I have a ifs longbed frame I plan on using this winter for a formula four project..I have read before in a post that you get more flew or something from a solid axle frame...Any truth or is it worth going out and finding a straight axle frame? I plan on puting new drop hangers and everything anyway...

If you're trying to go really low, a straight axle frame is both shallower (Brian E. said about an inch) and has more arch at the framerails.

If you're going drop hangers, your axle will never stuff up that far, so IFS should be just fine.

IFS is fine

If the rig will be high, IFs frame will be fine. However, they do have less arch for the front axle, and the height of the main rail is taller, IE higher chassis mount, lower belly clearance.

Depends if you are really really picky or not.

Mines on a IFS frame, its worked fine for me.

Mines on an IFS frame as well and it works fine but the next one we build will be on a early frame for the reasons mentioned above and I have a really nice SWB rust free early frame out back.:D

I e-hate you. I found my "dream" SWB 84 4x4 frame, and it's rusty from the cab back. It's going to get quite a few plates.

Whats rust?:D

If the rig will be high, IFs frame will be fine. However, they do have less arch for the front axle, and the height of the main rail is taller, IE higher chassis mount, lower belly clearance.

Depends if you are really really picky or not.

But if you notched for seat mounting, and notched for draglink/tierod clearance I'm pretty sure you could get it just as low as a straight axle frame.

Around here you can find an old straight axle truck sitting in someones field with trees growing up thru it and it won't have rust on it unless it was used as a mudtruck and has the frame rails packed with mud. :flipoff2:

Rust belt guys, what's a good way to determine if a frame is too rusty?

Mine has two full on "cancer" spots where the rear wheel arch curves to the level spot under the cab. 2" x 6"; easy enough to plate. when I cut the frame to length, it was good, solid steel with only a flake of surface rust; the small inner brace inside the rear (tire carrier) crossmember was rusted through, but both plates of the framerail box were nice and solid.

Without cutting holes all over...any non-destructive/semi-destructive tests? Hammer? Drill holes?

I have an xtracab donor frame, too...but want to give my axles as much room as possible in the axle arches... If the SWB frame turns out to be too rusty, would it be OK to cut 10" out of the level cab section of an xtracab frame to and sleeve/weld it to make it SWB length? Is this a BOD question?