5 1/2" Brake arm hits fork bottom.

[Duncan]

I have a problem with a project using a 1940’s 5 ½” brake. When the brake is applied the lever hits the fork bottom before the full braking force is available, The brake shoes are metal and recently relined they are on the minimum adjusting castellation, if I move them up one they will not fit in the brake drum. I have a couple of different brake cams and arms none of which will resolve the conflict.
Is this a common issue down possibly to a mismatch of parts? I would welcome any comments about how to resolve this or do I just need to get the brake are cut and re-welded at a different angle?

brake arm resting position.jpeg

brake arm hitting fork bottom.jpeg

Please ignore the nyloc nuts and oversized axle nut they came with the forks.

[SPRIDDLER]

I think the hub on my (one previous owner, an AMC dealer) '47 Ajay may have been further to the offside than yours as the brake arm lifted between the fork end cap and the brake outer plate.
Certainly the end of my wheel spindle is set further inside the spindle nut than yours. However, your brake arm looks a bit different from mine as yours seems to have a boss that's wider than the arm at the pivot end whereas mine hasn't.

The illustration 40-G12M-B65 on page 43 in the parts list isn't much help as it's more of an artist's impression than a drawing.
http://archives.jampot.dk/book/Spares_l ... 16M_18.pdf

100_1339.jpg

[Duncan]

Hi Nevill, there is a fat washer under the nut that may be giving an optical illusion. I have a couple of arms one is straight the other has a small offset, unfortunately neither resolves the issue. I did try spacing the spindle and torque arm over with washers but that alters the line of the cable out of the adjuster.

On your picture is the arm just about to engage?

There is some flex in the steel shoes and I not sure if I would be better with alloy ones but there is still very limited movement available for an emergency stop.

[ajscomboman]

Duncan I had this issue on one of Peter Shorts WD's. At the time I had several different lever arms and there are some around with a slightly different hex orientation which sorted out the issue. Trouble is it's not obvious to the naked eye, or not mine anyway. Trial and error we got one on there and it sorted the issue although it was still close of full braking. The other option is cut weld and re-chrome, but you've gotta trust the welder!

[g80csp11]

Looks like the brake shoes are worn out and excessive lining wear , and not adjusted . the steps between the 3 positions are pretty course
you could try oversize thickness linings to compensate for brake drum wear , or welding a thin shim under the adjuster
the cable / arm should never be less than 90 deg if adjusted correctly

brake.jpg

there were also a number of shoe expanders available that have the hex offset by 30 deg that would leave the arm in this position ( in all other dimensions they were the same). check yours is correct !

36-12-B51 is the cam expander number

https://www.amoc-parts.com/store/comers ... duct=23134

[Steven S]

I'm sure it's the lever. If you hold the lever vertically, with the hex at the top, your lever should have the point of the hex facing up. If you have the later lever, fitted from 1948-on, then the hex will have the flat facing up. They are otherwise identical.

[g80csp11]

Agreed Steve , it will be easier to confirm if the cam expander nut is removed so we can see

[Duncan]

Hi all thanks for your comments they have been helpful, the following picture shows the nut removed from the brake cam:

Nut Removed.jpeg

I have dived deep into the back of the shed to find the tea chest that has the 1947 16m project in it so that I could compare brake arms, lining the hex up there is a slight difference, I now know that I had fitted a later brake arm (the others I have are the same):

Brake arm comparison.jpeg

This is how it looks on the brake cam, just need to remake the cable that I shortened for the first one as the shoes bind on the longest setting:

Position of 1947 brake arm.jpeg

[ajscomboman]

Hi all thanks for your comments they have been helpful, the following picture shows the nut removed from the brake cam:

Nut Removed.jpeg

I have dived deep into the back of the shed to find the tea chest that has the 1947 16m project in it so that I could compare brake arms, lining the hex up there is a slight difference, I now know that I had fitted a later brake arm (the others I have are the same):

Brake arm comparison.jpeg

This is how it looks on the brake cam, just need to remake the cable that I shortened for the first one as the shoes bind on the longest setting:

Position of 1947 brake arm.jpeg

Or use a longer clevis that was fitted to 63 models I think.