Over steer

[geronimo1]

What do I need to replace to correct front over steer?

 

[Silver Fox]

What do I need to replace to correct front over steer?

Oversteer typically relates to the back of the car, and understeer is usually related to the front.

TRs can typically oversteer with the throttle (oh yea...). Understeer means the front tires continue straight even when you are trying to turn. Most cars are tuned that way from the factory for safety reasons.

What condition are you trying to correct? If it's understeer, you should try a stiffer rear sway bar and see if that helps.

What re you running for tires/wheels?

 

[charlief1]

Rob's pretty much right here. If you're talking about the nose dive then you need to look at the back, not the front.

If you're trying to make the car handle better overall then yu need better front and rear sway bars as well as better springs and shocks.

 

[geronimo1]

Thanks guys that really helps. It is understeer I am trying to tighten up a little. I will try a different rear sway bar then.

 

[charlief1]

HR makes a good one but it's kinda pricey.

 

[jdpolzin]

HR makes a good one but it's kinda pricey.

That would only add to his understeer problems. I would run a Spohn or Hellwig bar. Or you could get a Hotchkis bar if you can find one cheap. The HR bars work great to keep the car in a straight line at the track, and also on the street, hence UNDERSTEER!:biggrin:

 

[charlief1]

LOL I brain farted Jeremy.

 

[83hurstguy]

That would only add to his understeer problems. I would run a Spohn or Hellwig bar. Or you could get a Hotchkis bar if you can find one cheap. The HR bars work great to keep the car in a straight line at the track, and also on the street, hence UNDERSTEER!:biggrin:

Basically, you are telling him to use a stiffer rear bar (spohn/hellwig) to add rear oversteer, but saying if you stiffen the rear roll rate over a certain amount (with the HR bar), changing nothing else, you'll promote understeer in turning. That doesn't make sense from a dynamics standpoint at all. Essentially, what is so different between the HR bar compared to the Spohn bar, other than size of the bar?

The HR bar doesn't "induce understeer" at the track. It absorbs the twisting moment from the driveline and keeps the chassis straight, planting the rear tires. Edit: I should say, with the rear suspension being real stiff, you may see some goofy issues during turn in... and the car won't balance out very well, but of course most drag cars also use skinny front tires, which then completely throws handling into the garbage.

The best solution to correct an understeering G-body is fix the front suspension geometry. You can band-aid with a rear swaybar to an extent. It all depends on what you want to spend.

 

[jdpolzin]

Basically, you are telling him to use a stiffer rear bar (spohn/hellwig) to add rear oversteer, but saying if you stiffen the rear roll rate over a certain amount (with the HR bar), changing nothing else, you'll promote understeer in turning. That doesn't make sense from a dynamics standpoint at all. Essentially, what is so different between the HR bar compared to the Spohn bar, other than size of the bar?

The HR bar doesn't "induce understeer" at the track. It absorbs the twisting moment from the driveline and keeps the chassis straight, planting the rear tires. Edit: I should say, with the rear suspension being real stiff, you may see some goofy issues during turn in... and the car won't balance out very well, but of course most drag cars also use skinny front tires, which then completely throws handling into the garbage.

The best solution to correct an understeering G-body is fix the front suspension geometry. You can band-aid with a rear swaybar to an extent. It all depends on what you want to spend.

You answered your own question in this statement.




The HR bar doesn't "induce understeer" at the track. It absorbs the twisting moment from the driveline and keeps the chassis straight, planting the rear tires. Edit: I should say, with the rear suspension being real stiff, you may see some goofy issues during turn in... and the car won't balance out very well, but of course most drag cars also use skinny front tires, which then completely throws handling into the garbage.



Most of the problems with HR bars and Handling come from the mounting angle of the bars. The bar is designed to shoot the car straight. Now with the Spohn and Hellwig bars, you can set the bars angle in two different positions, one with not such an aggressive angle, and one that is more aggressive. The point is, you have to balance the rear bar for the application. You can be too tight and you can also be too loose. you need to tune the front and rear as one.

 

[83hurstguy]

Assuming a car understeers, and you add rear roll rate to add rear oversteer, and then keep adding roll rate with a bigger bar, how does the car return to an understeering rate? Turn-in is not necessary understeer, as turn-in is a transient response.

The angles of the links of the adjustable rear bars aren't what is changing the bar's behavior... what they do is adjust the lever arm acting on the bar, effectively changing the rear roll rate. "Understeer" is not defined as limiting chassis twist, therefore keeping the chassis straight.

An understeering car, by SAE definition, is one that requires more steering angle input as speed increases on a constant radius turn. It's by definition a steady-state condition. If you took a car with an HR bar out on a skidpad, you'd most likely finding yourself looking like a drift racer due to the back end wanting to step out.

 

[jdpolzin]

Assuming a car understeers, and you add rear roll rate to add rear oversteer, and then keep adding roll rate with a bigger bar, how does the car return to an understeering rate? Turn-in is not necessary understeer, as turn-in is a transient response.

The angles of the links of the adjustable rear bars aren't what is changing the bar's behavior... what they do is adjust the lever arm acting on the bar, effectively changing the rear roll rate. "Understeer" is not defined as limiting chassis twist, therefore keeping the chassis straight.

An understeering car, by SAE definition, is one that requires more steering angle input as speed increases on a constant radius turn. It's by definition a steady-state condition. If you took a car with an HR bar out on a skidpad, you'd most likely finding yourself looking like a drift racer due to the back end wanting to step out.

Sounds like you got it all figured out!