Racer Suspension

greg brillus

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Tim, you need to jack the rear of the bike up quite a lot, this will help the bike to "Turn in" on corners which is a great asset. On my twin racer the rear chain looked like it would fall off, but with the rider on it is fine.

(Vibrac asked for a new thread to be started. The first three posts here have been moved from the "Most Original Lightning" thread. BigEd.)
 
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Bill Thomas

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Did you ever work out the trail on your racer Greg ?.
Can't work out which way it would go with Standard forks, If we jacked it up too much,
I have used the long Petteford ? springs , But some people think it makes the Bike Twitchy ?,
Cheers Bill.
 

greg brillus

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Hi there Bill, Yes I probably did, but can't remember, I get a bit slack at writing things down.........I know the rear and front coilover shocks were 270 mm long and the attachment bracket that mounted it to the RFM was an extension as well. It would have added 40 to 50 mm to that again........I know after we fitted 18" rims front and rear I jacked the back up some more. I wanted to do the same at the front but this was too difficult. Anyway Phil who owns it now recons he can out-corner other riders on bikes with Featherbed frames, and this does not surprise me at all. It is still the best Vincent I have ever ridden, power, brakes, handling and even comfort........ I want to basically copy it, but even better for my next twin project........ This will be a road bike, not a racer.... Cheers.......... Greg.
 

vibrac

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I have an AVO shock on the rear and a new steering stem on the front. Clearance under the crankcase without catch tank is 7" on 18" wheels.
I remember the guy who raced in Japan 25 years ago (Reg Bolton. Big Ed) put extensions on his RFM to raise the rear but I would like to see how she steers before effectively steepening the forks.
Now Bob Newby has got a stronger 30mm belt I hope that the primary (we have to look standard) won't grow out for clearance of belt. More on that soon.
 
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vibrac

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As for chain being slack with jacked up suspension I see the belt drive nessitates a smaller rear sprocket range with a mid point around 45 so I am taking the opportunity to go 520 and use a range of Honda sprockets on a carrier ( cheap as chips)'not sure if that would make the slack effect worse
 

Chris Launders

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Be careful jacking the back end up too much on a road bike. I got my twin from a friend partly because he'd had a tank slapper and woken up in hospital, he'd repaired the bike and fitted a hydraulic steering damper.

When I got it and put it on the road it immediately felt strange and the first bump on a roundabout nearly pitched me off, I'd done just over a mile total !!!

I thought it had felt strange when I got on it and it had always looked "hump backed", on checking against a few others I found sidecar springs with the mountings at full stretch lifting the RFM pivot 1.5"and sagging springs in the front dropping that. My friend had never had a Vincent before so was not familiar with how it should have felt.

The previous owner to him had been Chris Williams, renowned sidecar racer and I wonder if he'd set it up for track use. Once I'd fitted "pettiford" springs at the correct length and new fork springs it was back to normal, still not happy with it I fitted one of the first JE steering stems, springs and AVO damper on the front and AVO coil over on the back, bliss.
 

Bill Thomas

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I think it was more the sagging front springs, The early Know thy beast said how bad the trail is when the forks come up too high, And to always use inner springs to stop them coming up too high.
I use D.D./ T.T. front springs, But I have had to pack them out a bit.
The Hydraulic damper is for me a MUST.
 

Chris Launders

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I've just recalled, I had noticed the sagging front springs after the previous owners crash and HE had fitted new "D" springs before I got it so my experience wasn't due to them.
 

vibrac

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Yes we have the JE with steering damper the springs are 30lb (without looking at notes) but when loaded with rider look about right
sfe.jpg
 

BigEd

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Yes we have the JE with steering damper the springs are 30lb (without looking at notes) but when loaded with rider look about right
View attachment 32242
Timetraveller's instructions say:

"Then the rider should sit on the bike, or get someone of a similar weight to do that and then check that the front of the lower link is now slightly above the rear of the link."
 
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