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do you have brake shoes to fit them or do you still have to make them?

... & are you going to line them with steel hoops or do the brake shoes ride on the aluminum hub directly?
 

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Discussion Starter #8
do you have brake shoes to fit them or do you still have to make them?

... & are you going to line them with steel hoops or do the brake shoes ride on the aluminum hub directly?

This is only semi-finished products. 10 days after the completion
 

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Oh :) then I can't wait to see the finished product.
You should consider making a larger, lighter axle and fit it with bigger bearings, looks like you have the room for it and that would reduce the need for a fork brace.
 

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As this is a vintage racing forum - Your brake is illegal for any form of racing.

Also it is weak from the hub centre toward the drum. Billet aluminium either heat treated or none treated is not ideal for drum brakes, you would be wise to cast (irregular grain). What it the drum material? Are the brake drums cast in or a shrink fit and then pegged?
 

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it does look cool
that would be a shame if it didnt expand and maintain roundness because of the billit material's uni-directional grain
back in the late 70/s when i was relining drums for bultacos mostly i used diesel cylinder sleeves sourced from the local scrap yard
its a lovely fine grain form of cast iron machines very nicely,gripped the brake shoes with authority as well
 

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Judging by the number of vent plates I guess you are going to produce a good number of these? And that your post is some sort of low key advertisement? Well lets hope your well insured or perhaps you are too far away to care..........

290mm for a drum brake is far too big, there's a very good reason why Ceriani, Oldani, CMA, Seeley, Robinson never made a brake bigger that 230 (9") only Fontana built a 250. Its not the brake efficiency that the issue its the brakes internal stress, the movement / flexing of the brake plates and worse of all its the gyroscopic forces generated by a brake / wheel that size - Those forces will fight the rider when they try to turn the bike and if they are unlucky and get the front end airborne it will not want to come down again and can pull the bike one or the other.

Photo - Imola, Rivazza a fast corner following a 700mtrs decent of straight ish track on which a good twin can top 125mph. Would you trust your life on the brake above? Or on cast Magnesium 250 Fontana that will still stand a bike on its nose after 3 laps of the Isle of Man and fitted to the bike pictured? Rivazza has about 40mtrs of run off, a little kitty litter then mostly grass or rather just enough time to kiss your arse goodbye.
Triton Imola 1.jpg
 

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How big was the Yamaha TD/TZ front drum brake? They were huge and heavy and were used for years. Replaced by RD350 disks, but that's not the point.
 

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Same point applies. Too big too heavy too much brake.

Not that long ago there was a Triton build featured on this site. The front brake was a replica Ceriani made in Italy (couple of brothers), one of those was purchased by a client and handed to me to build into his Featherbed special.

The brake was a steaming pile of crap. The brake cams were mild steel and not hardened, both wheel bearings were a loose slip fit in the hub and there was no lead on any shoe so brake would have been very grabby. The levers were cheap pressings in a very soft alloy and the threaded linkages were sloppy in the clevis link threads. Whilst sorting the bearing fit I clocked both drums and they were between 10 and 15 thou eccentric to the bearing seats but the drums were actually round!!! I then noticed that the drums linings were varied thickness by guess how much? Between 10 and 15 thou. My point is - When I tried the return this steaming pile they wouldn't take it back, so I had to sort it out, another £600 later, machining for new bearings and spacers, sort the drums, clevis parts and set up the brake it is now good but add the sort out cost to the purchase price and he could have got something race quality!

It like buy shit tyres and expecting to go racing - when you need them to stick they won't, its just not worth the risk. Buying Brembo is one thing but buy from an unknown half way around the world is something else.
 

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260mm

Correct it weighs a tonne and not very good. Helped keep the front wheel on the floor though!

- - - Updated - - -

How big was the Yamaha TD/TZ front drum brake? They were huge and heavy and were used for years. Replaced by RD350 disks, but that's not the point.
260mm

Correct it weighs a tonne and not very good. Helped keep the front wheel on the floor though!
 

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Discussion Starter #20
Judging by the number of vent plates I guess you are going to produce a good number of these? And that your post is some sort of low key advertisement? Well lets hope your well insured or perhaps you are too far away to care..........

290mm for a drum brake is far too big, there's a very good reason why Ceriani, Oldani, CMA, Seeley, Robinson never made a brake bigger that 230 (9") only Fontana built a 250. Its not the brake efficiency that the issue its the brakes internal stress, the movement / flexing of the brake plates and worse of all its the gyroscopic forces generated by a brake / wheel that size - Those forces will fight the rider when they try to turn the bike and if they are unlucky and get the front end airborne it will not want to come down again and can pull the bike one or the other.

Photo - Imola, Rivazza a fast corner following a 700mtrs decent of straight ish track on which a good twin can top 125mph. Would you trust your life on the brake above? Or on cast Magnesium 250 Fontana that will still stand a bike on its nose after 3 laps of the Isle of Man and fitted to the bike pictured? Rivazza has about 40mtrs of run off, a little kitty litter then mostly grass or rather just enough time to kiss your arse goodbye.
View attachment 78793
This is not an ad, I and my friends modified with a motorcycle. I am in China, send pictures just want to communicate with everyone.
 
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