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Honey, my WLA front brake shoes shrunk in the oven!

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Hopper

Posts: 35

Joined: Wed Jan 20, 2010 9:52 pm

Post Thu May 17, 2012 2:19 am

Honey, my WLA front brake shoes shrunk in the oven!

So I decided to get my new WLA front brake linings bonded onto the old shoes because the old drum is so rough it will soon tear into the rivet heads. (Out of work, so on a real tight budget here)
But on reassembly, the shoes appear to be at least a quarter inch too short where they mate up to the cam. And they are about a quarter inch off matching the curve of the drum too.
I did not notice this problem on disassembly, so am pretty sure it fitted together in the normal way before.
Do you suppose the shoes contracted during the bonding process due to heat releasing stresses of a million duty cycles since 1942 and pulled the ends of the "C" in closer together?
Even with the offset cam lobes reversed, there is no way those shoes are close to mating up right.
Anyone ever come across this before?

Image

And does anyone have a good set of WLA front shoes out there they could measure up for me?
Mine measure 6-1/4" across the outside of the "C" as shown in pic, outside edge to outside edge.
I want to make sure my problem is actually undersized shoes before I get new ones shipped from the US to Oz and not something else like mismatched other components etc.
Would be much appreciated if someone could give me a meausurement for new or newish shoes that fight right.
Image
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Sidewinder

Posts: 89

Joined: Tue Dec 25, 2007 4:04 pm

Location: Norway

Post Thu May 17, 2012 5:46 am

Re: Honey, my WLA front brake shoes shrunk in the oven!

Hi Hopper. Did you place the shoes inside the drum to see if the curves match? It was like this on my BTSV both with new and old shoes. So i guess the drum has been turned once. I welded a piece of 3mm flat steel on both shoes in the area it tuches the cam. This worked out perfectly for me. So if you are one a tight budget this might do the trick. Note that the location of the pin on the other side of the cam can be adjusted if needed. Pleace concider safety and your mechanical skills before modifing brakes.
Torstein
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Hopper

Posts: 35

Joined: Wed Jan 20, 2010 9:52 pm

Post Fri May 18, 2012 4:55 am

Re: Honey, my WLA front brake shoes shrunk in the oven!

Thanks Sidewinder. Yes, the curve on the shoes is now 1/4" less than the drum. And I don't think WLA drums can have been machined because they are pressed steel and very thin.

So, I tried putting it together today and sure enough, those damn shoes have shrunk a quarter Inch, I am sure. There is not enough room for the spring to fit on the cam end of the shoes - the end pads of the shoes are too close to the circular grease guard lip inside the brake backing plate.

Like you say, safety item, so I am just going to chalk it up as a quite expensive lesson and buy a set of new shoes. Most of my riding of this old bike is on steep, winding roads with no guard rails so I really want the front brake to work reliably!
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45Brit

Posts: 1433

Joined: Tue Nov 27, 2007 2:29 am

Post Fri May 18, 2012 11:56 am

Re: Honey, my WLA front brake shoes shrunk in the oven!

Best way to get a reliable front brake on a WLA..

1) remove old brake and completely disassemble it

2) place all parts in a box

3) photograph box

4) send photograph to ebay

5) buy BSA front brake with about half the sale price

6) look on here for various threads how to fit it

7) spend the difference on something useful

:D
Shoot, a man could have a good weekend in Dallas with all that stuff...
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Hopper

Posts: 35

Joined: Wed Jan 20, 2010 9:52 pm

Post Sat May 19, 2012 10:02 pm

Re: Honey, my WLA front brake shoes shrunk in the oven!

I hear ya! And I just let a BSA front brake go with a pile of Matchless junk I sold last year!
But this front brake has worked ok for the past 30 years, most of it hauling up a sidecar, so I want to keep it original if I can.
Basically, all I want is for it to work as well as it did before I "fixed" it! :lol:
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Hopper

Posts: 35

Joined: Wed Jan 20, 2010 9:52 pm

Post Mon May 21, 2012 8:57 pm

Re: Honey, my WLA front brake shoes shrunk in the oven!

Measured my front shoes a little more carefully and they are only 6-1/8" so that would account for them being that critical 1/8 shorter than they need to be to match the cam.

Pulled my rear brake out and compared shoes, sho 'nuff, fronts are 1/8 to 3/16 shorter. (Rears are wider but should be same geometry as earlier models used front shoes in the back, with the same backing plate.)

So new shoes it is.

I don't know how hot the brake shop heated those shoes, or whether they threw them in a bucket of water to cool them off after baking, but they sure did a number on them.
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wilko

Posts: 159

Joined: Fri Jan 15, 2010 7:36 pm

Post Tue May 22, 2012 6:56 pm

Re: Honey, my WLA front brake shoes shrunk in the oven!

Just get a big hammer and belt the shoe in the middle. Nothing to lose!
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Hopper

Posts: 35

Joined: Wed Jan 20, 2010 9:52 pm

Post Tue May 22, 2012 8:18 pm

Re: Honey, my WLA front brake shoes shrunk in the oven!

wilko wrote:Just get a big hammer and belt the shoe in the middle. Nothing to lose!


Haha, great minds think alike.
I put one shoe in the vice and gently squeezed it to splay it out. And I mean gently. As soon as I applied minor pressure to the vice handle, holding it in next to the centre, the shoe cracked. As brittle as anything and too dangerous to use. Which is what made me wonder if they threw those things in a bucket of water instead of waiting for them to cool off out of the oven. Probably works ok on modern pressed steel auto brake shoes but not 70 year old castings.

So an order for a pair of new brake shoes turned into $300 by the time I added in a bunch of other other goodies I wanted, plus $60 shipping etc, so was an expensive mistake to get those linings bonded instead of riveting them myself!

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