*preface - i dont drive a honda, i just like this board. i have a 240sx, so any comments should be made knowing that i have macpherson struts, not double wishbone *

i am screwing with my coilovers and am having a hard time deciding on what height to set my car at. reading about suspension has just made me all the more confused and maybe you guys could help me out?

all i have ever heard people say is stuff like "2 inch drop should be fine" or " yea 2.5" inch is OK". what i am trying to find is some kind of reasoning backed up with math for what the most beneficial height for a car would be, given various statistics. if anyone knows of a good book on suspension or tire tech, please tell me.

i am switching back to my stock exhaust because i am selling my exhaust to get somthing else, so this will give me much better ground clearance. so i can probably lower my car like 1.5 - 2 more inches and not scrape.

this would probably put it somwhere around 4+ inches lower than stock height, where stock size 205/55/16 tires start to tuck into the fender.

i have always heard that the lower your car is, the better center of gravity, and therefore better handling. but all the street mod autocross cars and the amateur road race cars and stuff arent ghetto dropped .5 inches off the ground, and im sure most of them have adjustable suspension so that they could do it if they wanted, so there must be a reason.

So i dont think some massive drop is the best for handling, based on these observations. all the circuit cars that look like they are lowered to where they touch the ground usually have this look because of the aero work, not because the chassis is almost touching the ground.

the only car that i have seen that dosent fit what i am saying is the corvette. every corvette i have ever seen, on the street or on the track, is ALWAYS ludicrously close to scraping the road.


before i ramble on for too long, can somone try to clear this up? or suggest any good books on suspension / tire tech that i could find at barnes and noble or amazon? i have the skip barber book 'going faster' but it dosent get super technical in any one area.

thanks guys!!!

 

I think if you type in book or read in search, for this specific forum, there should be some threads that pop up.

Not being a dick, just trying to help.

 

no offence taken, thanks for the tip, will do.

 

First, I agree with 743's statement about what you'll find already posted in this forum. There are a great number of posts regarding good rading, both printed and online. Trust me, you'll find more than you care to read.

I will say a couple of things based on your comments that might get you started. Many of the road racing organizations that us Honda folk and other budget racers compete in dictate a minimum height requirement. We usually speak in terms of how high the car is off the ground rather than how much lower it is than stock, so you'll find most of us above the 4" mark because of the rules. However, as you've noticed, other classes allow body work to extend lower than that, and some classes are not restricted at all. At that point, your goal ride height is one that works with the aero of your car. For most of us, that means getting as little air pressure under the car as possible since this creates lift. For me, that's a low air dam on the front bumper. For others, it's a complete undertray to keep turbulance down to nothing. Either way, a car with a ride height of 1" will collect less air than the same car at 6". Also, we're regulated by the geometry of our suspension, and we reach a point where proper suspension dynamics are effected by a ride height that is too low. If I were to drop my car down 3 more inches (which I could do with the adjustable coilovers) I would be completely out of shock travel and I would seriously damage the suspension. Fortunately, I'm already pushing the min ride height, so there's no need for that.

This doesn't begin to explain all of your questions, but it may put into perspective some of the statements you made. My advice is to check your rulebook for your class and see what the regulations are. Then do some reading and experiment.

 

check out the Sociaety of Automotive Engineers website. It can get really technical, bu there are some very good articles for laypeople too. They also have a first-rate bookstore that sells the Carroll Smith series and others on the subject. Another resource is Mike Ancas's book from http://www.speednation.com.

 

try this link:

https://honda-tech.com/zero...89567

As for suspension, lower is better, until you screw up the suspension geometry (camber curve, bump steer etc.) or like Travis said, you run out of suspension travel. Rules vary, and I think World Challenge rules are at 3", while others are higher. Oh yes, lower is better, until the bottom of your car hits the track, or the gators at the edge, or your tire hits the inside of the fenders. The lower you go, the stiffer you need to set up your springs to stay off the bump stops, fenders, etc. It depends on how big your tires are, what your wheel offset is, and if you trail brake a lot, and which tracks you run. Start slowly at lowering and see what is happening under the fenders.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Buttcrack &raquo;</TD></TR><TR><TD CLASS="quote">
the only car that i have seen that dosent fit what i am saying is the corvette. every corvette i have ever seen, on the street or on the track, is ALWAYS ludicrously close to scraping the road. </TD></TR></TABLE>

leaf springs

 

Lowering the 240sx too low is a bad idea.

more than 1.5-2" beyond stock, and bump travel will cause pretty wild toe changes due to the stock suspensions built in passive rear steering.

read this:
http://www.whiteline.com.au/ar...a.htm

Kinda difficult to read b/c of the scan quality, but has some excellent info.

 

Tune to Win Carroll Smith
Competition Car Suspension Allan Staniforth

If you read those and you don't know where to go, IM me and I'll help you out.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Buttcrack &raquo;</TD></TR><TR><TD CLASS="quote">if anyone knows of a good book on suspension or tire tech, please tell me.</TD></TR></TABLE>


Modified by eHoward at 9:34 AM 2/9/2004

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by sykikchimp &raquo;</TD></TR><TR><TD CLASS="quote">Lowering the 240sx too low is a bad idea.

more than 1.5-2" beyond stock, and bump travel will cause pretty wild toe changes due to the stock suspensions built in passive rear steering.

read this:
http://www.whiteline.com.au/ar...a.htm

Kinda difficult to read b/c of the scan quality, but has some excellent info.</TD></TR></TABLE>

sorry i didnt mention, i drive an s14. do you know if it applies to this as well? also i have no hicas.