Racer Suspension

BigEd

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I could not think of Reg Boltons name the other day when I wrote but came across his mod in 25 years on research the only caveat I have is this was not with a JE stem
Anyway we have fitted a JE stem and a coil over and gone from a single to a twin and thats enough variables for now cant change too much at once. Eddie that photo is not so good the front bottom pivot is actually slightly higher than the concentric center and dont forget the whole shebang has not hit a bump or a road yet yet since being built. If its not its a coil cut or a lighter spring
Dear Tim,
Reg Bolton is still about and lives in the Goldcoast area of Queensland, Australia. I think he had (another) bad accident a year or two back so not sure if he does much motorcycling these days.
It is often a bit difficult to see what the angles are on a photo due to the angle the photo was taken so as you say with some use and being fuelled and oiled up for action should make a bit of difference.
I've done a few miles with the JE stem and I am still experimenting with spring weights, lengths, pre-load, etc. That is on hold for at present while I do some maintenance items and mods that I had logged for doing this winter.
 

Bill Thomas

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I raced once on the Blue Twin, With a padded out touring tank bag !,
I used to get Stomach Cramp, Nerves !, And found if I lay down on the bag, Down the back straight,
I could relax, For a bit !, I did look a sight, Nothing has changed :) .
 

timetraveller

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Tim, if it does turn out that the front is high compared with the rear then it is a heavier (stiffer) spring that is required, not a lighter one.
 

davidd

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I think it is sensible to be cautious about mixing and matching components. When talking about these components it is difficult to speak other than broadly or generally. The specifics do make a difference.

Broadly speaking, the unique design of the Vincent offers the opportunity to modify the rake by changing the the length of the backbone and suspension. As mentioned, this has led to much better handling of many racers, but the specifics do matter.

Also, broadly speaking, the new steering stem has no effect on the rake of the bike, so there is unlikely any problem with doing the Reg Bolton mod. The great benefit of trying the Bolton mod is that it is inexpensive to do and can be easily removed.

I am not sure that there is a good reason to do any of these mods (except for the new stem mod) on a streetbike. I do understand Greg's interest in putting these mods on a streetbike, because once you personally become aware that you can make a Vincent handle this well, you will find yourself less interested in riding stock Vincents.

Race bikes have always been about experimentation and beating the bikes in front of you.

David
 

vibrac

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Tim, if it does turn out that the front is high compared with the rear then it is a heavier (stiffer) spring that is required, not a lighter one.
I agree with what you say ( it is counter intuitive) but my lower spring rate comment was in relation to Ed saying it looked lower at the front
 
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