For all of you out there who have coilovers...

How do you determine proper ride height? I mean, I know you can balance out the car by corner weighting it, but still--what ride height should the car be at?

Would it be beneficial to lower the rear of the car more than the front to even out the F/R weight ratio?

Thanks. Oh, I have a 00 Si and just put on Konis/GC with 350F/400R.

 

Road racing, auto-x or daily driver? For a comp. standpoint, there are a few things to consider. NASA doesn't have a minimum ride height other than saying it can't drag along the ground. I think that SCCA says 5" min. @ the rocker panel. I am sure someone will come in to clarify that. I think a more important thing to consider is the amount of shock travel you will have at a certain height. I had my car lower but since I have a pretty low cost suspension I didn't have very much shock travel. The car actually handles better since I raised it. I have approx.
1 3/8" of compression travel up front. I then set the rear which has more travel btw. Another consideration is that as you lower the car you will gain negative camber (good up to a point - depending on use). Some classes don't allow camber adjusters. Some also limit the amount of negative camber you can run. Just some food for thought.


[Modified by civicrr, 2:24 PM 7/31/2002]

 

Hmm, interesting. Thanks for your input.

What do you think about weight transfer with ride height changes?

 

Although I have read a few books & followed Scott's disertations (sp?), I am no expert on the subject. Here goes anyway.

The roll center is affected by (ride) height & track. If you lower the height and/or widen the track, you will in effect be lowering the roll center. A lower rollcenter will lessen the cars tilt or lean in turns. This will yield better transitional response. e.g. going thru the 's' @ Sears Point. Now, will this lessen weight transfer? No. Just because the car isn't leaned over as much doesn't mean the weight isn't being shifted towards the outside tires by centrifugal (force) gravity. Here is another concept for you. The tire with the largest slip angle will slide the most. That is why fwd cars will tend to push more than rwd cars as a general rule. That is also why a car with stiffer rear springs will rotate more than one with softer rear springs given that the fronts remain the same. An excellent book for an understanding about weight transfer & slip angles is <U>Going Faster! Mastering the Art of Race Driving</U> I will have to review it since I couldn't remember the stuff I wanted to explain.


[Modified by civicrr, 2:25 PM 7/31/2002]

 

I heard that you should go as low as possible without bottoming.

CB

 

No, a roll center is an instantaneous point defined by suspension geometry about which the body rolls when subject to lateral force. The front and rear roll centers define the roll axis. Body roll is the mechanism thru which most or our lateral weight transfer is effected. On most of our H-A's the roll centers move in a one-to-one relationship with the body - so the roll moment arm (distance from the center of gravity to the roll axis) doesn't change significantly when you change ride height. If you were to change the the geometry such that the roll moment arm increased (lower roll centers) at a fixed ride height you would have MORE body roll. The effect of lowering with our geometries is paying us simply thru lower total lateral weight transfer.

Scott, who has forgotten and relearned many times.....

 

.....My "common sense" tells me this too, but it is very often VERY WRONG.

Scott?

 

Generally - yes. Unless you run into geometric problems. I think that most of us should leave a little extra shaft unused. Remember that the bumpers add some exponential rate gain near the end of their compression, so getting into them changes the roll stiffness balance of the car - and since I'm talking about the front that's an understeer contributor. I don't see the point in going to less than about 5 inches to the rockers on most of our cars.

Scott, who knows what you mean about common sense being wrong sometimes...

 

whoops! Thanks for correcting my mistake Scott. Here is something from the book I mentioned above that explains it in really simple terms. You know, language that I can understand. "Lowering the ride height on one end of the car would be the equivalent of softening the anti-roll bar or softening the spring rate at that end. Increasing the ride height is akin to stiffening the anti-roll bar or going to a higher spring rate."

Mike who is just happy to get back on track with a working engine this weekend.