Okay, cut the BS why coil overs?

[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.

[exwestracer]

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.

That's not strictly a ride height change. It's a weight jack, and cutting coils off the spring will increase the spring rate, further compounding the issue...


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.



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).

Well, ALL multi-leaf springs are progressive, as well as ALL pigtail coils (as found on the rear of most factory 4 link cars. Most front springs were linear rate. And you're right, progressive springs don't work all that well in handling applications.

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.

One of the problems with a big spring, especially when used at 50% motion ratio, is the difference in compression between the outside of the spring and the inside as the A arm moves through it's arc. That's another advantage of a coilove with any diameter spring; the single mounting point eliminates any "accordion" effect.

.

See above comments

[Ishmael]

Now that my brain is melted, and maybe this question was answered since its rediculously simple compared to everything else here but aren't qa1s designed to be a bolt on to stock lcas? If you want to accomplish ride height adjustment and have an adjustable shock they cost close to the same and you don't have to swap out springs so why wouldn't they be worth it for the money? Anybody posting that runs them on a camaro that can tell me if they are a bolt in?