What is Caster and what does it do?

When you get an alignment on your car, if you look at the printout once the work is done, there are three parameters that are measured up front: Camber, Caster, and toe. Camber and Toe are talked about a lot, and it is pretty well understood what they are and what they do.

But what is Caster? And what does Caster do?

Caster is a more difficult attribute to show and understand, and it seems like it is not talked about nearly as much as it should be. So we decided to put together this video to showcase Caster, and try to explain what it does and why it is important, especially if you are looking at changing your alignment settings, or modifying your suspension to get more grip up front.

Topics in this video:
00:00 - Introduction to Caster and what it does
01:05 - What is Toe? And what is Camber?
01:40 - Why does caster only apply to the front wheels?
02:05 - What is Caster?
03:35 - What is the difference between static alignment and dynamic alignment?
04:03 - How does caster increase traction?
05:28 - How can you see caster working on a car?
07:07 - What effect does caster have on ride height?
08:26 - What other aspects of the alignment are changing with caster?
09:32 - Why wouldn't you just maximize caster?
09:56 - What does adding caster do to tire wear?
10:30 - How can you actually change or adjust caster?
11:44 - Conclusions about caster

Thanks for watching!

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[NSUGS]

Exactly the tech talk I was looking for. Very in depth. Why you don't have more subscribers is beyond me. +1 from me!

[HassenHossenbaccus]

A bit late finding this video but exactly what I needed to get to grips with the concept. The visual props helped a lot and would highly recommend anyone into fine tuning their suspension setup to watch the whole video...a few times if needed like I did as it is really worth it.

Thanks for making this video as I am sure it will help countless of others like myself who would like to expand their knowledge. The whole channel is a wealth of information for any Subaru enthusiast :)

[nathanbarash]

Best explanation of Caster I've found. Thanks!

[oby-]

Amazing how caster has such an effect on camber. Although you did say it varies depending on which suspension system is in play. Thank you for your time to detail out this important alignment spec.

[Vamp]

Thank you so much for this in-depth alignment tutorial. I recently took my car to a local shop to have it aligned, and for some reason, everything is green except for the caster. The service technician advised that there was no way of correcting the caster issue, but after watching this video there is.

[sparkypete]

The best castor explained I seen online. I watched alot of videos on this.. this is the fundamental best

[donep]

Nicely done. Everyone into fine tuning their suspension should watch this. Well explained.

[johngraham]

Well I never knew what caster was. Heard of it but never thought about it. Nice explanation that even I can understand. The sheet of paper really helped.

[BEFITtingImage]

Best explanation I've seen so far - thanks

[SSLS]

Great visual on how caster effects your dynamic camber. Thank you!

[bendover]

1:11 “Toe, is very straightforward.”
Superior pun, my friend.

[Js]

Wow! UTI wasnt able to explain this to were i could understand it but, you sir have done it! Thank you.

[Vanderkitten]

Just came across this video. I am running significantly more caster with new plates on my bmw and was disappointed the static camber wasn’t more. The race shop that set it up said “this will be a huge improvement!!” I finally grasp fully how this new caster setting will work for me based on the issues I’ve been having!

[MrPachouko]

Best explanation ever. Have read about it but you really clarified it. Tx

[EJAZenarosa]

This explanation is very good. Thank you.

[dannymartinez]

You really know your stuff! Thanks for explaining everything in detail.

[ronchang]

@FlatironsTuning Can you tell us about any negatives to the Anti-Lift Kit on Scotty's car? I know that in addition to the offset bushing, it is also lowered. I know of the positives, but can you tell us if there are any negative attributes vs the stock flat plane mounting of the lower arm? Thanks!

[shaneil]

Another awesome video guys! You mentioned toe out can affect the camber dynamics as the wheel is turned, I have adjustable strut tops that have max castor dialed in and I do notice my inner edge wears first, I was wondering if I left the castor but adjusted the toe to give me toe in, I'm assuming that would reduce the dynamic camber, but my only question is, how does toe in affect the handling of the car and tyre wear?? I only run about a degree to a degree and a half front static camber if I recall correctly.

[Lucas-nzem]

Great content. What is your rule of thumb for max cross caster tolerance on the STI? My cross caster was out almost a degree and I found that shifting the subframe from side to side brought me within 4 minutes of cross caster which I believe is more than acceptable.

[chrischow]

Question about added caster - I am looking at an anti lift kit by whiteline for the a 2018 civic which is a Macpherson suspension design. The kit is a poly bushing that replaces the OEM bushing on the front lower control arms and adds +1 degree of caster. Because of the added dynamic negative camber that comes with added caster when cornering, would it cause abnormal tirewear even if aligned at factory specs? How often do tires need to be rotated with a such a part installed for a daily driven car? Thank you for the useful information!