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Brake drums won't go back on?
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greenbeam



Joined: 10 Jun 2015
Posts: 77
Location: Adelaide, Australia

PostPosted: Fri May 27, 2016 12:20 pm    Post subject: Brake drums won't go back on? Reply with quote

Hi all,
Very slow progress on my 1935 17HP Armstrong Siddeley Sports Saloon (See thread in 'other makes').

My late father had the brake shoes relined, and it looks like the drums machined. He then stored all this away for about 15 years.

Using the diagrams in the owners manual, I have now refitted the brake shoes, but the drums are very (very) tight. There is a light film of rust inside the drums, but I thought that would just rub off as the shoes bed in.

I have a couple of old shoes, and the linings look similar thickness to the relined shoes. I have the adjusters wound all the way in, and I've slackened off the 'fixed' end of the shoe mounts to let the shoes 'self centralise' in the drums.

I haven't dealt with drum brakes before. Am I missing something obvious?

Do I just refit the road wheels and roll the chassis back and forth, using the diameter of the wheels to generate the torque to 'rub' the drums in, or is that going to do damage to the shoes?

And, just in case... Are the shoes 'matched' to particular drums? Should I be trying to match the shoes to drums? Can't imagine things are that close tolerance, but I am a novice...

Any hints most welcome. My next bright idea is to run a wire wheel over the inside of the drums to clean up the rust film. Is that sensible?

Cheers,
Paul.
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1963 Sunbeam Alpine Series 3
1935 Armstrong Siddeley 17HP Sports Saloon
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greenbeam



Joined: 10 Jun 2015
Posts: 77
Location: Adelaide, Australia

PostPosted: Fri May 27, 2016 1:21 pm    Post subject: Reply with quote

A couple of pictures in case that helps:







Cheers,
Paul.
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1963 Sunbeam Alpine Series 3
1935 Armstrong Siddeley 17HP Sports Saloon
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kevin2306



Joined: 01 Jul 2013
Posts: 1331
Location: nr Llangollen, north wales

PostPosted: Fri May 27, 2016 2:02 pm    Post subject: Reply with quote

The locating plate to the right hand side of the set up (where it shows 2 split pins in place), that looks to be new? if it has been remade, could the centres of the slots be made longer (deeper), allowing the shoes to close up a little more, reducing the diameter overall?

Kevin
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petelang



Joined: 21 May 2009
Posts: 246
Location: Nottingham

PostPosted: Fri May 27, 2016 3:11 pm    Post subject: Reply with quote

I would be inclined to just chamfer off the leading and trailing ends of the new linings as that can make quite a difference on a new pair.
I don't know if yours is rod operated but you may find you need to free off the rod lengths and check that the brake camshafts are all nice and free and returning fully off.
On my Armstrong Siddeley 15 it has a tendency to brake camshafts sticking in the bearing on the rear axle casing as they have no external greaser or lubricator point.
When I relined the fronts I had to wind off the brake rods by a very long way and encountered seized threads on the rods which had to be dealt with to get the full stroke off.
Peter
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47Jag



Joined: 26 Jun 2008
Posts: 1470
Location: Bothwell, Scotland

PostPosted: Fri May 27, 2016 7:36 pm    Post subject: Reply with quote

The shoes don't look central. I would suggest you look at why the arc of the shoes as they don't match the arc of the backplate. To me the shoes look low. I don't recognise this design but on my Jaguar with Girling mechanical brackes you have to loosen the adjuster HOUSING so that it floats before you fit the drum or adjust the brakes after relining.

ART
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greenbeam



Joined: 10 Jun 2015
Posts: 77
Location: Adelaide, Australia

PostPosted: Sat May 28, 2016 7:10 am    Post subject: Reply with quote

Hi all,
Thanks for your responses. Working back through them:
1. Art, the fixed ends have been slackened off so they are 'floating' at the moment. Part of the adjustment process involves 'centering' the shoes inside the drum and then tightening the fixed pivots.
2. The arc of the shoes do follow the backing plate, it's just the angle of the photo.
3. Kevin, the clip on the right isn't new, just cleaned up, and the adjuster behind it is also the original one, again just cleaned.
4. The cables that actuate the brakes have been dropped off the actuating bar all together, so there is no residual 'pull'.
5. I haven't looked closely at the actuating cams - so they might be fitted incorrectly. I'll go back and have a play with them. I went by the pictures in the owners handbook for the orientation of the cams in front and back brakes, but they are flipped over for front vs rear brakes.
6. Pete - thanks for the tip about chamfering the ends - any tips on how to do this? Can I just use a coarse file?
7. Pete, I have used special grease designed for disk brake calipers *very* sparingly on the cam pivot, and other friction surfaces.

I'll report back after I have a second look at the cams.
Cheers,
Paul.
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1963 Sunbeam Alpine Series 3
1935 Armstrong Siddeley 17HP Sports Saloon
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47Jag



Joined: 26 Jun 2008
Posts: 1470
Location: Bothwell, Scotland

PostPosted: Sat May 28, 2016 5:40 pm    Post subject: Reply with quote

Paul,

I'll answer for Pete. A coarse file would do the job. You are looking at about 45 degree slope about 3/8" wide across the shoe.

You asked about matching the shoes to the drums. Best practice would be grinding the shoes to the same radius as the drums. Finding someone to do this nowadays can be difficult. Have you placed a shoe in the drum to see how they compare?

Art
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Peter_L



Joined: 10 Apr 2008
Posts: 2323
Location: New Brunswick. Canada.

PostPosted: Sun May 29, 2016 6:13 pm    Post subject: Reply with quote

Using a piece of plywood or similar, drill a hole at one end and bolt it to the hub using one of the wheel studs and nuts. Put a mark on the wood level with the brake shoe in the 12 o' clock position (or where ever) rotate the hub and see if the mark follows the shoe, it would show if the leading or trailing edges needed easing and if the surface of the shoes are 100% concentric.
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jp928



Joined: 07 Jun 2016
Posts: 247
Location: Australia

PostPosted: Wed Jun 08, 2016 7:11 am    Post subject: brake drums wont go on Reply with quote

Whenever you get drums machined they should be measured for exact diameter, and then the shoes can be ground to EXACTLY fit the drum diameter, so the maximum surface is in contact and working. If the shoes havent been radiused to the drum, this could cause your problem.

jp
26 Rover 9
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greenbeam



Joined: 10 Jun 2015
Posts: 77
Location: Adelaide, Australia

PostPosted: Sat Aug 20, 2016 12:20 pm    Post subject: Reply with quote

Hi all,
Thanks for the tips about diameter of drum and matching the shoes. I used coarse emery cloth to clean all the surface rust off the inside of the drums. After several tries to match up drum and shoes, I decided to removed the fixed end shoe mounts from the backing plates, reassemble the shoes, adjuster, etc OFF the backing plate and offer them up to the drum (which was face down on the bench).

Only one assembled shoe set would even go into a drum, and that was with adjusters wound all the way in. So, the problem was with the 'new' bonded linings.

I ended up taking all four drums and the sets of assembled shoes to a brake specialist. The fellow there agreed that the shoes were not properly matched and too large. A day later and about 1.5 hours labour cost and I now have shoes that easily fit in the drums! I now need to find some time to fit them back onto the axles.

So a lesson for me. Just because the parts look to be reconditioned, it doesn't mean they are correct!

Regards,
Paul.
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goneps



Joined: 18 Jun 2013
Posts: 601
Location: Auckland, New Zealand

PostPosted: Sat Aug 20, 2016 11:11 pm    Post subject: Reply with quote

I've had similar trouble with bonded linings on the Morris Eight. The drums have always fitted, but with little margin for adjustment. Clearly the standard bonded lining material available now is somewhat thicker than the original riveted linings. Skimming 1mm off the bonded linings gave much better scope for adjustment and avoided the possibility of binding.

Richard
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