understeer how do I minimize it?

[Jeremiel5]

lower front, or higher rear will help understeer.

lower rear, or higher front will help oversteer.

that's weird... the total opposite happens to me... when i have lower front and higher rear, i can oversteer better that's why i set my rears to 45-50 psi and my fronts to 32 psi whenever i drift and when i have higher fronts and lower rears, i understeer..... when i auto-x, i set my tires to 32 psi in front and 36 psi in rear and it works well for me. anyways, that's my experience, who gives?:)

[DSP74]

you are right in that respect, but you have to be *really* low in order to get to that point in the camber curve where you start loosing camber (basically where the angle between the control arm and strut is greater than 90*).

And if you are that low, chances are your car is stiff enough that your suspension isn't compressing appreciably to notice much difference in the camber curve, even if you are passing that point. Essentially, you could simply go with stiffer springs and have the same effect.

Camber control in a dynamic situation. Nothing to do with ride height (although I guess you could hurt the camber CURVE by being VERY, VERY low.....

If a car doesn't have enough negative camber a bigger bar will limit roll making the car gain less positive camber. Making the front end stick more.


Put the books away guys


edit: to clarify ALL cars lose camber during roll

[Fidhle007]

that's weird... the total opposite happens to me... when i have lower front and higher rear, i can oversteer better that's why i set my rears to 45-50 psi and my fronts to 32 psi whenever i drift and when i have higher fronts and lower rears, i understeer..... when i auto-x, i set my tires to 32 psi in front and 36 psi in rear and it works well for me. anyways, that's my experience, who gives?:)

I don't think you've ever actually driven a car...


Or learned to read...

[Fidhle007]

I actually want to jump in here for real too because there's a lot of false info being thrown around. Sway bars are not effectively the same as stiffer springs, because they TRANSFER force, rather than absorb it. When you decelerate into a turn (even just off the throttle, no brakes involved) the weight of the car is transfered forward and to the outside. This puts the more weight on your outside front tire than the others and causes understeer. A stiffer rear sway bar will help transfer some of that weight across the car and keep the inner tire down but a bigger front bar will help to keep the body flatter, allowing that outside front tire to do it's dirty work. The other thing a bigger front bar will help is turn-in, so you'll initiate easier but at the limit, it will lift the inside tire sooner than a smaller bar will. But really, when you're transferring that much weight across the car you should be relying on those outside tires because at the limit they'll be pretty light no matter what your bars are like.

[DCColegrove]

First off the e30 chassis can do some strange things because of the "designed in" suspension characteristics.

The rear camber shifts to negative on the loaded side and positive on the unloaded side (Is this making sense?) and has a tendency to dig the rear of the car in.

The OE (Motorsport) solution was to widen the trac, add additional front caster (to match that digging in action of the rear) with the offset cabs and to increase the rear ASB diameter to 14mm.

Having said that...

I can't remember what we were talking about...

It's weird getting old.

[325is///M-tech]

I agree With DSP74 From what I have found adding front bar and even adding some bump to the front struts has removed under steer. I would start with adding a set of camber plates and or a larger front sway.

[Fidhle007]

Let's start from the beginning, what do you want to do with the car?

[joshh]

Keep in mind here DSP74 is giving his opinion on the matter from his experiance.
There are many ways to get the same effect. Some work better than others for each individual.
Just throwing that in there.:???:

[nando]

Camber control in a dynamic situation. Nothing to do with ride height (although I guess you could hurt the camber CURVE by being VERY, VERY low.....

If a car doesn't have enough negative camber a bigger bar will limit roll making the car gain less positive camber. Making the front end stick more.


Put the books away guys


edit: to clarify ALL cars lose camber during roll

it has everything to do with how low you are. you aren't going to gain positive camber until you compress the suspension to the point in the geometry where the angle is more than 90 degrees - until then, you are still gaining camber. if you are rolling so badly that you are compressing the suspension way past it's normal range, you probably have too soft of a spring rate and are probably bottoming out the struts anyway.

[atomic]

http://www.rogerkrausracing.com/TechSheets/overunder.shtml

[Emre]

Typically understeer is corrected by reducing the front bar or increasing the rear bar.

That's the theory...but that assumes the suspension is already working optimally to begin with. Our cars have a pretty compromised suspension setup with insufficient camber gain in the front end during hard cornering. So, the conventional wisdom that increasing front rollbar thickness will worsen understeer does not apply in this case.

throwing a larger front sway bar on a car that already pushes isn't the answer.

If your car has a McPherson strut suspension and inadequate camber (i.e., is a BMW), then adding a larger front swaybar is absolutely the answer. Increasing front roll stiffness is critical.

To help with understeer, you can...soften the fronts

Not on an E30 you can't. Theory is fine. But real-life experience setting up and tracking cars is better. Just check your tire temps and you'll see what I'm talking about.

[Emre]

Keep in mind here DSP74 is giving his opinion on the matter from his experiance.

DSP74's experience is fully in line with what BMW racers have known since the 1960's. There is no controversy here. This is not a matter of subjective "personal experience." He is objectively correct.

Just look at what everyone is running the next time you go to a BMW CCA Club Race. Every single car in the field has an incredibly stiff front end (either springs or sways) and a relatively soft rear end. Many of the really fast guys in high-powered cars have no rear sways at all. Many guys in lower powered cars still favor relatively stiff rear ends. But one thing is common: the front ends are stiff as hell. Are these guys all idiots? Have they not read Carroll Smith? Do they want their cars to understeer?

The bottom line is that if you want good front-end grip on an E30 chassis, you should: (1) stiffen the front end through some combination of springs and swaybars; and (2) add more negative camber.

[DSP74]

. you aren't going to gain positive camber until you compress the suspension to the point in the geometry where the angle is more than 90 degrees - until then, you are still gaining camber

You aren't thinking about what the car does in a dynamic situation. Compressing the suspension will gain negative camber. However everytime the car roll you will gain POSITVE camber. No matter what. If we didn't, we wouldn't be running 3 or more degrees negative camber. We do that because we hope that after we lose the static camber we have adjusted in, we end up just about right during roll.

So you do gain camber in compression and lose alot more in roll

[joshh]

DSP74's experience is fully in line with what BMW racers have known since the 1960's. There is no controversy here. This is not a matter of subjective "personal experience." He is objectively correct.

Just look at what everyone is running the next time you go to a BMW CCA Club Race. Every single car in the field has an incredibly stiff front end (either springs or sways) and a relatively soft rear end. Many of the really fast guys in high-powered cars have no rear sways at all. Many guys in lower powered cars still favor relatively stiff rear ends. But one thing is common: the front ends are stiff as hell. Are these guys all idiots? Have they not read Carroll Smith? Do they want their cars to understeer?

The bottom line is that if you want good front-end grip on an E30 chassis, you should: (1) stiffen the front end through some combination of springs and swaybars; and (2) add more negative camber.

I don't think you got the point of my post. He may be correct in general but there is more than one way to get that soft rear and stiff front.

[moatilliatta]

maybe ill add my front sway bar again and see if mine will increase grip up front..