ebay - elcheap coilover springs

[BlitZ]

Not true. On any progressive springs , cutting any coils off will adversely change the dynamics of the spring , not the rate. If anything it decreses the spring rate. IE DONT DO IT

i stand to differ.. it will make it harder..

[bennjamin]

im only speaking from experience A angle grinder and the need to have a low car as a P plater isnt a good combo.

Anyway , it is stupid to do so DONT DO IT

[iced]

even if its progressive spring the rule still applies.
if you cut off the progressive part then it effectively becomes a linear rate. you are merely removing the progressive component.
im not too informed on the dynamics part of things. that is very deep into the mechanical part of things which does not involve only spring rate but rather the damper and everything else.
basically how the simplest progressive spring works is once the progressive part collapses and become dead coils the active coils remain active.
however, you are bringing up a topic all on its own which is not related to the basic fundamentals of spring rates.

you cant cut coils of a spring and make it softer.
2 identical springs with same wire diam, same coil gap.
the one with 5 coils will be stiffer than the one with 8.

[VTI-RRR]

thnks fopr the ifo guys but ill be buying springs off STTICH which would fit the coilover sleve.....

what you guys rekon???

these are the springs>>>>
****http://www.ozhonda.com/forum/showthread.php?t=75431****

[SeverAMV]

cutting springs doesnt make the spring rate any stiffer than it already is, you'll need to remake/heat them to make them stiffer. cutting springs just reduces the range of the compressions that the spring can make, so it gives you the illusion that it is stiffer. same amount of weight will still lower the car the same as before (as the spring will still have the same spring rate that it was originally wound to), only difference is that they'll bottom out sooner with more people, as they will reach their maximum compression sooner (at this point they'll just look like a cylinder with screw-type grooves).

you should only cut springs if you're absolutely sure you wont carry passengers, and you have measured it out to be the exact same length spring on each corner. but even then, its stupid to cut springs as you'll be affecting the bound and rebound rates (altho dampers are mainly responsible for this, theyre still attached to the spring and the spring does play a role in bound and rebound), and it will make your car's handling a little more unpredictable. luckily for me, you guys arent in south australia. i'd hate to see someone with cut springs take a corner too fast and see the rear randomly snap oversteer into someone else.

[JohnL]

cutting springs doesnt make the spring rate any stiffer than it already is, you'll need to remake/heat them to make them stiffer. cutting springs just reduces the range of the compressions that the spring can make, so it gives you the illusion that it is stiffer. same amount of weight will still lower the car the same as before (as the spring will still have the same spring rate that it was originally wound to), only difference is that they'll bottom out sooner with more people, as they will reach their maximum compression sooner (at this point they'll just look like a cylinder with screw-type grooves).

Sorry, but this is absolutely incorrect. Cutting coils off will always in every case increase the spring rate. A coil spring is simply a torsion bar that has been wound up into a coil, so, when the spring compresses the coil wire elastically deforms in exactly the same manner as does the wire in a torsion bar, i.e. the wire is twisted.

If you don't believe this then try this thought experiment (or you could do it for real if you were really sceptical / keen!):

Take two identical coil springs and cut a coil or two from one. Now uncoil them so that we make them into straight torsion bars. The one we cut will of course be shorter than the one we didn't. Now clamp each bar at one end so it can't move at that end, and now attempt to twist each bar with a torque wrench through say 90°. The shorter bar will require more torque to twist to 90°.

Still don't believe? Lets take it to an extreme to more clearly demonstrate the principle. Cut the short bar much shorter still, say to about 100mm long and twist again. You'll find the very short torsion bar will now be hugely stiffer than it originally was. This principle applies whether we shorten the coil wire length by a lot or by a little.

Things such as coil number, coil diameter and free length only affect spring stiffness in so far as they affect the length of wire in the coil (ignoring any dead coils that may be present in a 'progressive' spring). It may be however that coil pitch angle may have some very small affect; imagine a spring with a very steep coil pitch angle, the steeper the pitch becomes the more force passes through the wire in a sort of 'end-on' manner, though unless pitch angle is severe the effect is probalby quite small or the spring would attempt to rotate the spring seats as the spring compressed.

Having said this, I think you may be correct in that in some cases the shortened spring might possibly bottom out more easily than the unshortened spring, despite being stiffer. This is because the shorter spring lowers the ride height, but the stiffness increase may not be enough to compensate for the shorter distance from the top of the damper body to the bumpstop.

A cut spring will compress / lower less with X additional weight than the same spring uncut, because it is stiffer. The cut spring will probably ride lower with this extra weight but this is because the initial ride height will be lower.

If you cut coils off a spring this will reduce how far the coil can be compressed before it becomes 'coilbound', but the real limiting factor here will be the damper body and bumpstop lengths, i.e. the ride height will be lower and suspension travel less, but the 'bottomed out' height will be the same.

Heat treatment will make no difference to the spring stiffness, but it may have a significant affect on how far the spring can compress (wire twist) before it becomes permanently deformed or how long the spring might last. Nearly all steels (with the possible exception of some very exotic alloys that won't be found in springs etc) have the same elastic stiffness regardless of composition (alloy) or heat treatment (note that stiffness is not the same as strength). So, any two coils (or torsion bars) that are made from differing alloys or with differing heat treatment but having the same physical dimensions will have the same stiffness.

This doesn't mean they will be the same though. The difference will be in how far the spring can be compressed before it becomes either 'sagged' (permantly deformed) or actually breaks, i.e. where its elastic limit lies. Another likely difference may be in resistance to fatigue failure, whether this be from sagging over time or eventually breaking. Heat treatment / alloy also affect such things as shear strength, malleability etc, but this isn't an issue for springs.

[JohnL]

you should only cut springs if you're absolutely sure you wont carry passengers, and you have measured it out to be the exact same length spring on each corner. but even then, its stupid to cut springs as you'll be affecting the bound and rebound rates (altho dampers are mainly responsible for this, theyre still attached to the spring and the spring does play a role in bound and rebound), and it will make your car's handling a little more unpredictable. luckily for me, you guys arent in south australia. i'd hate to see someone with cut springs take a corner too fast and see the rear randomly snap oversteer into someone else.

You should never cut springs on a road car because its illegal! It may be OK on a race car, but only if you really understand what you're doing and why you're doing it.

Having said this I'll put my hand up to being guilty of this once, cut less than one coil from the springs on the rear of my old Cressida to get the rear end down a touch because it just looked silly at the standard height (bum in the air, massive rear arch gaps). I did make sure that I didn't end up with the springs loose at full droop, and it didn't affect the handling adversely (maybe just ever so slightly better!), but it was just a small cut!

Cutting the spring will affect the bump and rebound rates by increasing it, but most probably not enough! The problem with cutting springs (other than having a loose spring at full droop) is the increased risk of bottoming out because the rate increase is unlikely to be great enough to compensate for the reduced suspension travel.

Bottoming out in a corner causes an instantaneous weight transfer to the bottomed out suspension which also means an instantaneous transfer from the 'unbottomed' suspension on the same axle line. This can result in an abrupt and substantial reduction in grip at that axle line, the results of which can be unpredictable and dangerous as you say.

Also, cutting the spring may affect the correct seating of the spring on the spring seat at the cut end. Note that many if not most springs are ground and / or wound in a particular manner at one end (or both) to sit properly in the seat. Changing this may cause stresses in the seat and / or coil(s) near that seat that might potentially lead to spring or seat failure in the long term... maybe.

[SeverAMV]

Sorry, but this is absolutely incorrect. Cutting coils off will always in every case increase the spring rate. A coil spring is simply a torsion bar that has been wound up into a coil, so, when the spring compresses the coil wire elastically deforms in exactly the same manner as does the wire in a torsion bar, i.e. the wire is twisted.

If you don't believe this then try this thought experiment (or you could do it for real if you were really sceptical / keen!):

Take two identical coil springs and cut a coil or two from one. Now uncoil them so that we make them into straight torsion bars. The one we cut will of course be shorter than the one we didn't. Now clamp each bar at one end so it can't move at that end, and now attempt to twist each bar with a torque wrench through say 90°. The shorter bar will require more torque to twist to 90°.

Still don't believe? Lets take it to an extreme to more clearly demonstrate the principle. Cut the short bar much shorter still, say to about 100mm long and twist again. You'll find the very short torsion bar will now be hugely stiffer than it originally was. This principle applies whether we shorten the coil wire length by a lot or by a little.

Things such as coil number, coil diameter and free length only affect spring stiffness in so far as they affect the length of wire in the coil (ignoring any dead coils that may be present in a 'progressive' spring). It may be however that coil pitch angle may have some very small affect; imagine a spring with a very steep coil pitch angle, the steeper the pitch becomes the more force passes through the wire in a sort of 'end-on' manner, though unless pitch angle is severe the effect is probalby quite small or the spring would attempt to rotate the spring seats as the spring compressed.

Having said this, I think you may be correct in that in some cases the shortened spring might possibly bottom out more easily than the unshortened spring, despite being stiffer. This is because the shorter spring lowers the ride height, but the stiffness increase may not be enough to compensate for the shorter distance from the top of the damper body to the bumpstop.

A cut spring will compress / lower less with X additional weight than the same spring uncut, because it is stiffer. The cut spring will probably ride lower with this extra weight but this is because the initial ride height will be lower.

If you cut coils off a spring this will reduce how far the coil can be compressed before it becomes 'coilbound', but the real limiting factor here will be the damper body and bumpstop lengths, i.e. the ride height will be lower and suspension travel less, but the 'bottomed out' height will be the same.

Heat treatment will make no difference to the spring stiffness, but it may have a significant affect on how far the spring can compress (wire twist) before it becomes permanently deformed or how long the spring might last. Nearly all steels (with the possible exception of some very exotic alloys that won't be found in springs etc) have the same elastic stiffness regardless of composition (alloy) or heat treatment (note that stiffness is not the same as strength). So, any two coils (or torsion bars) that are made from differing alloys or with differing heat treatment but having the same physical dimensions will have the same stiffness.

This doesn't mean they will be the same though. The difference will be in how far the spring can be compressed before it becomes either 'sagged' (permantly deformed) or actually breaks, i.e. where its elastic limit lies. Another likely difference may be in resistance to fatigue failure, whether this be from sagging over time or eventually breaking. Heat treatment / alloy also affect such things as shear strength, malleability etc, but this isn't an issue for springs.

i get what you mean about shorter bars requiring more torque to bend, but it isnt really any stiffer/stronger than it was originally designed to be, it is only the illusion that it is more stiffer (i cant really explain what i mean too well), in the end, it is still of the same compound and of the same concentration. its a one of those paradoxical examples where less mass can produce more inertia and thus a greater resistance to flex. but yeah, i can see where you're coming from there.

with regards to the reheating of springs, i was referring to something i heard that people were doing, where they heat up the spring to reshape and make it shorter but thicker to increase the rigidity/stiffness.

[bennjamin]

when you reheat/ reset springs , you change their length only. Not any other dimensions ( IE thickness) Its to lower a car etc.

Good discussion guys !

[BlitZ]

i get what you mean about shorter bars requiring more torque to bend, but it isnt really any stiffer/stronger than it was originally designed to be, it is only the illusion that it is more stiffer (i cant really explain what i mean too well), in the end, it is still of the same compound and of the same concentration. its a one of those paradoxical examples where less mass can produce more inertia and thus a greater resistance to flex. but yeah, i can see where you're coming from there.

with regards to the reheating of springs, i was referring to something i heard that people were doing, where they heat up the spring to reshape and make it shorter but thicker to increase the rigidity/stiffness.

Good job john..

In lamen turns..

20 coils compress 15cm with 5kg....
b/c each coil will compress n amount.
15cm = n x 20

If I remove 1 coil..
it will only come down by n x 19


its so logical


90% of ozzie spring manufacturers... when they tell u they can do custom rates that normally just cut it and rebound the ends.

[fatboyz39]

I always thought when you cut the springs it increases the spring rates???

[bennjamin]

When you cut linear springs it increases the rate. When you cut progressive springs generally it increases the static rate. But dynamically ( when moving) the spring itself will still only move within its limits because you have not altered the stiffer rate , only the "comfort" rate (whic usually sits above as the closer coils)