Technical Questions on Spring Design

[Blue Smoke]

I've had just enough brandy tonite, that some of this thread is making me go "WhaaaT?"
I think there's some chain pulling going on!
1. no offense, but cutting a spring in half does not change the rate, just the total load capacity. 2. wire size, alloy, modulus of ridgidity/elasticity, coil pitch, and temper are all design ways of getting a specific rate. 3. once you have a given dia. and rate, you get load capacity from rate X #of coil spaces. 4. back to original Q. about spring lenght, given the limits of thread lenght on the shock body, there's only so much range in lenght that a spring of equal rate can vary and still fit the shock. IF this makes any n% difference in handling, I'd love to understand why????

 

[JPM]

Cutting the spring in half changes the rate. The rate is inversely proportional to the number of coils.
Cutting the spring in half doubles the rate by halving the number of coils.
The strength of the spring remains unchanged as it it determined by wire diameter and the spring diameter for a given material.

To achieve the same spring rate You could have a spring with more coils and thicker wire wound to the same diameter as another spring with thin wire and fewer coils.

The smaller spring would be much lighter and give better dynamic response less mass (F=ma.

The larger spring would be less stressed for the same amount of travel but less reactive due to the heavier mass.

So it seems that the spring design in a motorcycle is a compromise between strength and response.

To throw a spanner in the works we can throw in travel.

Am I in the ball park Jer?

Something to add for calculating spring rates.
What hasn't been mentioned is the end treatment modifying the spring rate.
For a typical fork spring the end is squared and ground so the number of coils you use in the equation is n-1. (from memory)


[This message has been edited by JPM (edited 01-22-2001).]

 

[RM_guy]

Jeremy,
Can you PLEASE kill the thread??? There is way too much misinformation in here to be very useful.

Originally posted by Jeremy Wilkey:
I'm going to let this go for a while longer then post what I find interesting and then ask my question to the mighty Mace, and JD... For insight.. I know of only 2 people in suspensnion who have ever acknolowegded what Kiwi is talking about but, I suspect that many others are silent on this.. More to come I'm sure..

Jer

How much longer do we have to wait??

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Did I do the double?
Ah,um...Sure did. I was right behind you!