new thread started see https://honda-tech.com/zerothread?id=1349453&page=1
I think this is the correct forum for this discussion.
The arguement is this. If i have a coilover with a 400 lbs spring and i preload that spring one inch i will now have 400 lbs of pre load. Coilover is not even in the car just sitting on the work bench. Now it i stand it up and place a 400 lbs weight on it the spring in not going to compress at all, It will take 401 lbs to compress the sping 1/400". Their are links in the above thread proving this.
The other side of the argumet says that one pound placed on the pre loaded spring will compress it 1/400".
I am not trying to be an *** here but i am pretty damn sure i am right.

 

You are right. A simple freebody diagram shows this to be the case.

 

You are right.

 

No problem man, wasent trying to start a flame war. Sorry about my attitude on the other thread.
So my next question is this, what would be the optimal preload? I dont know what the stroke range is on an average civic shock, but what would be the best droop to bump distance ratio? Even thought we all run konis and cant really mess with preload i think its still some thing worth asking. I am going to guess that we want more bump distance than droop considering you shouldnt be dropping wheels in to big *** holes or anything. Consider i am asking for a track car not a street car.

 

hmmm...someone better draw a FBD for me b/c mine doesn't bear this out.


edit: ok. i get it now.

 

I wouldn't worry about preload controling the shock bump/rebound limits since the only coilovers that can control preload have adjustable mounting cups, and thus the shock travel is unaffected by ride-height (corner-weight) adjustment.

 

you can read my rant on preload.

https://honda-tech.com/zerothread?id=1336324

 

Please see my next post where i relize how messed up what i am saying here is.

Great rant tyson, But i would still be interested in optimal droop vrs bump ratio for our cars. Considering that the spring rates we choose are going to affect this ratio. A 500lbs spring vrs 1000Lbs spring, the ride is going to sag an inch less with the 1000lbs spring so we lower the spring perch one inch to get the same static ride height. Now we have changed how far the piston is out of the shock at the same static ride height. With the harder spring your going to have less droop distance, because you had to lower the perch. Considering you have the same lenght springs. So this droop/bump ratio combined with spring rates should affect your maximum body roll before you lift a wheel. So using a shorter or longer spring could have its advantages.

edit to correct my self


Modified by ohjolt2 at 5:52 PM 8/26/2005

 

the handling differences between a 500lbs spring and 1000lbs spring is going to completely eclipse any minor effect of the difference of droop distance. so it really doesnt matter.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ohjolt2 &raquo;</TD></TR><TR><TD CLASS="quote">Great rant tyson, But i would still be interested in optimal droop vrs bump ratio for our cars. Considering that the spring rates we choose are going to affect this ratio. A 500lbs spring vrs 1000Lbs spring, the ride is going to sag an inch less with the 1000lbs spring so we lower the spring perch one inch to get the same static ride height. Now we have changed how far the piston is out of the shock at the same static ride height. With the harder spring your going to have less droop distance, because you had to lower the perch. Considering you have the same lenght springs. So this droop/bump ratio combined with spring rates should affect your maximum body roll before you lift a wheel. So using a shorter or longer spring could have its advantages. </TD></TR></TABLE>

That only applies for single adjustable coilovers, in which you can't control the preload anyway.

 

You guys know i just had a light bulb kick on in the old brain. That whole thing i sugested with the 1000lbs vrs 500lbs springs and lowering the perch does nothing for bump/droop ratio. All moving the perch down does is give you more bump before coil bind. When the perch moves down the actual distance between the top hat and the botom mount hasent changed. The only way to affect bumb/droop ratio is to change the static piston location of the shock, considering the ride height didnt change the spring lenght means nothing. So CG top hats will change your bump/droop ratio, so will pushing the shock deeper in the shock fork. So even on a car that doesnt bottom out CG top hats could be use full. My so whats the stroke lenght on a koni yellow? Question for lee grimes, bottoming out will ruin a shock but will topping out ruin a yellow also? i cant see topping out to full droop unless your lifting a wheel in a turn, or maybe you can brake hard enought to hit full droop on your rear shocks. so the ratio of bump/droop is adjustable and i still would like to know what is considered optimal.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ohjolt2 &raquo;</TD></TR><TR><TD CLASS="quote"> So CG top hats will change your bump/droop ratio, so will pushing the shock deeper in the shock fork. So even on a car that doesnt bottom out CG top hats could be use full. My so whats the stroke lenght on a koni yellow? Question for lee grimes, bottoming out will ruin a shock but will topping out ruin a yellow also? .</TD></TR></TABLE>

as far as i understand, Shorting a damper (like you discribed) doesn't change droop.

 

Well if i pull the piston out of the shock an extra inch at static ride height then thats one inch less that my wheel can droop. To take this to the extreme imagine a 5 inch top, if you put that on then their would be like no droop left in the suspension. See how it works?
From what i read in forumal cars they run zero droop in the front and very limited droop in the rear, if they ran zero droop in the rear they wouls lose traction over every bump they hit. Now i know zero droop isnt what we want for our hondas but their has to be some optimal ratio.

 

you missunderstood what i said, when i say shorting i ment, the lower mounting point.

The GC top mounts are infact, droop limiters.

 

By limiting the droop you change the roll properties of the car. when the body starts rolling one shock compresses and one extends. say per degree of roll each shock moves one inch. If the inside shock reaches full droop it stops moving and the outside shock must move twice the distance.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by slammed_93_hatch &raquo;</TD></TR><TR><TD CLASS="quote">you missunderstood what i said, when i say shorting i ment, the lower mounting point.

The GC top mounts are infact, droop limiters.</TD></TR></TABLE>
Makes no diffrence if the inch comes off the bottom or the top. The CG top hats do the same thing as stuffing the shock body an inch deeper in the fock. Lee grimes has a post some where with info on this.

edit to add link to lee's info quoted by RJ half way down the page
https://honda-tech.com/zerothread?id=1106020

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ohjolt2 &raquo;</TD></TR><TR><TD CLASS="quote">But i would still be interested in optimal droop vrs bump ratio for our cars. </TD></TR></TABLE>
I think you have made up new terminology with "optimal droop to bump ratio" as I don't really think it exists although it does sound important. The optimal droop condition and bump condition would be that the damper does not run out of stroke before the car runs out of need for such stroke. If you are not at risk of bottoming and topping out, it no longer matters. Now if you have a damper that has a very short stroke that is likely to be too short for the vehicle's actual needs based on the spring rate, where it sits static in the damper stroke, and how much travel is likely to be needed for the operation of the car, then you have a situation that you you need to select your priority and which you are willing to sacrifice. But in reality, that part really is ill suited to the car. On the otherhand, why not use a damper that actually has plenty of stroke to cover the needs of the car and not a narrow range that you have to target just right with a projected ratio so that you don't top or bottom out?

Look around in the world of real racing and you will not see this kind of thing if the dampers really fit the car. You will see it when the damper has been unitized for easier construction and possibly more generic manufacturing. It is certainly handy when you have a situation where your spring does not fall out of the perch when you jack the car up but that situation is completely erased when the car is actually on the ground and operating. Most of the kits that you see today using this kind of "preload adjustable" system are actually taking an ecomony of manufacturing to be able to make semi-generic short dampers, and threading on a variety of different mounts so they can be applied to a number of different applications and then marketing spinning that to the consumer that they now have some great and desirable new "adjustment". Once you get past the minor inconvenience of having the spring fall out of the perch when the car is jacked up, you have used up any advantage of this new adjustment. In the meantime, you had better hope that the short damper actually has enough stroke in it such that it doesn't run out of stroke before the car does. Aw heck, throw a big stiff spring at it and so that the car won't move much anyway and most guys who buy it won't really know the difference anyway but they'll get to play with their new "adjustment".

BTW, It is possible to over preload a spring on a car but that is typically only found when you have a very soft spring rate and you use a lot of preload pressure to hold the car up at the desired spring rate. From that point, if the coils are now too close together that the car can't get enough compression stroke before the spring goes to coil-bind, then you have too much preload. This is something you might see on the rear of a very light weight RWD drag car that you are trying to get a lot of suspension motion from at launch. In that case, you change the rate or play with other aspects of the spring to deal with it. In the categories or car weight and spring rates that we here on H-T normally deal with, then this will not occur.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ohjolt2 &raquo;</TD></TR><TR><TD CLASS="quote">
Makes no diffrence if the inch comes off the bottom or the top. The CG top hats do the same thing as stuffing the shock body an inch deeper in the fock. Lee grimes has a post some where with info on this.</TD></TR></TABLE>

yes it does, droop is the range from when the car is at static ride height, to the point were the spring begins to rattels in there mounts, changing the bottom mounting point has ZERO effect on this.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ohjolt2 &raquo;</TD></TR><TR><TD CLASS="quote"> Question for lee grimes, bottoming out will ruin a shock but will topping out ruin a yellow also? i cant see topping out to full droop unless your lifting a wheel in a turn, or maybe you can brake hard enought to hit full droop on your rear shocks. </TD></TR></TABLE>

i asked this same question, he said "no".

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by slammed_93_hatch &raquo;</TD></TR><TR><TD CLASS="quote">yes it does, droop is the range from when the car is at static ride height, to the point were the spring begins to rattels in there mounts, changing the bottom mounting point has ZERO effect on this.</TD></TR></TABLE>
hey slammed i belive your wrong but i am not going to argue it with you, i think some one else will explain it, also see the link.

Now on a seperate note i am stealing alot of knowlage from this thread
http://fsae.com/groupee/forums...1/p/1
I fully understand that those are not our cars but the science behind it can still have bearing on our cars. Its also i really good read where some very smart people discuss some cool ****. The very last post at the bottom of the first page of that link is what i am trying to explain in my earlier post.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ohjolt2 &raquo;</TD></TR><TR><TD CLASS="quote">
hey slammed i belive your wrong but i am not going to argue it with you, i think some one else will explain it, also see the link..</TD></TR></TABLE>


hahaha i thought the same way you did, then some one explained it to me.


droop travel, is measured from static ride height to the point were the spring becomes free, in the perch (the instant it because free).

 

OK install a koni normally and jack the car up untill the tire lifts, measure the distance from the tire to the wheel well. Now slam that shock an inch deeper in the fork and do it, Your measurement will be an inch less.
https://honda-tech.com/zerothread?id=1106020 read where RJ quotes Lee and shows the picture

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ohjolt2 &raquo;</TD></TR><TR><TD CLASS="quote">OK install a koni normally and jack the car up untill the tire lifts, measure the distance from the tire to the wheel well. Now slam that shock an inch deeper in the fork and do it, Your measurement will be an inch less.</TD></TR></TABLE>

You're reaching for supporting examples to make your argument - we call this a "straw man"

You cant slam it an inch deeper in the fork, you can only go 1/2" at the most by removing the brake line bracket, and you'll get just over another 1/2" at the top end by using a ground control upper mount.

With a good, off the shelf shock like the Koni Yellows for example (or Leda, etc) you will get the front tire off the ground before you run out of bump travel, and this is just not a situation you will ever encounter on a street or a race track. I'm not sure what you're getting at, and there's just no "optimal bump to droop" ratio at all. You just make sure the damper you want to use is appropriate for the applicaion and has enough travel in either direction. You should be much more concerned about the amount of bump travel you have, as that is always a battle to get enough of with a production chassis using off the shelf dampers running a ride height low enough to get good camber on the front tires. You cant compare this to a purpose built, formula racer - the requirements and design are so much different and not contrained within a production chassis, so there are many, many more suspension design variables at work, and the amount of bump/droop available is going to be affected just as much by their suspension design as their damper stroke range.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Tyson &raquo;</TD></TR><TR><TD CLASS="quote">you can read my rant on preload.

https://honda-tech.com/zerothread?id=1336324</TD></TR></TABLE>

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Tyson &raquo;</TD></TR><TR><TD CLASS="quote">

one misconception about preload is that it changes the spring rate, or makes the spring stiffer. absolutely not. if the spring is linear, the spring rate SHOULD remain the same, no matter the amount it is initially compressed. (not all springs are equal, some of the crappy taiwanese springs have exhibited non-linear behavior when they clearly were not designed to) </TD></TR></TABLE>

Its amazing how many people dont understand this.

 

ppl confuse spring rate with spring force. i can understand being confused by this, but ppl who really dont understand the difference should really not be talking about springs.