How Caster Works

Today we talk about caster, what it means for driver feel, and what it means for vehicle handling. Caster is very important, as it provides much needed steering feel and essentially allows the steering wheels to motorbike lean into a corner.

[MrTouge]

To be totally honest I cannot believe how long it took me to find this video. Literally weeks. What a great video explaining why Caster is important and what it does to your suspension while steering. I can't believe this video doesn't have more views. Thanks for the awesome video.

[flamingronin]

What is the difference between this and regular sugar?

[juge]

Finally a video that tries to explain the importance of mechanical trail for the steering feel and self centering (how strongly the wheels want to turn into the direction of travel).

In many videos about suspension geometry, they try to explain the effect of the caster angle by using for example office chairs with swivel caster wheels. But they fail to notice that swivel caster wheels actually have zero caster angle (the steering axis is vertical), but plenty of mechanical trail (how much the steering axis ground intersection point is forward of the tyres contact patch center).

It is the mechanical trail that gives majority of the steering feel and self centering. The more you have mechanical trail, the more you will get steering feel. Caster angle (and KPI angle) by itself gives only very little steering feel and self centering (it gives some, because it tries to lift the tyre onto its edge but the effect is very small when compared to mechanical trail). I think that the confusion between the effects of caster angle and mechanical trail comes from the fact that in majority of automobile suspensions, changing one setting also changes the other. It is possible to build suspension where caster angle and mechanical trail can be changed independently. Caster angles main use is to get better camber angles during cornering.

The effect of mechanical trail can most easily be seen by playing around with shopping trolleys or office chairs.

I think it would be less confusing to use the whole term caster angle, when talking about suspension caster angles to separate it from caster wheels. I would actually like to know why those caster wheels are called caster wheels even through they have zero caster angle? Is it the name of some old manufacturer (like hoover for vacuum cleaners) or is it derived from some old english or some other languages term or saying.

[andrewnash]

Thanks. Basically, when the wheel rotates and leans inwards to the turn there is more friction on the part of the wheel which is now leaning in to the turn and touching the ground. This friction causes the wheel to want to find the path of least resistance and lift the part of the wheel that is leaning in and touching the ground off of the ground. This causes the wheel to straighten and lift the leaning-in part of the wheel off of the ground. Makes sense! Thanks!

[NamanSharma-ujvx]

Does too much positive caster "tightens" your steering while too much negative caster "loosens" your steering? If yes, then why?

[onetransmission]

Would you like an explanation of front end geometry? I think that would help a lot.

[jheelpatel]

Hello I just wanted to ask lets say one wheel has positive caster and other wheel has negative caster what issues could occur?. Does this situation can cause vehicle pulls to one side or just tire wear at various points?

[stevesloan]

That was a great take.
Very smooth delivery and quick illustrations.

🤜🏼🤛🏼🇦🇺🐇🍀🍀🍀😎🤓

[db]

For 250, 000 miles I've been trying to figure out why my trucks steering doesn't return properly! Replaced every part on the front end multiple times brought it to multiple alignment shops no one can tell me why.
Doing my own research I've come down to the conclusion that something is off with my caster the vehicle pulls to the right and sterring feels lighter when I turn right but doesn't have good feedback. When you steer to the left feels heavier but to me has better Road feel.
The question I have is since it's steering easier to the right and heavier to the left do I take Caster out of the right hand side or do I add Caster to the left hand side since the steering doesn't return correctly, I was thinking adding Caster to the left hand side would make both sides lighter therefore correcting or helping my non return steering
Oh ya old girl has 370, 000 on her and has had this issue since I bought the truck with 100 000 MI
I bought it with stock upper A arms had this issue then! I installed cognito upper a arms still has the issue. I did turn torsion keys in, t A arms allow me to bolt ball joints in on top or bottom to fix camber issue from Turning in bolts on cam keys and raising the truck a little

[boxxxybabe]

Caster made easy!! Thanks for the info.

[leafaRPD]

At 2:38 you meant to say camber and said caster, right? Not being a douche, just trying to learn about it and got confused there. Maybe you can add some note via youtube to change that, if I got it right. Thanks again for these videos. I'm happy I've found your channel today =]

[rjm]

Are OEM caster specs the actual measurement at +/- 20 deg steering angle (i.e. lock to lock) or are they the true castor angle which the measurement must be converted to - i.e. measured angle / sin(20) ?

[MotoErgoSum]

Do you still have the FT86? I'm weighing suspension upgrade options and want to improve front end grip and overall steering feel. The stock tires and suspension understeer pretty badly in tight corners off the brakes. I'm wondering if adjustable pillowball mounts and other minor upgrades would help a lot or if I should just save up for a complete package to fine tune all of the settings. I know the stock tires are a huge part of the problem.

[okaythen]

For rear caster and front caster, you don't change those for track alignment right? They stay the same for street and track alignment? (c7)

[esnevip]

G'day mate, great stuff.
One nomenclature question:
What did you mean by pickup point?
Would you be able to tell me as the name of the part?

I.E Steering knuckle, Lower Balljoint, etc.

Cheers.

[stevenolson]

so if you had negative caster, or a situation where the 'moment arm' was behind the 'point of contact' (instead of in front like your example) of the wheel you could have a dangerous situation? going around a corner the car would want to turn more and more. Are there any examples of negative caster being used or usefull?

[sampathkumar]

Can u please make a video on how steering setup should be made for drifting..

[dontworryaboutit]

so here’s the thing idek if anyone will answer this but let’s say i’m going fast on a kart and i hit a bump i don’t want to lose control bc of how finicky my steering is what do i do ab that

[nickamarit]

My car has a caster difference of 1.10° (L=4.6° and R=3.5°).

I'm suspecting a bent frame.

How do I check if the cause for the caster inequality really is a bent frame? Also, if my frame really is bent, is there a way I can fix it?

[Atominisdeguonis]

Can you add website's link in the descripsion? (website you mention in the beginning)