323

I am considering to buy a 5 or 6 years old impreza, but many said that this car really tend to understeer on tarmac. What is the main reason of that unpleasent tendency and is there any way to solve it for a few $ ?

freakray

a strut brace will go a long way to solving the understeer issue with the Impreza.

Not that I can say I am really aware of much understeer on my Impreza and i drive it pretty hard.

kfoote

The understeer in basically all Imprezas except for the USDM STi is a function of an front engine, all wheel drive car. The understeer is there, and there's not really much you can do to get rid of it (an AWD car is actually faster on a road course if it understeers a bit rather than having neutral handling). If you currently have a front wheel drive car, the understeer isn't any worse in the Impreza than it is on the majority of FF cars.

__________________
2004 Subaru Impreza WRX STI (daily driver)
1999 Mazda Miata (track car, slow, but finished the SCCA Runoffs)
1987 Porsche 944 (being rebuilt)

Reed

you can get rid of most understeer by knowing how to drive your car. I have a 94 impreza front wheel drive and i can make it oversteer if i want to.

and, not to disagree, but i was under the impression that awd cars ( especially rally bred ones ) had more oversteer as they are made to kick out the back end and then have the front pull them through the turn

LjasonL

I have a 24mm rear swaybar. My car is neutral most of the tie, but can oversteer on command. It's all in how I modulate the gas. The oversteer is very smooth and controllable too. Best $150 I ever spent

scottb2004

yes that is true......awd cars are definately made for that. especially rally cars

Jay!

Most cars (except for high-end driver's cars) are set to understeer from the factory, because in general, the under-educated driving public will be safer crashing head-on into something instead of spinning into something.

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kfoote

You can make the car oversteer by changing your driving style, but in most situations it's not fast (or as jay pointed out, not "safe"). Every race prepped AWD car I have ever seen has mechanical (ie not driver induced) understeer: Audi A4, Audi RS6, Audi S4, Audi 90 Quattro, Subaru Impreza 2.5RS, Mitsubishi Eclipse, Eagle Talon, etc. The WRC cars understeer as well, but they initiate overster by driving style on loose surfaces. If you watch a WRC Tarmac rally, they all understeer on medium to high speed corners (in some very tight low speed corners they kick the tail out, but this is again, driver induced, not mechanical oversteer). Having run a 2.5RS, WRX, and STi on a road course all in stock configuration, they all understeer, and are all faster when they understeer. by adjusting the DCCD settings, it is possible to get a little oversteer in the STi, but the car was not nearly as fast. The understeer is due to a combination of factors, the two biggest ones being that the cars have a front weight bias and that the front wheels are trying to do two things (steer and drive) while the rear tires are just trying to drive the car.

__________________
2004 Subaru Impreza WRX STI (daily driver)
1999 Mazda Miata (track car, slow, but finished the SCCA Runoffs)
1987 Porsche 944 (being rebuilt)

323

thank you kfoot, it was very instructive

do you know what kind of differential they have in WRC cars compared to STis and EVOs?

kfoote

The WRC differentials are totally nutty, electronically adjustable F, R, and center diffs, and each diff is about $15,000. They are WAY above and beyond what is in either the street EVO or STi in terms of efficiency and adjustability. I'm not sure who makes the diffs, but the majority of the WRC teams are running Xtrac transmissions (another $25k).

__________________
2004 Subaru Impreza WRX STI (daily driver)
1999 Mazda Miata (track car, slow, but finished the SCCA Runoffs)
1987 Porsche 944 (being rebuilt)

Tomsriv

In general, increasing the size of the rear sway bar will make the car tend to oversteer. Like the moderator said, it would be the easiest way to solve the problem.

ScobyWRX

I have a 02 WRX and when I took it to the autoX the first time it under steered like mad
I changed my style of driving and got it to slide a little better but I did a little reading and found that other that driving style the easiest way to get a better balance is with a upgraded rear sway bar I have the Perrin adj 22-23-24 mm and the 23 is just right for me it sticks very nicely but when I want it to rotate just let off the gas mid corner and the back side will rotate just a little to make for a good exit