adjusting trailing arm

[puma]

For those who have adjustable trailing arm, how did you adjust them? There is no way to adjust "caster" on a rear wheel so what do you take for measurment when adjusting it?

thanks

[puma]

really, nobody bought adjustable trailing arms?

[Captain Snooze]

Yeah, I have RacerX trailing arms but I have never adjusted them. I just gave them to the suspension shop and asked them to fit them.

[Scargod]

Here's some info from Gforce (from 2017):

Originally Posted by Gforce

Caster is another description of hub pivot inclination, fore and aft. That is described by the vertical line drawn through the upper and lower "ball joints" on double A arm suspension. For multi link it can be hard to determine exactly where the lower pivot point is. I like this link as a show and tell for the suspension geometry, scroll down to the rear suspension.

https://www.edmunds.com/car-reviews/...alkaround.html

Caster is not relevant for non pivoting wheels but the geometry of the connected links is critical. The rear hub caster angle changes with suspension movement so it is the relative arcs that matter. If the trailing arm is longer or shorter than stock then the toe link effective length will be different from stock and deliver different toe rate changes from stock. If you know what you want in that regard you can play with the trailing arm length and an alignment machine if you want to see how it works.

Since the toe link length is connected to both the trailing link and lower control arm through the hub and that length determines the toe setting throughout the suspension arcs you should ensure your new trailing links are the same length as stock. The straight line length from the mounting bolt to the hub bolt is all that matters. Any curves or drops in the arm itself do not affect geometry. Just measure your old ones bolt to bolt and adjust the new ones to the same length, bolt to bolt. Sorry, you don't have your old ones so you'll need to get under a stock car or ask someone to measure theirs for you.

There will be a very slight change in anti squat effect from different length trailing arms also as the arc of the trailing arm influences anti squat angles.

[Tokay444]

That’s gotta be a new record.

[marco_mc22]

When I did my front caster adjustment I straightened everything measuring wheelbase, I assume you could do the same with the rear but the problem there is even a very small adjustment would affect a lot bumpsteer curve, which could lead to a very unpredictable car if it’s not what you’re searching for.
Anyway, if your front knuckle location is stock (aka you have stock LCA’s) you should try step by step increasing or decreasing wheelbase, use a tape to make a precise measurement at the wheel hub.