Alignment or Corner Balance first?
02-14-2009, 04:18 PM
#41
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Originally Posted by DCIdevil,Feb 14 2009, 02:53 PM
well beings the s2000 weighs what 2700lbs, i took a few pounds out of it so far and being i dont weigh 300lbs, your number is a little high.
Well with whatever they ended up with i'm sure it'll be better than what it was. (they can only do so much with the aggressive tires and wheel stance i'm running height wise).
Well with whatever they ended up with i'm sure it'll be better than what it was. (they can only do so much with the aggressive tires and wheel stance i'm running height wise).
02-16-2009, 11:34 AM
#43
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Originally Posted by bellwilliam,Feb 14 2009, 08:32 AM
have to disagree. you rarely see a racer NOT CW. CW is actually a lot simpler than everyone thought. not sure why some shop charges ridiculous amount of money for it. I think it is easier than alignment. except it is more time consuming.
that said. s2k is one of the car that comes stock pretty balanced. may be that' why it isn't as popular in this crowd than others.
you definitely need corner weight if you are getting different balance going right vs left. e.g: oversteer going right and understeer going left. OR more understeer right vs. left.
in Spec Miata world, they care more about CW than ride height. you often see uneven ride heights, that's to fix CW.
when you corner weight, you unhook one side of sway bars. it would be best to use adjustable end-links. so you don't throw CW off when you hook sway bars back on.
I CW again after the sway bars goes back on.
I personally prefer CW before alignment. but that's just me, you can argue either way.
that said. s2k is one of the car that comes stock pretty balanced. may be that' why it isn't as popular in this crowd than others.
you definitely need corner weight if you are getting different balance going right vs left. e.g: oversteer going right and understeer going left. OR more understeer right vs. left.
in Spec Miata world, they care more about CW than ride height. you often see uneven ride heights, that's to fix CW.
when you corner weight, you unhook one side of sway bars. it would be best to use adjustable end-links. so you don't throw CW off when you hook sway bars back on.
I CW again after the sway bars goes back on.
I personally prefer CW before alignment. but that's just me, you can argue either way.
I thought he referred to how important is to a NOVICE......
I'm taking that as someone who is just sarting to track their car - probably a HPDE at most....
Easier than alignment? Yup sometimes - certainly depends on the vehicle. Ever try alignment and CW on a torsion bar P 911? Will make you want to cry!
Again, if your not sure that your alignment is 99% there then save yourself a headache and align it first before you CW
And , yes, CW is far more important than even ride heights - we agree
- Except when you completely screw up your camber curves or bump steer due to lowering too much.
02-16-2009, 01:37 PM
#44
Former Moderator
Different but related question.
Is preload used to adjust corner balance or ride height?
If it's ride height can you please explain why so I can understand the reasoning.
Thanks
Is preload used to adjust corner balance or ride height?
If it's ride height can you please explain why so I can understand the reasoning.
Thanks
02-16-2009, 02:07 PM
#47
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preload gets really complicated. very good and technical reading here. thanks to Jason at miata.net:
http://forum.miata.net/vb/showthread.php?t=178130
The factory setup has lots of preload because they use soft springs. Are they poorly engineered? The softer your springs the more pre-load they need to have.
The pre-load a spring needs is a function of:
- shock body length setting
- desired static ride height
- spring rate
Change any one, and the pre-load needs to change.
Stop thinking about pre-load people. You are all confusing yourselves by looking at it the wrong way.
Repeat after y8s:
"Pre-load shmree-load does NOT change the spring rate"
Repeat as many times as needed until you accept the statment.
And then think of it this way:
Think first about the position of the wheel at:
1. full droop
2. bumpstop touch
3. full bumpstop compression
Adjusting the shock length will move the wheel position of the above 3 relative to the body, up and down by the same amount.
You then pick a static ride height. The distance from your static ride height to point (1) above gives you the droop travel. The distance from static ride height to point (2) above gives you bump travel, to bumpstop touch. The distance between (2) and (3) is the amount of travel the bumpstop is capable of.
Or like I typed earlier, you look at the max bump your wheel can take at which something rubs - in my car's case I *do* want this, then I set the shock length as such. In some cars this might be so low that the underbelly is only 2 inches from the ground (some NA's), which you might deem to be too low for a street car.
Then you think about your desired ride height, and how much bump and droop travel you have. With stiff springs you want to NOT corner on the bumpstops, but only compress the bumpstops in midcorner bumps, which is acceptable.
The pre-load you need will then be whatever it needs to be to get your desired static ride height. No more no less. No other significance. No special properties, doesn't change weight transfer, doesn't make anything softer or harder or smarter or faster.
Here are some more points:
The available travel along the shaft of the shock determines the distance between (1) and (2).
If you are at a certain setting and you decide you want to go lower, do you adjust the pre-load or adjust the shock length. Well, if you shorten the shock you maintain the bump travel, but your tire might rub or A-arm might hit something on large bumps. If not, then it's OK to do that. If you adjust the spring perch ("pre-load"), then you will reduce bump travel but maintain the wheel position at bumpstop touch and full bumpstop compression. If your springs aren't stiff enough, then you might be cornering on the bumpstops, which is not recommended unless the whole spring/shock/bumpstop system has been designed that way such as with the factory NB setup. (The NA setup is more kludgy).
Some shocks like JICs have such miniscule shaft travel, that you can't think simply about maximizing bump travel, because that would tend to eat into your droop travel. You probably have to think about centering the ride height position to have equal bump and droop. It also means you have to use stiffer springs than otherwise - soft springs will make you hit full droop and full bump more often.
Factory shocks, and factory replacement shocks such as Konis, Bilsteins, and some coilovers such as AD's, and Tein HA's, have *huge* shaft travel, that you will have lots of droop travel even if you try to maximize bump travel. Tein Flexes, and especially JICs, have a lot less shock travel that you have to consider available droop travel when you set your bump travel. Lack of droop travel *can* be a concern - if a tire lifts and unloads, you lose traction, simple as that.
The following will require more pre-load, as measured in inches:
- softer springs
- higher ride height
- shorter shock setting
- shock has short shaft travel available
IF your springs are stiff, and IF your shock has lots of travel, you may need to have the equivalent of negative pre-load - springs flop loose, so you will need tender springs.
With soft springs and a relatively high ride height, and lots of bump travel, the spring coils may bind before full bumpstop compression. You will *need* a longer spring because longer springs will compress a longer distance (delta length, not overall length) before bind.
Alas, Tein or JIC could have put in an explanation and nomographs in the Flex instructions relating ride height, spring rate, bump travel, etc, but they didn't. They should have shown what spring length you need, etc. Instead they dumbed it down to "set the body length and ride height to this", and a "not for road use" lawyer statement. Application, spring rates, front/rear under/oversteer balance be damned.
http://forum.miata.net/vb/showthread.php?t=178130
The factory setup has lots of preload because they use soft springs. Are they poorly engineered? The softer your springs the more pre-load they need to have.
The pre-load a spring needs is a function of:
- shock body length setting
- desired static ride height
- spring rate
Change any one, and the pre-load needs to change.
Stop thinking about pre-load people. You are all confusing yourselves by looking at it the wrong way.
Repeat after y8s:
"Pre-load shmree-load does NOT change the spring rate"
Repeat as many times as needed until you accept the statment.
And then think of it this way:
Think first about the position of the wheel at:
1. full droop
2. bumpstop touch
3. full bumpstop compression
Adjusting the shock length will move the wheel position of the above 3 relative to the body, up and down by the same amount.
You then pick a static ride height. The distance from your static ride height to point (1) above gives you the droop travel. The distance from static ride height to point (2) above gives you bump travel, to bumpstop touch. The distance between (2) and (3) is the amount of travel the bumpstop is capable of.
Or like I typed earlier, you look at the max bump your wheel can take at which something rubs - in my car's case I *do* want this, then I set the shock length as such. In some cars this might be so low that the underbelly is only 2 inches from the ground (some NA's), which you might deem to be too low for a street car.
Then you think about your desired ride height, and how much bump and droop travel you have. With stiff springs you want to NOT corner on the bumpstops, but only compress the bumpstops in midcorner bumps, which is acceptable.
The pre-load you need will then be whatever it needs to be to get your desired static ride height. No more no less. No other significance. No special properties, doesn't change weight transfer, doesn't make anything softer or harder or smarter or faster.
Here are some more points:
The available travel along the shaft of the shock determines the distance between (1) and (2).
If you are at a certain setting and you decide you want to go lower, do you adjust the pre-load or adjust the shock length. Well, if you shorten the shock you maintain the bump travel, but your tire might rub or A-arm might hit something on large bumps. If not, then it's OK to do that. If you adjust the spring perch ("pre-load"), then you will reduce bump travel but maintain the wheel position at bumpstop touch and full bumpstop compression. If your springs aren't stiff enough, then you might be cornering on the bumpstops, which is not recommended unless the whole spring/shock/bumpstop system has been designed that way such as with the factory NB setup. (The NA setup is more kludgy).
Some shocks like JICs have such miniscule shaft travel, that you can't think simply about maximizing bump travel, because that would tend to eat into your droop travel. You probably have to think about centering the ride height position to have equal bump and droop. It also means you have to use stiffer springs than otherwise - soft springs will make you hit full droop and full bump more often.
Factory shocks, and factory replacement shocks such as Konis, Bilsteins, and some coilovers such as AD's, and Tein HA's, have *huge* shaft travel, that you will have lots of droop travel even if you try to maximize bump travel. Tein Flexes, and especially JICs, have a lot less shock travel that you have to consider available droop travel when you set your bump travel. Lack of droop travel *can* be a concern - if a tire lifts and unloads, you lose traction, simple as that.
The following will require more pre-load, as measured in inches:
- softer springs
- higher ride height
- shorter shock setting
- shock has short shaft travel available
IF your springs are stiff, and IF your shock has lots of travel, you may need to have the equivalent of negative pre-load - springs flop loose, so you will need tender springs.
With soft springs and a relatively high ride height, and lots of bump travel, the spring coils may bind before full bumpstop compression. You will *need* a longer spring because longer springs will compress a longer distance (delta length, not overall length) before bind.
Alas, Tein or JIC could have put in an explanation and nomographs in the Flex instructions relating ride height, spring rate, bump travel, etc, but they didn't. They should have shown what spring length you need, etc. Instead they dumbed it down to "set the body length and ride height to this", and a "not for road use" lawyer statement. Application, spring rates, front/rear under/oversteer balance be damned.
02-16-2009, 02:45 PM
#48
Former Moderator
Okay, so adjusting ride height is the correct way to CB? but don't you want to keep your droop and bump at the same mechanical points.
Sorry for not completely understanding but it still seems preload is the way to CB vs ride height.
Rylan, sorry for not making my first question clear.
Sorry for not completely understanding but it still seems preload is the way to CB vs ride height.
Rylan, sorry for not making my first question clear.
02-16-2009, 03:03 PM
#49
Registered User
Originally Posted by macr88,Feb 16 2009, 03:45 PM
Sorry for not completely understanding but it still seems preload is the way to CB vs ride height.
This is something that you would understand better if you go out to your car and play around with it for a few hours.
What people talk about when they talk about "preload" for springs actually is adjusting the ride height. When you change the ride height at one corner, it changes the weight distribution among the corners. Try it, you'll see.