[DeTomaso] Uprights

[JDeRyke at aol.com]

The main failure modes in the rear upright area are first- inadequate 
press-fit of the stock ball bearings on the stub axles. Desired interference is 
0.0005"-0.0009". Your billet axles should take care of that handily but you 
can check it with a 5-place 0-1.5" micrometer. Unfortunately, a normal 
4-place micrometer is not accurate enough. The second mode is seizure of the 
internal spacer to the long stud serving as a pivot for the lower a-arm. The 
seizure comes from condensation inside rusting the stock hardened-steel spacer 
to the gr-5 stud, both of which are particularly sensitive to moisture 
corrosion. Once seized, the only fix is to SAW the stud off at both ends, then use 
a hydraulic press on the center part. Otherwise you cannot remove the lower 
a-arm to further work on the stud & spacer. This is so common with 
normally-ungreased rear uprights, Hall sells a kit to replace the parts destroyed by 
sawing.
This problem is often addressed by adding copious grease inside the housing 
to both fill the void-volume, preventing too much condensation from 
forming, and also by keeping the spacer/stud lubed up so condensation doesn't 
attack the sensitive parts. The stock setup requires periodic hand-greasing of 
this area plus the bronze bushings at each end. No one does this. Gary Hall 
sells drilled studs with zerks that first delivers grease into the space 
between the stud and spacer. Then grease migrates end-wise into the pivot 
bushings at each end to keep them lubed as well. 
Drilling the upright for a zerk (or two) only fills the void volume, 
depending on the grease used to migrate to both the end bushings. Some grease 
probably also gets into the area between stud & spacer but it's a convoluted 
path, so not sure how effective this is at allowing grease where-all it needs 
to be. With drilled uprights, you really should also drill a hole or two in 
the hardened steel spacer so grease has a direct path in between stud & 
spacer. Use carbide drills and expect to break one or two. 
I liked Gary's rather elegant solution, so I run that, plus some added 
insurance by substituting custom 316-stainless steel lower spacers for stock 
hardened-steel ones. No failures that I'm aware of by using drilled studs. I 
use plastic covers on the zerk ends to keep road trash away.
As for the non-hardened mild steel spacer between the axle ball bearings, 
the inboard end floats- the inner bearing is located only by the spacer & 
nut-torque rather than by a machined step. The 350-500 ft-lb of torque 
currently used on axle nuts slightly collapses/shortens the spacers during 
installation, much like a Ford pinion sleeve in a 9" rearend. Also, when a loose-fit 
axle starts moving inside its bearings, the bearings begin fretting the 
spacer ends too. When you tore yours down, one or both these were probably why 
the ends of the bearing spacer were indented or chewed-looking. 
Most guys face this area flat; structurally, you could simply leave the 
spacer ends alone with no effect on how it works, as long as the nut torque 
used is high enough. And as long as the axle interference fit is tight enough 
so the bearings don't start moving & again fretting the axle AND   spacer. 
Excessive spacer-shortening will eventually cause the splined u-joint holder 
directly against the axle nut to bottom at the ends of the stub-axle splines, 
producing a loose assembly even with very high nut torque.   Good luck- J 
Deryke