Car Setup

Author
Discussion

Nampahc Niloc

Original Poster:

130 posts

28 months

I would really appreciate any advice anyone can give on the effects of changing different aspects of the setup, and preferably why it has that effect.

I’m happy that increased rake means decreased understeer because of the increased wait at the front end.

What I don’t understand is why stiffening the front antiroll bar increases understeer, and vice versa at the back. Surely a stiffer front anti roll bar, means more stability at the front, less wait transfer and hence more grip at the front, which should mean less understeer? I’m obviously getting something fundamentally wrong here so please someone put me right.

Also, any advice regarding the effects of camber, toe etc?

Finally why is it important to have a soft anti roll bar in the wet?

Carnage

778 posts

182 months

Nampahc Niloc said:
I would really appreciate any advice anyone can give on the effects of changing different aspects of the setup, and preferably why it has that effect.

I’m happy that increased rake means decreased understeer because of the increased wait at the front end.

What I don’t understand is why stiffening the front antiroll bar increases understeer, and vice versa at the back. Surely a stiffer front anti roll bar, means more stability at the front, less wait transfer and hence more grip at the front, which should mean less understeer? I’m obviously getting something fundamentally wrong here so please someone put me right.

Also, any advice regarding the effects of camber, toe etc?

Finally why is it important to have a soft anti roll bar in the wet?
Ironic user name!

Keeping it very basic...

Increased rake places more weight on the front, less on the rear. This can lead to a more pointy car.

Don’t forget the overall weight balance has an effect on handling. More front weight equals less rear weight so more oversteer.

In (very brief) a softer ARB allows more weight transfer in the wet, is more compliant, and allows you to get the tires working.

A stiffer ARB gives a more responsive turn in but if too stiff removes compliance and actually reduces grip.

Toe in/out affects straight line stability and braking. It can be dialled in, for example on historic Mini’s, to the rear to make it more unstable and promote oversteer.

Camber affects the contact patch. Negative camber can provide more grip in corners - as the car rolls, it rolls onto the contact patch. However, it can have an effect on braking grip and again stability.

The various permutations can have a huge effect and I have deliberately kept this really simple.

Get one of Carrol Shelby’s books and he explains it brilliantly.

cookracing

155 posts

96 months

My rule of thumb is, (very) broadly speaking: softening things up gives more grip, at the expense of responsiveness. Reason being, the platform is more supple, and the tyres have more chance of making full contact with the road, more of the time as opposed to being too rigid. For springs / dampers you'd potentially have to raise the car as you have more travel, so raising the centre of gravity which isn't ideal. Trade offs.

But of course which end you add grip to makes a difference to the car handling.More at the front, potentially more oversteer. More at the back, potentially more understeer.

LawrieC

51 posts

54 months

Yesterday (20:39)
quotequote all
I found this in a book a few years ago - food for thought, but what do you do first

Oversteer reduction.
Stiffen front shocks.
Soften rear shocks.
Stiffen front anti roll bar.
Soften rear anti roll bar.
More front toe in.
Increase rear toe in.
Reduce front negative camber.
Stiffen front springs.
Soften rear springs.
Lower front tire pressure.
Raise rear tire pressure.
Reduce rear track.
Install wider rear tires.
Raise front end.
Lower rear end.

And remember

Understeer: When you hit the wall with the front of the car
Oversteer: When you hit the wall with the back of the car
Horsepower: How fast you're going when you hit the wall
Torque: How far you move the wall

Nampahc Niloc

Original Poster:

130 posts

28 months

Yesterday (21:00)
quotequote all

Carnage said:
Get one of Carrol Shelby’s books and he explains it brilliantly.
Any book in particular? I’ve had a look on google but can’t actually find anything authored by him. Though I might just be putting in the wrong search terms.

Carnage

778 posts

182 months

Yesterday (21:15)
quotequote all
To be fair, not surprised you can’t find them - I meant Carroll Smith. Prepare to Win is probably the best at explaining.

Another good one is Competition Car Suspension by Allan Staniforth.

http://www.carrollsmith.com/books/index.html

https://www.abebooks.co.uk/book-search/title/compe...