so how exactly do i go about reducing understeer without increasing oversteer? My car feels pretty well balanced at this point on the track (auto-x), but i still can't get around corners as fast as I'd like to...
any advice?

car in question is:
1994 civic EX coupe
Eibach Pro-Kit springs
KYB AGX struts
stock front sway (19mm?)
15mm rear sway
stock trans (no lsd)
14"x6" rims, 205/55/14 Victoracers
Ingalls alignment adjusters fr/rr
-1.5* camber front/ -1.5* camber rear
+3.2* caster front
fr/rr toe set to within factory specs

most courses I set shox to 2 fr / 3 or 4 rr
initial turn-in response feels nice & crisp, but it seems like the longer i'm in a turn, the more the car wants to push...
my 2 guesses are either the longer i'm in a corner, the more the tires heat up & increasingly lose traction,
or more likely- i could use a stiffer rear sway and turn the shox down in the rear which would soften it up a little on initial turn-in but keep it from pushing around the rest of the corner...

any advice?



Modified by stmotorsports at 1:52 AM 7/21/2004

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by stmotorsports &raquo;</TD></TR><TR><TD CLASS="quote">so how exactly do i go about reducing understeer without increasing oversteer? My car feels pretty well balanced at this point on the track (auto-x), but i still can't get around corners as fast as I'd like to...
any advice?

car in question is:
1994 civic EX coupe
Eibach Pro-Kit springs
KYB AGX struts
stock front sway (19mm?)
15mm rear sway
stock trans (no lsd)
14"x6" rims, 205/55/14 Victos
Ingalls alignment adjusters fr/rr
-1.5* camber front/ -1.5* camber rear
+3.2* caster front
fr/rr toe set to within factory specs

most courses I set shox to 2 fr / 3 or 4 rr
initial turn-in response feels nice & crisp, but it seems like the longer i'm in a turn, the more the car wants to push...
my 2 guesses are either the longer i'm in a corner, the more the tires heat up & increasingly lose traction,
or more likely- i could use a stiffer rear sway and turn the shox down in the rear which would soften it up a little on initial turn-in but keep it from pushing around the rest of the corner...

any advice?
</TD></TR></TABLE>


There are many possible reasons why your car pushes: everything from driver input to tire pressures, to static camber settings to tuning with a stiffer rear anti-roll bar and many things in between. One quite and dirty thing to try is skid pad testing, which will help determine whether your problem is a steady state problem or possible a transient problem.

 

hmm... 'dissertation' crack got removed

 

Get some real springs and a real swaybar in the rear.

 

Your going to get a 100 page thread going with this topic. It is a tough one to answer.
Each driver wants something different, so in all fairness, there is only a couple of things you can try, but it still won't feel perfect like I think your looking for, but here goes:

Remove the front sway bar links, yes, remove the links.
go to stiffer springs to counteract the weight shift, and w/o a front bar, it will allow the contact patches to "flex" helping counteract the push. This "step" of no front bar is something alot of drivers refuse to believe, and many seldom try it due to so much speculation that it doesn't work. What have you got to loose right? I have not run a front bar for years now, and it does work.

get a larger rear bar- and also add a pound or two in the front tires.
As for alignment, try 1/8" total toe out at the front, and 0, I mean 0 at the rear.
the toe out helps with turn in, while 0 at the back will allow the tires to operate at the proper slip angles to which they were designed to operate at. That is assuming your looking for the rear to pivot around at the apex and thus steer the car like everyone in auto x likes to do.

I am assuming that your entering each corner with a bit of extra speed as well, so remember time is gained off the corner and lost on the way in, don't over cook it.
slow in/fast out

on the springs issue: don't go too stiff in the front, this will keep the car from turning in. Your street springs and shocks aren't going to accurately "suspend" the car from falling over on the tires sidewall, better shocks and slightly stiffer springs will help counteract this side to side roll over your experiencing.
This "excess" sidewall rollover is forcing the contact patch of the tire to engage the tread face too much. The front sway bar is just adding extra dynamic load to the tire as well as the opposite side of the car is trying to lift and thus the bar is "extra" loading the tire that is in contact with the surface.
What you need to do is limit the amount of "overloading" and by removing the front sway bar links, you'll limit the suspension from transfering too much load to just one side.
Also, using stiffer front bushings will help limit the compliance (flex) your getting when the tire is trying to grip.

I hope this helps and that this thread doesn't get out of hand for you.

 

wow i can't believe i never realized that about the front bar wanting to overload the outside corner & unload the inside...
I'll definitely have to try that but by just removing the links, won't the bar itself be banging around in there? I'll probably just remove the entire front bar assembly temporarily to see how it goes- I have no problem with trial & error
As you can probably tell, this is my daily driver as well so I've been reluctant to go with real heavy front springs- it rides pretty stiff as it is. Not quite harsh, but I'd say right on the edge. Plus the fact that I've been going thru the entire suspension and replacing essential bushings with poly versions.

As far as overcooking the corners, I'm usually pretty good at getting in there and around the apex, but thats where the car wants to get slow & not exit- I get back on the throttle to pull out of the corner & the tires just won't grab. This is what is leading me to believe that I need to do something with my setup. I've been trying all different levels of throttle exiting, from feathering to mashing, early throttle starting at the apex and late throttle right at the exit hoping the car would just 'coast' thru the remainder of the corner. Now that I think about it, it almost seems like it's doing exactly what Roadracejunkie mentioned about the front bar crossloading.

Tire pressures- Victoracers in my version/size call for 44psi, I seated/mounted/initial filled them myself with nitrogen, and make adjustments at the track with a portable tank of dry air (dessicated in from the compressor and also out to the tire). Depending on the track, I usually run the fronts at anywhere between 44-48psi, and the rears usually around 42+ (almost always at least 2psi lower than fronts). I've also played with pressures extensively, and while it definitely helps to fine tune the balance of the car, it still doesn't help the push in the front end.

Anyways hope this additional info helps and sorry for the chapter 2

ps- fine with me if this thread gets out of hand- I can use all the thoughts i can get!!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by stmotorsports &raquo;</TD></TR><TR><TD CLASS="quote">As far as overcooking the corners, I'm usually pretty good at getting in there and around the apex, but thats where the car wants to get slow & not exit- I get back on the throttle to pull out of the corner & the tires just won't grab.</TD></TR></TABLE>
That would be the result of overcooking the corners. Not saying that's definitely your problem, but the end result is the same (ask me how I know ). Are you getting on the gas at the same time as when you unwind the steering wheel? Do you trailbrake?

AGX's are adjustable, right? What are your shock settings? When you say you played with the tire pressures a lot, how low did you go in the rear?

 

With a front wheel drive car, you'll probably want to try a later apex so that you get the car turned more before applying the power while exiting the turn. In a corner the front wheels have to handle both the lateral grip and the thrust from applying power, and as a result you might "overcook" the corner because you are asking a bit much from those round black things. So the answer to part of your problem might be a change in your approach to the corners.

 

Answer: Adjust in small steps.

All of what they are saying will reduce understeer, but your question was "without oversteer."

Generally, you want to stiffen the end you want to slide sooner, and soften the end you want to grip more. The issue is ballance, and not just creating a slide.

so adjsut in 1 psi tire pressure at a time, or 50 lbs spring rate, or a couple of mm on a sway bar.. then when you finally rear oversteer, back off.

Jon
(we can get into the driving aspects of how to end it later)

 

I'll be the first to admit I drive real aggressively on course. Sure sometimes I do get into a corner a little hot, but who doesn't? Isn't that the whole point- pushing the limits of the capabilities of the car and yourself as a driver? We have some of the top guys in our region that still wipe out every once & awhile (not mentioning any names- they might be reading this ).
I'm not trying to say that my driving is flawless and my only problem is in the car, because I'm always working on my driving skills and trying to improve wherever I can. But I still feel that I can mod my car further to allow me to get thru the course faster. Straightaways are an obvious problem, even having the z6 with some minor mods the car still feels substantially weaker power-wise than it could be, but I've currently got a motor build in the works so thats being taken care of hopefully...

But I honestly feel that I could be carrying a lot more speed thru the corners and getting away with it, I just have to find the mods that will allow me to pull it off. The more I think about it, I'm a little reluctant to remove the front swaybar completely because even tho it may reduce cross-transfer to the inside wheel, I'll be back to having more body roll which will give even more suspension angle changes and tire roll-over?
?? ??

I wish there was a smaller diameter front bar I could try but apparently there aren't a whole lot of choices- the 21mm that came on the EX/Si civics are pretty much the smallest ones you can get...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Roadracejunkie &raquo;</TD></TR><TR><TD CLASS="quote">....Remove the front sway bar links, yes, remove the links.
go to stiffer springs to counteract the weight shift, and w/o a front bar, it will allow the contact patches to "flex" helping counteract the push...

....on the springs issue: don't go too stiff in the front, this will keep the car from turning in. Your street springs and shocks aren't going to accurately "suspend" the car from falling over on the tires sidewall, better shocks and slightly stiffer springs will help counteract this side to side roll over your experiencing.
This "excess" sidewall rollover is forcing the contact patch of the tire to engage the tread face too much. The front sway bar is just adding extra dynamic load to the tire as well as the opposite side of the car is trying to lift and thus the bar is "extra" loading the tire that is in contact with the surface.
What you need to do is limit the amount of "overloading" and by removing the front sway bar links, you'll limit the suspension from transfering too much load to just one side.
Also, using stiffer front bushings will help limit the compliance (flex) your getting when the tire is trying to grip.
</TD></TR></TABLE>

the tire doesn't know the difference between load added to it by the spring, the shock, or the swaybar. all it sees is an increase in load. front end grip is not lost by overloading the outside front, rather its the amount of load transfer from the inside front to the outside front relative to the load transferred from the inside rear to the outside rear. if you have enough rear roll stiffness relative to front roll stiffness so that 100% of vertical load on the inside rear is transferred to the outside rear then it will not matter if you have a front swaybar or not.

vehicle responsiveness can be directly related to overall suspension roll stiffness. a car will not change direction until it has stopped rolling. therefore, the stiffer the suspension, the faster the car will react. there is one caveat though. a stiff car is not very forgiving of hacking at the wheel. fight the car too much and it will appear to push at corner entry. smooth steering inputs and a stiff suspension will make for a car that is very quick at changing direction.

once the inside rear tire is unloaded or airborne, any additional roll stiffness must come from the front of the car. go too soft with the front springs and swaybar and the car will roll a lot and not be very responsive. the idea that stiff front springs will kill corner entry responsiveness is entirely wrong.

rr98itr has gone to a no front bar setup on his roadrace car. the reason wasn't to reduce any load transfer due to the bar, the reason was to optimize the front tire contact patch. due to the suspension design of our cars front camber will change as the car dives and squats. a stiff front spring (scott's in the 1400lb range iirc) would limit the suspension deflection under braking and acceleration and in turn that limits the dynamic camber change. if one were to use a softer spring with a swaybar with the whole setup equalling the same roll stiffness they would have a larger dynamic camber change under braking and acceleration. at the level scott's at, it's splitting hairs.

when i was running my 93 coupe on eibach sportlines i discovered that a 24mm front swaybar was a huge improvement. overall grip increased and understeer was reduced. another thing i've learned is that increasing front rebound will reduce corner exit push, but at the expense of more entry understeer. if you can drive the entry aggressively and turn the car with the brakes it shouldn't be a problem. my car is so loose at entry right now it's not a problem for me at all.

nate

 

nate- you say going to the 24mm front bar actually reduced understeer? It just so happens that I have a GSR front bar laying around, so I may have to try that as well...
what model was your 93 coupe (ie- a/c, cruise, etc?) lightened at all? engine swap?
just trying to get an idea of your weighting relative to mine

as far as adjusting rebound, my agx's adjust rebound and valving simultaneously. I may have to go with something more like Konis for next year... ??

 

yes, the gsr/itr front bar reduced understeer in my car. the 5th gen's all suffer from unsufficient bump travel and poor static camber. the reduction in chassis roll kept me off the bumpstop a little better and kept the outside front tire happier.

my car weighs 2250 sans the driver. it is built for SCCA street touring so it has the original motor.

even with agx's, increasing the front damping force will reduce corner exit understeer. fiddling with the shocks is even easier/cheaper then fiddling with the front bar.

nate

 

i've found that higher shock settings in the front actually made it push worse- more so on exiting corners but notably on entry as well. This what was leading me to believe that I need to soften the front a bit...

I think my real problem is that I'm having trouble trying to figure out exactly whats causing the car to handle the way it does. I'm definitely putting a lot of wear on the outer shoulder blocks, which seems to be quite a bit better since I fine-tuned the alignment settings a little bit more aggressively, I just can't tell if it's something that would be corrected with less roll in front (ie- keeping off the bump stops, less camber angle changes, etc) or softening up the front a bit because that's generally the school of thought- you soften the end you want to carve the tighter arc...
I guess I'm just trying to understand what should theoretically do what and why before I just go throwing parts at it

nate- just out of curiousity, how did you have the rear of your 93 setup?

 

the trick with using a stiffer front damper to reduce corner exit understeer is to not create corner entry understeer and unwind the wheel early at corner exit.

the rear of my car is setup with about .5 degrees negative camber and zero toe. i also have a 23mm rear bar and revalved koni's.

nate