Fork check springs

Were works only I believe David, 36 - 38.  No platform to adjust but maybe different ratings.  Never seen any advise on their effect on handling.  Ease of manufacture comes to mind for race equipment.    

Cheers

Jon 

Hi David/Jon,

   The works bikes first used these springs in 1936 and they were fitted to all racing spec Inters from 1937 onwards. These had a threaded top clevis to alter the tension length which gave a progressive action to the fork movement. This gave a similar effect to the normal friction side dampers, but was a constant progressive action rather than the variable movement with the friction system. The other advantage was to reduce unsprung weight.

   Riders could adjust these for individual race tracks, but this meant having to remove the clevis pin for each adjustment with the chore of lining it up to re-fit. Paul Norman of racingnorton has made new versions of these which use a top and bottom adjuster, one using a right hand thread and the other a left hand thread. This means when you undo the lock nuts and turn the spring this either shortens or lengthens the overall length with-out removing the clevis pins and can be done in a couple of minutes. I'm not sure if the works bikes used this system.

Last one I looked closely at was Ian Bains Jimmy G machine,  I didn't notice dual adjusters  Thanks for the info Richard.  I'd like a Compendium of RC's singles knowledge ! 

Cheers

Jon 

Hi Jon/all,

   Thanks for your kind comments, it's been a long learning curve. I'm not sure how much of Ian's bike is from the original machine, so probably not an accurate reference. I always try to refer to original photos as racing machines are constantly modified and up-dated. Previous to these large diameter springs the works machines used smaller diameter but still parallel and with threaded clevis ends. These were fitted from 1932 to '35. 

  I would like to get something into print before I get too old, but would probably have to self publish as I have no previous track record as an author. There is a lot of mis-information out there and this becomes the truth just because it's in print. If I did so I think the most useful would be a buyers guide as the premium prices OHC machines command has lead to a spate of bikes coming up for sale that have been assembled purely for financial gain.

Richard; may be the compendium route is not a bad starting point for publishing.  We have  some great sources within he club who could contribute specifically on this model.

I dare say a good command of English and a keyboard will also get you a long way. A bit of  collaboration and some recording sessions to consolidate the knowledge.  Its the same  conversation I has with Stu Rogers yesterday.  A wealth of information and experience, I could  talk with him for hours!  ... mostly listening and ends up an hour later depending on his dog walking needs!

A year by year development of the OHC machines in road and race form by the factory and the unique mods carried out by the specialist tuners and racers as a definitive document on the machine.   Niels Schoen did a great book on his uncle's Inter but he was a draughtsman, capturing the machine to component level with his CAD skills, Most Beautifully.  And of course  George Cohen did a great service to the Flat Tank Norton with his book.

The audience may be small but as you point out the value of the machines is high and it is easy to fall for a "wrong un".

Best regards

Jon

Hi Jon,

   Thanks for the advice, but time is a bit of an issue with an old house and old bikes all needing work. I might have a re-think in the winter, but don't hold your breath. I don't have a copy, but I think the subject in Niels book was a 1947 30M Manx and that level of input would be beyond my ability. On the issue of provenance, 2 Inters have gone through auctions this year and sold for £18k and £21K and both of which had 16H/Model 18 frames and forks, which is unfortunate for the new owners.

  Barry Stickland kindly sent me a close-up photo of the check springs on his 1937 Inter outfit fitted with racing forks. This is the outfit that featured this April's Roadholder 412. The springs in question were sold by the late Arthur Skinner about 20 years ago and feature the top and bottom adjuster with the left hand thread and Barry found this a real benefit when he was setting-up the outfit.

David,

   I checked the photo in Mick Woollet's book, and If you look closely you can see the check springs and their links. The bike is the latest 1934 works model with the magnesium alloy engine. Several racers and riders have used hydraulic dampers on these forks over the years. I have never used them myself, but it might improve the ride.

P.S. No problem with the mild sarcasm, but just putting the record straight and high-lighting the pitfalls of buying.

For what it’s worth,

I have owned 4 Commandos 7 Ducati, including 2 bevel twins and a bevel single, a myriad of other makes and finally a couple of 500T’s.

I know little about cammy Nortons other than I would like to own a pre war inter before I go.

Should I ever be in a position to buy one the first person I would call on for advice would be Richard Cornish. He was invaluable with his advice on my 1st 500T restoration when I called him a few years ago.

Keep it up Richard!

Hi all,

   Thanks for all your positive comments. Norton singles have been a life-long interest for me, inspired by my father. I don't think anyone will ever be able to learn every detail, but these posts are a good platform to share and learn from our own experiences.

   Just thought I would add a photo of my dad's 1936 ES2 outfit with my older sister, circa 1951. Note the bike has Inter forks which were an optional extra.