caster mod by crossmember relocation.

[scum1]

I am about ready to section my crossmember and during the process I am goin to remove the upper coil pocket of the crossmember, and fabricate a new upper bag plate, as well as move the crossmember forward 1", to better align the wheels in the wheel well.

as i was thinking about this, i will be in a unique position to be able to leave the upper control arm in its stock location (fore/aft wise), and move the crossmember (and subsequently) the lower control arm forward towards the front..

I have read various threads on caster mods... doing what i suggested above would no doubt increase the caster right? im literally moving the whole control arm forward an inch while the upper stays where it was.

Has anyone done this before? is 1" going to yield too much caster increase...to be honest im not sure how to even measure caster. other than tell if both wheels are the same from a point on the lca to a point on the frame.

while i was looking at everything it dawned on me that could be fairly easy to do while im fabbing this all up..if im picturing it right.

[PGSigns]

I moved my lowers 5/8 and was able to get 5 degrees of caster when it got aligned. only moving the lower control arm will not gain you but about half what you move it in movement of the wheel forward because the spindle (drop spindle) is about half way between the two control arms. Also when you move the cross member forward you can run into the stock steering if you plan to run it. Why are you going to cut up the spring pocket? Normally it just get a plate over the hole and the bag gets mounted to that. With a cupped or aftermarket lower control arm the bag is in a good position done that way. My 65 sets the cross member on the floor when aired out.
Jimmy

[scum1]

ah i see what your saying about the movement forward with reference to the spindle..

i currently have cupped lcas and the upper bag plates on the bottom of the spring pocket. the reason i am doin all this is..

1. i dont like how much the lcas are cupped nor the welds on them. i would feel more comfortable with them being rebuilt not as deep, and with my welding.
2. I can get the angle of the lca at full drop, to match the upper bag plate (parallel)
3. I think the ride quailty would be better if the bag was closer to its relaxed height when at ride height, for example having the bag 7" from plate to plate at ride height vs 5"...does that make sense..it does in my head lol
4. i like doing stuff like this, so its not a hassle, its a project.

in my mind you wouldnt have to cup the lca at all...if you could raise the upper mount. so a small cup and upper bag plate at a different angle and raised slightly would mimic the aftermarket x members in that respect.


as far as the caster effect. moving the crossmember forward, i was prepared to deal with the relocation of the steering box( i have to move that up 1" due to the sectioning anyway) and idler arm. just slide everything forward with it.

are you suggesting that moving the xmember forward an inch, while leaving the upper, will correlate to a 1/2" of difference, where you moved it 5/8? is that worth it? i was under the impression the more caster on these trucks the better, to an extent. like i said i kinda just brainstormed the idea while i was looking at it. not sure if its a good idea or bad idea.

[PGSigns]

The 5/8 was to get me the ability to get to the 5 degrees I wanted on the alignment. I had a goal of 5 so just did not need to go more than that. I did not want to have to shim the upper a ton to get back to 5 if I over shot. That could make it tougher to get the camber set. 1 degree is about .017 per inch. so if the ball joints are say 10" apart to make the math easy moving the lower .170 get you a degree. So .625 forward added a little more than 3.5 degrees with no added shims to the top making 5 easy.
Jimmy