Severe Understeer

I dont have my alignment specs, on me, I will get them at lunch. But here is the situation. Last night, running a back road, I found the car understeers severely. Worse now with my setup than the stock car did.

 

Here is the setup:

Cobb Front and rear sways (rear set to full stiff)

18x8 wheels, w/ falken rt615 tires

Enduratech Coilovers (set 1 click from full soft, front and rear) (corner balenced)

 

 

Alignment specs to come.

 

I know I am going to add some dampening, but where?

 

The car would turn in nicely while trailbraking, but under light acceleration, or even a neutral, settled turn, it would understeer badly.

 

Any insight?

Understeer as in: the front-end was resisting (or "pushing") through the turn, or actual loss of traction at the front axle?

 

I only ask because I see the term used interchangeably on here, all the time.

Thats the same thing.

 

Pushing indicates losing traction, and tracking out before the rear.

 

But if your asking, both, loss of traction, pushing, and not turning in.

I know what you mean, just wanted to clarify. (I've heard people refer to increased steering effort as understeer, even though the car is still tracking it's line.)

 

Depending on the alignment specs, I would try biasing the front camber a bit, and slightly biasing the tire pressures to the front (start ~2PSI). You can make the rear damping a tad stiffer, but I prefer increasing the traction at the front axle rather than decreasing the traction in the rear, to achieve neutral handling.

 

Increased caster LCA bushings will also give you added dynamic camber, so you don't have to run excessive static camber to still achieve good grip up front.

 

Also, you could swap the stock swaybar back in front.

Maybe you are just overdriving the car. NO matter how good of a suspension setup you have, if you are comming in too fast or not driving smooth, the car will understeer. remeber that the car weights 3400+ lbs, and if you turn to fast or come in to hot, it will understeer even with race tires. I dont know if you have ever autoxed or race the car on a track, but doing that will help you fin the limits of the car so you can stay on them. In the meantime, i would put your strut adjustments somwhere in the middle of there range with the rear slightly less stiff than the front. also, if you set you front sway bar alittle softer, you may get some more weight transfer in the front which will allow your front tires to build up some more grip.

Maybe you are just overdriving the car. NO matter how good of a suspension setup you have, if you are comming in too fast or not driving smooth, the car will understeer. remeber that the car weights 3400+ lbs, and if you turn to fast or come in to hot, it will understeer even with race tires. I dont know if you have ever autoxed or race the car on a track, but doing that will help you fin the limits of the car so you can stay on them. In the meantime, i would put your strut adjustments somwhere in the middle of there range with the rear slightly less stiff than the front. also, if you set you front sway bar alittle softer, you may get some more weight transfer in the front which will allow your front tires to build up some more grip.

 

Not trying to challenge your experience, but the two highlighted phrases are contradictory to my understanding.

 

1) Running softer damping (to a point) should help traction by adapting to the road surface quicker. Perhaps you can explain this to me in an auto-x context?

 

2) Swaybars reduce roll through jacking forces and increase weight transfer across an axle. Increased weight transfer reduces the cornering efficiency (grip). However, in a McPherson strut design, reducing body roll reduces the camber loss during suspension compression, which improves grip. So it's really a fine balance. I agree that adjusting the front sway softer will reduce understeer, but your reasoning was confusing to me.

I need to consider the LCA bushings.

 

I also would prefer to increase front grip.

BTW. I have yet to take the legacy to the track, but I do know how to find limits.

 

I have a good amount of driving experience and training, so I know I over driving the car in its current form....thats why it understeered.

 

I have pretty good knowledge in settling a car, weight transfer, and the importance of smooth driving. So please no more driving tips, just suspension setup tips please.

Not trying to challenge your experience, but the two highlighted phrases are contradictory to my understanding.

 

1) Running softer damping (to a point) should help traction by adapting to the road surface quicker. Perhaps you can explain this to me in an auto-x context?

 

2) Swaybars reduce roll through jacking forces and increase weight transfer across an axle. Increased weight transfer reduces the cornering efficiency (grip). However, in a McPherson strut design, reducing body roll reduces the camber loss during suspension compression, which improves grip. So it's really a fine balance. I agree that adjusting the front sway softer will reduce understeer, but your reasoning was confusing to me.

 

 

1. An under-dapened spring will cause the spring to spring back to fast. an out of control spring is not good for keeping tires on the ground. you want the car to settle in to a turn and not bounce out. too stiff will prevent the proper weight transfer from occuring and that will hurt grip too. for the most part, coilover dampening is better in the middle of the adjustment range. the valving is almost never linear and only really good dampers will have proper dampening in the limits of the adjustment. so its best to stay more in the middle of the adjustment range and just play with relative difference between front and rear. Remember the name of the game is proper dampening. going all the way hard or all the way soft on a strut is almost never a good thing.

 

2. to a point the front of the legacy will increase in camber before it begins to decrease so some compression and roll is good and beificail for dynamic camber. softening the front bar will increase front end grip. having the rear struts slightly softer than the front will keep the rear and lift-oversteer in check. this is my experiance when autoxing.

So you suggest stock front bar, and up the dampening in the front?

no, i suggest the soft setting on the front bar if you can and up the dampening on the front and rear, but keep the rear softer than the front relativly.

 

lets put it this way. I have have a very similar setup to yours.

i have tien flex coilovers corner balanced with perrin 25mm solid bars set to the soft settings for both front and rear on 245/40/17 Bridgestone re-01r tires. the shocks go from 1-17 in the adjustment range. at teh autox last weekend, i started off with 11-front, 7-rear. i was pushing like crazy(understeer) then i went to 9-front, 7-rear, and it gripped alot better, later, i went to 7 front, 7-rear and it started to push again because it was too soft and i was over-whelming the front tires. in the end 9-front, 8-rear, got me my fastest time. the point of this is, absolute dapening does not always intuitivly affect overall handleing and grip. you have to look at the whole picture. And all of this means nothing if you dont drive the car smooth. if you are jerking the wheel around and not being smooth on the gas and brake, then even the perfect suspension setup wont help.

Don't know what your alignment is, but having more front camber than the rear would also help with that understeer as well as bumping up the psi in the rears. When i autoX I set my coilovers fairly stiff in the rear over the fronts (my spring rates are 7F and 9R) , i also run 3-5 more psi in the rear over the fronts. Also my front camber is -2.5 and rear camber is -1. With this setup my car wants to oversteer like crazy. For trackday/HPDEs, i run higher damping in the front, 3-4psi more in the front tires, and camber is still at -2.5F and -1R. Still kinda wants to oversteer cuz of the of spring rates and the camber settings, but i manage it with the throttle.

 

Cliff notes : If you want more oversteer make the rear settings stiffer than the front and run more negative camber in the front over the rear.

no, i suggest the soft setting on the front bar if you can and up the dampening on the front and rear, but keep the rear softer than the front relativly.

 

lets put it this way. I have have a very similar setup to yours.

i have tien flex coilovers corner balanced with perrin 25mm solid bars set to the soft settings for both front and rear on 245/40/17 Bridgestone re-01r tires. the shocks go from 1-17 in the adjustment range. at teh autox last weekend, i started off with 11-front, 7-rear. i was pushing like crazy(understeer) then i went to 9-front, 7-rear, and it gripped alot better, later, i went to 7 front, 7-rear and it started to push again because it was too soft and i was over-whelming the front tires. in the end 9-front, 8-rear, got me my fastest time. the point of this is, absolute dapening does not always intuitivly affect overall handleing and grip. you have to look at the whole picture. And all of this means nothing if you dont drive the car smooth. if you are jerking the wheel around and not being smooth on the gas and brake, then even the perfect suspension setup wont help.

 

Don't know what your alignment is, but having more front camber than the rear would also help with that understeer as well as bumping up the psi in the rears. When i autoX I set my coilovers fairly stiff in the rear over the fronts (my spring rates are 7F and 9R) , i also run 3-5 more psi in the rear over the fronts. Also my front camber is -2.5 and rear camber is -1. With this setup my car wants to oversteer like crazy. For trackday/HPDEs, i run higher damping in the front, 3-4psi more in the front tires, and camber is still at -2.5F and -1R. Still kinda wants to oversteer cuz of the of spring rates and the camber settings, but i manage it with the throttle.

 

Cliff notes : If you want more oversteer make the rear settings stiffer than the front and run more negative camber in the front over the rear.

 

i appreciate the input guys!

 

Now, you guys are contradicting eachother on the dampening settings. Should it be stiffer in the front or the back for neutral-slightly oversteer settings.

Its really all about personal preference and how you drive. I like to keep me rear in check more than he does. and also, my spring rates are different than his (mine are 9k F and 6K R. what we both have in comon is that we dont have our coilovers dampenig settings on the limits of the ajdustability range. YOu have to play with the settings to get it right and autox is the perfect environment for it. i suggest you sign up for a local event and start your struts right in the middle of the dampening range. and you become a better drive, adjust to see how it affects handling.

Yeah, I know an autocross is a great place to learn and test settings. Once again your preaching to the choir.

 

Thanks for input though.

Its really all about personal preference and how you drive. I like to keep me rear in check more than he does. and also, my spring rates are different than his (mine are 9k F and 6K R. what we both have in comon is that we dont have our coilovers dampenig settings on the limits of the ajdustability range. YOu have to play with the settings to get it right and autox is the perfect environment for it. i suggest you sign up for a local event and start your struts right in the middle of the dampening range. and you become a better drive, adjust to see how it affects handling.

 

Are you sure about this? Is it custom setup? I thought USDM Tein Flex came with 8k F and 9k R.

Were your tire pressures correct?

Before doing anything.....what are your alignment settings, spring rates, tires and tire pressure? Don't bother fiddling with adjustments til we know this info.

 

If it's understeering badly in a steady sweeping corner after the car has already taken a set, adjusting the damping isn't gonna do much for you.

 

- Andrew

Are you sure about this? Is it custom setup? I thought USDM Tein Flex came with 8k F and 9k R.

 

you are correct, my mistake.

Yeah, I'm no expert, but what's your tire pressures?

 

I imagine you should be running balanced or a little lower in the front, in this situation.

 

Joe

Tires: 235/40 Rt615's

 

Spring Rates: 8k front, 7k rear

 

Alignment: -1.7 front camber

-1.5 rear

 

Tire Pressures:35psi all 4 corners.

 

I know tire pressure can make a difference. But its going to need more than just a PSI adjustment, so theres all the facts, what do you think?

Tires: 235/40 Rt615's

 

Spring Rates: 8k front, 7k rear

 

Alignment: -1.7 front camber

-1.5 rear

 

Tire Pressures:35psi all 4 corners.

 

I know tire pressure can make a difference. But its going to need more than just a PSI adjustment, so theres all the facts, what do you think?

 

My car is quite neutral with these settings: -2.5(F) -1.5® 0 toe all around.

 

On Subarus, I generally like to keep at least 1 degree camber difference between the front and rear. More in the front as the correct way to reduce understeer is to increase front end grip. You can also get wider rims in the front and run the same tire size, stretching the front tires will also give you more front end grip.

 

Get better tires.

^thanks. I generally always said the same thing untill I was recently advised differently. Im going back to more front camber.

 

Get better tires? Than the rt615's? Wow. Whats better? Advans neovas? Thats all i can think of. But they are sooo $$

I'm surprised that set-up gives you severe understeer. A little more front camber would help, or getting 7k front springs. A little at the limit understeer in a tight corner maybe, but severe understeer in a steady corner i wouldn't think so.

 

How much of a drop do you have?

 

- Andrew

i still think its just they way the car is being driven.