H: Hubs, Wheels and Tyres Trevor Southwell re brakes

[Cyborg]

Sounds like you know your beast.

Well… whenever I feel like I‘m starting to get everything straight in my head, something will pop up that proves me wrong. A continual learning process. Then there are the times when I wish I had continued with a detailed thread so I could refer back to it during the frequent times I can’t remember what the hell I did.

I think I’ll add a triangular bracket to support the balance beam. It’ll look period correct more or less…. at this point I’m talking lipstick anyway. I was surprised at how much and how easily it moved. Not like I was experiencing an adrenaline dump and applying a lot of force. The stock fender with a front stay would reduce the flex in the FF32 to a degree. I’m far from being knowledgeable about brakes… that’s David’s department, but if I had to pick one thing off the shelf to improve the brakes, it would be a set of Neal’s shoes.

 

[davidd]

The 90 degrees that I was speaking of is simply tracing how much of the 360-degree circle each shoe lining covers. That would have been a calculation that Vincent or Irving made. The cast in the dips prevents a brake reliner from covering the ends which could potentially degrade the braking. I would not discourage anyone from experimenting with this, but I think most folks want to do it for the increase in surface area, which doesn't work. I intend to use milled linings as the RD-4 linings are available in grooved versions. Dick Hunt in the UK suggested that he always used grooved lining on the racers. The lining tends to shed so much dust it is best to evacuate it. It will improve the performance as the lining will be warmer and it will not be riding on the small bits of lining that are being shed.

If you want any of the sources I use for information, just send me a PM.

David

 

[fogrider]

Thanks David. I understand the 90 deg coverage, on all the shoes I have, the grooves make space for a 5.25" lining, I reckon that on the drum surface that equates to some 86 degrees. Close enough. I just think the same linings would be better moved up the shoe so the effort of the cam is better applied, that is what appears to be required from the design layout I saw - it was in a vehicle engineering and design text book in our main reference library. That related to the location of the linings on the backplate , rather than the percentage of lining coverage.
The bike is off the road for the winter months and has quite a few bits off at the moment- rocker bushes to replace, clutch needs work, gearchange bushes, but I will have the brakes ready for assessment by late spring I'm sure.
If it works, it works, If I'm prove wrong , it was an interesting try !
Regards all, Terry.

 

[vibrac]

the way David does it, is certainly the best and a real winner! (Ben and Josh)

 

[Monkeypants]

I mentioned that my Rapide brake is stock other than the cables, which are Teflon lined very heavy custom cables from Venhills. I forgot to mention that it also has the alloy Lightning style brake plates and finned Shadow drums. So not really stock at all.
I'm sure the weaknesses in braking would show up in racing, but for a roadbike it works really well.
We've only had to test the panic braking once and it almost outstopped the riders.
We were traveling west on a old Northern California 2 lane highway at 70 mph, came around a gentle bend and there was an old Ford pickup pulling out of a hidden driveway. The driver saw us just as we were about to smack into her. She did the very worst thing possible, she stopped the truck with it sitting right across our lane. There was oncoming traffic so the other lane was not available, even if I had been able to make that adjustment in time.
I hit both brakes hard and we came to a stop just five or six feet from her door!
I could see a look of horror on her face.
I ended up sitting well forward up on the tank with my legs hooked behind the bars. Gina slid forward into the rider's position. Our legs weren't strong enough to hold us back against the braking forces.
That was pretty impressive braking. My Norton Commando with its stock front and rear disc brakes would not stop that quickly. It might nowadays as I replaced the stock front brake with huge 6 piston 340 mm unit. That stops!
The Vincent front brakes came to me with one green lining and one red lining on each brake. John Mcdougall suggested that was just someone using up old parts, however I found information on the red and green linings in an old MPH. Iirc the red lining works very well even when completely cold whereas the green lining likes a bit of heat.
Eventually those linings wore out and I assumed my days of having great brakes on that bike were over.
I had some new green Ferodo linings on the shelf. These had been purchased at Vintage Brake in the US a few years earlier. I had them bonded onto the old shoes and I think the brake is just as strong as before. I arced them in with stick on emery and also touched up the drums using the stick on emery the other way around. That got rid of all pulsation. For some reason with the new linings in place strong brake pulsation showed up where there had been none of that before. Arcing the linings did not help, the problem was in the drums. It wasn't difficult to fix.

Glen

 

[vibrac]

I found the Questmead receipt for the Mintex M24 equivalent - they called it 242. Expensive, but my sons' touring twin will chirp its front tyre with modern Bridgestones on it. ( If need be ). I think my B twin will be wearingreturn it next year.

I asked my favourite lining people (the lightning fast return Saftek) and their M24 equivalent is BRN

 

[fogrider]

Do I need to make one of those well known statements like - " this procedure is at your own risk and no liability is held etc etc " !