Slimline Featherbed Landspeed Racer Build

lcrken

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Hope I'm posting this in the right sub-forum. I'm rebuilding my landspeed Norton, and replacing the wideline featherbed frame with a slimline. The wideline is going to end up as a street bike.

First step was checking the frame for straightness. I measured the rake some time ago at 24°, but the stock rake for all featherbeds is 26°. I learned on the forum that featherbeds are very prone to bending at the steering head, so mine needed some straightening. I checked the front down tubes with a straight edge, and they were clearly bent near the steering head. This is the setup I used to bring the rake back to 26°'





The upright post is an old fork tube with a plate welded to the bottom and machined in the lathe to be flat and perpendicular to the post. It's bolted to the steel table. A small hydraulic jack under the rear cross member provides the force, and an oxy-acetylene torch with rosebud tip brings the tubes up to an orange heat in the appropriate area. I was fortunate that it only took two tries to get it right. I also put a bar through the swing arm pivot and measured its height at both ends to ensure that steering head and swingarm axes are perpendicular. Fortunately, they were, so I didn't have to do any twisting on the frame.

I thought about raking it out a bit more for high speed stability, but didn't because I'd like to keep it close to stock for later use. I can get the same stability by using fork yokes with less offset, which will provide more trail.

Ken
 

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Fast Eddie said:
So, the 1007 road going hot rod / street beast is finished then ...

Ah well, sometimes the urge to start another project is too hard to resist. Besides, I need to have a race bike ready in time for next year's season. I missed this year, and don't plan to do that again. I am still going on the 1007, currently waiting on a 36 tooth front sprocket from Norvil, but still making small progress on other bits. I'll have another update soon.

Ken
 
The frame is now straight, cleaned up where the PO cut off lugs, and painted in my favorite Rustoleum gloss black. There are still dings and dents in the tubes here and there, but this is a race bike, so I'm not going for show finish here, just decent appearance and good rust protection. I think I'll make some bornze bushes to replace the rubber bushes in the swingarm, and then its on to assembly.



Ken
 

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Hi Ken,
Will the bronze bushes offer any handling benefits or are you making them for a different reason?

Ed
 
APRRSV said:
Hi Ken,
Will the bronze bushes offer any handling benefits or are you making them for a different reason?

Ed

I believe eliminating the possibility of swing arm motion anywhere except in the vertical plane is a good idea for high speed stability. I'm running in classes at Bonneville that have records well over 150 mph. In the early '50s, Norton switched from the rubber Silentbloc bushes to sintered bronze bushes on their Manx race bikes, and it was common practice in later years for racers to do the same. When I got interested in motorcycles in the late '60s, the bronze replacement bushes were still a popular upgrade. It may not be necessary to replace the rubber bushings, but it seems like a good idea to me, and there doesn't seem to be any downside.

Ken
 
lcrken said:
APRRSV said:
Hi Ken,
Will the bronze bushes offer any handling benefits or are you making them for a different reason?

Ed

I believe eliminating the possibility of swing arm motion anywhere except in the vertical plane is a good idea for high speed stability. I'm running in classes at Bonneville that have records well over 150 mph. In the early '50s, Norton switched from the rubber Silentbloc bushes to sintered bronze bushes on their Manx race bikes, and it was common practice in later years for racers to do the same. When I got interested in motorcycles in the late '60s, the bronze replacement bushes were still a popular upgrade. It may not be necessary to replace the rubber bushings, but it seems like a good idea to me, and there doesn't seem to be any downside.

Ken

Ken, I had wondered about solid bushings since receiving my wideline frame and swingarm and realizing the silentblocs had a rubber layer.

Any chance you might make me a pair for a fee? Otherwise, do you know if they are available from any suppliers?

Thanks,
Ed
 
Nice looking kit, Paul. The reinforcing plates that bolt onto the frame are a great touch. The swingarm pivot holes eventually get really sloppy. I fixed them on my previous featherbed frame by welding on some heavy washers, but your solution looks simpler to implent. The holes on this frame are not worn yet, and I don't expect to put many miles on it, so hadn't planned to do any mods to the frame. Might have to reconsider that.

Ken
 
A conversion kit is also available from Unity, but a bit more expensive than Paul's, and may require some fitting.

http://www.unityequipe.co.uk/



Ken
 

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Hi Ken
Like the way you corrected the rake angle, I went about straightening my 650SS frame in a different way but yours is a lot simpler, my frame also had a twist at the head, as well as damage at the rear, so was a real pain in the but to get correct.

When I rebuilt my Manx (1955 model) I modified the swing arm silent blocks to needle roller on the shaft and needle roller thrust bearings, in hindsight I should have stuck with the silentblock setup, as I was never going to out ride them, but in your case you are going a fair bit faster so need to have no movment sideways.

For my 650 SS build I bought new silentblocks but I remembered what a pig of a job it was to remove them from the Manx swing arm I left the original 1963 rubbers in place, with no ill effects at this stage, if they turn up I will replace them.

keen to see more on the progress on your build
Regards
Burgs
 
I think the stock rake on a Manx frame is 24.5 degrees - (19 inch wheels). The aftermarket frames which use 18 inch wheels often have 26 degrees rake. An original Manx handles very differently to a modern one. The Molnar-engined Manxes Ken McIntosh builds in New Zealand have original rake and wheel size.
 
I believe eliminating the possibility of swing arm motion anywhere except in the vertical plane is a good idea for high speed stability. I'm running in classes at Bonneville that have records well over 150 mph. In the early '50s, Norton switched from the rubber Silentbloc bushes to sintered bronze bushes on their Manx race bikes, and it was common practice in later years for racers to do the same. When I got interested in motorcycles in the late '60s, the bronze replacement bushes were still a popular upgrade. It may not be necessary to replace the rubber bushings, but it seems like a good idea to me, and there doesn't seem to be any downside.

Ken
When the Silentbloc bushes are replaced with bronze, the handling becomes better. You can feel the slightest flex in a featherbed at the handle bars. If you are brought up being used to it, you are usually very good in the rain.
 
A Manx with 24.5 degree rake and 19 inch wheels is very stable, but it over-steers slightly if you accelerate when cranked over. It creates a very positive safe feeling. With 26 degree rake and 18 inch wheels, the bike handles like a Suzuki - better suited to modern tyres and tighter tracks. A lot depends on your mindset - if you tend to do things smoothly and slowly, the older style is better.
 
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