Massive Understeer At The Track, What To Do?

[ScatterBrain]

Great thread, It's really help me set my car up. However I've run it to a problem with my current setup. I'm now getting too much diagonal weight transfer, So much so it's lifting the inner rear wheel off the ground on hard corners. Subsequently when this happens the rear wants to start to slide. I've tried putting the 30mm front bar back on which fixed it a bit, but hasn't eliminated it. I was thinking more negative camber on the rear could help but I'm not sure If I would be heading in the right direction or not. Any advice would be greatly appreciated.

Current setup:

BF Sedan

265/35/18 tyres all round

Tein coilovers

30mm front bar

22mm rear bar

Front Alignment

7.5° Castor

-3.5° Camber

1.1mm Toe

Rear Alignment

-0.75° Camber

2.8mm Toe

Thanks

[Guest XR09]

Bugger. Mine does that too. Even coming up my drive if I stop at the right time it will teeter between two wheels. Fun in the drive but sucks at the track.

For mine spring rate, or try going a lower CG, You cant really play with your track so it's left to the spring rate to lessen lateral load change.

Going a little lower will lessen the lateral change. Which might help keep the wheel down but will dull turn in.

If it is lifting a wheel the damper is at its full extension. So I am thinking you could try going down a bit. A balance between turn in and the car staying flat.

Are your Teins street ? You might be driving beyond them.

How many G's are you pulling when it lifts ?

Just an out there thought. But what are the clickers set at on the rear. Just thinking too much rebound and it might be packing up a bit. Probably too easy a fix to be it.

[ScatterBrain]

The Tein's are actually the ones for the GTPs, Dampening I think is about 3/4 to hard on the front and about 1/2 to hard on the rear. How many G's, umm not sure exactly I've never measured it maybe .8 at a guess. Ride height Is about 330mm at the moment.

[Guest XR09]

I wouldn't want to go lower than that.

Maybe give the guys @ Fulcrum a ring. There pretty good.

[xr_velocity]

Great thread, It's really help me set my car up. However I've run it to a problem with my current setup. I'm now getting too much diagonal weight transfer, So much so it's lifting the inner rear wheel off the ground on hard corners. Subsequently when this happens the rear wants to start to slide. I've tried putting the 30mm front bar back on which fixed it a bit, but hasn't eliminated it. I was thinking more negative camber on the rear could help but I'm not sure If I would be heading in the right direction or not. Any advice would be greatly appreciated.

Current setup:

BF Sedan

265/35/18 tyres all round

Tein coilovers

30mm front bar

22mm rear bar

Front Alignment

7.5° Castor

-3.5° Camber

1.1mm Toe

Rear Alignment

-0.75° Camber

2.8mm Toe

Thanks

Alignment won't keep your rear trye on the ground. Are you sure the rear is lifting? It sounds odd that it would be doing that at all. If your inside rear is lifting off the ground that means your outside front has to be almost at full compression...since you have a 30mm sway bar on front that is odd, hence my question are you sure your rear is lifting. It would be hard to get that much roll in a car with such stiff sway bars. Are you referring to being on the brakes and coming into a corner which would make your outside front compress?

[xr_velocity]

http://www.trackpedia.com/wiki/Suspension

There are some good explanations here about sway bars and stiffness..."When cornering, the bar will twist with the outside end being pushed down, and the inside end being lifted (just like the body of the car). On the outside tire, this downward pressure helps increase tire traction. However, on the inside tire, the anti-roll bar is pushing up on the suspension reducing the downward force the spring is trying to place to keep the tire on road. If the anti-roll bar is too stiff, it will overpower the spring, prevent it from extending enough to keep the tire on the road, and the wheel will actually lift off the ground. This is not an optimum situation, but it is common in several racing classes. The cause is not so much poor engineering, but the limitations of the class rules that allow the engineer to compensate for it."

Could be your scenario.

The Teins are already pretty stiff so adding some VERY stiff roll bars for this car and you have problems...which you are seeing now.

[ScatterBrain]

With 27mm bar on, the outer front corner of the the car would dip 30-60mm mid corner. If I was to tap the brakes the car would dip maybe another 10mm extra. When I fitted the 30mm bar, it would only dip 20-40mm mid corner. That fact that it lifts the inner rear wheel doesn't really bother me, It's more the fact that once it does the wheel that is still on the ground seams to have very little grip. So what I'm after is a way to increase the mid corner grip of the outer rear wheel.

I have tried the factory rear bar with 30mm front previously and the car didn't fell very stable through the corners at all, It was like the back just wanted to slide every where.

A few of the other racers suggested that -1.5° of camber in the rear should fix it, but the trade off being less traction in a straight line. Whether or not it's true, I don't know.

Regards Mitch

[xr_velocity]

You should be worried about lifting a rear tyre off the road, you'll never get as much grip from one wheel as two.

It's the stiffness somewhere on your rig that is causing the rear wheel to lift, alignment will do nothing for you until you can get the wheel to stay on the ground.

[xr_velocity]

http://stealthtdi.com/SwayBars.html

This sums up how to fix your issue of lifting a rear wheel.

[Guest XR09]

I have 30mmF - 23mmR bars. Works well on the FG with the Teins.

The FG is a stiffer car then the B series. Still not near as stiff as the chassis in the Cromidore unfortunately.