I somewhat brought this up on an old thread but no one seemed to reply back. I am curious on how to calculate the proper spring rate for a particular car’s application and the different variables that should be given to find a more accurate number. the things I can think of is car weight, type of tires(H, ZR, slicks), strutsbeing used, other suspension modifications (sway bars, bushings, roll cage, etc.), and of course goal of the vehicle(drag, autocross, daily driver, etc)
now figuring out all these variables, is there a general rule of thumb on how to calculate the spring rate or is it more of a guesstimate? I am fairly sure i will be using Eibach as the manufacturer of the springs(ERS line you can request spring rate and length).
Any help is appreciated. Even if you cant help but can link me to someone that could help i will greatle appreciate it. At this point I have more money than knowledge on what I’m doing, which is a new problem i have never faced, and I want to thoroughly research any way i modify my car.
As for the actual calculation I can not help you but for a point of reference, for auto-x the average front spring rate is about 350lbs. and the rear 600lbs. The lenght will be determined from the shocks and actual set up of the car. My road course racing set up has 750lbs. up front and 900lbs. in the rear!!! Works beautiful on the track.
As already known: set up the rear of the car first. I first had a 1989 LS Integra. I put Cadilac springs in the rear(unknown rate), stock shocks, Yokahama tires, DC Sports Intake, Custom 4-1 Headers, no cats, custom exhaust, dynomax muffler, removed A/C and all sound deadening and consistently placed 2nd and 3rd in every auto-x event in CSP!!! It was like sex on wheels - damn that car felt good.
now on this note- If I were to use a “race car” application, is this something that would be completely ustreetable? Would a milder application be a larger or a smaller cps # i’m assuming it would be smaller but just want to make sure the #'s look so. I did notice the difference between 1.5 and 2.5 for the front is about 800 lb/in( i believe that is the units)
also is wheel travel the same as wheel rate as regards to how you mention them? And as of curiosity how did you get the calculations necessary to figure out these #'s? I’m not questioning the validity, just curious how you figured this out. Thanks for the reply I had a feeling you would be able to help out!!
and Sugar Booga your spring rates seem to be fairly close to DB2’s and from my viewpoint, that prolly isnt coincidence you prolly both did your research on this. Good for me to see though to see more than one example and both coming out close to one another- even though its only 2 example 2 is twices as much as one!!!(I’m good with math huh!! hehe)
As usual, more good reading from DB2-R81. Call me dumb, but what is cps?
I have another question, that may or may not be related, how does adjustable compression work on shocks? I mean, what’s it for? I understand adjustable rebound from playing with my konis and from another post from DB2-R81, but I haven’t been able to find good info on what compression adjustment is primarily used for. I’m taking a wild guess and guessing maybe it’s used to make a sort of progressive spring rate out of a linear (is that the right terminology?) spring rate, but that’s just a total guess.
I really gotta go buy some good suspension books…and more driving time…
Originally posted by spikius I have another question, that may or may not be related, how does adjustable compression work on shocks? I mean, what’s it for?
If I’m not mistaken its for turn in, your initial weight transfer. I’d explain it but I suck at explaining things so I’ll leave that to a guru.
Originally posted by Ben Ogle
[B]
If I’m not mistaken its for turn in, your initial weight transfer. I’d explain it but I suck at explaining things so I’ll leave that to a guru.
Ben [/B]
Oh, that makes sense , I understand what you’re getting at, I never thought about that. good point, any guru’s care to elaborate/correct?
FYI this is a reply from Wei-Shen aka the NSX driver along with the G2 race car at sebring
>Brian, it is virtually impossible to answer your question without more information.
>
>On my NSX we have 800lb springs in the front, 500lb springs in the rear. For bumpy tracks like Sebring, we will run without a roll bar in the rear to soften it up to get the power down. The NSX is rear drive, rear weight bias…the Integra is front wheel drive, front weight bias.
>
>I would recommend you contact Comptech Machine at www.comptechusa.com. They provide race modifications for Integra owners including the Real Time Integras driven by Peter Kleinubing and Hugh Plum.
>
>Wei-Shen
> ----- Original Message -----
> From: Brian _
> To: wchin@ctinet.net
> Sent: Saturday, August 31, 2002 2:53 PM
> Subject: DA body style suspension question
>
>
> I am currently setting up a 91 integra for autocross use and would like to know if you have any input as to what a good spring rate would be for a track driven DA. I understand you are going to more than likely put your car’s springs through more of a test than i will be. Also if you have any advice on manufacturers to use for springs and struts i would appreciate it. I am planning on using Eibach ERS springs with a custom spring rate and koni yellows with a modified shorter shock rod.
I dont think he understodd I was trying to find out about the DA that they race. i think it was more of a “stop bugging me kid call these guys” response but also I didnt want to beat him down trying to get more info out of him since i really wouldnt be buying anthing from him.
Originally posted by spikius Oh, that makes sense , I understand what you’re getting at, I never thought about that. good point, any guru’s care to elaborate/correct?
Since no gurus are stepping foreward I guess I will attempt to explain. It is best explained by example. Lets say you have an integra with the same spring rates front and rear (it makes this a hell of a lot easier) and you have AGX’s set softer in the front than the rear. If you are going down the road and you yank the steering wheel to the right (not recommended btw), the softer shock (the front left in this case) will compress faster than the stiffer one on the same side (rear) thus moving the weight more to the front of the car. After this initial weight transfer the springs take over (well kind of, they had influence the whole time but that makes things more complicated).
That is how I have interpreted what I have read in various places and heard from various people. If this is wrong in any aspect please correct me.
Always think of dampers as some thing which controls the rate of oscillation of the springs, cps = cycles per second, related to springs, oscillation per second.
Therefor bump dampening controls the rate, but not the amount of suspension compression.
Why bump rate? When a vehicles tire encounters a raised irregularity in the road surface it is traveling over, the tire, wheel, suspension will move upward. Bump or compression adjustment varies the speed, rate of upward suspension movement and spring compression, attempting to keep the tire in contact with the surface of the road. You have no control, steering or braking or the ability to apply power when your tire is skipping off irregularities.
In your example, variable compression dampening will allow you to control the rate of weight transfer, or spring compression to the front left suspension.
On race car front suspension adjustable compression dampening is most often used to control weight transfer during cornering turn in and braking maneuvers.
Sweet! Many thanks for the great replies Ben and DB2-R81, very informative. Ya, what Ben said in his explanation was what I was envisioning after he mentioned turn in. Thanks for the even more elaborate explanation DB2-R81!
Originally posted by gen2ls/vtec
[B]now on this note- If I were to use a “race car” application, is this something that would be completely ustreetable? Would a milder application be a larger or a smaller cps # i’m assuming it would be smaller but just want to make sure the #'s look so. I did notice the difference between 1.5 and 2.5 for the front is about 800 lb/in( i believe that is the units)
also is wheel travel the same as wheel rate as regards to how you mention them? And as of curiosity how did you get the calculations necessary to figure out these #'s? I’m not questioning the validity, just curious how you figured this out. Thanks for the reply I had a feeling you would be able to help out!!
and Sugar Booga your spring rates seem to be fairly close to DB2’s and from my viewpoint, that prolly isnt coincidence you prolly both did your research on this. Good for me to see though to see more than one example and both coming out close to one another- even though its only 2 example 2 is twices as much as one!!!(I’m good with math huh!! hehe)
, I understand what you’re getting at, I never thought about that. good point, any guru’s care to elaborate/correct?