Caster question

[Niklas Vesterinen]

Is there any downside of having maximum positive caster?

Let's say that with maximum positive caster you were able to achieve good and even tyre temps with lesser negative camber. Is the fact that you got maximum positive caster gonna effect the car in any other way? And in that case, how would it differ if you had lesser positive caster?

 

[Michael Herrmann]

i think the caster moves the weels of center to the front or to the back what will result in a longer or shorter weelbase

longer weelbase: more stable in highspeed corners but tight turns maybe a problem cuz of understeer
shorter weelbase: less stable in highspeed turns but it turns in pretty well

 

[Christopher Aponte]

I was once told that with example the Seat Leon, the higher you have the caster, the more understeer you will get in high speed corners, but for slow corners it is just right

BUT, the slow corners must be below the 110 km/hour.

 

[Neil Gault]

as a rule it is usual for understeer to increase positive caster, if you have oversteer then reduce caster.

 

[Niklas Vesterinen]

I just spoke to someone who said that the only disadvantage of high caster is the added steering effort. But he was not 100% certain either.

Would be great if someone could shed some light on this.....

 

[Dave Stephenson]

my understanding of it in laymans terms has been iots biggest effect is on steering responsive. which of course affects understeer/oversteer and stabilty

 

[Mikkow]

I was once told that with example the Seat Leon, the higher you have the caster, the more understeer you will get in high speed corners, but for slow corners it is just right

BUT, the slow corners must be below the 110 km/hour.

This appears to be the most true thing so far. The caster will make the wheels get more negative camber the more you turn the wheel. In fast turns you don't turn the wheel much yet there's tons of G-forces (due to downforce and high speed), and the car will lean to the outer tires. If now these tires don't have enough negative camber to flatten themselves well to the ground, the limited contact patch should give worse grip up front. I..e understeer.

 

[Niklas Vesterinen]

I was once told that with example the Seat Leon, the higher you have the caster, the more understeer you will get in high speed corners, but for slow corners it is just right

BUT, the slow corners must be below the 110 km/hour.

This appears to be the most true thing so far. The caster will make the wheels get more negative camber the more you turn the wheel. In fast turns you don't turn the wheel much yet there's tons of G-forces (due to downforce and high speed), and the car will lean to the outer tires. If now these tires don't have enough negative camber to flatten themselves well to the ground, the limited contact patch should give worse grip up front. I..e understeer.

I don't know. I've been working on my setup for Spa and i didn't notice any understeer in the highspeed corners when i changed from minimum to maximum caster. I checked the left front tyre temps right after i exited Fagnes which i guess is the turn that is the hardest for the left front and also is pretty high speed. The tyre temps where very even and good with maximum caster but only after i removed a little negative camber first.

In general the only difference that i saw was that i was able to remove a little negative camber but otherwise i didn't really feel to much of a difference to the handling of the car.

But as i'm very new at setting up the car and fairly new to the game i thought i should ask some professionals.:wink:

 

[Neil Gault]

why max caster can be bad? well with caster at the max when you corner you get camber gain and too much camber will heat up the tyres and wear them out too quickly.

 

[Niklas Vesterinen]

why max caster can be bad? well with caster at the max when you corner you get camber gain and too much camber will heat up the tyres and wear them out too quickly.

As i said in the first post, that had already been dealt with by reducing camber as the caster went up. My tyre temps are even and is not the issue here. With this in mind my questions was if the added caster was going to effect the car in any other way. Remember the camber gain has been neutralized.

 

[Klyde Parker]

Howdy,

A friend of mine drives F3000s in "REAL" life. This is how he explained it to me. Think of a motocycle with extended (chopper) forks... that would be an example of LOTS of positve caster. Now, picture the forks on a racing motocycle... that would be an example of LESS positive caster. Ever see a race bike with chooper (extended) forks???? NOPE - so why would you want a race car with LOTS of positive caster???

Just some food for thought!

Klyde

 

[Mikkow]

Howdy,

A friend of mine drives F3000s in "REAL" life. This is how he explained it to me. Think of a motocycle with extended (chopper) forks... that would be an example of LOTS of positve caster. Now, picture the forks on a racing motocycle... that would be an example of LESS positive caster. Ever see a race bike with chooper (extended) forks???? NOPE - so why would you want a race car with LOTS of positive caster???

Just some food for thought!

Klyde

What's your friends name? I'd love for him to tell more about all this kind of related stuff, and also try out the F3000 and other cars in Race 07 + expansions for some impressions.

As for not seeing race bikes with positive camber doesn't really logically transfer to "so why would you want a race car with lots of positive caster", as they are different and set up different.

 

[Günthar Rowe]

Think of a motocycle with extended (chopper) forks... that would be an example of LOTS of positve caster. Now, picture the forks on a racing motocycle... that would be an example of LESS positive caster. Ever see a race bike with chooper (extended) forks???? NOPE - so why would you want a race car with LOTS of positive caster???

You (and your F3000 friend) are correct for motorcycles, but not for cars. This is a great way to visualise the workings, but not the application in car physics.

Firstly, I can only think of 2 motorcycles in modern times, in the world that had front wheel drive and both were actually All Wheel Drive. Here lies just one very large difference. Secondly, motorcycles don't run flat tire contact surfaces. Thirdly, motorcycles are pushed/leaned over into a corner to make them turn (after the initial opposite input to initiate the turn).

So, on a FWD car (WTCC etc) you will find castor settings around the positive 9 - 11° in Real Life. Sims are not real life and therefore see a high range on FWD cars anywhere from 6 - 12°.

On a RWD car (like the BMW E90 320si) more common castor settings around 4 - 7°...

Toe can sort out the sluggish feeling from induced castor.

 

[Günthar Rowe]

I find on tracks like Le Mans that high castor is great as this track is very high speed and the less camber needed helps in the braking area, whilst the castor gives me the increase in camber when needed in corners...

 

[Klyde Parker]

You (and your F3000 friend) are correct for motorcycles, but not for cars. This is a great way to visualise the workings, but not the application in car physics.

Firstly, I can only think of 2 motorcycles in modern times, in the world that had front wheel drive and both were actually All Wheel Drive. Here lies just one very large difference. Secondly, motorcycles don't run flat tire contact surfaces. Thirdly, motorcycles are pushed/leaned over into a corner to make them turn (after the initial opposite input to initiate the turn).

Oh please,

Gimme a break, I was trying to give an easy to understand general description of the FOREWARD and AFT positions concerning Caster. I wanted to give a simple example that Caster is a reference to the degree of angle (positive) between the the axis of the wheel and the steering pivot point. Your firstly, secondly and thirdly refencences seemed a bit excessive and NOT appreciated.

Klyde.

 

[Günthar Rowe]

NOPE - so why would you want a race car with LOTS of positive caster???

I guess that I took your reference to "lots" of positive castor as doing things incorrectly, were in fact on some car types it is quite necessary. I meant lots to be around 10-12°. was not trying to flame you. And am sorry if it came across that way. I have come across other threads that have had people stating incorrectly that high castor is bad in a setup...