View Full Version : Length of coil over springs
Derald Rice
05-10-2019, 10:36 AM
If I put two springs on my workbench, both the same spring rate, one is 8 inches and the other is 10 inches, what are the arguments for using the shorter (or longer) spring ??
Will one or the other have a better ride quality or performance ??
What are the main reasons, other than fitment, for choosing one over the other ??
mike223
05-10-2019, 10:51 AM
Will one or the other have a better ride quality or performance ??
What are the main reasons, other than fitment, for choosing one over the other ??
The only difference is what range of movement you need the spring to respond to.
Both springs react to loads exactly the same way - xxx lbs per inch, until you run out of spring travel (completely compressed or completely unloaded).
CraigS
05-11-2019, 06:45 AM
The only difference is what range of movement you need the spring to respond to.
Both springs react to loads exactly the same way - xxx lbs per inch, until you run out of spring travel (completely compressed or completely unloaded).
I agree. I had been using 10 inch rear springs for ever. When I used my same 3 link rear shocks on the new IRS retro fit, I needed a bit more clearance so I used 9 in. I was concerned that I could possibly coil bind the shorter springs but fortunately QA1 now has a line of 'Hi travel' springs.
mike223
05-11-2019, 08:08 AM
We should probably also note that this conversation mainly applies to constant rate coilover springs as delivered by the manufacturer.
If you were to just cut a 10" spring down to 8" you're going to change the spring rate (because a 10" spring is going to be slightly different in order to maintain the same spring rate as an 8" spring).
Also OEM springs in production vehicles are often variable rate springs (all bets are off).
I'm certain Craig knows all that - but you never know who else will happen along and read the thread.
Agree with all the above. Now, selecting a longer spring with a lower rating and using more pre-load to achieve ride height will provide a softer ride and increase weight transfer.
mike223
05-11-2019, 10:11 AM
Now, selecting a longer spring with a lower rating and using more pre-load to achieve ride height will provide a softer ride and increase weight transfer.
Agreed - ideally, you pursue that until you run out of suspension travel.
Or until you set up poor handling characteristics by getting one end of the car too far out of balance from the other end.
In oval track that could also involve getting one side of the car too far out of balance from the other side.