cut springs

[chuckles]

Now i have a question. Why do cut springs bounce? is it because they can't release the energy properly or what??

[Ghiadude]

because by altering their length there is less of the spring to take the same weight. this causes the shocks to suffer and eventually fail and then there is nothing to control the natural oscillation of the spring.

[xbgs351]

Originally Posted by tx3dude

because by altering their length there is less of the spring to take the same weight. this causes the shocks to suffer and eventually fail and then there is nothing to control the natural oscillation of the spring.

No, it's generally because the cut spring is stiffer and the dampeners can't control the increased spring rate.

[Ghiadude]

Thats not what ive been told but i have been known to get things wrong.

[chich]

Originally Posted by xbgs351

No, it's generally because the cut spring is stiffer and the dampeners can't control the increased spring rate.

The spring doesn't just magically get stiffer when you cut it. The springs rate remains the same however when you cut it you have less coils absorbing the same amount of force, which basically throws the spring/damper relationship in the bin.

[VSSII]

It's Albert Einstein.. He and his laws of physics are punishing you for being a tight **** and not spending 220 measley dollars on some King springs to keep your car roadworthy!

[chich]

Originally Posted by VSSII

It's Albert Einstein.. He and his laws of physics are punishing you for being a tight **** and not spending 220 measley dollars on some King springs to keep your car roadworthy!

The laws of physics are actually Mr Newtons _2:

[Full Spectrum]

Cut springs pop out more and may cause you to bottom out, There designed with say 7 coils at a strength rating of (Example only) 300kg, When you cut 3-4 coils from that it's strength then will suffer you put yourself and other in danger, they are then faulty.
Stock springs are soft and bounce more to make the occupants feel less of the bumps. So when lower they will bounce like a kangaroo and the occupants will feel it.
That is why kings and the other make them right, There strength is intact they are stiffer.
And cut springs are illegal also, Only need a cop to see a car bouncing up and down and they might pull the car over.

[VSSII]

Originally Posted by chich

The laws of physics are actually Mr Newtons _2:

How embarrassment. I humbly apologise (as I slink off to the fridge for another Sunday afternoon beer. This better be the last one!)

[xbgs351]

Originally Posted by chich

The spring doesn't just magically get stiffer when you cut it. The springs rate remains the same however when you cut it you have less coils absorbing the same amount of force, which basically throws the spring/damper relationship in the bin.

It doesn't magically get stiffer, but it does get stiffer.

Here is the equation for the stiffness of a coil spring:


Where:

k = spring constant
G = Modulus of rigidity
d = wire diamter
n = number of active coils
D = Mean coil diamter

If the spring is cut the number of active coils is reduced and the spring rate increases.

[xbgs351]

Originally Posted by SlickHolden

Cut springs pop out more and may cause you to bottom out, There designed with say 7 coils at a strength rating of (Example only) 300kg, When you cut 3-4 coils from that it's strength then will suffer you put yourself and other in danger, they are then faulty.
Stock springs are soft and bounce more to make the occupants feel less of the bumps. So when lower they will bounce like a kangaroo and the occupants will feel it.
That is why kings and the other make them right, There strength is intact they are stiffer.
And cut springs are illegal also, Only need a cop to see a car bouncing up and down and they might pull the car over.

Back by popular demand:







Cutting springs can be bad if you don't know what you are doing. This applies to everything you ever do on a car. Remember your life and others depends on your work.

Putting excessive heat into the springs when cutting is bad as it can create a Heat Affected Zone. This may result in possible failure near the cut. There are ways of avoiding excessive heat.

Cutting variable rate springs is stupid. Only ever cut a linear spring. I'm not a fan of variable rate springs in a performance situation, so replacing these springs with lowered linear rate springs would kill two birds with one stone.

Don't cut springs that have been finished to sit flat (ie hq kingswood style). Only cut springs such those found on X series falcons. ie constant outer diameter and no special end finish.

As for spring captivity, this issue remains the same regardless of the method of lowering. Just because you have purchased brand name springs doesn't mean you don't have to check for captivity. I have pulled brand new King Springs from an XF Falcon that were not captive. The most common captivity solution is the use of short bodied shocks. I have seen race cars use a cable to stop the suspension drooping too far when the car is lifted.

Anybody who doesn't believe that cutting coil springs is a legitimate method of lowering a car should read: "How to Make Your Car Handle" by Author: Fred Puhn and "Boss 302 Chassis Modification" by Autolite (A Ford Company).

Personally I prefer to custom order my springs. It is the only way I can get an adequate spring rate. I have found that lowered cars typically have a smoother ride when using stiffer springs than usually supplied by the spring companies. This is because the stiffer springs reduce suspension travel over bumps, which prevents or reduces contact with the bump stop. The bump stop is order of magnitudes stiffer than even the springs.

They also handle better on rough surfaces. The reason for this is that the stiffer springs don't waste valuable suspension travel due to body roll. This suspension travel should be used to soak up bumps.

Remember having adequate suspension travel will give greater handling gains then those achieved by excessively lowering your car. LOWER is often SLOWER.

Then there's those with cut King springs(normally on light RWDs like Gemini's and 180sx's). The smallest road indentation makes you feel like your driving down a set of stairs! It gets worse when you actually do! Bring a folding chair and sit on the side of Parramatta Rd Granville on a Saturday night. The sparks from cut springed ricers at 70ks on the dog of a road makes a good fireworks display!

[xbgs351]

Originally Posted by chich

The laws of physics are actually Mr Newtons _2:

No they aren't. The Three laws of motion are Sir Isaac Newton's.

[Gammaboy]

Originally Posted by xbgs351

It doesn't magically get stiffer, but it does get stiffer.

Here is the equation for the stiffness of a coil spring:


Where:

k = spring constant
G = Modulus of rigidity
d = wire diamter
n = number of active coils
D = Mean coil diamter

If the spring is cut the number of active coils is reduced and the spring rate increases.

Thanks for posting that, i couldn't be arsed trying.... some people just open their mouths and remove all doubt.