A breif overview of my current suspension:

Off the shelf Koni SA's
GC's with 450# front 550# rear
Stock front sway bar, ST rear bar on softest setting.

At Fontana this weekend the rear is squatting more than I would like, even causing some tire rub. I'm very happy with the balance of the car right now, but would like to stiffen the rear springs. Will I have to stiffen the front to avoid adding more oversteer bias to the car?

Thanks

 

Adding more rear spring will create a high roll stiffness in the rear, yes.

 

In a word? Yes. At least I think so. There's a couple of options though. You could stiffen the front and maybe use less agressive sways bar all around or use a stiffer spring in back but lower the rear tire pressures. Just a thought.

 

What many of the fast CRX guys around here do is run springs in the rear that are 200lbs (400/600 or 500/700) stiffer than the front. Then they run either no rear bar or the stock rear bar.

I would think running higher rear springs (650?) with the ST bar would make a CRX extremely loose.

On my ITC Civic I run 450/650 with the ST rear bar, but the longer wheelbase makes that an apples to Oranges comparison.

Check with Phatty (phatS) or Alex (Hracer) for some true advice. I'm just passing along 2nd hand info.

 

If I go with stiffer springs in the rear but a smaller rear bar, don't I end up in the same place? I mean, wouldn't my overall rear roll stiffness be about the same as it was with softer springs and stiffer bar?

 

The majority of ITA CRX drivers out there use a 22mm rear sway. with 650-800lbs rear rates and around 450-500 front rates. At this point it becomes an art to balancing the suspension through shock settings, tire pressures, alignment, etc. I personally didnt like the feel of my crx with a 22mm rear sway and 750 lb rear springs. I think I am going to go down to 650-700's and a stock rear sway. There are just so many options. Some like it loose and same find it hard to drive that way.

 

Rubbing where? You could raise the car a bit or add some spacers. Not sure how much rake a CRX likes, the Integra is a bit better ballanced with a little dialed in.

 

The outside of the tire is rubbing the fender lip. I've rolled it with a bat and that helped, but did not cure it completely.

 

I'm sure you could play with your rear toe to keep the car balanced as you want.

 

I guess the other question about rubbing the fender would be what wheel and tire size and what offset you're running.

 

Is rear camber adjustable? Adding rear camber would help to make it stick better with a higher spring rate.

 

Running Rota 15x6.5" 40mm offset, tires are 205/50/15 Azenis or Victoracers. I do have adjustable UCA's in the back but can only get about 1.5' neg camber out of them.

 

How is the rear end squatting, do ou mean rolling or doing the same on both sides? If youa re hitting your tires on the body, you either have insufficient avalable travel or not enoguh roll stiffness. If you don't want to change your balance on the car, you could simply raise the rear ride height a bit. Your rear roll center will change a bit but but overall it will be the cheapest and quickest thing and probably have the least effect on balance change if you only to it a bit.

If you do make changes, do them one at a time. If you go up in rear spring rate or sway bar, you will add the top the oversteer but if it is too much then you may need to stack a change on a change or add something to the rear. I would not suggest changing rear toe though as this has different effect at different dynamic situations and can make the car unstable. If you aren't allowed to change anything else, then rear toe can be done in moderation but otherwise is better to simply set at a good number (like zero or no more than 1/16th total in or out) and change other things. Some specific tracks might acceprt moe rear settting like tighter slower track but usually is tracjk specific).

If you want to change nothing else raise the car until it stops hitting the tires then make a decision from there.