[DeTomaso] Uprights

[Will Kooiman]

Thanks to all.

Mine was taken apart several years ago, and all of the parts are still in
pretty good shape.  This was the story where it died just outside Little
Rock.  I had parts shipped to my brother's house, and then Mike Trusty
helped get me back on the road.

I like the aluminum conversion that Ken described.  I thought about going
that route, but I want to get my car back on the road.  I do not want to
spend the next 5-10 years upgrading everything.  I just want to do the
current thought using a relatively stock approach ­ i.e. ball bearings,
stock uprights, u-joints, etc.

I am sitting on the fence on using drilled shafts with zerks vs. zerks in
the uprights.  I have heard both arguments, and now I need to mull it over a
while.
--
Will

From:  Jack DeRyke <JDeRyke at aol.com>
Date:  Sunday, July 14, 2013 8:02 PM
To:  Will Kooiman <will.kooiman at gmail.com>, <detomaso at poca.com>
Subject:  Re: [DeTomaso] Uprights

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