Another drum query

acotrel said:

Acebars, a friend uses two 8 inch Triumph hubs, back to back, on his 650 Triton racer. The weight is not a problem. I appreciate what you are saying about the weather affecting the brakes. My comment was only relevant to places without extremes. In that situation a mediocre disc brake is far superior to any drum brake. If a disc brake ever drags, simply apply rubber grease to the seals.

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To Acotrel;
I understand your comments, but here in good old Blighty where a lot of road salt is dumped over the tarmac in winter, merely greasing the seals is not a cure in itself, as the salt/road crud gets into the seal groves as well, which also require cleaning out thoroughly and the seals replaced, they tend to stretch after prolonged use with brake heat.

acotrel said:

Acebars, a friend uses two 8 inch Triumph hubs, back to back, on his 650 Triton racer.

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Can I ask if he's got them setup on a pair of roadholders? And if so how he did it to match the road holder leg with the Triumph plate?

You could always give Dave Degens a call

http://www.dresda.co.uk/

He has done loads of conversions, Triumph TLS into Norton drum etc

This isn't relevant, but my Norton SLS brake is great!

The twin Triumph brake is fitted to ordinary manx roadholders. I'm presently in Kyneton, I've got a pic of his bike at home. I will post it after the weekend. I think he uses two 1955 type backing plates. you still have to tighten the brake to one side.

I'd really appreciate that, thanks acotrel.

I'm fairly certain the brake is two 8 inch Triumph drums, back to back with an aluminium spacer between them :

Thanks Acotrel a fascinating idea, although it's a little difficult to tell from the photo you've shown.

I understand these are two pre-unit 7 inch hubs bolted together with an aluminium spacer between them (I can find no such 8 inch drum)? Such as the image below.

This setup will give according to the tables just around the same braking as the Suzi 4ls.

I have looked at some pre-unit hubs and the price is horrific, I could easily buy a suzi 4ls drums for the same price as 2 or 1 pre-unit hub



Seems like the Triumph 2ls is the best bang for buck of all of them.

When I first started racing my 500cc Triton, it was fitted with a Triumph GP brake similar to the one in your pic, except that it had an extra fin outside the spoke flange. In my very first r ace , I reached the end of the front straight at Calder raceway, and couldn't stop the bike. I had a very strong grip on the lever, and when the linings finally heated up and worked, I was shot over the front of the bike at high speed. I slid on my back across the corner and into the escape road. One good thing came out of it - my sons were 6 and 8 years old and watched it happen, so they never raced motorcycles. And I didn't have to watch that and worry! My oldest son later owned a Kawasaki ZXR750. I asked him only once 'You've never thought of racing ?'. He answered ' NO - we saw what happened to you ! '

Just for a bit of amusement , I thought I would post this photo. It was taken at Phillip Island in about 1967. I'd fallen off at about 90 mph onto the non-skid, in the previous race, after the Triumph brake locked. That day I fell off four times, but kept getting back onto the bike - my record ! :

This is how you are supposed t o do it ! :

Acebars said:

This setup will give according to the tables just around the same braking as the Suzi 4ls.
.

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Wasn't the Suzi 4LS brake renowned for its sometimes savage action ?
If you are going ice skating with it, a disc would be for more predictable ??

Those back-to-back Triumph brakes/hubs would weigh a ton ?

For what it's worth I reckon a decent disc brake would be much better and far safer than the best drum. Surely in the UK they have managed to come up with a UK road proof disc?
When I had my 650SS with the standard 8"SLS front brake, which had had the drum and brake linings skimmed, so it was as good as could be achieved, there were two occasions when I was almost in deep trouble. One time the boss and I were touring in Cornwall, loaded, two up, panniers, tank bag camping gear etc. Rolling down the hill into Lynmouth there was a loooong tailback of traffic, so I was gently rolling down the long but not particularly steep hill on the outside of the tintops. Third gear, throttle closed, then second gear with just a dab of front brake, then with a bit of back brake, then the front brake lever was into the twist grip, we were only doing about 15 or 20 mph at this stage, but it wouldn't go any slower. Approaching a T junction, where I HAD to stop, standing on the rear brake, front brake into the twist grip, first gear, really I don't want to repeat that. Fortunately the at the junction there was room to squeeze into the side of the road and run it up the grass bank, but that was pure luck. This little crisis came out of nowhere. The next thing on the upgrade list was a disc brake! Bugger originality.
What I'm trying to say is that drum brakes fade, and you end up with no brakes. Don't think that the back brake will help, they only do about 25% of the braking effort. On a road bike, for the sake of your neck (literally) you need a good reliable front brake that will not lock up, grab, or fade.
cheers
wakeup

Acebars said:

Thanks Acotrel a fascinating idea, although it's a little difficult to tell from the photo you've shown.

I understand these are two pre-unit 7 inch hubs bolted together with an aluminium spacer between them (I can find no such 8 inch drum)? Such as the image below.

This setup will give according to the tables just around the same braking as the Suzi 4ls.

I have looked at some pre-unit hubs and the price is horrific, I could easily buy a suzi 4ls drums for the same price as 2 or 1 pre-unit hub

Seems like the Triumph 2ls is the best bang for buck of all of them.

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this is vewry intresting :!:

wakeup said:

For what it's worth I reckon a decent disc brake would be much better and far safer than the best drum. Surely in the UK they have managed to come up with a UK road proof disc?
When I had my 650SS with the standard 8"SLS front brake, which had had the drum and brake linings skimmed, so it was as good as could be achieved, there were two occasions when I was almost in deep trouble. One time the boss and I were touring in Cornwall, loaded, two up, panniers, tank bag camping gear etc. The next thing on the upgrade list was a disc brake! Bugger originality.
What I'm trying to say is that drum brakes fade, and you end up with no brakes. Don't think that the back brake will help, they only do about 25% of the braking effort. On a road bike, for the sake of your neck (literally) you need a good reliable front brake that will not lock up, grab, or fade.
cheers wakeup

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re;" which had had the drum and brake linings skimmed"

Sorry, but this is maybe an improvement on the brake, but nowhere near the ultimate standard fitment front stopper for a Norton. "0r any Brit bike"
In an ideal world you need both the drums skimmed, the brakes fitted with oversize linings, the general constants of opinion is one green and one brown on the front, all brown on rear. Then with a .020 shim fitted under each brake flat that rests on the pivot pin, skimmed down to the exact inside diameter of the brake drum. File a 30 degree lead taper on the lining to stop them grabbing.
Standard drum brake linings when replaced “from the box brought over the counter,” across the broad in the motorcycling world of practically all marques do not fit the wheel brake drum, have to be spaced out to get the linings within .020 thousands of an inch of the drum.
I had an Atlas with a Tickle 2LS done with green linings for racing and, being a bit of a demon breaker at the Brands Hatch hair pin, was not out braked on the track in the 1970s. I obviously wouldn’t say that now, four pot calipers have a servo action, six pots even more.

wakeup said:

For what it's worth I reckon a decent disc brake would be much better and far safer than the best drum. Surely in the UK they have managed to come up with a UK road proof disc?
When I had my 650SS with the standard 8"SLS front brake, which had had the drum and brake linings skimmed, so it was as good as could be achieved, there were two occasions when I was almost in deep trouble. One time the boss and I were touring in Cornwall, loaded, two up, panniers, tank bag camping gear etc. Rolling down the hill into Lynmouth there was a loooong tailback of traffic, so I was gently rolling down the long but not particularly steep hill on the outside of the tintops. Third gear, throttle closed, then second gear with just a dab of front brake, then with a bit of back brake, then the front brake lever was into the twist grip, we were only doing about 15 or 20 mph at this stage, but it wouldn't go any slower. Approaching a T junction, where I HAD to stop, standing on the rear brake, front brake into the twist grip, first gear, really I don't want to repeat that. Fortunately the at the junction there was room to squeeze into the side of the road and run it up the grass bank, but that was pure luck. This little crisis came out of nowhere. The next thing on the upgrade list was a disc brake! Bugger originality.
What I'm trying to say is that drum brakes fade, and you end up with no brakes.

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It's not clear how you got the brake hot there. I have managed to make my SLS fade, but it really took hard braking from 90mph at every bend from the Mountain Mile to the Bungalow.

In road racing drum brakes and pudding basin helmets killed a lot of guys, however they both looked really great. What is your priority ?
My Seeley 850 has two Lockheed calipers fitted with asbestos pads, a nice fast torquey motor, a close box, and it is very light. I can outbrake anyone else very safely, and get back on the gas instantly without necking myself. Did you know that if your brake drags, the bike becomes stable, and can steer itself off into the boondocks ? I ended up dodging trees at one race meeting. Even in historic racing t he option to use at least a single disc on the front should be allowed, guys getting killed will kill our sport. If I had my way drum brakes would be banned.

Bernhard....With the exception of the different linings the front brake was as you described, it was set up by Joe Dunphy (as I remember) who at the time had a service doing exactly what you described. It was a good brake, very powerful and smooth, but it would fade. It would pull up beautifully from 90mph....once, then it needed a couple of minutes to cool down.
Triton Thrasher .... The bike was pretty heavily loaded, the hill was very long, and I was cruising down, initially braking gently, just trying to maintain a reasonable (slowish) speed. The hill was too long, the bike was too heavy, the brake got too hot. In retrospect, had I known the road, I would have been in second gear with my speed down to a fast walking pace far earlier. However I didn't know the road, so I had no idea how long the downhill bit was, or that there was a "T" junction
In general use it was an excellent brake, very controllable and quite powerful. With the bike loaded, downhill, the brake simply could not dissipate the heat. My point was that sometimes the road rider can encounter situations that the racer does not. For that reason I would suggest a decent disc brake.
cheers
wakeup

Wakeup, you are so correct. I don't know what the discussion is about on this topic, some people just will not be told !
Riding a motorcycle is extremely dangerous if you cannot grab a handful of front brake with impunity. Disc brakes have no self-servo and they are much safer than any drum brake, even if the master cylinder ratio is wrong. The dual discs on my Seeley 850 only require the same light touch that my 7R AJS used to require for strong braking , however the difference in safety is extreme. My only really damaging crash in road racing came when I was a bit out of practice, and put only the slightest amount too much pressure on the drum brake to avoid hitting another idiot. Seriously, it was actually a 'near death experience ', and not something I can ever laugh about. The bloke that caused that incident is still around and he stays well away from me when I'm on a motorcycle. When you destroy a helmet that is very serious, and I haven't forgotten.
I think there is a tendency to look at old motorcycle road racing footage with a level of scorn, however a lot of bloody good riders were killed in the old days through machines, equipment and circuits which were simply unsafe - the risks had not been minimized to a tolerable level. There is a thing that happens in car racing in Australia. Some guys race cars from the thirties and a couple of them have simply fallen over. One killed the driver. I suggest it is a matter of priorities - should we try to recreate the past by using something simply because it looks good, and kill people in the process ? Some of that old crap should simply be in museums.

In road racing drum brakes and pudding basin helmets killed a lot of guys, however they both looked really great. What is your priority ?

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Not racing them and looking great? :lol:

I think I've decided on the suzy 550 4ls after all, also gives me a wider variety of clocks to choose from either on the rear British ratio or front Jap ratio.

I know you guys are right, I'm not debating it, discs are superior in every way other than looks, but I must make it clear I am not racing the bike otherwise I would not hesitate to mount an 80s or more modern dual disc setup.

I imagine the way I will use the 4ls will be more than adequate with the stopping power there only if I need it should some situation arise.

The only other option I can think of are those cover you can put around your disc brakes that make them look like a drum, forget where I saw that.

P.S. Pudding basin helmets are really great around town, so easy to pop on and off! 40mph max though imo!