What worn components would cause understeer?

[Jared at Pelican Parts]

So yesterday im getting off the 5 on a nice long 90 degree exit ramp that exits perpendicular to the freeway at a 30 foot elevation change. I hit the apex and the car starts oversteering a bit, certianly not confidence inspiring.

Are there any common worn parts that would cause this?

Suspension is otherwise stock SC

[widebody911]

Tire & tire pressures?

[Jared at Pelican Parts]

tire pressure is ok.. I run a little more in the back than the front..

typically 37/40 front/rear

[Superman]

That's certainly plenty of tire pressure.

One of the most important benefits of autocrossing and DE'ing is the information you get. The surprizes you get. My car oversteers deliciously as I turn corners in street driving. I always always always finish the turn with the throttle and the rear snaps into place. After five years, this still gives me joy at each turn.

I expected this car to oversteer at autocross also. SURPRIZE! At slower speeds and deeper throttle positions (such as at autocross) I have to fight this car around the 180-degree turns. And I mean fight. Working the throttle and the steering wheel, and even the brakes! In second gear, turning sharply around a 180-degree turn at autocross with the throttle open, this car understeers horribly.

But at higher speeds such as you get at DE events, the car is back to oversteering. Don't know if this helps you.

[widebody911]

Drop a couple pounds in the rear and see what happens.

(edit - meant to say 'rear')

[Jared at Pelican Parts]

but would this also have to do with worn sway bar bushings, shocks etc... i plan on renewing all my suspension as soon as i get my new cooler in

[dd74]

Like Thom says, Jared. Mess with tire pressures first.

[Gunter]

Jared Fenton: 37/40 PSI on an SC? What kind of tires and how old are they?
The manual says 29/34. What is your Camber and toe on all four? Castor in front? Good luck with getting the ring-nuts off the external oil thermostat; read the posts on that subject, it's fun!

[Jared at Pelican Parts]

Bridgestone Potenza RE750's about a year old

thanks for offering help

[jluetjen]

Alignment also has a big part to play. Basically you need to know that everything is set-up correctly, otherwise the car's handling will be off.

[widebody911]

I used to run RE730s I ran 34 front, 36 rear, on 7" & 9" Fuchs. 22mm front torsion bar, 29mm rear, 1/32" front toe, 1/16" rear, -2 degrees front camber, -2.5 rear

[Gunter]

Right on, John, I just did my alignment after the car didn't handle right and have a noticable difference. Of course, before any alignment the mechanical components have to be right: struts, balljoints, bushings etc,
A wild guess isn't going to help.
Just asking what could be wrong without giving details about camber, castor and toe is meaningless.

[dd74]

Yes, alignment was a major factor too, as well corner balancing. I drove at Willow before and after an alignment and corner balance, and the difference was quite noticeable.

[Jared at Pelican Parts]

How exactly does a corner balance work?

I aswsume you add weight to opposing sides of the car to balance it out?

[dd74]

Originally posted by Jared Fenton

I aswsume you add weight to opposing sides of the car to balance it out?

To me, it's almost voodoo science, but it works. I've seen Tyson do it in action, but could barely follow him. I believe it is counter-weighting from corner to corner, but I know more knowledge about this than mine exists on the board.

What I do know is if I had a choice between spending a bunch on torsion bars, monoballs, bigger sways and stuff and a good corner balance and alignment, I'd opt for the corner balance and alignment. All the rest of it matters little unless you have a good baseto work with first. In fact, you may find you won't need all the other stuff once you do have a corner balance and alignment.

[widebody911]

Originally posted by dd74
In fact, you may find you won't need all the other stuff once you do have a corner balance and alignment.

And if you do all the other stuff, you're going to need a corner balance and alignment anyway...

[dd74]

Very true...

[B D]

Jared take it to Darren at Westend he charges about $60/HR last time I was in and he transformed my car in just over 3 hours best money I have spent to this day on my car. He will explain everything he does to the car and what he finds. I sat in the drivers seat while he did all the work. He did the alignment, corner balance, set the camber and balanced and rotated the tires. Several board members have used him and would agree it's the best money spent. He is the only one in the shop and the only one to touch your car.

Westend Allignment
Darren #310-808-9233

[no substitute]

If you drove your car on one wheel, we'll say the left front for the sake of argument, all the weight would be on the left front. If we decided that both front wheels would make for a better handling car we'd want the weight equally distributed from side to side (in general). Tilting the car to the left or right would achieve this. Now we know of course, that it is best to have all four wheels on the ground. Thus we would want the same left to right equality we had in the front for the back. The backs of our cars are heavier than the front, so the left and right rear weight will be a higher amount (someone correct me here if I am wrong, but I believe this is correct) than the front, but approximately equal from side to side. The problem is when we have four wheels and tilt one corner up or down it affects not only the other corner on the same side, but also the corners at the opposite end. Thus one has to go back and forth and get the two fronts as close to their ideal, and equal from side to side, as well as the backs. No, the car won't necessarily end up absolutely perfect, or even have perfectly even ride height, but it can be done to reasonable tolerances on a street vehicle. It's an involved process, and some vehicles come out better than others.
Loose sway bar bushings make a given bar less effective. In general, stiffening rear components, e.g., bigger sway bars (or shorter arm setting) or torsion bars make for more oversteer. Lessening same in the front has a similar effect.