Misc: Everything Else Brakes, Linings, Drums and Shoes

vibrac

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I have heard that there is an optimum lining for either cast drums or steel drums (I think it was in the context of talking about cast V pressed drums) however I wonder if that applies to cast drums and those machined from steel Billet
 

Chris Launders

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I have a bike that had a machined from billet steel drum but it didn't work as well as I hoped, I have since had a drum cast and I've machined that and there is no noticeable difference, unfortunately.
 

Matty

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Hi If you look back on this thread you will see that my problem with poor brakes proved to be that I had steel drums with the incorrect linings for years and then Saftec said that steel drums need a woven green lining to work. Most Shadows use cast drums which work OK with the linings most brake reliners use but these do not work well with the steel drums most Comets have.
So I replaced the nearly new linings on the Comet front with green Saftec woven linings and bingo I have a very acceptable front brake.
Matty
 

Matty

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For those who want to know about and setting up Vincent brakes, in addition to the above there is more and useful information in an excellent article by Michael Symonds on page 23 of the July 2020 issue of MPH.
Though whatever method is used, it becomes obvious how to do it once the mechanics are understood
 

Matty

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I do not have an update on the new shoes because I had my front shoes relined with green woven material by Saftek for round about £50 the four..
They have now done around 200 miles and function much better than any of the other sets I have fitted in the last few years
The pivots in my old shoes are quite worn, but I think this allows some "float" and the cam to push the shoe along into better contact with the drum. I have also cut off about 25% of the cam end of each trailing lining to increase the leverage and allow for the higher wear rates of the leading shoes.
The more purist mechanical engineers may think my approach too pragmatic, but it has worked very well for my use of the bike and was simple to do.
Even so I would be interested in any constructive comments.
Matty
 

davidd

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It is dangerous to guess which lining that is, but Safetek sells a very large amount of ScanPac product, so I would guess it is GGW (Green Gripper Woven). I had a pair of shoes lined recently and it was $89 for the pair, so that's a good price. I was required to use stock shoes, which is a mistake. The thicker shoes are a real help.

I found that one had been flattened after it was returned. You have to measure the length of the shoes carefully. If one shoe is longer than the other then the long one has been flattened. It gets longer when it begins to collapse in the center. If both shoes are the same length they are probably both flattened.

If you reline a flattened shoe it may have the effect of ratcheting up the force on the shoe.

Shoe Fracture 1.jpg


I don't think that the worn pivots will help much. Floating shoes usually only float in one direction (toward the drum.) Worn pivots may allow the shoes to move away from the drum and reduce the braking or increase the lever travel. I believe I wrote about making the 7" shoe float by using Triumph shoes with a single pivot. I have not tried it, yet.

I think that grinding or cutting back the lining is a good way to tune the shoe assuming you can remember the measurement of the tuning for the next time!

David
 
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Matty

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That broken shoe is pretty impressive, how does that happen - unless the shoe has been made of some very inferior material. The forces required to break through the wide flange must be very great unless there is a crack or flaw in the casting - is the shoe bent (flattened) as the lining is pressed on ?
My worn pivot idea is that the cam pushes on the end of the shoe and sort of jams it into the drum at the other end - afraid the theory defeats any skills I might have had in my youth with 3 dimensional geometry and vector algebra to do any mathematical analysis of the idea !!!
Matty
 
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