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

[Carguy60]

Hi Mike,
Thanks for sharing this information.  The '74 I just bought came with a stack of receipts from "Panteras by Wilkinson" in Southern California. One of the receipts from 2005 lists a rebuilt steering rack.  The receipt does not show the mileage but based on other receipts around the same time I estimate the mileage at about 15,000 at the time.  The car now has about 24,000 miles.  When I was under the car I did notice the boots still look clean and new with no sign of leaking. 

The car tracks straight without any wondering and I haven't noticed any noise. Is there any way to tell if it was properly done aside from waiting to see if it fails?  I take it that the boots should be packed with grease rather than oil? 

I'm sorry to miss out on the Fun Rally this year. I'll try to plan for next year!

Dennis
7260


> On May 12, 2015, at 9:13 PM, Mike Drew via DeTomaso <detomaso at poca.com> wrote:
> 
>   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
> <Dangerous Bushing.JPG>
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