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Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
Brampton Coil Over Shocks
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<blockquote data-quote="Oldhaven" data-source="post: 125108" data-attributes="member: 2879"><p>From my real world bad experience, with no spring or coil over to stop it the two upper links come to rest against the handle bar and the steering damper puts a 1/2 inch deep dent in the front fender. If you are lucky the front brake cable doesn’t get trapped up there. The bike is rideable in this kneeling state and handles OK at low speeds, though I don’t recommend it. Full extension in this condition is highly unlikely. I have small dents in my fork tubes from over extension, but they were there before I did the coil over conversion, from who knows what happening since 1948. </p><p>With the standard Brampton spring constrained at both ends the fork travel depends on spring strength in compression and extension. With a coil over the fork travel depends on the limits in the internals of the damper, modified by the compression and rebound damping effect and the preload of the spring. My Works damper allowed full compression but has a 1/2 “ stop on the damper rod to limit the extension and protect the fork tubes. The way the internal rebound damping is valved with three flapper valves I doubt I ever saw full extension in normal riding though that is where it went while on the center stand. Full extension of the damper rod even with the limit stop still puts the lower links in a below horizontal angle and it’s possible this might make the forks more like unmodified Girdraulics during braking. That is speculation though. The damper rod and piston did occasionally bottom with major road bumps, and I could have increased the preload or changed the compression valving but the ride was comfortable as I had it. The spring is 120 lbs/in. Maybe a 130 or a bit more would be better, especially if riding two up or heavily loaded. </p><p>The pictures of the other coil over conversions even earlier Works conversions look like they have less travel than my Works conversion and users are happy with that. If I fix mine it will be even more limited than it's previous 1/2 inch reduction since that extra extension is not necessary and may be detrimental. I can see making the mounting arrangement at the cylinder end as short as possible whether it is up or down since it will allow more compression travel. I see no reason that the total allowable travel of a Brampton coil over should be more than the design limits of the original spring, and any conversion should probably follow that consideration going in. (personal opinion).</p></blockquote><p></p>
[QUOTE="Oldhaven, post: 125108, member: 2879"] From my real world bad experience, with no spring or coil over to stop it the two upper links come to rest against the handle bar and the steering damper puts a 1/2 inch deep dent in the front fender. If you are lucky the front brake cable doesn’t get trapped up there. The bike is rideable in this kneeling state and handles OK at low speeds, though I don’t recommend it. Full extension in this condition is highly unlikely. I have small dents in my fork tubes from over extension, but they were there before I did the coil over conversion, from who knows what happening since 1948. With the standard Brampton spring constrained at both ends the fork travel depends on spring strength in compression and extension. With a coil over the fork travel depends on the limits in the internals of the damper, modified by the compression and rebound damping effect and the preload of the spring. My Works damper allowed full compression but has a 1/2 “ stop on the damper rod to limit the extension and protect the fork tubes. The way the internal rebound damping is valved with three flapper valves I doubt I ever saw full extension in normal riding though that is where it went while on the center stand. Full extension of the damper rod even with the limit stop still puts the lower links in a below horizontal angle and it’s possible this might make the forks more like unmodified Girdraulics during braking. That is speculation though. The damper rod and piston did occasionally bottom with major road bumps, and I could have increased the preload or changed the compression valving but the ride was comfortable as I had it. The spring is 120 lbs/in. Maybe a 130 or a bit more would be better, especially if riding two up or heavily loaded. The pictures of the other coil over conversions even earlier Works conversions look like they have less travel than my Works conversion and users are happy with that. If I fix mine it will be even more limited than it's previous 1/2 inch reduction since that extra extension is not necessary and may be detrimental. I can see making the mounting arrangement at the cylinder end as short as possible whether it is up or down since it will allow more compression travel. I see no reason that the total allowable travel of a Brampton coil over should be more than the design limits of the original spring, and any conversion should probably follow that consideration going in. (personal opinion). [/QUOTE]
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Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
Brampton Coil Over Shocks
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