Author Topic: Can someone please educate me on belts?  (Read 529 times)

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Offline Tim OConnor

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Can someone please educate me on belts?
« on: 30 Aug 2022 at 21:36 »
My 1920 W-20 came with a solid belt. A friend pointed out that it was a modern industrial belt.

I noticed in many of the photos of the belt driven bikes that the bikes have "link-belts".

I ordered a Brammer belt from Veteran Triumph Spares.

Then last week while going through the excellent book "Two Wheels To War" an old ad for a Dunlop Belt Fastener! From what I can tell this is for a SOLID V-belt. Is that correct??

I checked my bike and it indeed has a Dunlop Belt Fastener just like the one in the ad!

So..

Should I be using a solid V-belt or a Brammer Link belt??

« Last Edit: 31 Aug 2022 at 02:49 by Doug »
1920 2 3/4 W-20

Offline cardan

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Re: Can someone please educate me on belts?
« Reply #1 on: 31 Aug 2022 at 10:24 »
Hi Tim,

In the later history of belt drive motorcycles in the UK (1910-mid 1920s) most belts were "solid" V belts with a joiner. There were exceptions - a very complicated and expensive link belt by Whittle for example - but most makers built pretty ordinary V belts, albeit with their own features (canvas, rubber, strengthening, etc), and joiners too.

In the US, flat belts were most common and chain drive came in much earlier - almost universal by the mid teens.

I don't know when the Brammer-style "link" belt became popular in the UK, but it was in the "restoration age": i don't think it was around in the period when belt-drive bikes were new?

These days you have a choice of belts, but as usual nothing is easy.

1. Modern industrial V belts, available in a huge range of sizes, are fantastic. If you have a frame with removeable seat stays, an endless V belt is a game-changer. If you can get exactly the right length it will run smoothly, never slip, and last forever.
Beware, however, cutting an industrial belt and fitting a joiner. Modern belts often get their strength from a kevlar (?) "rope" that runs through the belt. There is no strength in the belt to support the screw that fastens the belt clip, and it will pull out. Old belts used multiple layers of canvas.

2. You can/could buy cut-to-length V belt designed to take a fastener: we bought some fabulous stuff out of the USA about 20 years ago and I'm still using it. The UK version was green "vari rope". It was always rubbish and wore quickly, but was useable.

3. The final possibility is the "link belt". The Brammer version often used in the UK looks pretty good and seems to work OK, but some of the other versions are brightly coloured and plastic-looking, but seem to work OK. Personally I don't like the look...

If your frame unbolts, and you want to ride the bike, I recommend a modern V belt of the appropriate width and length. Cheap and trouble-free once setup. If you have a transmission specialist in town, they can help to determine the correct belt.

Leon

Offline Tim OConnor

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Re: Can someone please educate me on belts?
« Reply #2 on: 31 Aug 2022 at 11:14 »
Fantastic info! Thank you!

Do you have any part numbers or sources for that US belt that seemed to work well?
1920 2 3/4 W-20

Offline cardan

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Re: Can someone please educate me on belts?
« Reply #3 on: 03 Sep 2022 at 03:53 »
Sorry, no... lost in the mists of time. It was bought on a large roll - maybe 100yds - and was black, and "C section" or 7/8" across the top. That was 20 years or so back - let me guess it is no longer available.

Leon

Offline eddie

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Re: Can someone please educate me on belts?
« Reply #4 on: 03 Sep 2022 at 07:22 »
Tim,
        As yours is a 1920 machine, you should be able to unbolt the lower end of the upper stay of the rear of the frame and fit a modern endless belt. It's only on the veteran machines that you need a belt with a joining link.

   Regards,
                 Eddie.

Offline Tim OConnor

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Re: Can someone please educate me on belts?
« Reply #5 on: 03 Sep 2022 at 12:13 »
Great! Any sources or specifications?
1920 2 3/4 W-20

Offline ian scott

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Re: Can someone please educate me on belts?
« Reply #6 on: 10 Sep 2022 at 23:07 »
Iíve used a modern endless belt on my 2&3/4 for years. Itís called Opti Belt. It slipped a few times initially but softened up or bedded in quickly. Itís given many miles of trouble free transmission. Photo attached showing identifying details.

Offline ian scott

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Re: Can someone please educate me on belts?
« Reply #7 on: 10 Sep 2022 at 23:13 »
And to add to my post. I started with a brammer style belt. It was terrible. It slipped lots and stretched regularly. I was often removing links. Plus it needed lots of tension not to slip. I was worried about the load on the gearbox and wheel bearings. The endless belt doesnít need that kind of excessive tension.

Offline Tim OConnor

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Re: Can someone please educate me on belts?
« Reply #8 on: 11 Sep 2022 at 12:25 »
Thank you!
1920 2 3/4 W-20

Offline graeme

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Re: Can someone please educate me on belts?
« Reply #9 on: 13 Sep 2022 at 07:48 »
Hi Tim

The critical mark you need reference to is C 79 - this means a C section belt that is 79 inches long. Any stockist of industrial belting should be able to help you here.

Cheers, Graeme

Offline ian scott

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Re: Can someone please educate me on belts?
« Reply #10 on: 13 Sep 2022 at 09:49 »
.

Offline Tim OConnor

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Re: Can someone please educate me on belts?
« Reply #11 on: 13 Sep 2022 at 11:18 »
Thank you very much!

1920 2 3/4 W-20