Just started an A-arm conversion on my FL350. Plan is to use 250x and / or 250r quad front end parts. (have a complete 250x front w/ hubs & brakes, but only 250r arms & spindles). Did a bench mock up and discovered that with the arm mounts perpendicular (90 degress) to the ground, and arms directly over each other as on the quads, the uppr ball joint is forward, giving a negative caster situation. Checked my wifes 250ex and friends 450ex, and both have about zero caster by raking the arm mounts up in the front.

Question is should I rake the front mounts up, or just off set (low arm forward a bit) to achieve zero or positive caster?

Pictures...

My junk in the front is raked back but I don't have a degree wheel to tell you how far... I have a speed square I can use to get you close.... Do you have the chassis from the atv handy just copy or duplicate that angle...

Caster = ??? in at the top???
camber = ???

The "Instructions" don't tell you what the caster camber is?

Is the caster camber adjustable?

The Pilot caster camber is not adjustable but they still tell you the settings are...

LEE!

First. The 250X front end is based on the 250R. The 300EX is based on the 250X, in fact the knuckle is the 250X part. The 400EX is based on the 300EX. This dose not mean you can mix and match parts but there are many similarities.

The 250R arms are a narrower base than the others but all the others have the same base dimension and the same end tube dimension.

Second. The arms are made to be mounted at an angle, it’s called mechanical compliance (in the US). This angle allows the wheel ride back and over an obstacle. This is what makes the VW front end so good off road. Too much angle hurts the steering and spring rate, too little and the front end pounds on the rocks.

For the 250Rand 250X the angle is 16 degrees. 300Ex is 15 and the 400EX is 13.3 degrees.

Third. Once you have the lower arm at the correct angle the upper arm is at the same angle (this is not true for the FL400 but that is a really long story) and directly above the lower arm when looking flat at the lower arm. OK, English dose not do this well. If you look at the side view of the lower arm draw a line perpendicular to pivot axis of the lower arm from the front of the pivot tube. The front of the upper arm pivot tube will line up with this line. Go back out to the garage and look at the wife’s 250X you will see what I mean.

Forth. This is where I post a nice picture to explain what I am trying to say. I’ll try and post it by Friday.