Dirt cheap lowering

Ponycarman · 07-08-2004, 12:50 PM

There are numerous ways to make a car handle better without it having the ride of a dump truck.

High spring rates are not one of the ways.

Lowering the car helps by putting the center of gravity lower and making the car more stable. Think of you standing on the bottom rung of a step ladder vice the top of it, same thoery at work.

Lessening the weight transfer (body roll) helps a lot too. You can do that with high rate springs or with more moderate springs and stiffer swaybars. High rate springs make for a harsher ride. Softer springs allieviate that but use stiffer swaybars to counteract and side to side weight transfer. It's a balancing act as you have to match the front and rear setup witht he weight of the car and then you still need enough shock to handle the combined spring and sway bar rates.

Then there is unsprung weight, the stuff on the road side of your springs, like the rear axle. More is bad, so an 8.8 equipped car will not handle as well as an otherwise identically equipped 7.5 equipped car.

Then there are all the mushy soft bushings used to soften the ride. Especially the ones in the rear suspension. They don't help at all.

However, the ultimate determining factory in handling is almost always the tires.

I can put the slicks off an F1 car on my Mustang and it won't handle like an F1 car, though it will handle a lot better than stock tires. Conversely, I can put the stock tires off my Mustang on an F1 and it'll suck in the handling department and it probably won't handle too much better than my Mustang does.

Lots ofways to skin a cat here, but darn few that produce a useable pelt.

Steve

**SpectorV** · 07-08-2004, 04:21 PM

well if the spring rate is specific then no matter what the rate will remain the same, if its progressive i can see the rate being worse the more you cut from it. Who knows get them tested if you can to see if the rate changed, perhaps its just lower to the ground perhaps the change in geometery neted a better cornering car.

Danger Dude · 07-08-2004, 04:46 PM


Quote: Originally Posted by SpectorV well if the spring rate is specific then no matter what the rate will remain the same, if its progressive i can see the rate being worse the more you cut from it. Who knows get them tested if you can to see if the rate changed, perhaps its just lower to the ground perhaps the change in geometery neted a better cornering car.

Actually that is not exactly true. the more coils you have the more flex in the coils the less coils the less flex. so as you shorten a spring by reducing the number of coils the higher the spring rate or less flex. The only exception is like on the C springs which has a dead coil which adds little to no tension and can be cut without changing the rate.

Zim · 07-08-2004, 05:27 PM

yeah whats up with that stupid dead coil anyway lol

Danger Dude · 07-08-2004, 05:45 PM


Quote: Originally Posted by ZimStang yeah whats up with that stupid dead coil anyway lol

Remember the C springs are also used on Fox bodies. They were much lighter cars which gives them a super firm ride but also the desired lower front stance which was very popular in the 80's

The dead coil is nothing more than a built in spacer. It provides nada to the spring rate when left on or cut off. So if you are into the mean lean or the even drop you have a choice with one spring. Kind of a neat Idea if you ask me

Zim · 07-08-2004, 06:13 PM

yeah good point... The invoice that came with my springs said they were used back on the 80 somethin cougars. That suprised me.

**SpectorV** · 07-08-2004, 06:34 PM

I guess if all you are about is looks and not handeling then cutting them is not the worst thing in the world, I guess its getto cars that have FAR to much cut and they bounce as they go down teh road and are like 2 inches off the ground that give cutting a bad name.

Danger Dude · 07-08-2004, 07:56 PM


Quote: Originally Posted by SpectorV I guess if all you are about is looks and not handeling then cutting them is not the worst thing in the world, I guess its getto cars that have FAR to much cut and they bounce as they go down teh road and are like 2 inches off the ground that give cutting a bad name.

Exactly I have a guy down the street that cut like 3 coils off his honda and wonders why his fender wells scrubb all the time

Stock Mustang springs are not that bad but cutting springs on regular passenger cars that are design with a smooth ride in mind dont work to well

Tbird232ci · 07-09-2004, 01:22 AM


Quote: yeah good point... The invoice that came with my springs said they were used back on the 80 somethin cougars. That suprised me.

C-springs dont work so good on the 83-88 cougars and birds, ass end sags too much, probably the same for the 81-82's also

Ponycarman · 07-09-2004, 09:04 AM

What is clear to me is someone here knows little about the facts of suspension design but sure has a lot of incorrect opinions.

The bouncing Honda analogy is a prime example of someone not knowing anything but doing it anyway. The bounce is caused by one thing, too high a spring rate without a corresponding increase in shock rate. Ever see a dump truck bounce around like those Hondas? Probably not, because they have the shock rate to properly dampen the spring. Of course odds are if you could find a shock with the rate needed to control the hop that Honda would ride like a dump truck. Too much spring rate. To cure that you'd need a spring with the same ride height as the cut spring but made with thinner wire. Then you'd up the swaybar diameter to control weight transfer (also known as body roll). Of course with that much cut from the spring odds are they are either sitting on the bump stops or are very close.

My advice to anyone interested in some factual thoughts on suspension design is to buy a book and read it.

Oh, and with my huge drop I still don't need caster/camber plates. Wonder why that is? I know but I wonder if anyone else does. I haven't checked my bumpsteer yet, but I suspect it'll be acceptable based on it's on the road performance so far.

Steve

Ponycarman · 07-09-2004, 09:45 AM

I once read something that kinda stuck with me. It basically said that if you couldn't explain something so that a 10 year old could understand it then you didn't really understand it either. Now I am not saying anyone here is 10 years old, physically or mentally, but I'll see if I can explain why cutting a coil spring increases the spring rate.

First a little about how coil springs are made and how they work. Coil springs are made from a length of spring steel wire. The diameter and length of the wire will affect the stiffness, or spring rate, of the coil. More on this later. Now when a coil spring is compressed it is easy to see how the thickness of the wire can affect the rate. What may not also be obvious is that the wire will twist when it is compressed too.

A simple hands on experiment will show what I mean. If you have a length of PVC piping, say 1/2" pipe three foot long. Take each end in a hand and try to twist it. It should be fairly easy to twist that pipe enough to see the twist with the eye. Now cut the pipe down to one foot long and try to twist it now. Much more difficult to do. The pipe has a certain amount of twist per foot of pipe, much as a length of coil spring wire does. So a 3 foot long piece of pipe will allow three times as much twist as a one foot section. Again, same with the spring wire. By shortening the amount of wire used in a coil spring you lessen the amount of twist in the coil spring. That is why cutting springs increases the spring rate.

Now, a bit about spring design. I've shown you how shortening the spring affects the spring rate but you can also affect the spring rate by increasing the diameter of the wire. That seems obvious but if you want to you can refer to my PVC experiment above and add a three foot section of 1 inch PVC pipe to it and compare the twist in that to the twist you get from the 1/2" pipe of the same length.

If you really wanted to get fancy you could rig up a test that clamped one end of the pipe (any pipe you're testing). the other end you fabricate a 1 foot long arm to hang weight from. Then you make a mark on the unclamped end and add weight. You can measure the amount of twist for the amount of force (in ft/lbs) and can quantify the changes in a scientific manner. Or you can take my word for it, doesn't matter to me.

This is exactly the principles used by everyone that makes coil springs. All you are paying for is the name and the experience. If that makes you comfortable then so be it. But keeping my wallet full makes me more comfortable than pissing away money on things I can do. Of course I do my own work so that has a lot to do with it.

Steve

Smokedya95stang · 07-09-2004, 10:44 AM

corey, monster garage uses cutting torches to cut springs all the time.

Danger Dude · 07-09-2004, 12:13 PM


Quote: Originally Posted by Smokedya95stang corey, monster garage uses cutting torches to cut springs all the time.

Monster Garage is not making cars to be driven every day are they now!!!!

I can just see the Green fox body they did making a lawn mower out of it driving to work everyday YEAH SURE !!!!

thirstymate · 07-13-2004, 03:54 PM

good post, i do all my work to my cars, the one thing i never did was suspension. i understand how it all works and what does what, i understood springs from a literal standpoint but not from a physics stand point. Also im thinking about lowering the front of my car, the rear also just not as much, when looking at my springs there are those inner coils that are used as "seats" i guess when you cut your springs how did you regain that, IE- if you just cut off 1 coil there will no longer be a flat end to the spring it will be the angled piece of coil coming around.. will that flatten out when its installed or did you do something else. i just dont see it sitting right without that smaller coil.