I have a set of coil-overs coming and I'm trying to learn what to adjust in order to get my car dialed in the way I want it. From reading : http://member.rivernet.com.au/btaylo...ineTuning.html I have some idea about the affects of spring rates, alignment, etc. My question is what about ride height and shock adjustments?

using the same table as Chris did (in the above link) how would I fill in the following:

.................................increase......... .increase
adjustment..............understeer.....oversteer
Front shock C/R.............?...................?
Rear shock C/R.............?...................?
Front ride height.............?...................?
Rear ride height.............?...................?


My coil-overs only have one adjustment for both compression and rebound so I've tied them together. Does this even make sense?

TIA

 

This table follows the same general principles as the other. But it's not as simple as shown below. These are general indications, but they may not be accurate on your setup. It's just general behavior that stiffening anything in the front suspension tends to promote more understeer...etc. But it requires further analysis for each setup. A roll axis that angles downward toward the front of the car also promotes roll understeer...

.................................increase......... .increase
adjustment...............understeer......oversteer
Front shock C/R..........higher...........lower
Rear shock C/R...........lower............higher
Front ride height...........lower............higher
Rear ride height............higher...........lower

 

I don't try do deal with these issues myself. I have John Mueller and Road Race Chassis to set the car up for me. We have even gone to changing the alignment, depending on whether the track is running CW or CCW. Suspension tuning is not something I care to tackle with 5 thumbs on each hand.

 

try

adjustment..............to increase oversteer or decrease understeer
Front shock C/R.......decrease/increase
Rear shock C/R........increase/decrease
Front ride height.....decrease
Rear ride height.......increase

 

+1 on this info, everything I've tried and read tends to agree with that.

 

What in god's name have I just gotten myself into. My coilovers have arrived and I'm reading up on how to work with them. Now wonder suspension tuning is such a freaking black art. How the FF does anybody figure this out?

The upside is that the mechanic who is going to do the actual install is a master of the black arts. However, I would like to know what is going on so I can give him good feedback as we make adjustments.

Anyway, the responses on how to make adjustments is great. I'll update my web-site in a few days and I'll post a link. I think it would be cool to build up a good knowledge base for people (like myself) trying to learn this stuff.

 

Don't forget tire pressure affects understeer/oversteer...as in increase rear tire pressure and decrease front air pressure for increased oversteer.

on edit: that site you linked in the beginning makes no sense to me. How does increasing tire pressure (less tire patch) help improve a "push" situation? It'll just end up sliding out easier. A fatter patch out back with less pressure will make it harder to kick the rear out...

 

There's usually a 'base' configuration to start from which should be a starting point and the manufacturer can tell you those settings. You can work from there going by the post from ez which sums it up pretty much.

Do bear in mind that while this is a general 'direction' of adjustments you have to consider the base values of your coilovers. If the manufacturer has built in some oversteer in the setup anyway, you might not be able to remove it completely - if you have an already softly sprung front and a really hard rear, decreasing the front damping might not do a lot.

Depending on the coilovers you have, changing the damping alone may or may not make that huge a difference. (If you want to make it radically different then you might want to change springs.) If your adjustment range is quite narrow then it can be viewed as a good thing - you can't really make that much of a mess and a bad thing - if you really don't like it and want to make huge changes then it's going to get quite involved. Anyway, if you're really unhappy, I'm sure they can re-valve them quite cheaply.

Oh, and some people confuse the number of steps with resolution. Some dampers have only 4 steps but have a wider range than 6 step set ups. And the 36 step adjustable doesn't necessarily mean you can turn it all the way from a solid rod to zero damping.

 

One of the best things you can do to figure out what you've gotten into is to pick up Shelby's "Prepare to Win" and "Tune to Win." And if you're a real glutton for punishment, the Millikens' "Race Car Vehicle Dynamics." Then, when you've learned lots about suspension, you do the smart thing and let somebody who *really* knows what they're doing set things up for you!

Dave

 

Perhaps I was over dramatic. I'm actually very excited about the coilovers. There just happens to be a lot to learn in order to be good at tuning them.

I do have an excellent mechanic who knows what he is doing. I also have a number of friends in the area who are more knowledgable than myself. So I feel fairly comfortable moving in to this. Like I said: I'm very excited about this.

 

If you're an SCCA member, Randy Pobst had some good things to say this month in Sportscar....

 

Jake, I told you I'd be happy to discuss the basics with you. Just gotta give me a call man! Do yourself a favor and go ahead and order a probe type pyrometer.

 

Longacre Memory pyrometer , I want one!