Okay, cut the BS why coil overs?

[JRouche]

I see some guys talking about adjusting, but they are adjusting the shocks, NOT the springs.

Two legitimate uses of coilovers I see here (besides the coolness factor which is legit also) were from falcon and Stu.



Makes it easier to creep up on you preferred ride height. Yup Falcon.

And what Stu said, weight balancing. Its amazing to see how far off the side to side numbers are off. I have a set of digital scales. They are fun to play with. And you can jack the weights around with coilovers. But you still need to adjust the components of the car around to get a proper balance. Stiffening up one side to adjust for an imbalance will solve issues on a car that is really set up. As best as you can. But take it too far and the imbalance is gonna cause more problems. But I think Stu meant it for a car that is really set up and the driver is looking for the "sweet spot". Scales and coilovers can help you find the sweet spot. JR

[Chevy]

I see some guys talking about adjusting, but they are adjusting the shocks, NOT the springs.

Two legitimate uses of coilovers I see here (besides the coolness factor which is legit also) were from falcon and Stu.

Makes it easier to creep up on you preferred ride height. Yup Falcon.

And what Stu said, weight balancing. Its amazing to see how far off the side to side numbers are off. I have a set of digital scales. They are fun to play with. And you can jack the weights around with coilovers. But you still need to adjust the components of the car around to get a proper balance. Stiffening up one side to adjust for an imbalance will solve issues on a car that is really set up. As best as you can. But take it too far and the imbalance is gonna cause more problems. But I think Stu meant it for a car that is really set up and the driver is looking for the "sweet spot". Scales and coilovers can help you find the sweet spot. JR

Agree completely with JR and of course the two originally posters, Falcon and Stu. These two elements are CRITICAL to properly setting up the car for dynamic handling situations like the autocross or being able to set the old car up so it can run with (and even beat) a modern sports car in the twisties. As JR originally pointed out, nearly all short/long A-arm suspensions are designed so that the LCA is parrellel to the ground at ride height. To ensure that the car can be set up so that the LCAs are parrellel to the ground at ride height, you need coilovers--especially if the car has other mods and/or is a work in progress. When you relocate your battery to the trunk, do you want to have to buy a new set of springs? When you do a motor swap, ditto? How about when you buy a new set of tires with a little different aspect ratio? Coilovers solves all these issues with a few simple turns of the the wrench. The alternative is a whole collection of different rate/length springs and the time to swap them in and out, which gets expensive and tedious.

The other issue, that of weight jacking in the chassis, is also super-critical for dynamic situations and another element tha can't be accomplished without either coilovers or a vast collection of springs to swap in and out. It also changes anytime you move any weigh around in the car. With coilovers, that is not a problem...just a few turns away from being back where you need it.

These two elements make the difference between a well-sorted out classic Pro-Touring car that can run with modern Corvettes on the track and and an old car that someone has bolted some modern parts on.

[terryr]

They could also allow you to move the lower mounting point out nearer the tire. This would make the motion ratio closer to 1 to 1. [with custom lower arms.]

Easier to change springs. Good for race cars.

Easier to package custom suspensions.

[exwestracer]

They could also allow you to move the lower mounting point out nearer the tire. This would make the motion ratio closer to 1 to 1. [with custom lower arms.]

Easier to change springs. Good for race cars.

Easier to package custom suspensions.

Yes. Even though there is a lot of work involved in moving that lower mount out (including cutting the stock spring bucket out and moving the upper mount), it allows you to run much lower spring rates and remove a lot of the load from the control arm. Look at the lower control arms available from AFCO, etc. and you will see that they are MUCH lighter due to the force being transferred to the spring way out by the ball joint. Springs get lighter (3" vs. 5") as well. Not much gain in comfort, but a big step in reducing unsprung weight which gets more and more important as you go to low profile tires...

[JRouche]

Yes. Springs get lighter (3" vs. 5") as well. Not much gain in comfort, but a big step in reducing unsprung weight which gets more and more important as you go to low profile tires...

Unsprung weight and suspension springs..

Always something to look at. We used to have heavy leaf springs up front, prolly the worst for weight to spring value. Then we got coil springs. Much better. Then a car company used strait spring bars for suspending the car. Torsion bars, even better unsprung weight issues. OH, how bout a rubber spring. Thats pretty light. Air springs. They have to be the lightest. But Id love to learn about a cantilever suspension.

But for a simple reduction in unsprung weight Im thinking air springs are the simplest. And not without some performance. Talk about reducing unsprung weight, rubber air springs are the king. JR

[Bryce]

Thanks JR,

ridetech did come out with a new cockpit adjustable shock valving. Kinda like what certain OEM cars have.

One more idea. Coilovers can easily allow multiple mounting locations. So the ride height can be changed dramatically without bottoming out the shock but the suspension geometry will suffer. This would mainly be for a rear suspension setup when changing from roadcourse to drag. You can raise the car by changing the lower C/O mounting position.

[wmhjr]

Thanks JR,

ridetech did come out with a new cockpit adjustable shock valving. Kinda like what certain OEM cars have.

Related question. Has anyone ever had one of those OEM cars that had adjustable suspension that they really liked from a performance perspective? Not talking about "load level" type stuff - but actual performance. I wish i could say I have, but I've never liked the ones I've driven.

[Bryce]

from what I know, it adjusts compression and rebound at the same time. So a stiff shock verse a lighter shock.

[70camaro406]

Is adjusting the shocks (variable control) easier on a coil-over shock since it's easier to access over a traditional coil spring with the variable shock inside? I mean, since you can get variable shocks for both types of springs, is it just as easy to adjust the shocks on both types? Or is the coil-over shock easier to adjust? I know that I want the double adjustable shocks for my 2nd gen Camaro, just unsure about the spring, like the original poster.

[Bryce]

when the shock is inside the spring its hard to reach the adjuster knobs. where a coilover has easy access to the knobs.

[70camaro406]

I figured it would be harder. But is it still possible to reach them?

[Roadbuster]

I figured it would be harder. But is it still possible to reach them?

Some adjuster knobs have a allen head in the center and the shocks come with a hex driver to get to the adjuster through the springs. Doesn't always work, and you might have to lift the car to make the adjustments, but better than disassembly.

A point in general with any type of shock is that there is a design sweet spot. The size of this sweet spot is proportional to the length of the shock. For our cars it is not much about +/- 0.5 inches. For a front suspension that is about +/- 1 inch of ride height adjustment. Running the shock out side this parameter will still allow it to work but will compromise performance on either compression or rebound.

For example: Varishock VAS 11111-350 coil overs have 3.50 inches of travel, which translates to 7 inches of wheel travel. The Compressed Length is 9.30 inches, Extended Length is 12.80, Minimum Ride Height of 10.70 inches, Maximum Ride Height of 11.40 inches. The minimum Ride Height is defined as 40% of travel available for compression (bump), 60% of travel available for extension (rebound). The maximum Ride Height: 60% of travel available for compression (bump), 40% of travel available for extension (rebound). All this is from the instruction sheet.

So for these coil overs 11.40 - 10.70 = 0.7 inches which translates to 1.4 inches of adjustable ride height. That is why shims or multiple mounting holes are required to adjust the ride height without pushing the shock outside its spec range.

Note that this range is for the shock. If you use a coil over, air spring or conventional spring you still want to set up the shock to be in its optimum range for the best performace.

Jon

[LSx_88_Ciera]

Not really related to coil-overs but here is a good visualization of the effects ride height has on suspension geometry and ride height seemed to be a frequent topic in here.
http://www.racingaspirations.com/?p=286
I am working on a version based on the one above that allows you to enter the specs instead of the dragging points around.

[70camaro406]

Thanks for all the great info, Jon.

[monteboy84]

Still a good topic here, I've had some different experiences pertaining to this since the thread was first posted. Mainly circle track, but still relevant.

One thing we're almost always fighting with suspension geometry is the fact that most everything moves about a radius, which creates issues like bumpsteer, ackerman, camber gain/loss, etc.

With a conventionally mounted spring, one end is moving on a radius, which arcs the spring as the suspension moves through its travel. This introduces unknowns into the equation, such as rate change, and geometry-induced deflection which will change with every different spring. With a coilover, we're eliminating that and making all spring travel linear.

Also, coilovers allow the spring to act on a point much closer to the wheel centerline, which brings the wheel rate much closer to the actual spring rate. This also reduces the amount of flex in the lower control arm, which acts as a Class 2 Lever in a conventionally sprung suspension.

Now, all of this is getting fairly intricate in the gains it actually provides, and in most cases the average Pro-Tourer won't see much of a gain versus things like correcting the terrible factory geometry. But, if you're in pursuit of the "best of the best" it's certainly something worth looking into. For a racecar where they're allowed - it's a necessity if you want any chance at winning.

-matt

[overZealous1]

didn't read anything but the first post, so i'm sure it has been covered. harmonics of the spring.

thats about it. oh ya, ride height.

[HWYSTR]

Many are confusing ride height with weight jacking, but think that's been covered already, just as shock adjustment vs coil adjustment.

One thing I'd like to point out is that the rate of a spring that is smaller in diameter increases much more rapidly as it's compressed and is less granular than one that's larger in diameter. Height of a spring play a factor too. Total weight of what each spring is supporting is also a factor, like coil-over type suspensions generally are better suited for lighter cars, such as race cars. These reasons are why you don't see coilovers being used exclusively in production passenger cars (where it would certainly be a benefit on the assembly line).

That 'sweet spot' or range of motion the suspension travels in is where the spring also should be operating in it's range of compression where the rate is most linear. A spring at it's limit of compression (coil bind) or completely unloaded is not in it's 'sweet spot', if you can imagine.

.

[exwestracer]

Many are confusing ride height with weight jacking, but think that's been covered already, just as shock adjustment vs coil adjustment.

One thing I'd like to point out is that the rate of a spring that is smaller in diameter increases much more rapidly as it's compressed and is less granular than one that's larger in diameter. Height of a spring play a factor too. Total weight of what each spring is supporting is also a factor, like coil-over type suspensions generally are better suited for lighter cars, such as race cars. These reasons are why you don't see coilovers being used exclusively in production passenger cars (where it would certainly be a benefit on the assembly line).

That 'sweet spot' or range of motion the suspension travels in is where the spring also should be operating in it's range of compression where the rate is most linear. A spring at it's limit of compression (coil bind) or completely unloaded is not in it's 'sweet spot', if you can imagine.

.

If you change ride height by shortening or lengthening the installed height of a spring, you are jacking weight around...doesn't matter if its a coilover or big coil, tire pressure (it's an air spring), or a torsion bar. The only way to change ride height without jacking weight is to change the location of the spring in relation to the control arm or frame.

We test coil springs all the time (with a Longacre spring rater), and most linear springs show VERY little change in lb/in of rate, no matter where they are in their range of travel. That's exactly why we use them on race cars.... Most OEM springs are NOT linear; they are progressive to allow soft ride when lightly loaded, but not allow the car to bottom when heavily loaded or subjected to severe bumps. Progressive springs are easily identified by the varying distance between coils from one end of the spring to the other.

Many modern automobiles DO use a version of a coilover setup. It's just really big and looks like a Mc Pherson strut. If it has a single bolt and bushing at the bottom, it's just a coilover...

[HWYSTR]

If you change ride height by shortening or lengthening the installed height of a spring, you are jacking weight around...doesn't matter if its a coilover or big coil, tire pressure (it's an air spring), or a torsion bar. The only way to change ride height without jacking weight is to change the location of the spring in relation to the control arm or frame. ...

Exactly. But, as an example, you can use an adjustable spring cup at the frame side and remove the appropriate amount of coil(s) from the spring to achieve the original mounting position, and adjust from there.

We test coil springs all the time (with a Longacre spring rater), and most linear springs show VERY little change in lb/in of rate, no matter where they are in their range of travel. That's exactly why we use them on race cars.... ...

Coil over springs or traditional 5 - 5.5 springs? Some aftermarket springs have much better quality control than others, hence why many have problems with aftermarket springs, and why so many say to go to someone that can provide springs for your application. Most of the problem is with the quality control though. That problem can be with both, coil over and conventional 5 - 5.5 springs.

Most OEM springs are NOT linear; they are progressive to allow soft ride when lightly loaded, but not allow the car to bottom when heavily loaded or subjected to severe bumps. Progressive springs are easily identified by the varying distance between coils from one end of the spring to the other....

Yes, though cars from the musclecar era didn't come with variable rate springs. Hotchkis originally tried using variable rate springs in their' kits, but found they didn't work very well. (Boaty, or from weight it just compressed the 'variable' part of the spring at normal ride height).

Many modern automobiles DO use a version of a coilover setup. It's just really big and looks like a Mc Pherson strut. If it has a single bolt and bushing at the bottom, it's just a coilover...

And here is the point I'm trying to make about the diameter of the spring itself. The larger the diameter of the coils in a spring, the longer the lever arm, and the compression can occur much more granular, if I'm explaining that right.

.

[79T/Aman]

"And here is the point I'm trying to make about the diameter of the spring itself. The larger the diameter of the coils in a spring, the longer the lever arm, and the compression can occur much more granular, if I'm explaining that right."

Larger springs react slower due to having to overcome their own weight but are a much more stable physical part when positiond half way between the inner pivot point and the ball joint, coil overs should be located as close to the ball joint as possible, doing so reduces the spring rate needed from the spring making the whole package lighter.