Coil overs and oversteering..

[330iGT]

Can adjusting coilover dampening to full stiff( only adjustable in the rear) cause more oversteer? I'm currently running the same tire width all around, Full stiff UUC sway bars all around, and have not gotten an alignment since I need to buy new wheels and tires.

Tire pressure is a couple PSI less in the front than the rear.
Should I change my sway bar up front to a medium setting?

[cpt97M3]

Originally posted by 330iGT
Can adjusting coilover dampening to full stiff( only adjustable in the rear) cause more oversteer? I'm currently running the same tire width all around, Full stiff UUC sway bars all around, and have not gotten an alignment since I need to buy new wheels and tires.

Tire pressure is a couple PSI less in the front than the rear.
Should I change my sway bar up front to a medium setting?

I assume you shock rebound damping. Yes, increasing the shock rebound damping will make the car oversteer more. In general, you want a damping setting to match the springs, and then you would use the swaybars to trim out the balance.

As to whether you should change the sway bar setting, we would need a description of what you are doing with the car, and what the car is doing. Is this track, autox, street? What other mods do you have?

Chris

[330iGT]

No A/x, but street and track.

Don't have any other mods that will change handling except those mentioned. I do have my weak 205 all-seasons, that are going to be replaced with 235 s03's, but I don't really see how tires affect oversteer.
Driving style is aggressive.
I used to be able to hold my foot on the gas longer when the shock setting was at 5(9 being the softest, 1 being the hardest) but with the setting at 1, the car can't take a coner without oversteering.

Now on the street, it's somewhat OK because of quick reflexes, I can countersteer, but I don't think i'll last on the track with this much oversteer.

[eurorides]

soften the rear if you want understeer.

[cpt97M3]

Originally posted by 330iGT
No A/x, but street and track.

Don't have any other mods that will change handling except those mentioned. I do have my weak 205 all-seasons, that are going to be replaced with 235 s03's, but I don't really see how tires affect oversteer.
Driving style is aggressive.
I used to be able to hold my foot on the gas longer when the shock setting was at 5(9 being the softest, 1 being the hardest) but with the setting at 1, the car can't take a coner without oversteering.

Now on the street, it's somewhat OK because of quick reflexes, I can countersteer, but I don't think i'll last on the track with this much oversteer.

Well, if you are loosing traction earlier with the shock on the stiffer setting, then it's too stiff. Soften it up until the car puts down power well, and it not to "twitchy" or "nervous". This is easier to do in a controlled environment then on the street of course, since you really can make the car difficult to drive, not to mention slow with the shocks too stiff.

Tires can make a huge difference in the balance of the car, for a lot of reasons. Think of sears roadhandlers on an M3. No grip at all. Maybe it's balanced for arguments sake. Car probably doesn't lean much, cause there's no grip. Now, same car, Hoosier Autocross specials. Lasts 10 laps at the autocross. Car has incredible grip. But now the M3 leans over, runs out of front camber since we are getting into the bad part of the camber curve, and we are running low on travel in front since we have massive grip, and we hit the bumpstops, so the wheel rate goes up high, and we have massive understeer, just from changing tires. This of course is an extreme case just to prove a point, but tires can make a difference in the balance of the car.

But that's not your problem in this case, so soften the shocks back up some until you maximize grip, and test in a safe, controlled enviroment (like an autox).

Chris

[330iGT]

Excellent post Chris.
My rears are pretty warn down, so that may amplify the problem as well. When I get my wheels and tires, and an alignment, I'll see how everything goes then.

I may see you at a A/X this summer, i'm also in the socal area.

[cpt97M3]

Originally posted by 330iGT
Excellent post Chris.
My rears are pretty warn down, so that may amplify the problem as well. When I get my wheels and tires, and an alignment, I'll see how everything goes then.

I may see you at a A/X this summer, i'm also in the socal area.

Yep, worn tires especially if they are worn different, can also affect the balance. Also good to have an alignment done.

I do lot's of autocrosses in SoCal. I was at Hollywood Park today. I will be instructing at the BMWCCA autox in San Diego on 8-Mar, and other events throughout the year. Hope to see you at one.

Chris

[B.Watts]

Question...you've installed coilovers without an alignment? You might want to do that sooner rather than later as any changes you are making could be based on an out of alignment suspension that is really the cause of your problems in the first place. A full stiff rear bar isn't doing you any good in putting down the power either. Stiffer sways is not always the goal.

[330iGT]

Originally posted by BMWRacerITS
Question...you've installed coilovers without an alignment? You might want to do that sooner rather than later as any changes you are making could be based on an out of alignment suspension that is really the cause of your problems in the first place. A full stiff rear bar isn't doing you any good in putting down the power either. Stiffer sways is not always the goal.

I should I have included I got my coilovers about 4 days ago. I had an allignment done with my shocks and springs, but I need the coils to settle in first.

But thanks for the tips, can't hurt to have more info.

[B.Watts]

Originally posted by 330iGT
I should I have included I got my coilovers about 4 days ago. I had an allignment done with my shocks and springs, but I need the coils to settle in first.

I'm not following. Coilovers ARE shocks and springs... Did you have an alignment done after you installed the coilovers or not?

[330iGT]

Originally posted by BMWRacerITS
I'm not following. Coilovers ARE shocks and springs... Did you have an alignment done after you installed the coilovers or not?

I used to have eibach springs and Bilstein shocks, then I upgraded to coilovers about 5 days ago. I got an alignment with my eibach/bilstein combo, but have not gotten one with my coilovers as I am waiting for them to settle in. Once they are settled in, I will getting an alignment and possibly a corner balancing since the car is going to start seeing alot of track time.

So to answer your question, I have not gotten an alignment with my coilovers, but my car isn't set to stock alignment specs either.

[Jim O.]

There isn't enough information to really be able to make any recommendation. Which coilovers are you using? What spring rates? Coilovers aren't generic - they aren't all the same, and won't all respond the same to turning a knob on the strut housing. Mainly because the knobs do different things on different coilovers. What are your alignment settings? Saying that they aren't stock isn't enough - need to know exactly what settings you're using.

More information is also needed on exactly where in the turn the oversteer is occuring. Corner entry, mid-corner, corner exit, power on, etc. Each has different possible causes and cures.

Also, more information is needed on your driving. What exactly are you doing when the oversteer occurs? Walk us through a corner, saying exactly what you're doing at what point in the corner.

Without this into, all that's possible is a wild shot in the dark. And my shot would be that it sounds like you have way too much roll stiffness for your level of driving and your driving style. I'd back off my sway bars, especially the rear bar, to full soft, then see how the car handles. This is even more critical if your coilover setup has significantly higher spring rates than your older setup.

One comment about rebound damping. Reducing rebound damping doesn't always cure oversteer. It depends on where in the turn the oversteer occurs, and what is causing the oversteer. Sometimes adding rebound reduces oversteer, because it slows down the weight transfer from the rear of the car to the front - the rear squats down under power, and the additional rebound keeps the weight down on the rear tires despite small modulations of the gas pedal...

Jim

[hccyong]

Originally posted by 330iGT
Can adjusting coilover dampening to full stiff( only adjustable in the rear) cause more oversteer? I'm currently running the same tire width all around, Full stiff UUC sway bars all around, and have not gotten an alignment since I need to buy new wheels and tires.

Tire pressure is a couple PSI less in the front than the rear.
Should I change my sway bar up front to a medium setting?

The oversteer that additional rear damping adds will be most noticeable on turn-in and quick transitions such as slaloms. I would suggest that you go to a skidpad or somewhere you can do a fairly steady turn. Adjust your tire pressures and bars so that you like how it feels in steady state.

And then adjust your rear shocks so that they work well in transitions. Depending on your setup, you may find that even when working well on the skidpad, you are understeering in the slaloms. That means you either need to slow down your steering a little and wait for the tires to grip or you can try increasing your rear shock stiffness. If you're finding yourself oversteering in the slaloms, soften the rear shocks.

Note that how much throttle you're applying will make a big difference in the slaloms, so keep it consistent. For example, when I accelerate through a slalom, I get some understeer. And therefore I back off the throttle, and then I get some oversteer