H: Hubs, Wheels and Tyres Trevor Southwell re brakes

[Monkeypants]

My

Until the beginning of this century, I kept updating my original front brake whenever something was invented, thicker cables, longer levers, reinforcement of the brake plate and also the Bert Weisz modification (see photos). It usually helped somewhat, and for people living in America on the wide empty prairy it's all fine, but in the hugely hectic traffic in my home area (Rotterdam) a standard Vincent brake is life-threatening! The VSM (Speet) brake was already a huge improvement and the German brake will certainly be too. Even better are disc brakes but that is a bridge too far for me.

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My stock brake will lock the front wheel at speed, if the lever is gripped hard.
It doesn't overheat when ridden hard. I'm not sure how a stronger brake could improve on that.
It does have the finned Shadow drums, they might help a bit.

 

[Michael Vane-Hunt]

Or, Glen, your massively strong grip is the answer. We mere mortals are in awe of your powerful arms ever since you showed us easily starting your Rapide by hand..

 

[Monkeypants]

The only thing is, when I had the Leo Lee Rapide, it did not have such a strong front brake. That brake had new shoes and new Shadow drums. It was fitted by John Mcdougall when he restored the bike, so it was done properly.
I'm not sure why there is such a variation in Vincent front brakes.
Tony Cording had barely any braking on his D Prince, even after much fettling by the local fellows.

Glen

 

[davidd]

Almost all Vincents with a Girdraulic will lock the front brake at any speed because the use of the front brake causes the fork to extend and go rigid. Once it goes rigid, the front wheel will bounce almost continually, although only enough to lighten the wheel enough to break free and squeal. A better test is to do a "stoppie." You have to have lots of traction to do a stoppie. A stoppie with little traction is a squealing tire. The new steering stem will eliminate this problem.

After Harry Lindsay won the Tostal in Ireland on Gunga Din he complained to Phil Vincent that the brakes were inadequate. Vincent started saying that they were the best brakes in the industry and asked him to grab the brake lever and squeeze to check the adjustment. Harry squeezed the brake several times causing the shoes to bend and and the brake plate to warp. Vincent quickly looked at Harry's hands and said "Your hands are too big!" And so they were.

I consider Glen to be very skilled as a rider and craftsman. I mention this only because I think that the Girdraulic adds a major variable when trying to achieve maximum brake performance. When added to all the other variables, it is a steep hill to climb.

David

 

[Monkeypants]

Thanks David.
I havent checked for front end going rigid when braking at very high speed. I shall try that in the new year.
Here is an old video I made in response to a claim that Vincent brakes are completely ineffective.
If you ignore my silliness, I think it can be seen that the front end compresses nicely and transfers a lot of weight there. Is it possible that with the girdraulic setup the suspension lock up only occurs with some bikes and not others?

 

[fogrider]

Interesting comments, from experience too. I have a magazine compilation of (British) sports model road tests. 25 bikes of the fifties and sixties plus one BMW R69. Bearing in mind my Highway code is early 90's - it states braking distance from 30mph = 30 ft.
Nearly all the bikes tested rated 29 ft, except the Vincent Black Shadow at 22.5 ft and a Comet 22ft. Only the BMW exceeds at 20ft but which has an 8" full width drum. Good engineering Erik !
Most of the 29ft brakes were considered by the testers to be good or excellent - which puts the Vincents in the better than excellent bracket, so as Monkeypants says, why are'nt they all now ?
The Black Shadow is JRO 102 and was tested when new, no wear or neglect ? Or factory selected bits, who knows ?

Years ago, I fitted an equivalent of Mintex M24 to my sons touring twin. Turned to size, but no other mods ( though it does have alloy back plates).
Those linings were very expensive, Questmead in the Bradford area. The guy told me to ensure they were properly bedded in and that the heat cycles were most important. I followed his instructions and they are damn good brakes.
I'm sure the racers on here know more about the heat cycle process. Questmead even offer to do that to the linings before delivery - extra cost, err....no thanks !
I rang them recently and they no longer do that material and recommended something else. Maybe in the spring I ought to shell out for their alternative. Maybe.

 

[erik]

the problem is of you have a modern ABS brakes car infront of you .The road test from the 90th is history. More than 30 years ago there was less traffic in every corner of our country .Maybe in Britain it is different ? And I know the brakes of the earles forked BMW. In modern traffic here in Germany it is very inferior.Erik

 

[fogrider]

Back to the origins of this discussion - Trevor Southwells adviser concluded a mod was required to move the pivot 1mm up towards the cam to even out lining wear. I've been pondering about this and it's occurred to me that the reason the pivot end of the linings wear more than the rest is, simply ,because the pivot end touches the drum first. A hard brake application puts all the lining in contact pretty well all at once, but, trailing the brake, or light braking , which is routine road riding, ( eg for corners or traffic issues) , the pivot end is rubbing the drum whilst the cam end has'nt fully made contact. If that's a sound assumption, there is no point whatsoever of moving the pivot point 1mm, 2mm or whatever because the shoe still rotates about the pivot making that end of the lining take more wear.
Seems logical , is it ?

 

[Peter Holmes]

I know it is very easy to say, but don't you just ride accordingly, even if I am following at a sensible distance I still try to make sure that I am not centrally behind the vehicle in front, thereby keeping my escape route clear should I need it. I continually see drivers in modern cars with superb braking systems, driving so close to the vehicle in front that even if their car could stop on a sixpence as we used to say, and their reflexes were on a par with a Formula1 racing driver, they would still be ploughing into the rear of the vehicle in front.

 

[Peter Holmes]

I definitely think the brake linings are a major factor in braking performance, for a good few years I was using the so called faulty manufacture alloy brake plates with all the wrong dimensions, possibly Slater, without a doubt the best brakes I ever had, but when they eventually wore out the difference in thickness of lining material was very obvious to see, one shoe end down to the rivets, and the other end with a considerable amount of lining material left, so obviously they had to be replaced, but as I previously stated, the best front brake I ever had.

On the other hand a few years ago I had some work done by a well known Vincent specialist that involved relining the brakes, I was told at that time that the lining material used also was also used on milk float brakes, after using the brakes for a while I can see why!