Author Topic: Spring travel  (Read 112 times)

Jimr1999

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Spring travel
« on: 26 Mar 22, 07:02 am »
Morning all,
First spannering together yesterday of the springs on the BSA 3W. As they are an utter unknown, made out of wood bed slats, and may not make it to the final assembly I put a band hinge leaf to the hub underneath, then a full spring hub to hub, then a long thin stainless steel tie/washer (2 foot rule from old ones that have gone out of standard) then another shorter spring on top - times four - like the original BSA.

Loading the front end yesterday with my 100kg frame the amount of travel was minimal, less than 25mm. After my initial experiments with the springs and loadings this has come as a bit of a surprise. I am considering losing the shorter springs to get more bounce...

Question.
What is a typical amount of deflection on cyclekart springs for a similar loading?
Is harder better for our circuits?

As always your input is valued.
... You can lead a horse to water, but a pencil must be lead.

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ChrisS

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Re: Spring travel
« Reply #1 on: 26 Mar 22, 08:12 am »
Can't speak for others but mine drops 30mm with 60kg applied.

Chris Brown

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Re: Spring travel
« Reply #2 on: 26 Mar 22, 08:26 am »
Don't be in too much of a rush to change things, my Morgan seemed stiff enough with 40mm diameter springs, but they became coil bound in use. I swapped them to 30mm diameter of the same wire gauge and they're fine, static testing gives you some idea, but you won't know until you drive it.

David F-R

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Re: Spring travel
« Reply #3 on: 26 Mar 22, 09:02 am »
Morning all,
First spannering together yesterday of the springs on the BSA 3W. As they are an utter unknown, made out of wood bed slats, and may not make it to the final assembly I put a band hinge leaf to the hub underneath, then a full spring hub to hub, then a long thin stainless steel tie/washer (2 foot rule from old ones that have gone out of standard) then another shorter spring on top - times four - like the original BSA.

That is looking very smart Jim.
I'm not quite as green as I'm cabbage sounding.

Jimr1999

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Re: Spring travel
« Reply #4 on: 26 Mar 22, 11:33 am »
Thanks all, I will leave them be for now and design the spring clamps for adjustment enough if I need to soften up. All is unproven until it rolls I suppose.  ;D
... You can lead a horse to water, but a pencil must be lead.

TheGiantTribble

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Re: Spring travel
« Reply #5 on: 28 Mar 22, 09:51 am »
One of the things about CK's is although they are light and not that fast, the large diameter of the wheels
seems to increase the effect of force acting on the suspension...leverage I guess.
So I wouldn't worry about not much movement when you load it with a static load.
Also I can't help wondering...old cars often had their springs wrapped with string/rope, might be an idea, not
to look authentic (although it's a good excuse)but to assist with resisting the wood from splitting???
Also love the use of a 2 foot ruler...Genius!

Jimr1999

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Re: Spring travel
« Reply #6 on: 28 Mar 22, 11:55 am »
@Giant Tribble. You read my mind with the string thing. I intend to do some french whipping to tidy them up
... You can lead a horse to water, but a pencil must be lead.