Lowered on Stock Coils
07-26-2012, 05:25 AM
#21
Sorry for the long post, but Engineers are a little obsessive about details, we just can't help it...
When cutting stock springs, it is usually recommended only cutting 1/4 coil on some models and 1/2 coil (at a time) on other models that weigh more due to higher spring rates.
You got lucky on cutting a full coil the first time, but it still looks like you could go a little more by the pics, but be careful. The spring rate is not stiff enough to go any further without upgrading to stout shocks & struts, you are probably questionable now.
I would recommend Koni yellows, they are designed for such usage, plus they are easily adjustable to fine tune your ride.
Think of it like braking distance. Your OEM brake work well if you don't need to stop in a much shorter distance, but higher end brake systems will have no problem. It is similar that you are requiring the shocks & struts to stop a full load, but in a much shorter distance.
So by shortening the springs, you will be grossly over taxing normal/average shocks & struts. You will be into the jounce bumpers too easily and too often. You will have to be very careful when driving on bumpy surfaces, not recommended for a DD.
One more issue:
I see lots of people deleting the spring isolators on their Mustangs. This is not a good idea on a street car.
When a coil spring is compressed the spring metal actually twists on the C/L of the coil metal. This will translate into more road noise but will also gradually grind away at the mating surfaces because the spring is made of much harder steel. These ground surfaces will rust and eventually fail, but it could take many, many miles in some instances. The isolators prevent these issues.
I just upgraded to the M/M C/C plates and those things are a well designed work of art. They look good and work great. A little more expensive, but well worth the cost. I highly recommend them.
By cutting your springs, you will be in need of a new alignment. Some cars are worse than others, but you certainly do not want to burn through tires.
When cutting stock springs, it is usually recommended only cutting 1/4 coil on some models and 1/2 coil (at a time) on other models that weigh more due to higher spring rates.
You got lucky on cutting a full coil the first time, but it still looks like you could go a little more by the pics, but be careful. The spring rate is not stiff enough to go any further without upgrading to stout shocks & struts, you are probably questionable now.
I would recommend Koni yellows, they are designed for such usage, plus they are easily adjustable to fine tune your ride.
Think of it like braking distance. Your OEM brake work well if you don't need to stop in a much shorter distance, but higher end brake systems will have no problem. It is similar that you are requiring the shocks & struts to stop a full load, but in a much shorter distance.
So by shortening the springs, you will be grossly over taxing normal/average shocks & struts. You will be into the jounce bumpers too easily and too often. You will have to be very careful when driving on bumpy surfaces, not recommended for a DD.
One more issue:
I see lots of people deleting the spring isolators on their Mustangs. This is not a good idea on a street car.
When a coil spring is compressed the spring metal actually twists on the C/L of the coil metal. This will translate into more road noise but will also gradually grind away at the mating surfaces because the spring is made of much harder steel. These ground surfaces will rust and eventually fail, but it could take many, many miles in some instances. The isolators prevent these issues.
I just upgraded to the M/M C/C plates and those things are a well designed work of art. They look good and work great. A little more expensive, but well worth the cost. I highly recommend them.
By cutting your springs, you will be in need of a new alignment. Some cars are worse than others, but you certainly do not want to burn through tires.
07-26-2012, 10:25 PM
#22
A spring will have a max load at a max travel rating.
By eliminating coils on a linear rate spring, you are effectively lowering the load capacity of the stock spring. The load rating per inch of travel stays the same but the travel is reduced, therefore the load the spring will carry is reduced.
The suspension will be into a jounce position and M/M condition at a much reduced load than the stock spring.
This is why the aftermarket lowering springs are progressive springs. Their rate per inch of travel increases as the spring is compressed. This allows the springs to have a similar max load at the max travel height of the installed spring.
Dan
Maybe our suspension guru Jazzer can chime in here?
07-26-2012, 10:35 PM
#23
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In question is the max load the spring can see before it fails. Springs usually fail before they hit a M/M condition of the spring as opposed to M/M of the suspension.
A spring will have a max load at a max travel rating.
By eliminating coils on a linear rate spring, you are effectively lowering the load capacity of the stock spring. The load rating per inch of travel stays the same but the travel is reduced, therefore the load the spring will carry is reduced.
The suspension will be into a jounce position and M/M condition at a much reduced load than the stock spring.
This is why the aftermarket lowering springs are progressive springs. Their rate per inch of travel increases as the spring is compressed. This allows the springs to have a similar max load at the max travel height of the installed spring.
Dan
Maybe our suspension guru Jazzer can chime in here?
A spring will have a max load at a max travel rating.
By eliminating coils on a linear rate spring, you are effectively lowering the load capacity of the stock spring. The load rating per inch of travel stays the same but the travel is reduced, therefore the load the spring will carry is reduced.
The suspension will be into a jounce position and M/M condition at a much reduced load than the stock spring.
This is why the aftermarket lowering springs are progressive springs. Their rate per inch of travel increases as the spring is compressed. This allows the springs to have a similar max load at the max travel height of the installed spring.
Dan
Maybe our suspension guru Jazzer can chime in here?
Honestly, I hear you and I understand what you are saying, but this is just a DD and lowered for asthetics and not performance....although it does corner at tiny bit better due to a lower center of gravity (I ASSume)
07-26-2012, 10:45 PM
#24
I really appreciate you taking the time to type all that out.
One problem I do have with your explanation is that from the moderate amount of research I've done, by shortening a linear rate spring you are increasing the spring rate...as long as the coils are not "overheated" so to speak, which will change the characteristics of the metal.
One problem I do have with your explanation is that from the moderate amount of research I've done, by shortening a linear rate spring you are increasing the spring rate...as long as the coils are not "overheated" so to speak, which will change the characteristics of the metal.
It is a physical impossibility to increase the rate of a linear rate spring by reducing it's length. You take the free length (with most springs), minus the compressed length (design height at full suspension travel). Minus the compressed length from the free length. This length in inches multiplied by the springs constant rate is the max load the spring can safely support.
In a progressive rate spring you will be increasing the rate per inch of travel by removing the upper coils, but you will be significantly reducing the max load the spring can safely carry by reducing it's safe travel. Does that make sense?
Some people report that their suspension is stiffer by removing coils. What they are experiencing is that much of their travel is into the rubber jounce bumpers which will greatly dampen the travel to protect suspension components this will make the ride much more "bumpier". You can get aftermarket jounce bumpers that are shorter, but they are not for street use, only track use. Hitting a pothole or speed bump (as examples) on the street could catastrophically damage suspension components when they hit M/M conditions.
Aftermarket lowering springs have progressive springs rates so that at the max spring compression the spring has at least the same load capacity as a stock spring. This is assuming that the spring is properly designed which is not always the case. At least the FRPP springs are properly designed by Ford.
07-26-2012, 10:55 PM
#25
Do yourself a favor and keep an eye on your rear jounce bumpers. Replace them when they start cracking and failing, maybe even upgrading to Urethane. Once the jounce bumpers are effectively "gone" you can do serious damage to your car when hitting a M/M (Metal to Metal) conditions.
M/M conditions are when expensive parts start failing (bending & breaking). It can get expensive rather quickly.
I have experience in testing labs where such things are tested for durability. When M/M conditions occur, you can shred tires, bend unibody frame rails and bend/break upper & lower control arms. This damage can be extensive rather quickly.
You can reduce your chances of failure by driving slow over large bumps.
Last edited by Old Mustanger; 07-26-2012 at 11:03 PM.
07-27-2012, 11:32 AM
#27
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Join Date: Jun 2011
Location: East middle of no where, WV
Posts: 585
Not a problem, I am just trying to input some honest Engineering concepts so people are not lead astray by other people who do not comprehend the true issues.
Do yourself a favor and keep an eye on your rear jounce bumpers. Replace them when they start cracking and failing, maybe even upgrading to Urethane. Once the jounce bumpers are effectively "gone" you can do serious damage to your car when hitting a M/M (Metal to Metal) conditions.
M/M conditions are when expensive parts start failing (bending & breaking). It can get expensive rather quickly.
I have experience in testing labs where such things are tested for durability. When M/M conditions occur, you can shred tires, bend unibody frame rails and bend/break upper & lower control arms. This damage can be extensive rather quickly.
You can reduce your chances of failure by driving slow over large bumps.
Do yourself a favor and keep an eye on your rear jounce bumpers. Replace them when they start cracking and failing, maybe even upgrading to Urethane. Once the jounce bumpers are effectively "gone" you can do serious damage to your car when hitting a M/M (Metal to Metal) conditions.
M/M conditions are when expensive parts start failing (bending & breaking). It can get expensive rather quickly.
I have experience in testing labs where such things are tested for durability. When M/M conditions occur, you can shred tires, bend unibody frame rails and bend/break upper & lower control arms. This damage can be extensive rather quickly.
You can reduce your chances of failure by driving slow over large bumps.
I honestly do not want to be argumentative here, but:
It is a physical impossibility to increase the rate of a linear rate spring by reducing it's length. You take the free length (with most springs), minus the compressed length (design height at full suspension travel). Minus the compressed length from the free length. This length in inches multiplied by the springs constant rate is the max load the spring can safely support.
In a progressive rate spring you will be increasing the rate per inch of travel by removing the upper coils, but you will be significantly reducing the max load the spring can safely carry by reducing it's safe travel. Does that make sense?
Some people report that their suspension is stiffer by removing coils. What they are experiencing is that much of their travel is into the rubber jounce bumpers which will greatly dampen the travel to protect suspension components this will make the ride much more "bumpier". You can get aftermarket jounce bumpers that are shorter, but they are not for street use, only track use. Hitting a pothole or speed bump (as examples) on the street could catastrophically damage suspension components when they hit M/M conditions.
Aftermarket lowering springs have progressive springs rates so that at the max spring compression the spring has at least the same load capacity as a stock spring. This is assuming that the spring is properly designed which is not always the case. At least the FRPP springs are properly designed by Ford.
It is a physical impossibility to increase the rate of a linear rate spring by reducing it's length. You take the free length (with most springs), minus the compressed length (design height at full suspension travel). Minus the compressed length from the free length. This length in inches multiplied by the springs constant rate is the max load the spring can safely support.
In a progressive rate spring you will be increasing the rate per inch of travel by removing the upper coils, but you will be significantly reducing the max load the spring can safely carry by reducing it's safe travel. Does that make sense?
Some people report that their suspension is stiffer by removing coils. What they are experiencing is that much of their travel is into the rubber jounce bumpers which will greatly dampen the travel to protect suspension components this will make the ride much more "bumpier". You can get aftermarket jounce bumpers that are shorter, but they are not for street use, only track use. Hitting a pothole or speed bump (as examples) on the street could catastrophically damage suspension components when they hit M/M conditions.
Aftermarket lowering springs have progressive springs rates so that at the max spring compression the spring has at least the same load capacity as a stock spring. This is assuming that the spring is properly designed which is not always the case. At least the FRPP springs are properly designed by Ford.
Thanks for the information on progessive vs linear spring cutting, and about the jounce bumbers. I have however heard from many different sources that less than 2 coils is "safe" on the SN95 & NE's. I have not even cut the back yet, FWIW.
I tend to drive with 2-3 miles of the posted speed limit and crawl over bumps in any car, just because I've seen first hand how they can tear up a car if not taken slowly....so I'm really worried M/M conditions as I don't intend to go much lower than I already am.
07-27-2012, 11:32 AM
#28
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