness, which does look very thin in the photo. These look like the old linings and not your new ones?

The problem with all this cam (or shoe cap) shimming is that the radius of the braking surface of the shoe should not be less than that of the drum. If your new linings are genuinely too thin to give a tight arrangement at the cam, you can shim the linings themselves, but you still have to be very careful to ensure that the resultant braking surface radius is correct such that you get good drum contact all over the shoe when the brake is applied.

In fact, looking very closey at your lower picture, it does look like the shoe is only in contact with the drum over the middle two thirds or so of its length, suggesting its radus is less than that of the drum.

Hope this helps more than it confuses!

[plj]

Thank you Ian,

Yes the linings are the old ones but have only just reached the replacement stage, which I have put off until I reach a decision on shimming (and find my riveting tool). I think the best plan is to assemble the new linings without clenching the rivets and see what contact that gives. Does anyone have views or experience of fettling the cam end of the brake shoes?

Regards,

Philip

[Trevor Wilkinson]

I know that for Au***n 7 brake shoes replacement "saddle" ends are available, so it would appear normal to tackle the problem here.

[garagiste]

Joining the tread as am undertaking exactly the same exercise at present having got fed up with dubious brakes. Finding all sorts of nasties.

Super pictures, but are you using a reamer on the pivot that fits the back plate bushes? If so this might be part of the problem.

The shaft if the pivot mounting that sits in the back plate bush is 9/16" diameter (ie the ID of the back plate bush), the section that the shoes sit on is 1/2" diameter.

At least they are on all mine.

Keep this tread running as it will prove of mutual interest.

Have got to first change front axle as don't like the look of one of the stubs! All this on a car that had been rebuilt!

[plj]

Thanks for all input. I cleaned everything up and loosely assembled the new linings to the shoes, see photo, it looks better but I think once the linings have bedded in and worn a little the operating lever will still be over centre. The second photo shows the wear and scuffing on the cam and also what I thought were brass slipprs to the end of the shoes prove to be some dobs of braze which have been added! I spoke recently to Ian Harris about new cams and he thought they would cost around £30.00 each to make as they would have to be hardened, I haven't asked if they would be cheaper in large batches, anyone interested? The shoe saddle ends as used on the "Herbert's" sound like a good idea, does anyone know of something similar for minors, my other alternative might be to get rid of the brass, build up with MIG and grind to profile. I haven't been doing any reaming on the shoes, the reamer was the only exact half inch round section I could find apart from a 3 metre long rod which I was too idle to cut.

Regards,

Philip

[garagiste]

Philip,

Cams ground and hardened, from Sports & Vintage Motors at Shrewsbury are £ 29.38 inc VAT. (Nov 2011 price list) This sort of thing is usually ex stock.

David.

[Ian Grace]

Yes, S&V has the cams, Woodruff keys, bushes, fulcrum pins and brake shoe return springs if you need them, but not the shoe caps - I have never seen them offered anywhere, and they would be quite tricky to replace. I have seen lots of caps with rectangular steel plates of various thicknesses welded/brazed on.

Philip, your second photo with the new linings fitted certainly looks a lot better - I think you now just need to get the caps back to their original profile - they get dented by the cam action quite easily - or at least after 80 years of braking and abuse! I was amazed when I took the brake drums off my fabric saloon to find that there was hardly a discernable mark on the shoe caps - and they have done 4,000 miles from new.

[plj]

Ian,

Does the S&V catalogue have enough in it relating to s.v. cars to make it worth me buying a copy. £10.00 is neither here nor there but the principle of paying somone purely in order to give them more money does grate a bit.

Regards,

Philip

[Ian Grace]

Definitely so - the SV Minor has many parts in common with the M Type - brakes, hubs, clutch, steering, suspension, transmission, and so on.

Their catalogue became very dog-eared and oil-stained when I was getting my first Minor on the road back in the seventies, and that was a SV 2-seater.

[plj]

Thanks Ian, ordered this morning.

Philip

[plj]

Investigations continue. Having now stripped all four brakes I now find, one bent and one broken brake shoe, does anyone have two shoes in usable condition that I can purchase?

Philip

[plj]

Things don't get better, a previous owner must have had a brazing set for Xmas, pity he didn't get a brain to go with it. I note in various postings on brakes that braze has been used for pivot and cam bushes when they have fallen out of the backplate, is there a technical reason for preferring braze over weld? As you can see from the photos neither pivot is upright or square to anything, but the shape of the backplate does not make it easy to align, unless of course the plate itself is also out of true, any thoughts? Unless I can find some usable backplates (not much chance as I've had no luck with brake shoes) I will strip all four prior to remedial work as two others show signs of bodgery.

Regards,

Philip

[plj]

I'm sure I recently saw a post showing backplate repairs with a homemade jig to align things, now I can't find it!! Sure I didn't dream it but suppose it may have been on a different site, can anyone point me in the right direction?

Regards,
Philip

[garagiste]

I also saw it, so you you were not dreaming. Have not got time to hunt for it at present. MMM forum?

Where are you located? Might be able to help with one shoe and backplate.

Am at present undertaking a similar exercise. I am in the Welsh Marches.