I have run into an unexpected problem in my front disc brake swap. I have a 66 F250 2wd. Parts truck was an extended cab 74 F250 (so it has the big kingpins and dual piston calipers). Currently I have the 1966 springs and radius arms and the 1974 I-beams, spindles, brakes installed. Everything lined up and bolted on fine. Drives side looks good. Passenger side does not; the face of the rotor is 1/2 inch wider (towards outside of fender) than the drivers side and the whole spindle/caliper/rotor assembly is 7/8 inch forward in the wheelwell than the drivers side. So basically the wheel sits 1/2 further out and almost 1 inch further forward so it is not centered in wheelwell. This is causing serious tire/wheel fitment/clearance issues and I'm thinking it will mess up the steering geometry as well. 74 axles measure same as 66 axles from center of axle pivot to center of radius arm bolt, and from center of radius arm bolt to center of kingpin. Each axle is the same length (passenger and driver) for each year. Radius arms measure the same length as well. Right now the only thing I can see is that the 66 axles have a slight twist to them (must have been to center the spindle end up in the wheelwell) and I don't see the same "twist" in the 74 axles. The axles seem to be properly installed as the kingpins are both tilted rearwards for proper caster. Only solution I see is to reuse 66 axles and have some custom kingpin bushings made to allow use of 74 spindles. Any other ideas or thoughts? Thanks.

 

fuelie, I bolted a complete 76 axle setup under my 66 with no problems. The forum encourages total swap over piece meal. If it worked under one truck it will work under the next one.

Sorry to hear that you are having problems.

John

 

If the original I-beam has a slight twist, is it possible the truck was in a front collision at one time and that's how it was repaired.

 

If it were only that easy.

I have the whole front end from the 74, the only 74 parts I'm not using are springs (too tall for the 66 spring towers) and the radius arms. I'm reusing the 66 radius arms because I just like forged steel better than stamped sheet metal. The radius arm mounting points all measured out the same so it shouldn't matter. The 66 frame is not bent/tweaked, original undamaged radius arm mounting brackets still riveted on, and the 74 donor truck appeared to have suffered no front end damage, unless an axle was somehow tweaked in its prior life (maybe curb or huge pothole). The 66 axles are perfect and have no damage. Maybe the '74 axles need to be pulled and compared more closely for angles and bends.

I did a disc swap on my 65 F100 and had no problems. In my experience thus far, the F250 has proven to have plenty of small differences and niche parts that make this swap more complcated than a 1/2 ton swap.

 

I, like John, had no difficulties doing this same swap ('76 Crew cab to '65 F250). The only thing I can think of, short of damaged pieces, is that you don't have the rubber bushing seated all the way on the right side radius arm, thus pushing it forward. Check that and maybe you'll find something.

 

that was the first thing I checked, they are good to go. I'm beginning to think something is wrong with the passenger side I-beam. If it comes down to it, where can I go to get an I-beam "adjusted"? It seems like it would require a heck of a blow to bend that I-beam nearly an inch forward in the distance between the radius arm bolt and the kingpin, that can't be more than 6 inches or so (just guessing). Ouch.

 

Yeah, and I'm the other 'exception to that rule'. I wound up with a bow-legged truck by using the '78 I beams on my '65, because they had a different curvature vertically from the pivot out to the wheels, on both sides. A huge difference, and not from any accident damage. So my conclusion is that not all trucks are equal donors, though 98% of them are.
Have any junkyards near you with older Ford trucks? I'd take my tape measure and at least do some research. See if you can find any that are different from what you have. If they are all the same as yours, more head scratching is required. If there are variances, then you need a match. Though it is extremely puzzling why one side would be different than the other.

 

If you are measuring fitment from anywhere on the cab, that could acount for differences from side to side. I also use the forged radius arms (like the look). Is it possible the the pivot bushing is installed improperly? I would not take measuremnents from the brake rotor. I'd go from the end of the axle to the center of the king pin hole and from there to the center of the pivot bushing hole. Bending these I-Beams is/was common to correct for accident and other alignment problems. Finding a shop with the tools and capability to do this work today may be difficult.

 

no measurements have been made with reference to the cab, only referencing between individual 66 and 74 parts. Last night I swapped the original 66 I beam and hub onto the passenger side(remember I'm still sing the 66 radius arm), and it still sits too far forward. Before the swapping any parts it was ok, but then the radius arm bushings were severely deteriorated, with the new bushings propery installed, the extra thickness of the new rubber has pushed everything forward. The way its looking I have 3 options, 1)move the radius arm bracket rearward roughly an inch, 2) move the inboard I-beam pivot bracket forward(which should rotate the hub rearward), or 3) have one of the stamped '74 radius arms shortened by nearly an inch. The axles and radius arms share all the same dimensions, and a visual inspection shows the 74 axles to not be damaged (especially to the extent of misfitment). I'm gonna do more measuring before I decide what to do. Apparently whatever is wrong with it, has been wrong for quite some time, it just wasn't a problem because the radius arm bushing was so mashed up, because even the original '66 parts don't fit now.

 

This is weird!
Okay, how about this...is it possible one side of the frame may be bent, shortening it? There should be points you can measure it, either holes that are the same on both sides or crossmember bolts, etc. Measure it front to rear and also diagonally for square. Since the bumpers bolt right to the frame, it doesn't take much to knock these things out of square. There really isn't any reason you should have to move any of the mounting points for the suspension.