[Problem] Caster Angle & Scrub Radius

[Zika]

Hi,

i can`t Determine the accurate Caster Angle and Scrub Radius

*Caster Angle: Some Reference Advise to make Negative Angle and Others

Positive Angle (Positive Angle which Increase the effort) but we can not reach to

The suitable Angle for our car ..so what is the angle (range) most team use ?

*Scrub Radius: how to find the Suitable Scrub Radius? ...

Some Reference Advise to make it less than 1 Inch (2.5 Cm) and we calculate it was 4.2 Cm so what we shall do!!

[Zika]

Hi,

i can`t Determine the accurate Caster Angle and Scrub Radius

*Caster Angle: Some Reference Advise to make Negative Angle and Others

Positive Angle (Positive Angle which Increase the effort) but we can not reach to

The suitable Angle for our car ..so what is the angle (range) most team use ?

*Scrub Radius: how to find the Suitable Scrub Radius? ...

Some Reference Advise to make it less than 1 Inch (2.5 Cm) and we calculate it was 4.2 Cm so what we shall do!!

[Dash]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Zika:
Some Reference Advise to make it less than 1 Inch (2.5 Cm) and we calculate it was 4.2 so what we shall do!! </div></BLOCKQUOTE>

Add some Kingpin angle

[Zika]

thxx for your response any one can help us in this problem

[BillCobb]

Find or make a different wheel with a more favorable offset.

[PatClarke]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Some Reference Advise to make it less than 1 Inch (2.5 Cm) and we calculate it was 4.2 Cm so what we shall do!! </div></BLOCKQUOTE>

I suggest you abandon the project. It is obviously far too difficult for you to determine a solution.

Of course, you could build with 4.2mm offset and see what happens.

By the way, build a car with negative caster and see what happens when you drive it. You will learn an indelible life lesson.

Pat

[Dash]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by PatClarke:

By the way, build a car with negative caster and see what happens when you drive it. You will learn an indelible life lesson.

Pat </div></BLOCKQUOTE>


Sounds like fun. Would definitely be a challenge to the driver!

[exFSAE]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by PatClarke:
By the way, build a car with negative caster and see what happens when you drive it. You will learn an indelible life lesson. </div></BLOCKQUOTE>

I've driven cars (FSAE) with zero caster angle and positive trail with no issue. I suspect some negative caster and spindle offset would drive just fine. Steer-crossweight change in opposite direction as conventional, but maybe not a terrible thing. Or did you mean build a car with reverse mechanical trail?

Don't need much if any positive trail on these cars anyway given the very fast steering ratios.

[BillCobb]

My '58 Chevy had 1.5 degrees negative castor. Its a very driveable car. You would see why if you had manual steering. Oh, your DO!

That being said, I'd point out that with the steer ratios some of you are using, AND the gorilla shoulders your drivers are needing, that there ought to be a pair of dimes change in the thinking department. Some camber issues to deal with, but watching the autocross event makes it obvious that steering work is responsible for a larger fraction of screwups than max lat limitations.

[Zika]

thxx all for response

what about +2 for caster angle ..is it suitable or must increase it??

[exFSAE]

It's whatever you want, man. +2 is fine. +4 is fine. 0 is fine. -2 is fine.

YOU need to come up with the process or reasoning to come up with the number.. not just ask someone for the magic optimum answer.

[BillCobb]

I sorta like pi, but you can never really get it set acurately. 4*Atan(1) gets you pretty close. With a 4:1 steer ratio, you can see where this gets you in terms of effort levels.

The presents of 2 joints improves the appreciation of the moment, too.

[Adambomb]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by PatClarke:
By the way, build a car with negative caster and see what happens when you drive it. You will learn an indelible life lesson.

Pat </div></BLOCKQUOTE>

A couple years ago our Baja team did this. Steering didn't return at all, was pretty spooky. But then again just about everything related to driving that car was spooky. Actually I'm thinking that's the same one they t-boned our dually with (brakes? kill switch? reliable throttle mechanism? all over-rated, lets drive!). I happened to be a TA for the guy responsible for that suspension, and threatened to fail him out of principle.

[RollingCamel]

Steering effort was something we didn't really realize until we saw the size of steering wheel real teams use.

Zika are you from Egypt?