cutting springs
Senior Member
Joined: 11-06-06
Posts: 992
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From: Pontypool, Ontario
cutting with a hack saw will take a long time. use a band saw. cutting eibachs is an issue. If you cut the lower springs that coil bind it will make no difference. as they coil bind. If you cut more than one coil off the upper spring coils, you aint got much spring left that will work. Its sort of a ghetto mod but I have cut stock springs, no problems. i would recommend you go to H&R springs and sell ur eibachs so it would be better all round, H&R drop more than the rest afaik....
I cut one off the top n one off the bottom. Sits about the same as sportlines but smoother ride.
Cutting springs has always been a bad way to get to an end result. Will it work? Yes. Is it the best? Definitely not.
Also ride quality is subjective as one person is always different than another and might be willing to deal with more.
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Joined: 02-14-08
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From: long island
the ONLY REASON you should want to do this is if you want to drop below 3 inches and don't have the money for bags/don't want bags. otherwise, use aftermarket drop springs. tenzo makes a 2.5 inch drop, coilovers will drop you up to 3 inches.
First off, turtle you should not be coming to an internet forum for help with custom work, bolt ons are an exception. with the exception of those of you who did give some good input. there's a lot of forum mechanics and know it all's on here that could cost you a lot of money, or discourage free thinking.
the bottom line with cutting springs is don't heat them. the steel used for springs is the same grade steel they use to make a snap on wrench set. if you heat up a wrench it's going to weaken it. done deal. so use a cut off tool like a zip wheel with an abrasive disc. make sure the end of the coil is lined up on the rubber spring cushion or perch, so pretty much make it look as close to stock as possible. use your head. don't ride on something that doesn't look legit.
cutting off coils DOES NOT effect spring rate. heat does. I don't care what any know it all backyard forum mechanic says, the only thing to worry about is how your stock struts will hold. general motors imo put garbage struts on this car, I don't care if they said you have sport tuned suspension they put a solid rear on these piles of junk, it's nothing to party about. you will need to cut your bump stops and hopefully roll your fenders.
it should ride like stock, just watch out for bumps!
First off, turtle you should not be coming to an internet forum for help with custom work, bolt ons are an exception. with the exception of those of you who did give some good input. there's a lot of forum mechanics and know it all's on here that could cost you a lot of money, or discourage free thinking.
the bottom line with cutting springs is don't heat them. the steel used for springs is the same grade steel they use to make a snap on wrench set. if you heat up a wrench it's going to weaken it. done deal. so use a cut off tool like a zip wheel with an abrasive disc. make sure the end of the coil is lined up on the rubber spring cushion or perch, so pretty much make it look as close to stock as possible. use your head. don't ride on something that doesn't look legit.
cutting off coils DOES NOT effect spring rate. heat does. I don't care what any know it all backyard forum mechanic says, the only thing to worry about is how your stock struts will hold. general motors imo put garbage struts on this car, I don't care if they said you have sport tuned suspension they put a solid rear on these piles of junk, it's nothing to party about. you will need to cut your bump stops and hopefully roll your fenders.
it should ride like stock, just watch out for bumps!
NOOOOOOOOOOOOO. the eibachs especially, its a progressive spring rate. meaning on the ends you have a lower spring rate. so if you cut that off say "bye-bye" to small bump absorbtion, and "hello" to pogo effect.
cutting progressive rate springs = fail
cutting progressive rate springs = fail
Banned
Joined: 02-14-08
Posts: 1,769
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From: long island
stockers are not progressive spring rate. my progress springs are. they look like 2 different sets of coils on one spring wire. not hard to tell the difference. I am talking about cutting the stockers. I'm actually going to give this a shot this weekend. the only thing I'm concerned with is the "square or pigtail ends" 
in the rear. Not sure how they're going to sit on the perches. I have spacers so I may have to roll fenders. I just wanna get rid of wheel gap so I can stretch tires and not look stupid. If it doesn't work out I'll go back to my progress springs. What's the worst that can happen? no stock springs and matchbox car wheel gap? *shiver*
in the rear. Not sure how they're going to sit on the perches. I have spacers so I may have to roll fenders. I just wanna get rid of wheel gap so I can stretch tires and not look stupid. If it doesn't work out I'll go back to my progress springs. What's the worst that can happen? no stock springs and matchbox car wheel gap? *shiver*
Senior Member
Joined: 05-30-06
Posts: 2,975
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From: Upstate NY
I found this on a quick google search, I checked the math and confirmed it with my engenier friends this is all true. See http://www.eatonsprings.com/atqCutti...lculations.htm
""Popular wisdom" rules. Cutting coils does increase the spring rate. Let me explain why.
The strength of a spring, leaf or coil is a function of the cube of the steel used. Keeping with the subject of your question, coil springs, the diameter of the wire and the length of the wire will give us the amount of steel used.
For this whole discussion we will be talking about springs with the same wire diameter and the same inside diameter. The only thing that will change will be the length of the wire used to wind the spring.
The longer the wire is the lower the spring rate. As the wire get shorter, such as when cutting the coil, the spring rate increases.
So everyone has a clear understanding lets describe what "rate" is. Rate is the amount of weight it takes to deflect a spring one-inch.
A very common mistake is to think that spring rate is how much a spring supports. How much weight a spring is designed to support is called "Load" or "Designed Load" or"Load Rate". This is cover in Spring Tech 101.
Rate and Load Rate are two totally different animals.
The calculation to find the rate of a coil spring is:
11,250,000 times the wire diameter to the 4th power divided by 8 times the active number of turns times the mean diameter cubed.
Active turns are the number of turns of the spring that do not touch anything. Any part of the coil which makes contact with anything becomes inactive, that is it no longer functions as part of the spring.
The mean diameter is the inside coil diameter plus one wire thickness. Or the outside coil diameter less one wire thickness.
Let's say for example a 1967 Mustang GT front spring is made from .610 wire and has an inside diameter of 3.875" and has a free height of16.145" (not installed) and is deflected down to 10.5" (load height) when loaded to 1,519 lbs. (load rate) This spring has a spring rate of 269 lbs.
This spring has 9.33 total coils but 1.33 coils touch the spring seat so they are inactive leaving 8 active turns. (I know this from the Ford blue print).
The mean diameter is 3.875 + .610 (The inside is the important diameter because it is the inside of the spring which is used to locate the spring on the corresponding suspension parts. The outside diameter is not considered because it will change with a change of wire diameter)
Do the math-
11,250,000 x (.610 x .610 x .610 x .610) / 8 x 8 active turns x (4.485 x 4.485 x 4.485) = 269 lbs.
Double check the math - 16.145 - 10.5 = 5.645 deflection. 1,519/5.645 = 269
Now if we cut say 1/2 turn off this spring the active turns become 7.5.
So 11,250,000 x (.610 x .610 x .610 x .610) / 8 x 7.5 x (4.485 x 4.485 x 4.485) = 287 lbs.
While the rate is increased the load is unchanged. Rate is the amount of weight required to deflect the spring one-inch while load is the amount of weight the spring will support at a given height.
Cutting coils is limited to those types which have tangential ends. Tangential ends are those which spiral off into space. If you tried to stand the spring on end it would fall over.
Square ends and pigtail ends, both will stand up, and can not be cut because the finished product will not mount correctly in the suspension.
See this tech question on Cutting Coil Springs for a more complete explanation.
When altering ride height one must be aware of much more than just the springs. Brake lines, steering, shock length and other areas of interference. We do not offer coil springs which will alter any ride height more than 2-inches. Nor do we recommend anyone alter the ride height more than 2-inches.
While we have all sorts of springs which will vary ride height, spring rates and ride quality on the shelf, cutting coils maybe, in some cases, the only way to achieve the desired stance one is looking for."
""Popular wisdom" rules. Cutting coils does increase the spring rate. Let me explain why.
The strength of a spring, leaf or coil is a function of the cube of the steel used. Keeping with the subject of your question, coil springs, the diameter of the wire and the length of the wire will give us the amount of steel used.
For this whole discussion we will be talking about springs with the same wire diameter and the same inside diameter. The only thing that will change will be the length of the wire used to wind the spring.
The longer the wire is the lower the spring rate. As the wire get shorter, such as when cutting the coil, the spring rate increases.
So everyone has a clear understanding lets describe what "rate" is. Rate is the amount of weight it takes to deflect a spring one-inch.
A very common mistake is to think that spring rate is how much a spring supports. How much weight a spring is designed to support is called "Load" or "Designed Load" or"Load Rate". This is cover in Spring Tech 101.
Rate and Load Rate are two totally different animals.
The calculation to find the rate of a coil spring is:
11,250,000 times the wire diameter to the 4th power divided by 8 times the active number of turns times the mean diameter cubed.
Active turns are the number of turns of the spring that do not touch anything. Any part of the coil which makes contact with anything becomes inactive, that is it no longer functions as part of the spring.
The mean diameter is the inside coil diameter plus one wire thickness. Or the outside coil diameter less one wire thickness.
Let's say for example a 1967 Mustang GT front spring is made from .610 wire and has an inside diameter of 3.875" and has a free height of16.145" (not installed) and is deflected down to 10.5" (load height) when loaded to 1,519 lbs. (load rate) This spring has a spring rate of 269 lbs.
This spring has 9.33 total coils but 1.33 coils touch the spring seat so they are inactive leaving 8 active turns. (I know this from the Ford blue print).
The mean diameter is 3.875 + .610 (The inside is the important diameter because it is the inside of the spring which is used to locate the spring on the corresponding suspension parts. The outside diameter is not considered because it will change with a change of wire diameter)
Do the math-
11,250,000 x (.610 x .610 x .610 x .610) / 8 x 8 active turns x (4.485 x 4.485 x 4.485) = 269 lbs.
Double check the math - 16.145 - 10.5 = 5.645 deflection. 1,519/5.645 = 269
Now if we cut say 1/2 turn off this spring the active turns become 7.5.
So 11,250,000 x (.610 x .610 x .610 x .610) / 8 x 7.5 x (4.485 x 4.485 x 4.485) = 287 lbs.
While the rate is increased the load is unchanged. Rate is the amount of weight required to deflect the spring one-inch while load is the amount of weight the spring will support at a given height.
Cutting coils is limited to those types which have tangential ends. Tangential ends are those which spiral off into space. If you tried to stand the spring on end it would fall over.
Square ends and pigtail ends, both will stand up, and can not be cut because the finished product will not mount correctly in the suspension.
See this tech question on Cutting Coil Springs for a more complete explanation.
When altering ride height one must be aware of much more than just the springs. Brake lines, steering, shock length and other areas of interference. We do not offer coil springs which will alter any ride height more than 2-inches. Nor do we recommend anyone alter the ride height more than 2-inches.
While we have all sorts of springs which will vary ride height, spring rates and ride quality on the shelf, cutting coils maybe, in some cases, the only way to achieve the desired stance one is looking for."
Very good! Its nice to see a response to a question like this that doesnt involve bashing.
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Joined: 02-14-08
Posts: 1,769
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From: long island
^agreed, but whoever wrote up that thing is using too much math and not enough common sense. take it into your own matters and do some research. don't take my word or his word. make your own conclusions, and your way is always the best way!
Senior Member
Joined: 11-06-06
Posts: 992
Likes: 0
From: Pontypool, Ontario
stockers are not progressive spring rate. my progress springs are. they look like 2 different sets of coils on one spring wire. not hard to tell the difference. I am talking about cutting the stockers. I'm actually going to give this a shot this weekend. the only thing I'm concerned with is the "square or pigtail ends" in the rear. Not sure how they're going to sit on the perches. I have spacers so I may have to roll fenders. I just wanna get rid of wheel gap so I can stretch tires and not look stupid. If it doesn't work out I'll go back to my progress springs. What's the worst that can happen? no stock springs and matchbox car wheel gap? *shiver*
in the rear. Not sure how they're going to sit on the perches. I have spacers so I may have to roll fenders. I just wanna get rid of wheel gap so I can stretch tires and not look stupid. If it doesn't work out I'll go back to my progress springs. What's the worst that can happen? no stock springs and matchbox car wheel gap? *shiver*Stock Springs are progressive. The stock ones are very soft so be careful, once they are cut bottoming out will be easy