Coilover adjustments

[orangelmo]

Is there a general rule on say how many threads is equal to a certain adjustment measurement. example: 6 threads = 0.5"

[topcat]

Stasis SS : "The ratio between shock body motion and wheel motion is about 0.7 to 1. This means that the wheel
travels about 1 inch for every 0.7 inches of shock body travel. Therefore, for example, if you wanted
to lower the car ½ inch from its current ride height at the right front wheel, then you would have to
lower the lower spring perch on the right front shock body by ½ x 0.7 = 0.35 inches. The rear motion
ratio is slightly different"

[b6onboost]

My Stasis coilovers require three full 360 degree turns to raise or lower the front 1/4 inch. The rears are different, seem to have different threads, and I haven't messed with them enough to know.

[orangelmo]

Thanks for the info. Does that only apply to Stasis coils or can be used universally? I'm running Vogtland GTs

[actlsub9]

Front is about 0.70 : 1
Rear is about 0.55 : 1

[3ohAvant]

no, its pretty different from car to car, C/O to C/O. the thread pitch varies a lot.

[quattrotman]

Stasis SS : "The ratio between shock body motion and wheel motion is about 0.7 to 1. This means that the wheel
travels about 1 inch for every 0.7 inches of shock body travel. Therefore, for example, if you wanted
to lower the car ½ inch from its current ride height at the right front wheel, then you would have to
lower the lower spring perch on the right front shock body by ½ x 0.7 = 0.35 inches. The rear motion
ratio is slightly different"

Shock body motion has nothing to do with the actual ride height though. When the car is at rest it, shock travel is irrelevant. Basically all you need to know is that the amount you bring up or down the perch translates into the effective raising or lowering of the car. Bring the perch up 1 inch, car drops by one inch or vice versa. It;s pretty simple really.

[topcat]

It is important to know the ratio of shock to wheel travel. Not all C/O are a 1:1 ratio. My quote was from STasis install guide that I used. Once I initally installed and wanted to make an adjustment, I used the math to hit it pretty dead on. Once you know the ratio, you can mark the threads and lower/raise pretty accurately.

[actlsub9]

Bring the perch up 1 inch, car drops by one inch or vice versa. It;s pretty simple really.

No, that is not correct. It is not a 1 to 1 ratio on our cars.

[quattrotman]

No, that is not correct. It is not a 1 to 1 ratio on our cars.

I'm sorry, I don't mean to beat this to death but you are wrong. Let's pretend those shocks are rigid and don't move. If you thread the perches up 1 inch the car comes down as much as you have moved the perches. Period. There is no formula. I don't really even understand how shock travel is related. Do you lower the car based on how it's loaded? Do you put some cement bags in the trunk and lower it then. No. Put the car on a level surface and measure the height. Then take the coils down 1 inch. Bet that height is 1 inch lower. Doesn't matter how many threads or what ratio you're talking about. Now, if you've loaded the car or compressed the shock, then your calculations come into play. Even simpler> back when people cut springs it was the same theory. Cut off as much as you want to go down. 1 coil off, car drops by that amount. No different with a coilover system. I don't care what you manual says...it doesn't refer to the ride height adjustment. It refers to shock body travel. That means the shock has to travel for that calculation to matter. Ride height at rest is what we are talking about here.

[dougyfresh]

I'm sorry, I don't mean to beat this to death but you are wrong. Let's pretend those shocks are rigid and don't move. If you thread the perches up 1 inch the car comes down as much as you have moved the perches. Period. There is no formula. I don't really even understand how shock travel is related. Do you lower the car based on how it's loaded? Do you put some cement bags in the trunk and lower it then. No. Put the car on a level surface and measure the height. Then take the coils down 1 inch. Bet that height is 1 inch lower. Doesn't matter how many threads or what ratio you're talking about. Now, if you've loaded the car or compressed the shock, then your calculations come into play. Even simpler> back when people cut springs it was the same theory. Cut off as much as you want to go down. 1 coil off, car drops by that amount. No different with a coilover system. I don't care what you manual says...it doesn't refer to the ride height adjustment. It refers to shock body travel. That means the shock has to travel for that calculation to matter. Ride height at rest is what we are talking about here.

If your coil-overs are a 1:1 ratio then your theory makes sense.


Not all coil overs for our vehicles adhere to this 1:1 ratio. STaSiS coil overs come to mind as ones that do not adhere. It was posted in #2 of this thread regarding their coil overs.


Cutting springs is a whole 'nother animal. Non-Linear springs fail your theory. Linear rate springs probably hold true but, again, it depends on the suspension geometry.

[actlsub9]

If your coil-overs are a 1:1 ratio then your theory makes sense.


Not all coil overs for our vehicles adhere to this 1:1 ratio. STaSiS coil overs come to mind as ones that do not adhere. It was posted in #2 of this thread regarding their coil overs.


Cutting springs is a whole 'nother animal. Non-Linear springs fail your theory. Linear rate springs probably hold true but, again, it depends on the suspension geometry.

Only the suspension geometry and ride height affect the ratio (meaning the ratio changes throughout suspension travel).

Doesn't matter which coilovers or spring/shock combination you choose. Spring rate does not matter either.

[actlsub9]

I'm sorry, I don't mean to beat this to death but you are wrong. Let's pretend those shocks are rigid and don't move. If you thread the perches up 1 inch the car comes down as much as you have moved the perches. Period. There is no formula. I don't really even understand how shock travel is related. Do you lower the car based on how it's loaded? Do you put some cement bags in the trunk and lower it then. No. Put the car on a level surface and measure the height. Then take the coils down 1 inch. Bet that height is 1 inch lower. Doesn't matter how many threads or what ratio you're talking about. Now, if you've loaded the car or compressed the shock, then your calculations come into play. Even simpler> back when people cut springs it was the same theory. Cut off as much as you want to go down. 1 coil off, car drops by that amount. No different with a coilover system. I don't care what you manual says...it doesn't refer to the ride height adjustment. It refers to shock body travel. That means the shock has to travel for that calculation to matter. Ride height at rest is what we are talking about here.

Do yourself a favor and read up on Motion Ratio in suspension systems.

Motion Ratio is the ratio of shock travel versus wheel travel. It is equal to the Shock Travel (in inches) per 1 inch of Wheel Travel. Motion Ratio is used to account for the different suspension geometries and the resultant mechanical leverage on the spring.

There are many, many articles on this topic.

A shock manufacturer explaining motion ratio... http://www.swayaway.com/TechRoom.php

The main point here is... depending on the suspension if you adjust the spring perch on the shock, the ride height will not change by that same amount unless the motion ratio of the suspension is equal to 1.

If motion ratio exists is not a debatable topic, however optimizing motion ratio and how it affects suspension components is a very common topic in motorsports.

[Murre]

Does anybody know, what ratio KW2 and KW3 are using is our cars (A4 B6)??