Difference between Trim & Subtrim
 

you got it.

coarse, fine.

Nope.

When you set up your radio, it has Endpoint Adjustment, Trim, and Sub Trim.

Endpoint: This is the internal stop of the servo so it isn't fighting against the suspension limits of your car. You generally set this just short of the maximum steering angle allowed by your geometry, you really don't want the servo straining against the bump-stop

Trim: This moves the neutral point around inside of the set endpoint adjustment, but it will still go to both endpoints at full lock and 100% dual rate or steering throw setting.

Sub Trim: This moves the neutral point AND THE ENDPOINTS WITH THE NEUTRAL POINT. Using sub-trim to trim the car will change the steering throw left and right. It is necessary in some classes to use Sub Trim such as 1/12 scale, where the servo is exactly centered in the car and you want to use the exact same servo throw in both directions so you can have equal steering Ackermann on both sides, but is less useful in touring car or offroad where the steering throw endpoints may be different.

Thanks Desert. Ive always wondered this myself.

Although sub-trim is always recommended, I prefer to adjust a new setup with turn buckles (leaving both trim and sub-trim set to zero)... if I lose my center after a crash, maintenance/wear, etc... and I have to make a quick sub-trim adjustment during warmup before a race, then I'll make sure to go back at the end of my race day and set my sub trim back to zero and re-adjust my turn buckles again. So much easier to check the main screen and see everything zeroed out, never know if you accidentally bump a trim button and lose a setting that you might not realize right away until halfway through a race you discover that your car isn't tracking straight :(

i am the same way to try to keep it as close to 0 as i can. somewhat funny story, when i built my new xb2, i setup the remote i forgot to check the trim and sub trim settings on the remote. i powered up the servo to get center and then installed the servo saver etc. my first time running it was pulling slightly to the right, so i went to the trim settings and it was set to like 50 or 60 on the right. i forgot to verify it was at 0 before installing the servo. the next day i took the servo out and re-centered it and put it in again. it was 1 tooth over. i felt dumb for not checking it.

my steering end points were also set to 75. i must have used this slot and forgot to name it. i wonder which car i have no longer has that slot now? :)

On a 25 spline servo horn, you've only got ~14 degree increments to position your servo horn correctly. I use sub trim to compensate, and then never touch it. From there I adjust the turnbuckles until normal trim is 0.

Then I get lazy, and just use trim instead of detweaking my car after a crash :sweat:

I usually adjust subtrim first to get my steering centered ( after I install the servo horn as best as I can (eye ball) with both front wheels pointing straight) ..then use trim for quick adjustments in steering when I'm actually on the track.