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Rear Springs

Albervin

Well Known and Active Forum Website User
VOC Member
I have just been playing with the rear springs & damper on my Rapide. I discovered I have a pair of sidecar springs fitted and also the original style damper that was rebuilt 8 years ago is perfectly useable. Now, I have a spare pair of Comet springs so what is the general consensus concerning mixing a Comet spring with a sidecar spring? It is mentioned in Richardson but does it cause uneven movement & possible twist in the RFM? The bike is set up as per original & not fully sprung. I look forward to your input.
 

Howard

Well Known and Active Forum Website User
VOC Member
Hi

I don't like to see a thread with no answers.

I mixed and matched springs on a fully sprung Comet racer with no ill effects. Smooth tracks and low mileage isn't like road use though.

My feeling is that the springs are so close together that you could almost consider them as one. I think it's more of a turning moment you're worrying about, so the Vin set up would be less susceptible to uneven movent etc than a swinging arm setup with wide apart spring/dampers.

Just my initial thoughts, I'll think about it as the day goes on and let you know if I come to a different conclusion.

H
 
Last edited:

Ron Hiscock

Forum Website User
Non-VOC Member
I have two different spring rates on my Comet outfit which have worked OK for the last eight years. I experimented with various spring lengths and rates until the bike looked level when viewed from the side and not like an old horse with a doggey back. Ron Hiscock.
 

Howard

Well Known and Active Forum Website User
VOC Member
I have two different spring rates on my Comet outfit which have worked OK for the last eight years. I experimented with various spring lengths and rates until the bike looked level when viewed from the side and not like an old horse with a doggey back. Ron Hiscock.


My unscientific method, which may or not be right.
I measured the damper centres at max and min, so I knew the max spring travel possible.
Then it was a matter of making sure there was a small amount of spring compression stationary with rider.
Then I marked the spring boxes to register how much the springs had compressed.
Then ride around a set route and measure how much movement.
You need to adjust spring strength so that you occasionally get full travel to the bump stop. By adjusting or changing springs, and riding round your set route.

Anything more complicated than that on suspension, such as spring rates, damping rates etc I leave to the experts.

H
 

Albervin

Well Known and Active Forum Website User
VOC Member
I just took the Rapide out for a test & the ride was lovely & supple. BUT.... it bottomed out twice when going up my drive then into the shed. Both times there was a sharp increase in upward angle, maybe 20º or more. I will persist a bit more because the ride quality is a definite improvement over the twin sidecar springs. Maybe a Rapide plus sidecar spring will be the answer? The roads here are a little more uneven than the UK, Canada or Europe, I have no knowledge of the USA (yet) .
 

Howard

Well Known and Active Forum Website User
VOC Member
I just took the Rapide out for a test & the ride was lovely & supple. BUT.... it bottomed out twice when going up my drive then into the shed. Both times there was a sharp increase in upward angle, maybe 20º or more. I will persist a bit more because the ride quality is a definite improvement over the twin sidecar springs. Maybe a Rapide plus sidecar spring will be the answer? The roads here are a little more uneven than the UK, Canada or Europe, I have no knowledge of the USA (yet) .

You have a rose tinted view of the UK, if you think our roads are better then yours, specially after the last winter.

You may need more preload on the softer rate Comet springs from what you say. I've got some smaller diameter springs that I think (my poor old memory again) fitted inside the standard diameter ones giving more spring selection options.

H
 

Albervin

Well Known and Active Forum Website User
VOC Member
Howard, I was wondering how to increase the preload on the rear springs. How do you fit an inner spring? Do you need to modify the claw?
What about the longer Petteford springs? Do they foul the battery case? Should I consider the Thornton system? I am in a receptive state of mind here.....
 

Chrish

Well Known and Active Forum Website User
VOC Member
Alyn,

I fitted the Thornton system to the rear end of the "B" and it transformed the ride, Ive yet to incorporate your front end damper Brampton modification, damper inside the spring, the front end still bottoms out on the rough secondary roads here in Vic.....

Chris
 

Howard

Well Known and Active Forum Website User
VOC Member
Howard, I was wondering how to increase the preload on the rear springs. How do you fit an inner spring? Do you need to modify the claw?
What about the longer Petteford springs? Do they foul the battery case? Should I consider the Thornton system? I am in a receptive state of mind here.....

Alyn

I'm not an expert on Vin cycleparts, I've had an Egli since 1974, and I raced (at least I was on the track while other people were racing) a very special Comet for a few years.

The Comet had features such as home made TLS brakes and all-in-one spring damper unit on the Girdraulics, so the rear suspension may have been altered too, but I've nothing to compare it with.

I think there was an extra shoulder on the claw, to locate the inner spring, so that was probably a non Vincent Mod. Also when I look at the parts list the springs seem to be slightly conical at the ends, if this isn't draughtsman's licence, my outer springs were non standard, because they were parallel.

For more preload you need to screw out SP4 mounting eyes, but you'll have to make sure there's enough thread, they look short on the parts list, so you may need special ones made.

As I understand these things, there should always be some compression when stationery with the rider on, so if you go past that point, you need to fit higher spring rate springs, and back off the SP4 adjustment again.

I hope that reads ok.

H
 

timetraveller

Well Known and Active Forum Website User
VOC Member
I have used the Petteford solo springs with a fully sprung seat for years and the difference is remarkable. Not quite as good as a 'D' but certainly more comfortable both front and rear.
 
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