Straighten A Bent 9" Ford Rear End Housing:

All differentials will have some play. Some more than others. By the time that play is transmitted to the end of the axle, it can be quite large.

A 28" axle shaft (end to bearing), moved just 0.5º, will be 0.24" off at the bearing location.

Also, depending on the width of the bearing/depth of the bearing recess, you might end up with very little spline in the side gear, making accuracy even lower.

 

Gimp....isn't the goal to get the axle/bearing to slide smoothly into the housing? I'd think if it did, that would be close enough.

 

It might actually be, but remember, any offset in the axle will cause wear on the splines, and the side gears/internals of the differential.

Will that make a meaningful difference over the long-haul? Very hard to say.

If you have to rebuild your differential at 100,000 miles, instead of 180,000+ miles, will that be a big deal? Most likely not.

It all depends on how far exactly it is off. Remember, round-round guys often have camber built into the rear axle, so they are intentionally misaligned. That said, they do have axle splines built for that.

 

Rocky, I watched that video in the other thread, that procedure was probably " close enough" for him and his "customers" lucky for him there is some fudge factor due to the axle spline to side gear fit and granted, this same procedure is standard in some circles but everyone has different standards.
The problem is the original engineered centerline is completely disregarded.
I built my narrowing setup many years ago (have since sold it), my goal was to have each end "looking at each other", not only that; I wanted it all to be registered off the "true" centerline of the third member.
I machined the steel end slugs for both bearing diameters and for the alignment bar I used 1&1/2" (4340 if I remember correctly) t.g.and p. that means turned ground and polished to 1.500 diameter with .005 clearance on the slug bores.
This all registered off a gutted third member with brass sleeves in the bearing saddles with the caps lightly tightened to support the shaft as if Ford might have designed it.
Did it need to be that fussy? probably not but that's a burden a machinist bears, never did see a tolerance of "close enough" in the Machinerys Handbook.

 

That is how I have seen the guys who do it right do it Denny. There is a machine shop about 15 miles west of me that is set up to do it that way that will get mine.

 

That's how I do them. Pucks in both ends, both carrier bearing positions, gasket in-place on drop-out center sections, and banjo's. For banjos, I have a motorcycle coil-over spring, that I use to keep the carrier pucks in-place, since they don't clamp in.

I have done everything from a Ford 7.5 to a full-float Dana S135, and everything in-between.

 

Great thread. I used the heat and water treatment to straighten my Olds rear end after welding on the mounts for the transverse spring for my 34 Ford truck back in 1960. I got the idea from a body man who told me that anything is possible with heat and a little patience.
I have also used this same technique to straighten driveshaft ends that were slightly out of true.
Bob

 

I don't have a 9", but I do have a GM truck 12 bolt that I need to get spring pads put on. Should I be concerned of the heat and potential warpage when those are welded on?

 

Yes, and even more so due to the outer bearing design of the 12 bolt (10 bolt too).
It kind of depends on whether any narrowing is involved (or how much), and the type and location of any bracketry welded on the axle tubes, I had Dutchman narrow my 66 Suburbans' rearend housing twelve inches, I also replaced all the oem bracketry with coilover, four bar and panhard bar mounts.