coil over theory??
Discussion
am I correct
2000lb (900kg approx) car with equal corner weights = 500lb at each wheel.
front springs are 400lb/in and near vertical. 4/5 of distance from chassis mounts to hub mounts.
using height adjustable coilovers.
with no pre-load on the spring does the damper compress (each corner) by 1"
400
\/
o pivot
/\
500
If the above is correct then.....
If I now wind up all the spring platforms by 1" does it give 400lb preload to each damper (2000lb total at the wheels) and so statically the dampers do not compress?
If pre-loaded between zero and an inch then that allows the static ride height to be adjusted between the two extremes.
Is this theory correct?
2000lb (900kg approx) car with equal corner weights = 500lb at each wheel.
front springs are 400lb/in and near vertical. 4/5 of distance from chassis mounts to hub mounts.
using height adjustable coilovers.
with no pre-load on the spring does the damper compress (each corner) by 1"
400
\/
o pivot
/\
500
If the above is correct then.....
If I now wind up all the spring platforms by 1" does it give 400lb preload to each damper (2000lb total at the wheels) and so statically the dampers do not compress?
If pre-loaded between zero and an inch then that allows the static ride height to be adjusted between the two extremes.
Is this theory correct?
2000lb (900kg approx) car with equal corner weights = 500lb at each wheel. Yes
front springs are 400lb/in and near vertical. If yours are near vertical you must have seriously modified your suspension...
4/5 of distance from chassis mounts to hub mounts.chassis mount to tyre contact centre would be more accurate
using height adjustable coilovers with no pre-load on the spring does the damper compress (each corner) by 1" No, you've gone the wrong way. 500lb on the tyre equates to 625lb on the spring
If I now wind up all the spring platforms by 1" does it give 400lb preload to each damper Yes
(2000lb total at the wheels) No, as per above
Thereafter, just think of the car resting on the springs. The load on the spring is a function of the load on the wheel and the suspension geometry, as you described. The compression in the spring is the load times the spring rate. If you have wound up the spring beyond the full extended length of the damper rod by that amount or more, then your static suspension will be locked solid. Between that position and 'loose', you have working 'rebound'. Beyond that position you have working 'bump'.
Does this help?
Graham
front springs are 400lb/in and near vertical. If yours are near vertical you must have seriously modified your suspension...
4/5 of distance from chassis mounts to hub mounts.chassis mount to tyre contact centre would be more accurate
using height adjustable coilovers with no pre-load on the spring does the damper compress (each corner) by 1" No, you've gone the wrong way. 500lb on the tyre equates to 625lb on the spring
If I now wind up all the spring platforms by 1" does it give 400lb preload to each damper Yes
(2000lb total at the wheels) No, as per above
Thereafter, just think of the car resting on the springs. The load on the spring is a function of the load on the wheel and the suspension geometry, as you described. The compression in the spring is the load times the spring rate. If you have wound up the spring beyond the full extended length of the damper rod by that amount or more, then your static suspension will be locked solid. Between that position and 'loose', you have working 'rebound'. Beyond that position you have working 'bump'.
Does this help?
Graham
Ragtop said:
2000lb (900kg approx) car with equal corner weights = 500lb at each wheel. Yes
front springs are 400lb/in and near vertical. If yours are near vertical you must have seriously modified your suspension...
4/5 of distance from chassis mounts to hub mounts.chassis mount to tyre contact centre would be more accurate
using height adjustable coilovers with no pre-load on the spring does the damper compress (each corner) by 1" No, you've gone the wrong way. 500lb on the tyre equates to 625lb on the spring
If I now wind up all the spring platforms by 1" does it give 400lb preload to each damper Yes
(2000lb total at the wheels) No, as per above
Thereafter, just think of the car resting on the springs. The load on the spring is a function of the load on the wheel and the suspension geometry, as you described. The compression in the spring is the load times the spring rate. If you have wound up the spring beyond the full extended length of the damper rod by that amount or more, then your static suspension will be locked solid. Between that position and 'loose', you have working 'rebound'. Beyond that position you have working 'bump'.
Does this help?
Graham
Cheers Grahamfront springs are 400lb/in and near vertical. If yours are near vertical you must have seriously modified your suspension...
4/5 of distance from chassis mounts to hub mounts.chassis mount to tyre contact centre would be more accurate
using height adjustable coilovers with no pre-load on the spring does the damper compress (each corner) by 1" No, you've gone the wrong way. 500lb on the tyre equates to 625lb on the spring
If I now wind up all the spring platforms by 1" does it give 400lb preload to each damper Yes
(2000lb total at the wheels) No, as per above
Thereafter, just think of the car resting on the springs. The load on the spring is a function of the load on the wheel and the suspension geometry, as you described. The compression in the spring is the load times the spring rate. If you have wound up the spring beyond the full extended length of the damper rod by that amount or more, then your static suspension will be locked solid. Between that position and 'loose', you have working 'rebound'. Beyond that position you have working 'bump'.
Does this help?
Graham
I wasn't thinking.....of course ..load x distance 400 x 4 does not = 500 x 5 as you say would be 625 x 4 but as you say I'm not using measured dimensions, only ones to make the maths easy. Will measure next time I'm near the car.
I used vertical to keep it simple....more like 30deg from vertical. But then 625lb (vertical) per corner must compress with more force than that at the 30 deg angle (the hypotenuse of the triangle?)
Also to confirm (still using vertical rather than actual)
winding the spring seats up 1" from 'just in contact' means that the force to compress the spring by another 1/2" will be 1.5 x the spring rate? further 1" = 2 x rate etc.
Mick
Good morning Mick,
If a wheel is pushing the suspension arm upwards with a vertical force of 625lb at the spring mount, then clearly if the spring is vertical it has to push down with the same 625lb force to balance it. If the spring is pushing off-vertical, it has to push harder to achieve the same effect vertically (the extra 'push' acts horizontally). At 30 degrees from vertical for example, the spring reaction goes up ~15%, to around 720lb in your example, to achieve the same 625lb vertical push.
Have fun!
Graham
If a wheel is pushing the suspension arm upwards with a vertical force of 625lb at the spring mount, then clearly if the spring is vertical it has to push down with the same 625lb force to balance it. If the spring is pushing off-vertical, it has to push harder to achieve the same effect vertically (the extra 'push' acts horizontally). At 30 degrees from vertical for example, the spring reaction goes up ~15%, to around 720lb in your example, to achieve the same 625lb vertical push.
magpies said:
Also to confirm (still using vertical rather than actual)
winding the spring seats up 1" from 'just in contact' means that the force to compress the spring by another 1/2" will be 1.5 x the spring rate? further 1" = 2 x rate etc.
Yes winding the spring seats up 1" from 'just in contact' means that the force to compress the spring by another 1/2" will be 1.5 x the spring rate? further 1" = 2 x rate etc.
Have fun!
Graham
Gassing Station | S Series | Top of Page | What's New | My Stuff