spring rates, lengths, and sway bars (oh my!)

[Chris Sawatsky]

Ok so I'm looking to run a new suspension setup on my 88 crx Si for the coming season, and I'm looking for a bit of input.
My current setup is koni yellow shocks, neuspeed race springs, and stock sway bars

The tentative plan I have in my head is same koni's, Ground Control coilovers, 500f/600r, 9" length, stock front sway, and Suspension Techniques rear sway. The GC's would of course be adjusted for proper corner weighting. Which brings me to my question of what's desireable for corner weights. Perfectly balanced so all 4 corners have the same weight?
Will using the Ground Controls to adjust my car's height also change the spring rates?

What spring length is recommended for a GC setup? Anyone know what stock spring length is for a crx?

[Knestis]

I don't know CRXs well but I would be VERY surpised if you could get the corner weights all even. Get your ride heights in the ballpark first then, failing any logical reason to do otherwise, try to get the left and right front CWs matched first then, if possible, get the left and right rear matched up. Remember to do this with typical fuel and driver loads in the car.

I have played with "differential" set-ups on road racing cars, biasing corner weight (like the NASCAR guys do) to improve speed on tracks that predominantly turn in one direction. This is kind of fun but the time to be found here might be offset by the tail-chasing that is required - particularly if you are relatively new to this whole deal...

You actually MUST change the ride HEIGHT to change the corner weights but the RATES will remain unchanged. Think of a four-legged table - if all of the legs are exactly the same length (on perfectly level ground) the weight will be distributed evenly. If you cut one leg shorter than the others, weight will be carried disproportionatelty by the two legs adjacent to the shorter one, the extreme case being one or both of them in the air, supporting NO weight.

Springs of different rates change this action a little on a real car but, as you pull one wheel closer to the chassis (lowering ride height by raising the collars supporting th top of the spring), you are doing effectively the same thing as sawing off that leg, jacking weight onto the adjacent wheels. Raising the ride height (pushing the spring downward with the collar) has the opposite effect, jacking weight onto the corner being changed and its diagonal opposite.

I don't know enough about GC or Honda products to make any specific recommendations there - sorry.

Hope that helps?

Kirk

[Jon Nelson]

Hello Mr. Sawatsky;

There's a good article on corner weighting at the Grassroots Motorsports website, http://www.grmotorsports.com Look under tech topics, then corner weighting. Study it carefully!!

The ideal setup for a road racer is 50% cross weight, the total of one front and the OPPOSITE rear wheel, exprssed as a percentage of the total car weight.

The four legged table analagy is a useful one, and should help you through the whole ordeal.

You can't really get everything even, I could look up my numbers from last year and let you know as an example. Unless you actually move weight around, the actual and static weight of the four corners won't change, we're dealing with the forces that the wheels exert on the ground.

The whole 50% cross weight objective seems counter-intuitive, but assume it as gospel. This is very important. One of my spring perches moved itself down a turn or so last year, and when I corrected it, the car was magically transformed back to the way it felt the first weekend.

I ran 400f/600r, with no front bar, and stock rear. I liked this setup, but wonder if a little stiffer migh be good. I'll probably try 500f/700r next year, it seems to be a common setup on the '88-'91 CRX.

Concensus on sway bars is a little harder to come by, I might also try a bigger rear bar, but I would urge you to resist spending money on a bar or bars until you find you need it. Consider the bar(s) as a trim for your setup. With such high spring rates, there really isn't enough suspension movement for them to do much.

I think I used 7" springs. Use Eibachs. Ground control perches should be good, too.

As painful as it might be, I'd also get a prothane kit to do every concievable bushing in the car. It's a huge pain in the ass to put in, you basically will hate your life until it's done, it involves lots of swearing and cutting, etc., but should be good for reduced lap times and will make the car feel MUCH more precise. Start early, or simply pay to have it done.... I don't think you've got the tools to do it. I know I'm fortunate in that respect.

Hey, wait a second!!!! Don't get TOO fast on me!

Oh my!

BTW - Any news on any other new CRX's or Honda being built for next year?

'later

Jon

[Chris Sawatsky]

I've got some reading and research to do.
Regarding the bushings, we have a hydraulic press at work that makes doing suspension bushings very easy. In and out like butter. One of the benefits of working for a city, we have every conceivable tool

I don't know about any other crx's that will be racing next season, but my friend sold a d16a1 engine to some guy who was building a civic for his daughter to race with us.

[Jon Nelson]

Oh...... tools!!! Do they have torches,too?

The best way to remove the old bushings is to heat the crap out of them, thus burning the rubber out, then "lancing" the bushing out with the torches.

Lots of fun, especially if you do it inside.

'later

Jon