Here is the background. I have a 2002 WRX that is prepped for STX class. The car has 400lb front, 450lb rear springs, 24mm front bar(20 stock), 26mm rear bar(20 stock), 3.25 camber front, 2 camber rear, 0 toe, 245/40/17 BFG KD street tires.

I am having understeer issues with the car still. This past weekend at the Pro, I tried to toe the rear out and 60psi in the rear tires, and the car still pushed. I know I can reduce the rear camber, but I thought about it and I really would rather not take away grip from the rear to make the car handle like I want it to, but I don't know how to get any more grip in the front of the car. With that in mind, what exactly will reducing the front swaybar do for me in terms of front grip? What would increasing the rear swaybar do in terms of front grip? Or would that just decrease rear weight transfer and decrease rear grip?

Am I just maxed out of front grip because I'm on street tires and I *need* to take out rear grip in order to get the car handling right?

I appreciate any input

-Tom

 

Tom,

Let's look at what causes understeer. Basically the rear tires grip better than the fronts. so there are two ways you can attack the problem: decreasing rear grip or increasing front grip.

Looks like much of what you have done is decrease rear grip (bigger rear bar, more tire pressure, rear toe out, rear spring rate higher than front). While you can keep doing this (skinnier tires on the rear, higher rear spring rates), I suggest that maybe you've got to increase front grip. Try this:

Go back to the stock 20mm bar. Why, you might ask. Well the only reason for high spring rates is to decrease body roll. And the only reason to decreaase body roll is to reduce camber change while cornering and keep the tires flat on the ground. But if the effective spring rate at the front is higher than the back then when you enter a corner the outside front tire gets overloaded faster than the outside rear and you get understeer. So by reducing the front spring rate you might just reduce your understeer. the problem is, its a balancing act. Too little bar and you get too much roll and bad camber change. Too much bar and you get too much spring rate relative to the back and you get understeer.

Also is it possible that you have too much neg camber in the front? I suggest that you get someone to take still photos while you circle a skidpad or go through a sweeper and look at the outside front contact patch.

Also double check your alignment. I had weird handling problems and after chasing my tail for several weeks discovered that my rear toe was significantly out of whack.

Good luck,
Alan

 

Ok, but wouldn't decreasing the front bar allow *more* weight to transfer to that outside front wheel and then get it overloaded faster? I can try going down to the 22mm setting on the bar as its adjustable before I step down to the stock bar, but I guess I don't see how that will increase the front grip.......

Also, the "effective spring rate" is the same thing as the "wheel rate" that I've heard right? edit: http://www.swayaway.com/Suspension%20Worksheet.htm is a great website I just found to calculate wheel rate.....

As far as front negative camber. I still wear the front tires on the outsides more then on the inside, so I'm definetly using the entire tire. If I could I would probably go a little more negative, but I'm out of adjustments and I also have to drive the car to events

And the alignment is definetly correct. I just had it done on a rack last week and we used toe plates and a "smart camber" gauge to check the camber at the event.

Thanks for the suggestions....
-Tom

 

Tom I thought you were saying the car was crazy loose?

-3.25 camber in the front seems like way too much to me for street tires. The -2.0 neighborhood would be more ideal IMO. You could be driving on the inner edge of the tires on the front. Are you really sure you are using the whole tire? Taken tire temps?
I would also go down to a 22mm bar in the front.

 

Ok, but wouldn't decreasing the front bar allow *more* weight to transfer to that outside front wheel and then get it overloaded faster? I can try going down to the 22mm setting on the bar as its adjustable before I step down to the stock bar, but I guess I don't see how that will increase the front grip.......

Read this thread... All of it.

https://honda-tech.com/zerothread?id=231870

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by elgorey &raquo;</TD></TR><TR><TD CLASS="quote">Tom I thought you were saying the car was crazy loose?

-3.25 camber in the front seems like way too much to me for street tires. The -2.0 neighborhood would be more ideal IMO. You could be driving on the inner edge of the tires on the front. Are you really sure you are using the whole tire? Taken tire temps?
I would also go down to a 22mm bar in the front.
</TD></TR></TABLE>

When I tried 0.5 camber in the rear instead of 2, the car was crazy loose. I just don't want to loose camber to accomplish good handling.

As far as the front camber, I took tire temps on sunday at the pro. I was driving hard and probably overdriving a tad and I saw 10 degrees more on the outside 140something, compared to 134 on the inside of the tire. When I measured them after not overdriving the car, I had ~ 135 all around the previous day.

Also, if I wasn't using the whole tire, why would the outside of the tire be getting worn out while the inside is still pristine

-Tom


Modified by trhoppe at 6:50 PM 8/11/2003

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by trhoppe &raquo;</TD></TR><TR><TD CLASS="quote">When I tried 0.5 camber in the rear instead of 2, the car was crazy loose. I just don't want to loose camber to accomplish good handling. </TD></TR></TABLE>

Maybe there's a happy medium at 1 or 1.25 degrees of rear camber? You could also loosen the front end-links a bit...

 

How are your shocks set front and rear, and at what part of the corner is the car pushing? Slaloms, sweepers, turn-in, steady state, exit etc.? You may consider seesawing the front bar stiffness vs. shock stiffness to see if you can decrease steady state push while keeping the transitional response. With stiff springs and lots of static camber, I don't think you need the big front bar to quell dynamic camber change like with the DS setup. Plus, the big front bar is pulling weight off the inside front in a corner, decreasing corner+drive grip off the turn. Not sure if inside wheelspin is an issue with your suspension setup, but I suspect it might be with your power level

 

What Chris said, where is it pushining? If it is at turn in, then the camber could be the culprit (you need a better shaped contact patch to get the car to turn), once it starts sliding (at turn in) are you patient enough to let the car recover? Is it possible the tires are just plain worn out?

Also, what Chris said... Stiff front bar means less load on the inside front, and more load on the outside front. Are you overloading the front tires or just a tire?

So, so far I agree with the others, start with a softer front bar, and depending, maybe less negative camber up front. Not all cars will wear a tire evenly, just suffer with poor wear and fast times.

Finally, don't discount just loosening the rear up a bit, if it means the car turns and you get back on the throttle sooner, you *will* be faster.

Scott

 

Hate to offer advice on improvement to a very competent competitor, but I'd say you've got too much rear camber. Nothing more than 1-1.5 for autocrossing IMO.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by .RJ &raquo;</TD></TR><TR><TD CLASS="quote">

Maybe there's a happy medium at 1 or 1.25 degrees of rear camber? You could also loosen the front end-links a bit... </TD></TR></TABLE>

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">Read this thread... All of it.

https://honda-tech.com/zerothread?id=231870
</TD></TR></TABLE>
Wow, its like a lightbulb just went off in my head. I understand now *why* reducing the front bar will give reduce understeer......

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">
How are your shocks set front and rear, and at what part of the corner is the car pushing? Slaloms, sweepers, turn-in, steady state, exit etc.? You may consider seesawing the front bar stiffness vs. shock stiffness to see if you can decrease steady state push while keeping the transitional response. With stiff springs and lots of static camber, I don't think you need the big front bar to quell dynamic camber change like with the DS setup. Plus, the big front bar is pulling weight off the inside front in a corner, decreasing corner+drive grip off the turn. Not sure if inside wheelspin is an issue with your suspension setup, but I suspect it might be with your power level
</TD></TR></TABLE>
The shocks right now are just a *tad* stiffer in the rear then the front. This gives me AWESOME turn in, as well as slaloming, but the car pushes in sweepers. Perfect example is the big turnaround we had this past weekend in Peru. I enter this thing and the car responds beautifully, as I drive through it, I start to accelerate out of the turn. I might have gotten on the throttle a tad too much a few times, but the rest of the time I was nice and smooth. As I do this, the car starts to push...I can try to unwind a tad, but what fixes it in the end, is a lift to get the front pointed, and then back on the gas. Do that on the big turnaround and then 4 times for the 4 90 degree turns that come after that, and thats a chunk of time!

You are correct though, now with that much front camber, I probably don't need the big front bar. I do have some problems with spinning the inside front, and I guess that points one more time to the big front bar.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">
Also, what Chris said... Stiff front bar means less load on the inside front, and more load on the outside front. Are you overloading the front tires or just a tire?
</TD></TR></TABLE>
Yea, it seems that I'm overloading the outside front as I start to accelerate out of a sweeper or 90 degree turn.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">
Maybe there's a happy medium at 1 or 1.25 degrees of rear camber?

Finally, don't discount just loosening the rear up a bit, if it means the car turns and you get back on the throttle sooner, you *will* be faster.

but I'd say you've got too much rear camber. Nothing more than 1-1.5 for autocrossing IMO.
</TD></TR></TABLE>
Thats a very good point along with the other opinions. If I gave up a tad of rear grip to get the back end out, so I could get on the gas earlier, that would make me faster and probably 1.25 or so is where that would happen.....

Thanks for all the suggestions and answers to my questions!! This is great

Reading the other thread and these responses this is my plan
1) Decrease the front bar and increase the front shock. This will not actually decrease any grip at all, but will "move" grip from the rear to the front the way I see it. I will decrease the roll stiffness of the front of the car therefore putting more of the weight transfer on the rear. With this, the outside rear wheel should see more of the weight rather then the outside front and it will overload earlier and the car should understeer less. This should happen after the "transition" is over though as I get back on the gas, as the shocks take the initial load right? Increasing the front shock should keep the same response that I like in the transitioning handling and turn in that I like, but after the apex, the bar is taking over....

2) If decreasing the front bar will not make the car handle like I want, then I will lower the rear camber. The reason I don't want to lower the rear camber *yet* is that I think it would also affect my turn in as well as transitioning ability. It should make the rear of the car looser during a slalom as well as turn-in, two places where I *love* the way the car handles. If I cannot get the car the way I want to on turn-out though, I would be willing to give up a little there to gain it on 90 degree turns and sweepers. I guess this would be very course dependent though

Whaddya guys think?
-Tom




Modified by trhoppe at 6:58 PM 8/11/2003

 

no offense tom, but posting this in here won't help much. keep in mind, this is the same forum that if i post my car is understeering, everyone will tell me to take out my front bar. of course, they don't get to see the 1/4" deep grove in my left front tire from hitting the inner fender seam, nor the small dents in the strut tower from c/a contact, or the 4x4 patch of polished wheel well from the tire rubbing under compression.

if i were you i would look to the wrx that beat me to figure out how to get faster then him. keep in mind, keith is using the suspension in off the shelf form, ie: 8k front/6k rear. that spring balance, combined with upgraded front and rear swaybars would theoretically make his car understeer even more then yours. i've ridden in it on a surface that the car arguably works it's best on, and it understeers like a pig. (compared to my car) so i would have to throw out the theory that you have a poor spring and swaybar selection since your competition would seem to have an even worse swaybar and spring selection.

so then the only _major_ difference between your car and keith's car is the fact that he only has -.8* rear camber while you have -1.8*. i would try to dial out some camber and see what that does. that's less work then changing the bar too, plus you won't have to rework your ideal front camber. which, btw, if you soften the front bar, you will need _more_ negative front camber which will hurt your braking performance even more. remember those skidmarks you put down when you tried to disconnect ABS.

also, as we've discussed before, you can't and shouldn't try to use shocks to make up for insufficient responsiveness. for one, stiffening the front shocks won't improve corner entry hardly at all. the rear shocks will make a much bigger difference there, but the car will still wallow in slaloms. also, if you are trying to make up for too small of a front bar with shock, when you go to a bumpy surface that requires softer shocks you'll be sol.

you won't notice much of a change in transient reponse by dialing out rear camber. the only time you'll notice a change is when the car is at or close to it's terminal roll angle, ie, mid-corner. going back to zero rear toe will help that, and slight rear toe in will make it even more stable if you so desire. also, reducing your rear shock level will help too. generally speaking, shock will make a bigger difference then toe during the corner entry phase, but a shock change won't alter mid-corner like the toe would. so, if the car is too loose in transitions with less rear camber, reduce your rear shock level or increase your front shock level.

watching Seelig, the 2.5RS and keith during the challenge i can assure you, the outside rear on everyone of those cars was going positive camber, and every single one of them was faster then both you and i. me moreso then you, but faster all the same.

nate-hope that was all coherent. my ears are still ringing from the drive home...

 

ps. i am running 1/4" rear toe out with 65psi in the rear tires, full soft front shocks and full stiff rear shocks. my suspension is typical "rear stiff" theory and my car still plowed like a pig, though 65psi was WAAAY better then 25psi. unless i want to spend more time on the bumpstops, softer front suspension is out of the question, and unless i want to cage the car, stiffer rear suspension is out. (btw, stiffening the rear suspension is effectively the same as softening the front) all i'm left with is to roll my fenders and dial out some of my -2.5* of rear camber.

nate-long wheelbase sucks

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by solo-x &raquo;</TD></TR><TR><TD CLASS="quote">no offense tom, but posting this in here won't help much. keep in mind, this is the same forum that if i post my car is understeering, everyone will tell me to take out my front bar. of course, they don't get to see the 1/4" deep grove in my left front tire from hitting the inner fender seam, nor the small dents in the strut tower from c/a contact, or the 4x4 patch of polished wheel well from the tire rubbing under compression.

</TD></TR></TABLE>

Nate, that's because I think in looking for more oversteer, you have went well beyond the limits of the suspension of your car and now you are going backwards in car setup trying to dig yourself out of a hole. I don't claim to be the best driver in the world, but I do know a little something about car setup in relation to Hondas. You could claim the same about Daddio (only he is without doubt a good driver), but he sets up Neons--which is a completely different beast then your car. And I know you've tried his theorys and they did not work that well on your Honda.

If you would have told me how much rear camber you were running, I would have probably been shocked by the horror. And also, I still think your car is bordering on being waaay too low. Given the surface of Topeka, your car is going to respond just like it did at Peru--not very well.

Take this for what it's worth, but if I were sitting up a 92-95 coupe that weighed ~2250, I'd do 550ft/700 rear on your revalved Konis. Stock front bar and ~23-24mm rear bar. Camber would be about 3-3.2 in the front and 1.5-1.8 in the rear. You will *need* to roll your rear fender because the tire will contact the lip. 1/8 toe-out and 0 toe in the rear. Tire pressures = 37ish front and 30ish rear. Tires slightly tucked in the wheelwells, and not very tucked like yours are. You *need* suspension travel more than you need a lower CG. I guarantee this will give you all of the oversteer you can handle.

But back to the topic of Tom, I think Nate had a good idea in listening to KC and his setup. I've only driven one WRX on an autox course, but I was still impressed with how well they came out of tight corners. No, it didn't feel like a RWD car, but it was much better than a FWD car.

 

Yea try putting your factory front bar back on.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by siisgood00 &raquo;</TD></TR><TR><TD CLASS="quote">Yea try putting your factory front bar back on. </TD></TR></TABLE>

this is getting tiring. Removing your front swaybar is _not_ a cure-all for understeer. Identifying the cause of your understeer and addressing the cause is the only way to cure understeer. If you have insufficient front negative camber causing your understeer, removing the front bar won't help ANY, but the car might still rotate better. you haven't made it any faster though, as your orginal problem still hasn't been addressed.

tom, i did some more thinking about this problem last night. i now feel even more strongly then before that we have too much rear negative camber. pm me if you want to hear my reasoning. it makes so much sense i had to slap myself in the head for not seeing it sooner.

nate

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by solo-x &raquo;</TD></TR><TR><TD CLASS="quote">
Identifying the cause of your understeer and addressing the cause is the only way to cure understeer. </TD></TR></TABLE>

You DO realize the humor in hearing this come from someone who's running full soft front shock, full stiff shocks+1/4" rear toe out+65psi at the rear...

Tom's handling issues sound fairly similar to what my WRX did when it had too much front bar, and also when I tried overstiffening the shocks on stock tires. With the shock setup that normally works well on Hoosiers, the car transitioned decently but lacked any semblance of rotation. I realized this was NOT a curable condition, after going up to 76psi in the rear tires trying to make it rotate.

 

Nate,

I have to agree with Todd. If just from a kind of philosphical viewpoint. When I hear about settings way far away from the "normal" settings for a suspension (100 lb springs in front, 800 in the rear, or 65 psi tire pressures) then I know something's not right. Why not just spray ArmorAll on your rear tires before each run? Bet it would rotate pretty good then.

The Subaru does not have an inherently bad suspension design. By choosing correct spring rates and reasonable bar sizes there is no reason why the car can't get pretty close to neutral. It does have a front weight bias so it's never going to be able to rotate like a boxster but it doesn't have to push like a pig either.

Sounds to me like people are going to extremes to fight a problem that is never going to go away entirely. The car is never going to rotate like a Type R. But reducing mechanical grip at the rear to get it to is gonna make you slower not faster. Get the car to hook up coming out of turns and give up a little entrance responsiveness.

Just my 2cents

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by solo-x &raquo;</TD></TR><TR><TD CLASS="quote">ps. i am running 1/4" rear toe out with 65psi in the rear tires, full soft front shocks and full stiff rear shocks. my suspension is typical "rear stiff" theory and my car still plowed like a pig, though 65psi was WAAAY better then 25psi. unless i want to spend more time on the bumpstops, softer front suspension is out of the question, and unless i want to cage the car, stiffer rear suspension is out. (btw, stiffening the rear suspension is effectively the same as softening the front) all i'm left with is to roll my fenders and dial out some of my -2.5* of rear camber.

nate-long wheelbase sucks</TD></TR></TABLE>

nate,
I never knew you were running that much rear camber. Thats probably why you're getting so much understeer. Try moving it to around 1.5 and see what it feels like. Adjusting the rear camber on my 00 si made a huge difference on rotation. I was still also running the huge 26mm front bar/22 rear on 350/400 springs and still haven't driven a 6th gen civic or any integra that rotates as well as mine did.

 

Tom,

Less camber in the rear. Think around -1.0 to -1.25. Don't TOUCH the swaybars. The more you mess with things before and after events, the less changes you'll see and start blaming the wrong thing for the issues.

I know time is of the essence, but I've been driving this setup with only changing tire pressures, since MAY. I'm used to the car. I know what it's goiing to do (except when the brakes just aren't there... thanks for those pads by the way.... hehehe) If you notice, I don't make many changes at once.

I would also leave EVERYTHING you have and just make camber changes. I was thinking of getting camber plates in the rear to get more rear camber, but after seeing the past few events, I like the car the way it is. I have new brakes going in and new tires coming, but that's about it.

Really... don't mess with a whole mess of stuff at once. You'll never get a feel for the car.

Play with camber in the rear. That's going to help quite a bit. I still got plow on many corners, I've resigned myself to that. I just adapt my driving to what I KNOW my car is going to do. If it means waiting before hitting the gas, then I wait. Waiting and patience is much better than hitting tha gas and plowing.

(Just like how you used to brake... you need to feel your car, be the car, Tom. nanananananana... NANAnanananana. Be the car.)

(And what are you doing listening to 'them' honda people? :D )

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by WRXRacer111 &raquo;</TD></TR><TR><TD CLASS="quote">

You DO realize the humor in hearing this come from someone who's running full soft front shock, full stiff shocks+1/4" rear toe out+65psi at the rear...

</TD></TR></TABLE>

yep, it is humurous. those are band-aids for the real problem of too much rear negative camber. of course, i didn't realize how much toe out i was running before, but it does kind of explain why the car has developed a really scary corner entry attitude. removing my front swaybar _won't_ solve this problem, but the car might rotate better if i did remove the bar, but i'd have less total grip.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">Sounds to me like people are going to extremes to fight a problem that is never going to go away entirely. The car is never going to rotate like a Type R. But reducing mechanical grip at the rear to get it to is gonna make you slower not faster. Get the car to hook up coming out of turns and give up a little entrance responsiveness.</TD></TR></TABLE>

i understand that the car will never rotate like it's rwd, but i _know_ it can work better then a stock itr. i look at suspension tuning this way. the rear suspension's purpose in life is to maximize front grip. once that is accomplished i dial out rear grip with tire size, alignment, and pressures. i've been trying to limp by without rolling the fenders and have had to compromise with rear camber because of that. it would seem that if i want to win though, the rear alignment is going to have to be fixed. and you are wrong about going slower by making the car rotate more. remember, loose is fast and as long as you have first maximized your front grip, you _have_ to do _whatever_ is necessary to make the car loose. with the amount of camber i have i would need 1200lb springs to get the rotation i need. not gonna happen in a car that won't get a cage and has to be driven on one of the bumpiest racing surfaces short of rallye.

nate