Effect of changing spring pre-load on height and handling - Mitsubishi Evolution Forums: Mitsubishi Lancer Forum
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Old 09-15-2007, 12:02 PM   #1 (permalink)
 
Registered: Sep 2005
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Effect of changing spring pre-load on height and handling

My Zeal Function X coilovers come with independent spring pre-load and height adjustment collars. They have been corner-balanced but I have found that the coilovers have a tendency to bottom out on bad depressions in the road or over bumps.

To this end, I was thinking of getting adjusting the spring pre-load collars to get longer stroke, but before I do that, I wanted to check in with you guys on:

a. whether i would need to have the car corner balanced again. The spring pre-load adjustment collar has no visible effect on ride height as I can see

b. what effect on handling would there be to having a longer stroke?
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Old 09-15-2007, 05:51 PM   #2 (permalink)
 
Registered: Mar 2007
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Originally Posted by ghoonk View Post
My Zeal Function X coilovers come with independent spring pre-load and height adjustment collars. They have been corner-balanced but I have found that the coilovers have a tendency to bottom out on bad depressions in the road or over bumps.

To this end, I was thinking of getting adjusting the spring pre-load collars to get longer stroke, but before I do that, I wanted to check in with you guys on:

a. whether i would need to have the car corner balanced again. The spring pre-load adjustment collar has no visible effect on ride height as I can see

b. what effect on handling would there be to having a longer stroke?
A. Yes, changing the preload will affect the overall balance. TO what signifigance, I couldn't tell you.

B. A less aggressive feel in the overall handling.

Now a question for you. Are you sure the coilovers are bottoming out or is this setup new to you and you're just not used to the feel? I ask this because it's very easy to assume they're bottoming out due to the stiffness of the ride (less bounce and not really a soft ride). If they're actually bottoming out, something is significantly wrong with the adjustment or the coilovers themselves (blown).
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Old 09-16-2007, 01:17 AM   #3 (permalink)
 
Registered: Sep 2005
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The shocks are fine, just that the roads here in Dubai can be quite bad in some places, and the randomly changing traffic routes and construction do come as a surprise sometimes.

Regarding point A, I was under the impression that corner balancing is only affected by ride height and not spring pre-load, and the latter affects handling in the same way that changing damping settings do. Hence the question of how it affects handling, i.e. less front end grip or more front end grip?
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Old 09-16-2007, 05:17 PM   #4 (permalink)
 
Registered: Mar 2007
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Originally Posted by ghoonk View Post
The shocks are fine, just that the roads here in Dubai can be quite bad in some places, and the randomly changing traffic routes and construction do come as a surprise sometimes.

Regarding point A, I was under the impression that corner balancing is only affected by ride height and not spring pre-load, and the latter affects handling in the same way that changing damping settings do. Hence the question of how it affects handling, i.e. less front end grip or more front end grip?
It effects the balance depending on what degree it is done to, as height can also be affected by the adjustment, thus the statement is partially true. I'll use the Tein FLex in my example, as this is what I use and it gives me a frame of reference to describe from. It is a suspension with a fairly aggressive spring rate in stock form. If if were to adjust the spring load on it only, my vehicle heght would change dependant on how I adjusted it. The reason there is a seperate height adjustment is to allow you to compensate for this difference created. As well, the front and the rear coilovers are not the same heght and not the same springrate as each other, thus one is harder than the other and one naturally sits higher than the other. So, let's say you adjusted my preload by .5 inches in the front and .5 inches in the rear in the same direction, to say increase the preload (spring more tense). You'll notice the the vehicles height raised, but not evenly. Bottom line, you can't adjust the preload to get the effects you want and not change the height without effecting the balance.

To answer the other part of this question, it you were to soften the preload in the front and increase it in the rear, the front will grip more, and vice versa.
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Old 09-17-2007, 06:10 AM   #5 (permalink)
 
Registered: Sep 2005
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Interesting. The Zeal Function X is capable of spring pre-load adjustment without affecting ride height as the upper collar moves downwards to accommodate. I will investigate further and let you guys know how this turns out....
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Old 09-17-2007, 09:26 PM   #6 (permalink)
 
Registered: Jul 2007
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Originally Posted by ghoonk View Post
My Zeal Function X coilovers come with independent spring pre-load and height adjustment collars. They have been corner-balanced but I have found that the coilovers have a tendency to bottom out on bad depressions in the road or over bumps.

To this end, I was thinking of getting adjusting the spring pre-load collars to get longer stroke, but before I do that, I wanted to check in with you guys on:

a. whether i would need to have the car corner balanced again. The spring pre-load adjustment collar has no visible effect on ride height as I can see

b. what effect on handling would there be to having a longer stroke?
Fact: Every time a person mentions pre-load in reference to cars, God kills a manatee.

a. The collar on which the spring sits is the spring perch. On these designs, the only reason there is an adjustable spring perch and spring perch lock (the collar below it) is so that you can turn the two against each other as hard as possible, locking the two together. When you turn one, the other turns, and the entire shock body turns inside the adjustable lower mount. That raises and lowers your car's height at that corner without reducing available stroke, which is you don't have a lot of with short-stroke high-displacement coilovers.

b. As much stroke as you can get is generally what you want. More stroke = more distance the piston can travel before bottoming or topping out inside the shock body, assuming your spring has enough available distance between its coils before binding.

Determine what it is that is bottoming out before you go undoing your expensive corner-balancing procedure. Is it the piston inside the damper? Is it the tire on the wheel well? Is it the spring binding? If you have an adjustable lower mount, you should only use that to adjust height. There is no reason to reduce available shock travel if you don't have to, and (IMO) pre-load should never be used as a tuning method on a car, and the only time it plays a role in corner-balancing is if you have a car without an adjustable lower mount, but that's not the case here.
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Old 09-17-2007, 11:12 PM   #7 (permalink)
 
Registered: Sep 2005
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What's a manatee? Hope they aren't endangered, because I'm still trying to figure out the dark art of suspension tuning.

Going back to the setup, it appears that the coilovers are such that I have a spring perch adjustment on the upper half of the coilover that allows me to run a longer stroke without affecting the overall height, which is controlled by a separate collar on the lower half of the same coilover. At least that's what I'm been told about how it works.

I'm going to have to go back to speak to the guys who did my corner balancing (same guys who run the Radical Cup) as well.

My bad for not mentioning this before, but the bottoming out happens on the rear, not the front, and there are no marks on the tires, indicating that it is not hitting the arches. Rather, it feels like the shock bottomed out, and again, I am not able to confirm this without further investigation.
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Old 09-18-2007, 11:03 AM   #8 (permalink)
 
Registered: Jul 2007
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Originally Posted by ghoonk View Post
What's a manatee? Hope they aren't endangered, because I'm still trying to figure out the dark art of suspension tuning.

Going back to the setup, it appears that the coilovers are such that I have a spring perch adjustment on the upper half of the coilover that allows me to run a longer stroke without affecting the overall height, which is controlled by a separate collar on the lower half of the same coilover. At least that's what I'm been told about how it works.

I'm going to have to go back to speak to the guys who did my corner balancing (same guys who run the Radical Cup) as well.

My bad for not mentioning this before, but the bottoming out happens on the rear, not the front, and there are no marks on the tires, indicating that it is not hitting the arches. Rather, it feels like the shock bottomed out, and again, I am not able to confirm this without further investigation.
I'm pretty sure they are endangered, I'm not positive. They are like cows of the sea. But they are harmless sea giants, so there's no reason to kill them anyways.

The spring perch adjustment doesn't allow you to run a LONGER stroke. Technically, it can adjust available stroke but it can't extend it past the maximum allowable, only reduce available stroke which you don't want, so I would not really consider it an adjustment at all. You're correct on the rest of the setup though, all height adjustments should only be made via the adjustable lower mount if you have that option.

Are you positive no other rear suspension components are binding up, like the spring? How low is the rear? You'd need to be pretty low or have low rates + hit a hard bump or any combination to bottom out the rear. That is, unless, you have drastically reduced available shock travel in the rear by lowering the car using the spring perches, and now the lower mounts .
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