[DeTomaso] Stainless steel hardware and aluminum complications

[Charles Engles]

Dear Ken,

 

            Your comment about using stainless steel studs and hardware on
the ZF, reminded me of a lesson I learned from another Pantera owner and a
very experienced Ford Motorsports and Rousch Industries engineer.   After my
friend's Pantera began making troubling noises, it was determined that the
culprit was the aluminum crank pulley secured with stainless steel bolts.
Ultimately, it required major mechanical efforts to remove the cold-welded
stainless steel-aluminum from the balancer.   The pro told me to never use
stainless steel in aluminum because of the tendency to galling and worst
case scenario---cold welding.   I had *no* idea.

 

           Just yesterday I was working on a Windsor engine with an aluminum
intake manifold.  My brother told me that on its previous iteration, the
front nose (?) piece on the intake manifold coolant snout was very
problematic to get watertight.   Short story: I found that the two
*stainless steel* bolts did not completely thread down.  Each was blocked at
a different depth.   A thread chaser was a big improvement, but I re-tapped
both and finally got both bolts to seat properly.  Then, it dawned on me
that the snout-intake had been assembled, at least, two or three times
before I got it.   The problem was the stainless steel bolts galling the
bolts holes.  I also replaced the SS bolts with common steel bolts.

 

          In addition to the SS-aluminum galling propensity, there is also a
potential for electrolytic reaction of SS-alum to produce "tea staining" of
the *stainless*steel fasteners.

 

          Information links:

 

              Galling:
https://www.pencomsf.com/articles-updates/galling-of-stainless-steel-fastene
rs/

 

              Staining:
https://www.marshfasteners.com/can-stainless-steel-and-aluminum-be-used-toge
ther/#:~:text=When%20using%20stainless%20steel%20fasteners,also%20called%20'
tea%20staining'.

 

 

                      Metallurgically yours,  Chuck Engles 

                     

-------------- next part --------------
   Dear Ken,


               Your comment about using stainless steel studs and hardware
   on the ZF, reminded me of a lesson I learned from another Pantera owner
   and a very experienced Ford Motorsports and Rousch Industries
   engineer.   After my friend's Pantera began making troubling noises, it
   was determined that the culprit was the aluminum crank pulley secured
   with stainless steel bolts.  Ultimately, it required major mechanical
   efforts to remove the cold-welded stainless steel-aluminum from the
   balancer.   The pro told me to never use stainless steel in aluminum
   because of the tendency to galling and worst case scenario---cold
   welding.   I had *no* idea.


              Just yesterday I was working on a Windsor engine with an
   aluminum intake manifold.  My brother told me that on its previous
   iteration, the front nose (?) piece on the intake manifold coolant
   snout was very problematic to get watertight.   Short story: I found
   that the two *stainless steel* bolts did not completely thread down.
   Each was blocked at a different depth.   A thread chaser was a big
   improvement, but I re-tapped both and finally got both bolts to seat
   properly.  Then, it dawned on me that the snout-intake had been
   assembled, at least, two or three times before I got it.   The problem
   was the stainless steel bolts galling the bolts holes.  I also replaced
   the SS bolts with common steel bolts.


             In addition to the SS-aluminum galling propensity, there is
   also a potential for electrolytic reaction of SS-alum to produce "tea
   staining" of the *stainless*steel fasteners.


             Information links:


                 Galling:
   [1]https://www.pencomsf.com/articles-updates/galling-of-stainless-steel
   -fasteners/


                 Staining:
   [2]https://www.marshfasteners.com/can-stainless-steel-and-aluminum-be-u
   sed-together/#:~:text=When%20using%20stainless%20steel%20fasteners,also
   %20called%20'tea%20staining'.



                         Metallurgically yours,  Chuck Engles

References

   1. https://www.pencomsf.com/articles-updates/galling-of-stainless-steel-fasteners/
   2. https://www.marshfasteners.com/can-stainless-steel-and-aluminum-be-used-together/#:~:text=When%20using%20stainless%20steel%20fasteners,also%20called%20'tea%20staining