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Unread 04-28-2014, 09:34 PM   #1
Shawnsation
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Cutting too tall lift coils

I have been putting together a lift kit, and i changed my mind from 4.5" to 3", I'd like to know if I can cut my rustys 4.5" coils to a 3" lift, or will it have dangerous repercussions? secondly, is there any methodical way of knowing how much to cut off? other than T&E


Last edited by Shawnsation; 05-04-2014 at 09:41 PM..
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Unread 04-30-2014, 07:31 PM   #2
Jeep01AH
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I would sell them or send them back and buy new ones. I can't see cutting them working out very well.
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Unread 04-30-2014, 08:34 PM   #3
5-90
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You know those ricebois you see on the freeway that run over a dime and bounce for the next ten minutes?

That's cut springs. Don't do it.

Trade, exchange, or sell yours and buy the lift you want. Cutting coil springs changes the spring rate, which screws with suspension dynamics (I went through this with one of my boys - wanted to lower his Acura a bit (!) and asked me about cutting springs. I said don't - you only want an inch and a half, you can find purpose-made springs for that. He cut the springs anyhow - first time he complained to be about handling, I just told him "I told you not to do it. I never want to hear about this again. If you don't like the ride, buy proper springs like I said you should." He has since learned, it just took him a bit...)
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Unread 05-08-2014, 05:05 AM   #4
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Quote:
Originally Posted by 5-90
You know those ricebois you see on the freeway that run over a dime and bounce for the next ten minutes? That's cut springs. Don't do it. Trade, exchange, or sell yours and buy the lift you want. Cutting coil springs changes the spring rate, which screws with suspension dynamics (I went through this with one of my boys - wanted to lower his Acura a bit (!) and asked me about cutting springs. I said don't - you only want an inch and a half, you can find purpose-made springs for that. He cut the springs anyhow - first time he complained to be about handling, I just told him "I told you not to do it. I never want to hear about this again. If you don't like the ride, buy proper springs like I said you should." He has since learned, it just took him a bit...)
If they are constant rate springs, you won't change the rate by cutting them. Also, excessive bouncing would be caused by bad shocks, not springs.
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Unread 05-08-2014, 05:17 AM   #5
AngryRedBird
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These guys know what they are talking about.. I'd trust their word on this.. rkulp89 & 5-90 Reading their comment.. nothing more needs to be said..
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Unread 05-10-2014, 04:49 AM   #6
5-90
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Quote:
Originally Posted by rkulp89 View Post
If they are constant rate springs, you won't change the rate by cutting them. Also, excessive bouncing would be caused by bad shocks, not springs.
As I recall, the number of coils in a spring has an effect on spring rate, just as does wire diameter, distance between coils, Young's modulus, and the like. I don't recall the equation offhand.

Yes, the shocks are meant to dampen oscillations of suspension (which are cushioned by the springs,) but I believe that cutting a coil or two off of a spring actually increases the rate, meaning that the shock damper will have less effect in dampening oscillations - so it will oscillate longer.
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Unread 05-16-2014, 08:25 AM   #7
rkulp89
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Quote:
Originally Posted by 5-90
As I recall, the number of coils in a spring has an effect on spring rate, just as does wire diameter, distance between coils, Young's modulus, and the like. I don't recall the equation offhand. Yes, the shocks are meant to dampen oscillations of suspension (which are cushioned by the springs,) but I believe that cutting a coil or two off of a spring actually increases the rate, meaning that the shock damper will have less effect in dampening oscillations - so it will oscillate longer.
That is incorrect. The number of coils per inch/foot (how tight the coil is wound) effects the rate but not the number of coils in general. Cutting a coil off a 4" spring is not going to change the spring rate or ride quality, it's just going to lower the suspension.
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Unread 05-18-2014, 08:01 AM   #8
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Quote:
Originally Posted by rkulp89 View Post
That is incorrect. The number of coils per inch/foot (how tight the coil is wound) effects the rate but not the number of coils in general. Cutting a coil off a 4" spring is not going to change the spring rate or ride quality, it's just going to lower the suspension.
I would tend to beleive engineers who actualy design and build coil springs before i would beleive all the internet myths/experts all over the net...

notice this lil part....

If I add a coil, what does that do to the rate?
Adding a coil weakens the rate. Removing a coil strengthens the rate.

http://www.masterspring.com/spring-w...ineering-tips/

5-90 seems to be spot on............and you are incorrect

And i have personaly seen many cut springs to lower a ride and personaly felt how much stiffer a ride it makes....
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Unread 05-18-2014, 08:12 AM   #9
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To the OP..i would take the advice of replacing with the correct springs before ghetto cutting brand new springs.

plus,your jeep has leaf springs in the back,when you buy lift leaf springs they are longer than stock so the eye to eye stays in the stock position, but more of an arc in the springs,so when you take one leaf out to lower, it will set lower, but the eye to eye measurement will be longer with the weight on it...so it will bottom out the shackle end and/or invert the spring when fully flexed..
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Unread 05-20-2014, 08:24 PM   #10
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Thanks guys for the input, I'm just going to do it right, not much point in making more work for myself down the road
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