Figured that I need to relocate my lower control arm mounts about 4" lower to accomodate larger spindles and keep the geometry somewhat close to correct (with bigger springs/shocks).
What size steel should I be fabing this out of, and what is the prefered mounting method.
I was thinking of using a 4x4 box tubing (Width between the outside of the current mouunt is 3.75", welding two sets of angle Iron accross the top and bolting it to the old mount location, then taking a plasma to open up the bottom of the box where the control arm wil move in the Y axis.
Not sure on what thickness steel I should be fabing this out of. 1/4, 5/16, 3/8?
Thanks
Wow. 
4" lower mounting for (I presume) the inner C/A pivot? Man, that's a LOT. WTF are you working on? What's your ultimate plan? (race car, street car, 4x4, rock climber,etc) Then mebbe some meaningful answers can be formulated.
In reply to Jensenman:
Its a utility vehicle....if it ever sees more than 40mph I'll have brown stuff in my shorts.
Long story short, The OEM spindles have trashed brakes, and would cost a ton to rebuild. I'm putting Jeep Cherokee spindles on for better brakes and same bolt pattern.
The OEM spindles have about 4.5 inches of separation between ball joints, but the Cherokee spindles have about 9 inches. Now I can spread the control arms enough to fit them, but I think it would put too much stress on the ball joints and puts the spings and shock in a bind.
Thats where/why I was looking at a 4" drop to the LCA to try and get them back closer to the factory geometry.
As long as you raise the rear of the car by an equal amount you should be OK. I can't really advise metal gauge etc without pix, can you post some?
Cherokee spindles? Are you planning to use the whole front beam axle? That might be the simplest solution; at first blush it seems like more work but maybe not after considering all the angles (literally).
In reply to Jensenman:
They are 2wd spindles......specifically chose them based on cost (ebay 80 bucks shipped loaded with rotors/calipers), and same type of ball joint mount (will have to flip and sleeve one), so won't be using the whole beam/axle.
In reply to eebasist:
http://i34.photobucket.com/albums/d107/eebasist/Jacobsen%20UTV/CherokeeSpindleonArmSpringperchdist.jpg
http://s34.photobucket.com/albums/d107/eebasist/Jacobsen%20UTV/
Linky no worky. 'Image removed'.
Wow, that is a dinky little OE spindle, isn't it? 
I see the situation you have, and I'm with you; lower the inner mount for the lower control arm. Here's the thing; get the center to center measurements of the original ball joints, then the same for the inner control arm pivots before modification and compare those measurements. These measurements will likely be very close together. So you'll need to get the center to center measurements of the Cherokee ball joints, then duplicate the original ratio on your inner mounts. Here's why: changing the angle of the upper control arm will change the roll center height. You'll also need to consider the steering linkage, if the tie rod is at an angle (which, from the pictures, it looks like you would wind up with) you will have enormous bump steer problems. This doesn't sound like a big deal at low speeds like you mentioned earlier, but it is.
The inner mounts look to be approximately 3/16" steel, that's what I'd use and make sure it's boxed. I would also brace the mounts with each other and triangulate to the frame, maybe with round tubing or similar.
The spring perch would be easy; use a piece of tubing which will slide inside the spring, weld a ring on it at the spacing you need then install this on top of the spring before compressing it. You might make a round plate to weld onto the top of this spring spacer which would keep it centered in the original perch.
But before doing all that: is it possible to use the Cherokee (or perhaps some other type) of hubs on your original spindles (tapered wheel bearings are generally a few common sizes, sometimes you can find bearings which will allow you to do this, or have spacer sleeves made) and fab a caliper bracket? That would save a HEAP of fabricating. You might wind up using different calipers so they'll bolt on rather than use the Cherokee's 'slider' arrangement but that would still be a lot simpler than moving suspension stuff, fixing bump steer, etc.
You mentioned bolt pattern, I assume you have 5 on 114.3 (5 x 4 1/2"), that's pretty common. You might look at, say, later Fox body Mustang hubs and calipers, 88-up 2nd gen RX7, Nissan 300Z/ZX, etc.
In reply to Jensenman:
Just ordered the steel today...60 bucks for essentially three feet of 3/8 x4x4 box tubing.
I measured the thickness of the existing mount at a little over 5/16 so I figure for a suspension component that will see some serious stresses thicker is probably safer. The front will be a 9" piece and I'll use some angle iron welded to the top and drilled to take the bolt that goes thru the current control arm, and then drill on the bottom and open the box up for the travel.
I think I hear a plasma cutter calling my name.
Once I relocate the lower arms, the sping perch will be parallel again. Of course then I'll be faced with the dillema of what spring/shock to use
