Help with rear brake plate/cam
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Help with rear brake plate/cam
Hi
I assembled the rear brake yesterday onto the hub, fitted the wheel, tightened everything up and found that the rear brake arm is not returning to its neutral position!. On further inspection, I see that the brake cam is not the correct part and it looks like a bush for the wrong part has been welded onto the plate, no doubt the correct bush for the wrong cam. The problem is that when the bolt on the end of the cam is tightened to secure the brake arm, the brake arm compresses the return spring and the whole thing binds up. I did wonder why the bolt was loose when I got the bike, because in the loose position it does not bind up!
I think I can find someone who has the correct cam, but then I have the bush to deal with. Does the standard cam run in a bush? I can't see enough detail from the parts list or workshop manual.
Any other ideas very welcome.
Thank you
Steve
I assembled the rear brake yesterday onto the hub, fitted the wheel, tightened everything up and found that the rear brake arm is not returning to its neutral position!. On further inspection, I see that the brake cam is not the correct part and it looks like a bush for the wrong part has been welded onto the plate, no doubt the correct bush for the wrong cam. The problem is that when the bolt on the end of the cam is tightened to secure the brake arm, the brake arm compresses the return spring and the whole thing binds up. I did wonder why the bolt was loose when I got the bike, because in the loose position it does not bind up!
I think I can find someone who has the correct cam, but then I have the bush to deal with. Does the standard cam run in a bush? I can't see enough detail from the parts list or workshop manual.
Any other ideas very welcome.
Thank you
Steve
Re: Help with rear brake plate/cam
Do you have the large diameter but thin washer which goes between the shoe face and the brake plate on the cam?
Re: Help with rear brake plate/cam
Are you sure thats not the right cam as it looks the same as mine. I think they are weld in, Drags sell a replacement weld in bush but it looks slightly different to yours.
I would say it looks only tacked in too and may need a more substantial weld? Then perhaps you could reduce the depth of the flange so that when bolted up it doesn't bind itself up?
Adam
I would say it looks only tacked in too and may need a more substantial weld? Then perhaps you could reduce the depth of the flange so that when bolted up it doesn't bind itself up?
Adam
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Re: Help with rear brake plate/cam
Thats an interesting idea Adam; I could remove the bush and reduce in size. That would solve the problem.
Looking at the Drags site for Wheel type 5, it shows a nut on the end of the cam, whereas, mine has a small bolt, 7/32" I think. My parts list does not show either! Nor does my parts list show the bush 4080-00, but Drags site does.
I am wondering if my plate is from a different bike/year. There are 3 holes around the bush, which suggests to me that at some time, a bush was secured into place using 2 bolts (1 hole for return spring). Either that, or somebody has drilled extra holes for the end of the return spring as it fits rather nicely in all the holes.
My washer is indeed missing, I will find one but that will make the binding worse until I solve the above.
I will contact Drags tomorrow to get the dimension of their bush. If it solves the problem, Ill buy one and get it welded into place.
Out of interest, what year is your bike?
Thank you for responding Adam.
Looking at the Drags site for Wheel type 5, it shows a nut on the end of the cam, whereas, mine has a small bolt, 7/32" I think. My parts list does not show either! Nor does my parts list show the bush 4080-00, but Drags site does.
I am wondering if my plate is from a different bike/year. There are 3 holes around the bush, which suggests to me that at some time, a bush was secured into place using 2 bolts (1 hole for return spring). Either that, or somebody has drilled extra holes for the end of the return spring as it fits rather nicely in all the holes.
My washer is indeed missing, I will find one but that will make the binding worse until I solve the above.
I will contact Drags tomorrow to get the dimension of their bush. If it solves the problem, Ill buy one and get it welded into place.
Out of interest, what year is your bike?
Thank you for responding Adam.
Re: Help with rear brake plate/cam
I guess it also depends if the whole shaft has enough length to accommodate the extra washer too as to whether you will be able to make enough room by turning the bush down?
There is a whole rear brake plate complete with cam on ebay (all needs reconditioning) if you got stuck i noticed. Although its not labelled as for an ariel specifically, but it does have the anchor and lever.
Mine is a 45 but its a mismatch of parts so no guarantees its even slightly correct! You could always make a stud to screw into the cam to take a nut if you could make the overall length work out, if you wanted it to look closer to the original.
Adam
There is a whole rear brake plate complete with cam on ebay (all needs reconditioning) if you got stuck i noticed. Although its not labelled as for an ariel specifically, but it does have the anchor and lever.
Mine is a 45 but its a mismatch of parts so no guarantees its even slightly correct! You could always make a stud to screw into the cam to take a nut if you could make the overall length work out, if you wanted it to look closer to the original.
Adam
- Roger Gwynn
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Re: Help with rear brake plate/cam
Hi Steve sorry to say that your cam, cam bush and brake plate are all wrong! The bushes that Draganfly sell are the correct length for virtually all rear brake plates, as are the cams. Very early rear plates and many fronts have a longer cam but then they have a different number. I cannot think which brake plate yours has been made from. I thought it must be a 1954-55 s/arm one but the spindle hole looks to be the correct size for a rigid. The fulcrum adjuster is the post 1941 version and there looks to be a filled in hole where a cable lug would have been, which was only fitted on plunger and s/arm plates from 1953. It may have been modified more than once of course.
See https://draganfly.co.uk/shop/110647/bra ... 1/#4360-42
See https://draganfly.co.uk/shop/110647/bra ... 1/#4360-42
Roger Gwynn, Membership Secretary, curator of the Machine Register and the works drawings. Director of Draganfly Motorcycles, Craven Equipment and Supreme Motorcycles mostly retired.
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Re: Help with rear brake plate/cam
I am not surprised Roger, the hub is not correct either - its from an early pre-war bike. I obtained a very rusty correct hub, almost completely refurbished now. If the plate that is on ebay is correct, Ill buy it, refurb and match with my refurb hub. Ill then have a new wheel built around those parts.Roger Gwynn wrote: ↑Sun Dec 18, 2022 2:56 pm Hi Steve sorry to say that your cam, cam bush and brake plate are all wrong! The bushes that Draganfly sell are the correct length for virtually all rear brake plates, as are the cams. Very early rear plates and many fronts have a longer cam but then they have a different number. I cannot think which brake plate yours has been made from. I thought it must be a 1954-55 s/arm one but the spindle hole looks to be the correct size for a rigid. The fulcrum adjuster is the post 1941 version and there looks to be a filled in hole where a cable lug would have been, which was only fitted on plunger and s/arm plates from 1953. It may have been modified more than once of course.
See https://draganfly.co.uk/shop/110647/bra ... 1/#4360-42
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Re: Help with rear brake plate/cam
Looks right to me! Compare with pic in Simon H's post yesterday here
http://forum.arielownersmcc.com/viewtop ... 47&t=13160
SG
Web admin (webmaster@arielownersmcc.com)
'55 Huntmaster, '56 VH, ' 51 VH, '62 Arrow, '80 R100RT, '00 Sprint ST (now with a new Arrow project, and just now those 4-stroke Ariel parts can't even make one running bike...)
'55 Huntmaster, '56 VH, ' 51 VH, '62 Arrow, '80 R100RT, '00 Sprint ST (now with a new Arrow project, and just now those 4-stroke Ariel parts can't even make one running bike...)
- simon.holyfield
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Re: Help with rear brake plate/cam
This is about the best pic I have of the rear brake
cheers
Simes
'51 Square Four,
'58 Huntmaster,
'42 W/NG,
'30 Model A
https://ariel-square-four.blogspot.com
Simes
'51 Square Four,
'58 Huntmaster,
'42 W/NG,
'30 Model A
https://ariel-square-four.blogspot.com
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