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Wider swinging arm for Slimline Featherbed

Norton Models (not Commando or P11)

Wider swinging arm for Slimline Featherbed

Postby laurentdom » Sun Jul 09, 2017 8:44 am

Hi All,

I'm looking for a wider (at least 15 millimeters) than standard swinging arm allowing me to use e.g. a 400 x 18 Bridgestone Battlax BT45 rear tyre.

Of course the swinging arm pivot must be the same length as the standard one.

Have you ever heard of a supplier of that sort of thing?

Thks and regards,

Laurent
1960 De Luxe Featherbed chassis + 1972 750 Commando engine
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Re: Wider swinging arm for Slimline Featherbed

Postby lcrken » Sun Jul 09, 2017 12:07 pm

I have an oval tube swinging arm on my wide line featherbed that I got from Mick Hemming some decades ago that allowed me to run a 130/70 x 18 Avon race tire that is 5 1/8" wide. Bridgestone don't list a 400 x 18 BT45, but their 130/70 x 18 is listed at 5.0" wide, so it, or anything narrower, should fit.

This is not a great picture, but it does show the swinging arm.



Before the Hemmings swinging arm, I used one that Dresda used to sell, using rectangular section tubing. It also would accommodate a wider tire than stock, but I liked the Hemmings design better, so sold the Dresda and switched.

I don't know if either of them still makes swinging arms, but it might be worth checking.

Ken
Last edited by lcrken on Mon Jul 24, 2017 8:57 am, edited 1 time in total.
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Re: Wider swinging arm for Slimline Featherbed

Postby laurentdom » Sun Jul 09, 2017 11:46 pm

Thanks a lot for those details Ken.

My tyre is really a 4,00 x 18 BT 45 (and stamped like that). I got it a month ago from a german website (123pneus).

Hence in theory, it's width should be 101,6 millimiters but it is in fact 124 millimeters and that gap is the reason why it does not fit on my bike (Slimline featherbed with fully enclosed - DeLuxe type- rear chain).

Have a nice day.

L.
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Re: Wider swinging arm for Slimline Featherbed

Postby laurentdom » Mon Jul 10, 2017 12:32 am

Some more details:

124 mm is the width of tyre non-inflated / non fitted on the rim. It may differ when inflated/fitted but will still be more than 4 inches.

L.
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Re: Wider swinging arm for Slimline Featherbed

Postby lcrken » Mon Jul 10, 2017 8:58 am

laurentdom wrote:Thanks a lot for those details Ken.

My tyre is really a 4,00 x 18 BT 45 (and stamped like that). I got it a month ago from a german website (123pneus).

Hence in theory, it's width should be 101,6 millimiters but it is in fact 124 millimeters and that gap is the reason why it does not fit on my bike (Slimline featherbed with fully enclosed - DeLuxe type- rear chain).

Have a nice day.

L.


Interesting. I didn't mean to imply that you didn't have a real 4.00x18 tire, just that I couldn't find the width for it in the current listing. The Bridgestone web site I was looking at for motorcycle tires only lists BT45 tires in metric sizes, but it was the North American web site. I just looked at the international Bridgestone web site, and it does include a 4.00 x 18 BT45 rear tire. It lists it as 119 mm in width when installed on the recommended 2.15 rim. The international site shows one other inch size BT45, a 3.50 x 18 front. Apparently the NA distributor doesn't think we would be interested in their inch size tires. In any case, it would fit either of the swinging arms I mentioned above.

The BT45 makes a great street bike tire. I've run them on several bikes, and liked them a lot. Good traction but also reasonable mileage.

Ken
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Re: Wider swinging arm for Slimline Featherbed

Postby norton bob » Mon Jul 10, 2017 9:14 am

THe standard swing arm will not accept a tyre bigger than 3.50 in the 19 inch size, an 18 inch may gain a fraction more but it is the chaincase mounts that get in the way.

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Re: Wider swinging arm for Slimline Featherbed

Postby laurentdom » Mon Jul 10, 2017 11:57 am

You're right Bob.

My previous tyre was a 4.00 x 18 Metzeler Lasertech which was OK size-wise, but I had to rework a lot the chaincase mounts to achieve that.

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Re: Wider swinging arm for Slimline Featherbed

Postby robs ss » Mon Jul 10, 2017 4:32 pm

Ken McIntosh in NZ sells a swingarm which might suit your requirements.
It states:
100-400 - Oval tube Swing Arm $435NZD

Oval tube Swing Arm. Similar to 1954 works bikes. Bare. This allows the use of wider tyres. Appearance almost the same as original taper tube type. Highly recommended for improving the choice of suitable racing tyres. i.e. Avon 120/80 x 18".

You could use this link http://www.manxnorton.co.nz/catalogue/c ... =2&p_id=10

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Re: Wider swinging arm for Slimline Featherbed

Postby chris plant » Tue Jul 11, 2017 2:58 pm

hi all,i bought a swing arm from mick hemmings a long time ago,its not oval tube,its round,it will accept a 130x18 tyer,its a bit longer than a std swing arm,its got taper roller bearings in it,it has the brake anchor as per wideline ,and no fittings for a chain guard,rear chain adjusters are as per wideline manx? chris
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Re: Wider swinging arm for Slimline Featherbed

Postby madass140 » Wed Jul 12, 2017 3:30 am

Image
Of no use to you whatsoever, but these are the ones I produced some time ago, I wont be doing them again, sorry.
mylasttriton.jpg[img]mylasttriton.jpg[/img]
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Re: Wider swinging arm for Slimline Featherbed

Postby marinatlas » Wed Jul 12, 2017 4:50 am

Hi Don, yes I think I had bought one from you may be 10 or 12 years ago (more??), and may be an alloy chainguard too ........still running on my Atlas, nice !
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Re: Wider swinging arm for Slimline Featherbed

Postby acotrel » Tue Jul 18, 2017 2:28 pm

I think you are kidding yourself. If your slim-line frame is genuine, you might do better by looking for good 19 inch racing tyres in the sizes used on manxes in the late 50s, and set the bike up to have the same wheel sizes and steering geometry and rear suspension. When I was racing my short stroke Triton, I changed from 19 inch wheels to 18 inch to get good rubber onto the bike. It completely stuffed the handling and made the bike exhausting when ridden fast. If your frame is a replica with 26 degree head angle 18 inch wheels would suit it, so go for the wide swing arm. But if it's got the standard 24.5 degree head angle, forget it.
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Re: Wider swinging arm for Slimline Featherbed

Postby Bernhard » Sat Jul 22, 2017 4:08 am

If you just want a swinging arm company’s like Dresda e.t.c. would make you one-I don’t mean their box section ones. I had a s/arm modified for me 20 years ago, but I am not sure if Dave would do it now.

http://www.dresda.co.uk/parts.asp?filter=chassis

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Re: Wider swinging arm for Slimline Featherbed

Postby acotrel » Sat Jul 22, 2017 2:38 pm

The only featherbed swing arms I've seen which would accommodate a wider tyre were made out of oval section tube. The width between the rear frame tubes limits what can be used.
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Re: Wider swinging arm for Slimline Featherbed

Postby lcrken » Sat Jul 22, 2017 5:37 pm

acotrel wrote:The only featherbed swing arms I've seen which would accommodate a wider tyre were made out of oval section tube. The width between the rear frame tubes limits what can be used.


As I mentioned above, the one I bought from Dresda used rectangular section tube, which was narrower than the stock swingarm, and would accomodate a wider tire. It used some very small diameter tapered roller bearings at the pivot, that just didn't seem sturdy enough to me. I did use it for a while on the race bike with no problems, but I was happier with the Mick Hemmings replacement. It was, in spite of my unreliable memory, made from round tube, not oval, but still had enough clearance for the 130/65-18 Avon race tire I used.

Ken
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