Under / Over Steer

[My135]

I've heard these terms very often but I was not fully understood what do they imply. Any suspension experts here would like to help? On our 135, how to improve the understeer (which I heard most people complaint about it)? Thanks.

[cpt97m3]

Originally Posted by My135

I've heard these terms very often but I was not fully understood what do they imply. Any suspension experts here would like to help? On our 135, how to improve the understeer (which I heard most people complaint about it)? Thanks.

As they say in Nascar, understeer is when you hit the wall with the front end of the car, and oversteer is when you hit the wall with the back end of the car.

Basically understeer is when the front end looses grip first, and oversteer is when the back end looses grip first. Almost all street cars have understeer built in from the factory since it's a lot safer for your average person since as you approach the limit, you just turn the steering wheel more.

To decrease the understeer on the 135i, I would recommend adding some more negative camber on the front, either by removing the pins for a small gain, or adding M3 arms and/or camber plates for a lager gain. Also you can add larger swaybars to decrease the body lean and give the car more grip.

[My135]

Thanks for the explanation. Also, I noticed that I posted in the wrong section. I could have posted in the suspension section.

One more question, in theory, if I add a stiffer front sway bar, the front will have more grip and thus minimize the understeer but may introduce oversteer, am I right?

Thanks again.

[cpt97m3]

Originally Posted by My135

Thanks for the explanation. Also, I noticed that I posted in the wrong section. I could have posted in the suspension section.

One more question, in theory, if I add a stiffer front sway bar, the front will have more grip and thus minimize the understeer but may introduce oversteer, am I right?

Thanks again.

That's a more complicated question that it sounds. Anytime you add more front grip to decrease understeer, you can say you are increasing oversteer tendencies.

Having the 135i with strut front suspension lean less will increase the front grip. However, from a pure weight transfer standpoint, a stiffer front bar will actually increase understeer. Just adding a stiffer front bar though should help things along, and you should not have oversteer issues.

[ILMOSTRO]

Since you are asking this question then you most likely are not autocrossing or tracking your car. You are probably referring to just street driving or canyon runs. Basic tip is to correct driving habits before modifying your suspension. The 135 can be driven very hard up and down the twisty canyon roads with little understeer once you learn when to brake, turn in and add power.

I took Skip Barbers 2 day high performance driving school and learned so much regarding manipulation of the cars body weight. If you are having to add more steering then you're not doing enough foot work. Steer with your feet.

I am also enrolled in the July 20 2 day Advanced M School at VIR. I want to learn more and more about car control. You should look into these courses, they were great.

Brake before the corners, not during. That will help with the understeer.

Cheers!

[The Cthulhu]

Originally Posted by BR3CK

Since you are asking this question then you most likely are not autocrossing or tracking your car. You are probably referring to just street driving or canyon runs. Basic tip is to correct driving habits before modifying your suspension. The 135 can be driven very hard up and down the twisty canyon roads with little understeer once you learn when to brake, turn in and add power.

I took Skip Barbers 2 day high performance driving school and learned so much regarding manipulation of the cars body weight. If you are having to add more steering then you're not doing enough foot work. Steer with your feet.

I am also enrolled in the July 20 2 day Advanced M School at VIR. I want to learn more and more about car control. You should look into these courses, they were great.

Brake before the corners, not during. That will help with the understeer.

Cheers!

+100

did you do it in an f2000 or an mx-5?