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Time to adjust my rear toe angle

Old 11-05-03, 07:14 PM
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Time to adjust my rear toe angle

With the elimination of my FC's stock dynamic rear toe adjuster bushings brings the task of finding its optimal rear toe setting.

With the rear "steering", the car would understeer while entering a turn and progressivly balance out as the turn grew more forceful, feeling about like it should but only when at a roughly a half G of cornering acceleration.

Despite the car weighing 1220 pounds rear / 1200 front, it continues to understeer slightly and consistently throughout all ranges of cornering acceleration after installing toe elimination bushings. Having lurked here for a little while, there are a few items which come to mind that could be changed to balance out the handling.

1. Adding negative camber to the front wheels.

2. Adding toe-out to the rear wheels.

3. Adding a stiffer rear anti-sway bar.

4. Adjusting struts to favor a stiffer rear setting.

5. Changing rear spring rates to higher force/deflection rate.

6. Decreasing rear / increasing front tire pressure.



Of all these items, adjusting the rear toe intuitively seems to be the next logical phase to my particular situation of sorting out the car.

So . . if you racers and autoxers would be so kind, please post your rear toe settings. I'm guessing negative 1-2 degrees is necessary. I'm also thinking neg. 1-3 degrees negative front camber.

Thanks!!
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Old 11-05-03, 07:42 PM
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I would advise against playing with the rear Toe setting. If the rear wheels aren't tracking very close to straight you are wasting energy and traction with tire scrubbing. The first thing I would advise is to examine your driving style as I've come in hot and had a car with bad oversteer and actually had understeer in many cases. Try different lines through the corner and get a picture of exactly what the car is doing. Once you have the car behaviour better figured out you can examine if the car is indeed set up to induce understeer. I would focus on getting more traction to the front if this is the case. First thing to do is look at your tire temperatures and/or tire wear. If you get consistent temperatures and/or wear then your camber is roughly correct. For an example, A friend runs about 3 degrees all around the car on a Turbo II and it shows similar traits with the understeer. The change he is making is to soften the front slightly via an adjustable swaybar in an effort to get more front bite. We should be examining the roll centers and trying to figure out the roll couple of the car but for now, we're taking the quick route. I think this winter will involve a lot of measuring and figuring before next season in an effort to be much more informed as to the traits and tuning of the car.

hope this helps,

-Trent
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Old 11-05-03, 08:09 PM
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Try 1* of toe out in the front and 1* of toe in, in the back. that will help the back end to follow the front through the corners a little more. I personaly would not go any more then 2* out in the front or 1* in, in the back. Oh and try dragging the breaks into the corner (trail breaking) almost to the apex to plant the nose harder on the ground more. It will give you much better turn in.
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Old 11-05-03, 08:38 PM
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Thanks. From what I've read, rear toe-in increases understeer. Comments?
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Old 11-05-03, 10:54 PM
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Toe out makes the car hard to drive at speed. I'd recommend toe-in in the rear and 0 toe in the front.

The biggest problem FCs have is negative camber in the front and 0 or positive camber in the front. You need negative camber up front. You can slot the strut towers for FREE in front and get up to about -1 degree with stock style springs.
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Old 11-05-03, 11:21 PM
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Maybe I should work on the front camber then, and look at the toe angles from the lobby of an alignment shop. I should rotate the strut tops 90* back at least, for now.
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Old 11-06-03, 12:58 AM
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SLOT the fronts!

Quit screwing around, just slot them. You will need an alignment after you move the struts in on top. It changes the toe in front also.
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Old 11-06-03, 07:26 AM
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You don't want any toe out in the rear unless you have terminal understeer: as in you drive a stock tire high power 4WD Subaru on an autox for instance. Toe out on the rear makes the rear very unsettling under power.

If it's the front that's not working, start at the front.

What are you currently running as toe and camber on each end of the car? I don't see how people come up with all these "perfect" setups when we don't even know what's on your car now.

What is the front and rear alignment, tire sizes, spring rates and what type of shocks and sway bars are on the car? We need to know what adjustments your car is capable of accepting.
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Old 11-06-03, 09:21 AM
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Originally posted by turbojeff
SLOT the fronts!

Quit screwing around
Damn, you must know something.

As for current settings, the car has tokico HP shocks (non adjustable) and Eibach dual rate springs (anyone got some RB springs for sale?), and is about an inch lower in ride height than stock. I haven't measured the front or rear toe, but was thinking of replacing some of the toe angle contributed by the dtss bushings with a rigid adjustment.

Street tires are 205-60-15 Potenza and autocross tires are 225-50-16 Comp T/A. And it has the stock base model anti-sway bars!

I did some more reading last night and found that understeer or oversteer is caused by a difference in tire slip angles, while balanced response is due to identical slip angles. Adding rear toe-in would increase rear slip angle to the outside rear tire during a turn, relative to the front, which would theoretically reduce understeer.
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Old 11-06-03, 09:55 AM
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Originally posted by 88IntegraLS
I did some more reading last night and found that understeer or oversteer is caused by a difference in tire slip angles, while balanced response is due to identical slip angles. Adding rear toe-in would increase rear slip angle to the outside rear tire during a turn, relative to the front, which would theoretically reduce understeer.
Your making this overly complicated. It's the front that is not working, so fix the front. No need to remove grip from the rear in order to make the car neutral; that should be a last resort only.

The end of the car that is not sticking is the end of the car you work on. Only after exhausting all possibilities at the front do you then monkey with the rear.

FYI adding rear toe in is going to help keep the rear of the car behind you when under power in a turn. Think about it. If the outside rear tire is trying to steer the rear of the car towards the inside of the turn (because of the toe in), the rear is less likely to try and pass you on the outside when cornering . Adding rear toe in will not help an understeer in the far majority of cases.

Like I said, you have no idea what your alignment is NOW. Therefore you have no idea what you wish to do with it. You may have gobs of toe in the rear already. You may have gobs of front toe out; you don't know. Until you do know there is no sense trying to solve the problem because you don't know where you are right now.

You can't know which direction to go to get "there" if you don't know where "here" is right now.

Last edited by DamonB; 11-06-03 at 10:03 AM.
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Old 11-06-03, 10:09 AM
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There are so many tricks to correcting this. Some of which require you to do NOTHING to your alignment. So let's get a baseline for your car:

1) Current alignment settings
2) Spring rates
3) Sway bars
4) Tire pressures during competition
5) Driving style ... i.e. how late do you brake?

There's easy and cheap ways to fix this ... or you can throw money at it.
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Old 11-06-03, 11:01 AM
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Ah, but I'm not in this forum or even my FC to be a winner. I suck at driving. I'm just hoping to explore suspension settings and see what they do, so I guess I should not have posted this in the "race" section huh?
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Old 11-06-03, 11:08 AM
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Originally posted by 88IntegraLS
Ah, but I'm not in this forum or even my FC to be a winner. I suck at driving. I'm just hoping to explore suspension settings and see what they do, so I guess I should not have posted this in the "race" section huh?
Not at all. No need to be "hard core" or a winner just so you can make the car do what you want. The point I'm trying to make is like this analogy:

Spin a globe very quickly and with your eyes closed touch your finger to one spot of the world. Now with your eyes closed I will ask you "Which way to get to France?" You can't answer because you have no idea where you are right now; your eyes are closed.

Same with your car. There are some general things that are right in the majority of cases, but if you are not sure your alignment is even sound right now there's no telling what could be going on with the car.
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Old 11-06-03, 11:15 AM
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The stock DTSS got me halfway to france, so I was thinking of duplicating the direction it went.
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Old 11-06-03, 02:33 PM
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No one is coming down on you man, just trying to help you from getting some whacked out suspension setting or alignment setting that causes you to eat through a 500.00 set of tires in 6 months. You say that the DTSS got you half way to France, want to duplicate? What did it do? What do you need more of to get where you want to go? Why did it feel better? Aristotle couldn't answer that one, not enough info. Like a lot of my answers on the SAT, not enough info given.
Driving style has a lot to do with it. You can transform the handling of the car just by your driving. How do I know so well? Me and a friend co-drive a full race FB in Solo I and auto-x. He will come in and tell me that the car is real tail happy in certain corners, or pushing like a pig in others. I get in the car and the car will understeer where he oversteered and almost spin where he said it understeered. Same car, NO adjustments. The difference for $500 Alex? Driving styles. We talk and adjust and go back out and make the car as neutral as ever, all by just adjusting your driving style. Stay off the power a little longer, drag the brakes through a corner a little longer, etc. See if that helps, be safe and have fun!!

Travis
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Old 11-06-03, 07:17 PM
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True.

I got a chance to open the car up on some curves and a long, empty straight stretch of highway today. At 120, the car is very unstable. On some spirited curve driving, I did start to find a technique to keep the car stuck to the ground to my liking. Usually the car would push if I didn't ease in the steering for a turn while trail braking right to the apex, but other times I would hear a rear inside tire start to sing first, usually after the apex and right as I started to add in throttle. The car still has its base model open diff.

Based on my hypothesis of the car's stock DTSS being designed to add rear negative toe during cornering forces, I have decided to experiment with adding slight amounts of negative toe and see if the high speed instability lessens. I never noticed this tendency before, but 120mph is sensitive territory that can expose the car's tendencies better than, say, 70.

And Jeff I'm going to slot the front strut tower bolt holes and max out the front camber!
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Old 11-07-03, 07:14 AM
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Originally posted by 88IntegraLS
other times I would hear a rear inside tire start to sing first, usually after the apex and right as I started to add in throttle. The car still has its base model open diff.
That's your open diff spinning the inside rear tire. If the inside rear is starting to sing, no sense in giving it more throttle.
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Old 11-07-03, 07:45 AM
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Originally posted by 88IntegraLS
Based on my hypothesis of the car's stock DTSS being designed to add rear negative toe during cornering forces, I have decided to experiment with adding slight amounts of negative toe and see if the high speed instability lessens.
I would highly recommend you NOT doing this. Adding more toe out in the rear will make the car more unstable ... especially at higher speeds. If you want the car to feel more glued, you want to go the opposite way ... add more toe in (positive toe). Your understeer issues need to be resolved by adding more front grip (i.e. more camber, more caster) and some suspension fine tuning (like bringing your front/rear tire pressures closer together).
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Old 11-07-03, 12:39 PM
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By negative toe I meant 'toe in' in the rear. Looks like my terminology is opposite yours.

thanks for the advice.
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Old 11-07-03, 01:40 PM
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You might want to consider changing your terminology. Most alignment shops think the same way .... positive toe = toe in; negative toe = toe out.
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Old 11-07-03, 02:29 PM
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I knew that was coming.

You're right about the car needing the front worked on. It pushes hard while entering a tight turn but seems to not push as bad once a turn is estabilished.

On the subject of tricks to put negative camber on a coilover-less FC, has anyone tried elongating the lower knuckle bolt holes about a quarter inch? I hava an S4 so I can do that; the knuckles are replaceable. I had a volkswagen car that had this feature - the camber could be adjusted by sliding the lower knuckle in or out a little.
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Old 11-07-03, 02:32 PM
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Is the car for aotux or road courses?

I might be wrong and someone correct me if I am because I'm not an autox guy, but I think many autocrossers have the front and rear toed out a bit.

On road courses you should never need toe out in the front or rear and if you do to fix an issue, you have fixed the wrong thing typically. Some guys run 0 toe in the front and rear. I have tried everything from 0 to 20 minutes in on the front and rear and every combo of these settings. The car seems the best balanced with 10 minutes in on both the front and rear with 2.5* camber in the rear and 3.5* in the front. Probably more camber than I need or should have, but thats all I can dial out in the rear and keep it as low as I want It's all about compromise you know. But that is my car (an fc vert with basically all the suspension goodies I could have ) not yours.

Try trailbraking into the turn more as already mentioned. Also an overbalanced throttle through the turns will make the car push or cause throttle oversteer depending on your power level, but usually it pushes.
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Old 11-07-03, 02:48 PM
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Originally posted by RX-Heven
Is the car for aotux or road courses?

Autocross and fun on the street.
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Old 11-07-03, 06:26 PM
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Originally posted by 88IntegraLS
I knew that was coming.

On the subject of tricks to put negative camber on a coilover-less FC, has anyone tried elongating the lower knuckle bolt holes about a quarter inch?
Uh try slotting the strut towers. Like I said before, you'll get about -1 deg of camber. That will make a world of difference compared to what you have now.

Then put on a TII rear bar if they are different. Get or make an adjustable rear link to get rid of some of the rear's negative camber (depending on where you are at now).

Becareful not to do all those changes at once or you'll end up going backwards off a turn. A friend of mine did basically 3 changes at once to reduce understeer in his TII. He went sideways over a curb leaving work (we call it turn 1).
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Old 11-07-03, 06:46 PM
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Originally posted by DamonB
That's your open diff spinning the inside rear tire. If the inside rear is starting to sing, no sense in giving it more throttle.
So what you're saying is, I'm acting like I have a real race car when I drive this thing (by putting power down too early for the open diff).


Ha this thread is a kick. You guys are great. Most people on this forum don't even drive hard and know what's going on with the car.

Jeff I have my own "turn 1". I did a 360 on it with the Integra one rainy day when I was trying to drift it. It was sweet! I ended up in the grass; the car was fine because was facing backwards as it went over the shoulder, but I was a little embarassed.
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