Massive Understeer At The Track, What To Do?

[xr_velocity]

Thanks all. I know it is not a sports car, but the understeer really is shocking, not normal at all.

I know some of this is driver ability for sure.

I was actually about to call Heasmans today, didn't get time...though will do so tomorrow.

Is still want the car road drivable, so it can't be super firm, needs to behave in the wet etc. I am after a compromise that is fairly neutral.

[Rosie]

Thanks all. I know it is not a sports car, but the understeer really is shocking, not normal at all.

I know some of this is driver ability for sure.

I was actually about to call Heasmans today, didn't get time...though will do so tomorrow.

Is still want the car road drivable, so it can't be super firm, needs to behave in the wet etc. I am after a compromise that is fairly neutral.

That Phone call won't do you any harm!

Just tell them what you want to achieve and have them test your Shocks and Springs, before you go any further.

- This costs a little!

- You need to find out what it is you have right now, before you spend any more Money unnecessarily!

Good luck!

[Smoke them tyres]

Disagree (politely) that the sway bar is an aid. All cars need some form of lateral control, whether the c of g is above or below the roll centre (the lever moment still exists).

To me, it is extra spring rate in roll and only roll. Why add spring rate and destroy ride quality when it is not needed???? (ie. in a straight line). It is a natural balance to the (extra) loads applied by cornering.

The reason why it should be taken off at the rear IMO is that with the fuel tank now being within the wheelbase, there is not much weight both over/beyond the axle and above the c of g to generate significant amounts of load transfer. A soft spring and no swaybar will work with these fixed factors in the car (especially when considering the exact opposite situation that the front has to deal with).

Additionally, overly stiff spring rate will have an effect in the fore-aft plane by reducing that load transfer (and thus traction) during braking and acceleration, reducing the traction available for both of those phases.

Weather factors such as overly hot, cold or wet will also be adversely affected as the tyre needs to be in it's temp window to generate sufficient grip to make the stiffer springs work in this narrower window. The tyre will not generate the grip it can if left to it's own devices. Less speed, more slip angle and more tyre wear will be the result.

The golden rule is....the softest suspension necessary to do the job. If a wheel is verified to be coming off the ground with these overly heavy and under-tyred cars, I would suggest that something is wrong with setup. The V'8s can corner at much higher levels with more tyre and less weight and only go on 2 wheels with the aid of some corner edging......

Some of the camber figures quoted also have me somewhat perplexed. With or without with the camber kits (unless the car is ridiculously low) the max negative camber achievable is usually about 2 to 2.5 degrees with NO shims fitted. 4 degrees would need about/at least another cm of inward movement by the upper control arm in the static position. The corresponding toe in is also a good indicator of the camber being run. 3mm (1/8") of toe in per side will make a tyre wear evenly for -2.5 degrees of camber.

I don't know that these cars will ever be "pointy" in the front end considering their weight and tyre width. The job is to get the maximum from the front and to help "unload" it with some weight transfer to the rear, not pile it back to the front with a stiff rear bar. It has enough to deal with.

Edited 15/09/11 12:47 PM by Smoke them tyres

[Smoke them tyres]

Other points to consider;

-that a car can be "balanced" slow or fast

-the rear end geometry is much better than the front. Combined with the less weight makes it the end with the most grip available

I have always gone for the maximum grip at whichever end of the car I can get it at, and then get the other end to keep up with it, not de-tune the good end.

[Rosie]

Disagree (politely) that the sway bar is an aid. All cars need some form of lateral control, whether the c of g is above or below the roll centre (the lever moment still exists).

To me, it is extra spring rate in roll and only roll. Why add spring rate and destroy ride quality when it is not needed???? (ie. in a straight line). It is a natural balance to the (extra) loads applied by cornering.

The reason why it should be taken off at the rear IMO is that with the fuel tank now being within the wheelbase, there is not much weight both over/beyond the axle and above the c of g to generate significant amounts of load transfer. A soft spring and no swaybar will work with these fixed factors in the car (especially when considering the exact opposite situation that the front has to deal with).

Additionally, overly stiff spring rate will have an effect in the fore-aft plane by reducing that load transfer (and thus traction) during braking and acceleration, reducing the traction available for both of those phases.

Weather factors such as overly hot, cold or wet will also be adversely affected as the tyre needs to be in it's temp window to generate sufficient grip to make the stiffer springs work in this narrower window. The tyre will not generate the grip it can if left to it's own devices. Less speed, more slip angle and more tyre wear will be the result.

The golden rule is....the softest suspension necessary to do the job. If a wheel is verified to be coming off the ground with these overly heavy and under-tyred cars, I would suggest that something is wrong with setup. The V'8s can corner at much higher levels with more tyre and less weight and only go on 2 wheels with the aid of some corner edging......

Some of the camber figures quoted also have me somewhat perplexed. With or without with the camber kits (unless the car is ridiculously low) the max negative camber achievable is usually about 2 to 2.5 degrees with NO shims fitted. 4 degrees would need about/at least another cm of inward movement by the upper control arm in the static position. The corresponding toe in is also a good indicator of the camber being run. 3mm (1/8") of toe in per side will make a tyre wear evenly for -2.5 degrees of camber.

I don't know that these cars will ever be "pointy" in the front end considering their weight and tyre width. The job is to get the maximum from the front and to help "unload" it with some weight transfer to the rear, not pile it back to the front with a stiff rear bar. It has enough to deal with.

Camber figure of 4 degrees at the front is as quoted!(With Camber Kit)

- I carry the Print out of the Suspension settings in my 'non-Factory' Log Book

- The V8 Utes run 5 degrees at the front!

- The Car is only 1 inch lower and the ride is a good compromise between Road and Track work!

- The Car turns in and gets the power down extremely well.

- Thru tight Corners and high speed sweepers!

Spent some time tuning the rebound in the Rear!

- Then added a Kaz 1.5 Diff to assist turn in and Power down.

- I get extremely good wear out of the Race Tyres!('Two' different sizes and profiles x 18)- Secret Mens busines.

- 'Two' Days at Bathurst (Approx 500km), plus 'two' Track Days at Wakefield!

- Steer Tyres always go first though!

Car, with full Tank and Driver, weighs 1920kg.

[Slash]

Induce oversteer before understeer kicks in. Problem solvered

[Rosie]

Induce oversteer before understeer kicks in. Problem solvered

Whatever works...

[Guest XR09]

A very slow way to go around too.

Look at Mr beans lap around the top gear track. It looked very slow. He was never out of shape and really did not use three quarters of the road in most places. But smashed the crap out of everyone's lap time.

And yup STT sway bars are good and will increase the spring rate on the side of the car with the load load. Allowing you run run a softer spring rate. Running as soft as you can will increase tyre life and improve consistent laps times.

Probs didn't explain it well with AIDS ha ha The springs are what balances a car. As in 60/40 55/45 or even 50/50.......wonder what a front engined and gear box 50/50 would be like to drive ???? Have driven 50/50 Alfa's but the gear box was in the back.

Running with no rear would worry me though...no offence. Major lateral weight change and it would really load up in mid corner costing you I think.. turn in would be great but at or near the limit I think it would just go in circles. I don't think I could grab it back in time anyway. have you had it at a track without the rear yet ???

I have not really suffered bad understeer. It will push if I give it too much to early. But turn in and corner speed has always been ok for about two ton in full flight. And as I have said I do it for a sweep when we are doing bikes. Never had it down for a fully timed track day and I could be doing 1.30 round QR for all I know in a car. And being use to bikes I am probably braking way too early. And why I am not having understeer probs.

All I know is I am having a hoot and that is what it is really all about.

[xr_velocity]

Just called Heasmans. Given that I have the idea in mind to keep the car street oriented first and foremost for the time being, suggestion was some Bilsteins and King 520lb springs in the front and leave the 370lb Lovells rear springs in there. Try get a bit more camber with an adjustment kit as well. Leave rear alignment as is though as I am happy with it.

Their thought was that the fronts are just too soft for a heavy car with a lot of nose weight...which is something I was considering already, but didn't want to have to do :(

I think my next step from here will be to get a set if Kings front and rear because I want to raise the car anyway, sick of scraping things under the car! I will persist with the Lovells shocks for now and see how that goes.The Lovells springs are the SL and SSL ones from memory. I think I should have gone with standard and SL.

I will take the rear sway bar off this weekend to see how it feels on the road and gauge whether or not I may like it at the track...without going silly of course.

Edited 16/09/11 06:14 AM by xr_velocity

[nelsonian101]

Keep it simple. Don't get caught up in too much theory.

If you seriously want to reduce understeer at the track.

1. Proper R Spec tyres. A very effective symptomatic cure. Even if it doesn't address the cause.

2. As much front negative camber as you can get. Camber kit is required to get over 2 deg.

3. Stiffer front springs, preferably with your shock absorbers valved to match spring rate. My fronts are over 600lb which are fine for me on the street too.

4. Already assumed you are using the biggest solid front sway you can fit.

5. Speak to a suspension shop that knows how to set Falcons up. (preferably with experience in V8 utes) I recommend Wholesale suspension and East Coast Suspension in Sydney.