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Civic Spring Rate/Suspension Questions


spdracer22

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What would be a good starting point for Civic spring rates? The car is a 97 CX Hatch, roughly 2450lbs with me in it. I'm not going to be running HC (car is turbo'd) but I'd like to get an idea of what some people are running. Feel free to PM me if you don't want to post the rates you use. Thanks in advance for the help!

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A few questions anyone will have when trying to address your question:

 

1.) Your Experience level?

2.) What is on the car now?

3.) What do you want to do with the car? AutoX, HPDE, Daily Driver etc.. .

4.) What is your budget?

 

Honda Racers use anywhere from 400# to 1200# springs

 

I'm not a HC racer but I've used and enjoyed 550# front and 450# rear Omni Power Coilovers to start and now I am running Koni Spss3 650# front and 850# rear. I do AutoX and HPDE and pretty soon, Time Trials.

 

If you want to start looking: Setups I would look at

Under $800 budget = PIC Performance Apex, Omni Power, Used Koni Sports/Ground Control

Around $1,000 = Koni Sports/GrndCtrl, PIC Select Coilovers

Under $1500 = Koni Race Spss3/GrndCtrl, Buddy Club RSD for that JDM BLING

 

You will get the most years of use and versatility out of the Koni + Ground Control Setups. Koni Sports are probably going to be your best choice b/c they offer a great warranty on their Sport shocks. The Koni Race Shocks do not have warranties and I am not sure about PIC.

 

koni and G/C products here - also Check deals on Honda-Tech forum - http://www.redshiftmotorsports.com/SearchResults.asp?Cat=36

 

http://picperformance.com/store/scripts/prodList.asp?idCategory=82

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If you car is track only:

650lbs/ich front, 850lbs/inch rear would be a good starting point. Make sure you have shocks that can handle this much spring rate (ie Koni "yellows" with spss3 valves).

 

If it's your street car then:

300lbs/ich front and 400lbs/ich rear would be good. It's still going to be a stiff ride but it will not brake your tail bone like the above spring rates will.

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1.) Your Experience level?

Prior RR, 3 years SCCA Solo, 10+ years Karts

 

2.) What is on the car now?

I just had my koni sports revalved with the SPSS3 valving, but I didn't have them shortened.

 

I don't currently have any springs. I did have H&R's 'Race' springs on it, but I just sold them. The problem with them was that they were progressive, and the first 5" of spring was supposed to be bottomed out; something I didn't do. So, the front springs were working at less than 250lbs/in, but the bump rubber was bottomed out throughout the entire stroke.

 

According to the spring tester at work, the total rate (combined spring and bump rubber) was going from 304 lbs/in at 0.75" travel to 850 lbs/in at 1.5" travel. (a 550lb increase over 0.75in!!!) The rears were rated by H&R as 385, but again were progressive. I didn't test them or the rubber on the spring tester, but again, the rubber was bottomed throughout the stroke, so I'm guessing somewhere from 150 lbs/ride to maybe 450 or so at 1.5" travel.

 

Here's my data from the fronts:

Travel.....Spring.....Rubber.....Combination

0.75........168.........136..........304

1.............197........204...........401

1.25.........231........348..........579

1.5...........270........580..........850

 

 

3.) What do you want to do with the car? AutoX, HPDE, Daily Driver

Currently the car is dedicated solo. The only driving on the street I do with it is *maybe* to and from the event, if it's close and I don't pull it. I want the best racing setup I can get...street comfort isn't a concern to me.

 

This year, the car will be autocrossed again in Street Modified. I'll also be doing some HPDE's and working on a TT license. Next year, I'll be doing TT and working on my competition license. I plan on running TTS and ST2.

 

4.) What is your budget?

I already have the dampers done, so I was looking at Ground Control sleeves. I have the money budgeted for them.

 

 

If you car is track only:

650lbs/ich front, 850lbs/inch rear would be a good starting point. Make sure you have shocks that can handle this much spring rate (ie Koni "yellows" with spss3 valves).

Really, that high in the rear?

 

I've done some preliminary calculations based on the damper motion ratios, current weight and distribution, etc, and I come up with 1018 lbs/in fronts and 581 lbs/in rears at 1.5" travel and 1.5G max cornering (R-comps, obviously).

 

This is why I'm so confused about this. I calculate one thing, and it makes sense to me, but then people tell me another thing, and it too makes sense to me...

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I've done some preliminary calculations based on the damper motion ratios, current weight and distribution, etc, and I come up with 1018 lbs/in fronts and 581 lbs/in rears at 1.5" travel and 1.5G max cornering (R-comps, obviously).

 

This is why I'm so confused about this. I calculate one thing, and it makes sense to me, but then people tell me another thing, and it too makes sense to me...

 

if you want your car to handle good ok go with the suggested rates above. If you want a car that pushes (under steer) then go with the rates you came up with.

 

On honda-tech.com there is a pretty good write up on why the setup you mentioned actually doesn't make any sense for a FWD car. Maybe some one has it saved, i don't

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I've done some preliminary calculations based on the damper motion ratios, current weight and distribution, etc, and I come up with 1018 lbs/in fronts and 581 lbs/in rears at 1.5" travel and 1.5G max cornering (R-comps, obviously).

 

I can tell you what I did. I did those suspension frequency calculations and came up with ~650 lbs/in front and 400 lbs/in rear. For my first 2 years I used 672 front and 392 rear (funny numbers because thats 12 and 7 kg/mm). The car was very stable and easy to drive, however it pushed and was slower than the leaders by about 2 seconds a lap. So I switched the rears to be 896 based on racers experience. The car now has a neutral to loose setup and gained those 2 seconds a lap.

 

I don't know too many technical details, but I believe the problem with the calculations is that they are based on a neutral car setup. That is why my calculations worked for the front. However, for a front drive car you want the rear to be loose, hence the much stiffer rate than the calculations would lead you to believe. I haven't tested this theory, but I would guess that the calculations would work very well for a balanced rear drive car (like a BMW).

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spdracer22,

 

cool experience you have.

 

I've read the thread on H-T about the "Rear Biased Setup" that slammed_93_hatch is talking about and I basically came away with leaning towards the US norm, rear biased setup, even though the numbers do not JIV.. .

 

I've been advised to go with 600-900# rates for mid range race rate to start with.. . I have 650# fronts and 850# rears and this setup has yet to go on my car this year.

 

Since you did not get your Konis Shortened, you will need to get the G/C top hats front and rear. An explanation is in the H-T link below

 

Here is a Suspension thread from last year that I started when I just got into HPDE > http://www.honda-tech.com/zerothread?id=1746209

that thread helped me get pointed in the correct direction

 

I hope this helps you out

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As soon as I posted my reply, I remembered my OTHER spring rate calculation spreadsheet I made that's based on Milliken's ride frequency method.

 

I had asked about this before on SCCA Forums, and I got a link to a decent writeup on FWD setup...how I forgot this, I don't know. The link is below:

 

http://farnorthracing.com/autocross_secrets10.html

 

In it, he gives some good explanations about what the car should be doing, and that the ride frequencies should be roughly 2Hz front and 2.5Hz rear. Based on my spreadsheet and what you guys have told me, 650F/850R get the frequencies to about 1.87F/2.72R...pretty much what he was saying.

 

My initial assumptions 6 months ago were to use heavier springs in the back, but never got much support because there's only one other decently competitive Civic (or Honda for that matter) that I autocross with here in MI, and most replies I've gotten compare better to my first calculations using the 'neutral RWD' assumption.

 

Needless to say, I'm definitely going to go with what you guys are saying, and I'm definitely confident in it. I just needed to find a good group of REAL Honda racers (read: not ricers like on most forums) to set me straight.

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I just remembered another question...what are you guys using for bump rubbers? OEM Honda? Modified? Aftermarket?

 

Edit:

 

Also, I have Suspension Techniques F/R ARBs. I was thinking about going to an ASR 32mm rear bar. What do you guys think? Does someone make an adjustable front bar?

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That website link is TITS bud. Good find and thanks for sharing!!

 

I can't wait to try my Koni Race setup this year. Hopefully I will be done refreshing my entire suspension before my 1st Auto X on the 17th.

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850# w/ 32mm ASR rear bar.. .650# w/ Suspension Techniques front bar.. .

 

Sounds Real Stiff & sounds like a Auto X setup to me but I know of RR people running 1000# + rear spring rates with big bars as well. Personal preference I guess.

 

I would prefer to run the smallest bars possible and tune with spring rates and then bound and rebound from there.. .

 

I'll be testing my Koni Race with 650F and 850R with GSR sway bars front and rear and see how it does. If body roll is minimal I might even take the front or the rear bar off depending what I think will work best.. .

 

I think the East Coast Front Runner Chad Slagg's setup in rescent years was like 600#f with no bar and 700# rear with only a stock 15mm GSR bar.. . He runs something different now

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I'll run the Front & Rear ST bars for now, then, and see how they do...it'll be extremely different with the new springs and dampers alone.

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To OP:

 

A wise man once said,

 

"The FWD chassis? It's this simple: Any weight on the inside rear could have been on the inside front."

 

I run 1200 lbs rear springs and don't have a front swaybar (on a 2250 lb Prelude, YMMV)

 

Good luck.

 

-Chris

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To OP:

 

A wise man once said,

 

"The FWD chassis? It's this simple: Any weight on the inside rear could have been on the inside front."

 

I run 1200 lbs rear springs and don't have a front swaybar (on a 2250 lb Prelude, YMMV)

 

Good luck.

 

-Chris

I think I know what you mean, but would you care to explain?
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I'll give this a try -

 

I think he basically means that when looking at the forces involved on the 4 corners of the FWD car when cornering, if any weight is on the inside rear, the outside tires and the ""Inside Front"" are not achieving max load(max traction) available.

 

The outside front is already getting most of the grunt. So if any can be transfered to the inside front, thats a good thing. I don't think that having the inside REAR 6" off the ground is a good thing b/c you're probably getting pretty close to picking up the inside front too, making the car real sensitive to inputs and unstable.. .

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That's what I was thinking, I just wanted to make sure. What you said goes along with what I said over on H-T. The higher you get the IR off the ground, the more it's going to be transferring to the OF. I think that's why you don't see the RTR cars with the tires 12" off the ground. As long as it's off the ground, the other corners have to carry the weight, but the closer you can get it to the ground without touching, the more that's going to be on the IF.

 

I still have to get back into the swing of driving like a road racer, but once I do, I plan to do a lot of spring rate testing, starting with the 650/850 numbers you guys have given me.

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When is your first track day?

 

I should be hitting up an Auto X next weekend and a HPDE April 7th at MAM.

 

I'll let you know how I do with 650f and 850r

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Unless I can find one sooner, it looks like the one at Putnam Park in May. I'm not going to be able to make Mid-Ohio due to my brother's Cost Guard Basic graduation...

 

I'm definitely interested in what you find out...

 

Edit: First autocross event is May 6.

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What you said goes along with what I said over on H-T. The higher you get the IR off the ground, the more it's going to be transferring to the OF.

 

I want to comment that this is not exactly true. I think you are misinterpretting what is being said on H-T.

 

Of course, as load transfers from the IR to the OF, that corner lifts as spring load is relieved, but remember that once the tire comes off the ground, that's it. There is not more load transfer occuring from that wheel to any other. Instead, any more load going to the OF is coming from the OR and the IF.

 

Slight wheel lift in corners is just fine, but huge wheel lift is not. Reduced overall grip will result from overloading the OF, reducing the load on the IF and OR, and from running the OF outside it's optimal camber.

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No, what you said is exactly what I was thinking...maybe I just didn't say it correctly. Obviously, since all of the weight carried by the IR is carried by the other three tires as soon as it leaves the surface, to get the IR any higher, the load on the IF and OR corners has to decrease... So, at least in my mind, you would want the IR off the ground, but as close as possible to keep the IF loaded as much as possible...please explain it to me if I'm wrong...

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No, what you said is exactly what I was thinking...maybe I just didn't say it correctly. Obviously, since all of the weight carried by the IR is carried by the other three tires as soon as it leaves the surface, to get the IR any higher, the load on the IF and OR corners has to decrease... So, at least in my mind, you would want the IR off the ground, but as close as possible to keep the IF loaded as much as possible...please explain it to me if I'm wrong...

 

Yeah, maybe I just didn't understand what you were saying. But I just wanted to clarify for people the difference between wanting to unweight the rear wheel and tuning in massive wheel lift. My extension to your first point was that if your IR is even just barely off the ground, there is nothing to be gained by further biasing your setup.

 

On an autocross course it may be different, but on a road course, where my experience lies, rotation has to be balanced with overall lateral grip. The traction potential of a tire cannot be compared the typical friction formula(F = Friction Coef * normal force). While a tire does gain traction potential as you load it, it does so with an increasingly diminished return. Simply stated, the more load you transfer, the less overall traction you can have(one tire can't do the work of 4). Because of this, you have to be careful with how much you rear bias your roll rates. At the point of wheel lift, it's time to start looking somewhere else for rotation.

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850# w/ 32mm ASR rear bar.. .650# w/ Suspension Techniques front bar.. .

 

Sounds Real Stiff & sounds like a Auto X setup to me but I know of RR people running 1000# + rear spring rates with big bars as well. Personal preference I guess.

 

I would prefer to run the smallest bars possible and tune with spring rates and then bound and rebound from there.. .

 

I'll be testing my Koni Race with 650F and 850R with GSR sway bars front and rear and see how it does. If body roll is minimal I might even take the front or the rear bar off depending what I think will work best.. .

 

I think the East Coast Front Runner Chad Slagg's setup in rescent years was like 600#f with no bar and 700# rear with only a stock 15mm GSR bar.. . He runs something different now

 

Chad's EM1 is on PIC Select R4's, although I'm not sure what bars he was running.

 

Typically you'd want tune with the ARB's and compression/rebound if you've got it, and not the springs though.

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