[DeTomaso] Steering rack follies (and a warning...)

[MikeLDrew at aol.com]

All,

As you know, Lori and I rebuild Pantera steering racks just for the fun of 
it.   She's done about a dozen now (with me) and I've done something like 
130-140 or thereabouts?   I lost count years ago.

Lately, I've had a couple of very scary racks pass through my hands and 
thought I should share what I've been seeing.

The fundamental problem Pantera racks have is that the passenger-side 
support bushing falls apart.   It's a stamped tin cup with a plastic insert, and 
over the years that insert simply falls apart.   Rebuilding the rack becomes 
necessary when the bushing is worn to the point where there is visible 
unwanted movement on the passenger side, accompanied by audible clunking when 
going over bumps such as railroad tracks.

Broadly, there are two philosophies regarding the style of replacement 
bushing to be used.   Some vendors sell a bushing that is designed to replace 
the stock one, while others sell a bushing that is designed to be inserted 
alongside the stock one, augmenting it.

(I'll skip for the moment the plastic bushings sold by some vendors; they 
are simply laughable, and quickly fail.   I'm only concerning myself with the 
widely used brass replacement bushings).

For those who haven't peered inside their steering racks, allow me to try 
to describe the situation inside.   The aluminum rack housing has a certain 
inside diameter until about three inches in.   Then, there is a very slight 
shoulder, and the inside diameter becomes ever so slightly smaller.   The 
stock bushing is located inside this smaller diameter region, and is a firm 
press fit.   It is further retained with a pointed sheetmetal screw inserted 
into a hole in the side of the steel bushing cup.

The replacement bushings (which I get from Hall Pantera, or Precision 
Proformance) are designed to have nominally the same diameter as the stock 
bushing--1.2025 inches.   The augmentation bushings (which come from Pantera 
Performance Center) are slightly larger, at 1.2165 inches, enabling them to be a 
press fit in the larger, outer portion of the tube.

Here is the scary part.   Somebody is making bushings that are only 1.1965 
inches, which might be a lighter press fit in the smaller region, or even a 
slip fit.   I have now encountered two racks, one of which had been 
*professionally* rebuilt fairly recently, where these smaller bushings were being 
used in the larger portion of the tube.   Not only were they not a press fit, 
they weren't even a slip fit--they were rattling loose inside the housing!   
Whoever rebuilt them didn't understand that they were supposed to be 
replacing, rather than augmenting the stock bushing.   The new bushing was simply 
slid into position, and then nominally retained with a flat-tip allen-head 
set screw.

The problem is, this set screw wasn't retaining anything at all.   The 
bushing is supposed to be retained primarily by the friction of the press fit, 
and the set screw simply gives peace of mind.   In these two cases, 100% of 
the responsibility for retaining the bushing in place rested with the set 
screw, which was simply not up to the job.

When I opened up the rack the other day, the bushing was rattling around 
loose inside the boot!   (See attached).   You can see the stock set screw, 
and just to the right of it, an Allen set screw.   The set screw wasn't 
protruding inside the housing, which suggests that it broke off or was worn off.   
My finger points to a slight indentation in the bushing where there may or 
may not be remnants of the set screw.   

This rack was extremely worn-out (that is, the stock bushing was totally 
shot).   When the brass bushing happened to find its way into the tube, the 
situation was improved, but when it would fall out, the rack would only be 
supported by the stock bushing again.   Apparently this bushing would routinely 
travel into and out of the tube as the driver went down the road and turned 
the wheel to the left and right.   What's even more frightening is the fact 
that the rattling-loose bushing could, possibly, fall out of the end of the 
tube, and then be trapped between the end of the tube and the inner edge of 
the tie rod, which would restrict the wheels from turning to the left!

I have no idea who had rebuilt this rack; the owner of the car just 
purchased it recently and it came to him like that.   I know that some Pantera 
vendors continue to rebuild racks themselves, while others contract the work out 
to various specialists who may or may not know what they are doing.   
(Years ago, while performing tech at the track event, I discovered a 
vendor-supplied rebuilt rack where the person doing the work forgot to secure the tie 
rod to the rack; in just a few miles it had unthreaded itself and was 
literally hanging on by only a single thread!   I pulled the boot back to examine 
it, turned it by hand and the tie rod came off the rack completely!)

Whether this particular rack I had in my hands yesterday was sourced from a 
Pantera vendor, or a local mechanic had done the job, is beyond knowing.

We could have taken the rack apart and repurposed the bushing that had 
fallen out of it, and repositioned it to replace the stock bushing, and it 
probably would have worked reasonably well.   But since I had a supply of the 
slightly larger Hall-type bushings on hand, we elected to just stick with what 
we know.   The old stock bushing was removed, the new one was inserted, a 
hole drilled completely through the side for the set screw to engage, and then 
the pointed (stock) set screw was installed and secured with Loc-tite.   It 
ain't going nowhere now.

I should further mention that this rack came to me with spiffy new boots 
secured with band clamps that needed to be cut off to be removed.   The boots 
were non-standard, quite a bit longer than stock, and just about every drop 
of oil had leaked out of the rack long ago.   Some people persist in using 
gear oil in this application, as was done when they were made 40 years ago, 
but the current production (new) racks all come with special moly grease (NOT 
axle bearing grease, which is far too thick) instead of oil, and that's 
what I use too.   (Coincidentally, I was chatting with Dennis and Adam Quella 
today and they said they use the same type of grease, and view using oil as a 
ridiculous thing to do in this day and age).

While arguably there is probably nothing wrong with using the augmentation 
style of bushing, it is critical that if you elect to go that route, that 
you install a bushing intended to be used as such.   Since some bushings are 
designed to replace the smaller, stock bushing, mistakenly using one of those 
to augment the stock bushing could potentially lead to catastrophe.   This 
new owner got lucky….

Mike
-------------- next part --------------
   All,
   As you know, Lori and I rebuild Pantera steering racks just for the fun
   of it.  She's done about a dozen now (with me) and I've done something
   like 130-140 or thereabouts?  I lost count years ago.
   Lately, I've had a couple of very scary racks pass through my hands and
   thought I should share what I've been seeing.
   The fundamental problem Pantera racks have is that the passenger-side
   support bushing falls apart.  It's a stamped tin cup with a plastic
   insert, and over the years that insert simply falls apart.  Rebuilding
   the rack becomes necessary when the bushing is worn to the point where
   there is visible unwanted movement on the passenger side, accompanied
   by audible clunking when going over bumps such as railroad tracks.
   Broadly, there are two philosophies regarding the style of replacement
   bushing to be used.  Some vendors sell a bushing that is designed to
   replace the stock one, while others sell a bushing that is designed to
   be inserted alongside the stock one, augmenting it.
   (I'll skip for the moment the plastic bushings sold by some vendors;
   they are simply laughable, and quickly fail.  I'm only concerning
   myself with the widely used brass replacement bushings).
   For those who haven't peered inside their steering racks, allow me to
   try to describe the situation inside.  The aluminum rack housing has a
   certain inside diameter until about three inches in.  Then, there is a
   very slight shoulder, and the inside diameter becomes ever so slightly
   smaller.  The stock bushing is located inside this smaller diameter
   region, and is a firm press fit.  It is further retained with a pointed
   sheetmetal screw inserted into a hole in the side of the steel bushing
   cup.
   The replacement bushings (which I get from Hall Pantera, or Precision
   Proformance) are designed to have nominally the same diameter as the
   stock bushing--1.2025 inches.  The augmentation bushings (which come
   from Pantera Performance Center) are slightly larger, at 1.2165 inches,
   enabling them to be a press fit in the larger, outer portion of the
   tube.
   Here is the scary part.  Somebody is making bushings that are only
   1.1965 inches, which might be a lighter press fit in the smaller
   region, or even a slip fit.  I have now encountered two racks, one of
   which had been *professionally* rebuilt fairly recently, where these
   smaller bushings were being used in the larger portion of the tube.
   Not only were they not a press fit, they weren't even a slip fit--they
   were rattling loose inside the housing!  Whoever rebuilt them didn't
   understand that they were supposed to be replacing, rather than
   augmenting the stock bushing.  The new bushing was simply slid into
   position, and then nominally retained with a flat-tip allen-head set
   screw.
   The problem is, this set screw wasn't retaining anything at all.  The
   bushing is supposed to be retained primarily by the friction of the
   press fit, and the set screw simply gives peace of mind.  In these two
   cases, 100% of the responsibility for retaining the bushing in place
   rested with the set screw, which was simply not up to the job.
   When I opened up the rack the other day, the bushing was rattling
   around loose inside the boot!  (See attached).  You can see the stock
   set screw, and just to the right of it, an Allen set screw.  The set
   screw wasn't protruding inside the housing, which suggests that it
   broke off or was worn off.  My finger points to a slight indentation in
   the bushing where there may or may not be remnants of the set screw.
   This rack was extremely worn-out (that is, the stock bushing was
   totally shot).  When the brass bushing happened to find its way into
   the tube, the situation was improved, but when it would fall out, the
   rack would only be supported by the stock bushing again.  Apparently
   this bushing would routinely travel into and out of the tube as the
   driver went down the road and turned the wheel to the left and right.
   What's even more frightening is the fact that the rattling-loose
   bushing could, possibly, fall out of the end of the tube, and then be
   trapped between the end of the tube and the inner edge of the tie rod,
   which would restrict the wheels from turning to the left!
   I have no idea who had rebuilt this rack; the owner of the car just
   purchased it recently and it came to him like that.  I know that some
   Pantera vendors continue to rebuild racks themselves, while others
   contract the work out to various specialists who may or may not know
   what they are doing.  (Years ago, while performing tech at the track
   event, I discovered a vendor-supplied rebuilt rack where the person
   doing the work forgot to secure the tie rod to the rack; in just a few
   miles it had unthreaded itself and was literally hanging on by only a
   single thread!  I pulled the boot back to examine it, turned it by hand
   and the tie rod came off the rack completely!)
   Whether this particular rack I had in my hands yesterday was sourced
   from a Pantera vendor, or a local mechanic had done the job, is beyond
   knowing.
   We could have taken the rack apart and repurposed the bushing that had
   fallen out of it, and repositioned it to replace the stock bushing, and
   it probably would have worked reasonably well.  But since I had a
   supply of the slightly larger Hall-type bushings on hand, we elected to
   just stick with what we know.  The old stock bushing was removed, the
   new one was inserted, a hole drilled completely through the side for
   the set screw to engage, and then the pointed (stock) set screw was
   installed and secured with Loc-tite.  It ain't going nowhere now.
   I should further mention that this rack came to me with spiffy new
   boots secured with band clamps that needed to be cut off to be
   removed.  The boots were non-standard, quite a bit longer than stock,
   and just about every drop of oil had leaked out of the rack long ago.
   Some people persist in using gear oil in this application, as was done
   when they were made 40 years ago, but the current production (new)
   racks all come with special moly grease (NOT axle bearing grease, which
   is far too thick) instead of oil, and that's what I use too.
   (Coincidentally, I was chatting with Dennis and Adam Quella today and
   they said they use the same type of grease, and view using oil as a
   ridiculous thing to do in this day and age).
   While arguably there is probably nothing wrong with using the
   augmentation style of bushing, it is critical that if you elect to go
   that route, that you install a bushing intended to be used as such.
   Since some bushings are designed to replace the smaller, stock bushing,
   mistakenly using one of those to augment the stock bushing could
   potentially lead to catastrophe.  This new owner got luckya|.
   Mike
-------------- next part --------------
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