Aluminum nuts & bolts for replacing the OEM ones.

[greenpigs]

Try and not laugh too loud OK!

  Like most everyone my car has fasteners that are 40+ years old & instead of getting repo or cleaning the crappy old ones up I think I will swap some out for aluminum. Now of course if it is a suspension piece or a high stress area on the motor I will keep the steel bolts. Anyone have any tips on what you think is safe to replace?    
 

[daveco]

Not very many, maybe screws for plastic trim. Even on aircraft you see very few aluminum bolts or screws. Loads of aluminum rivets, but not many threaded aluminum fasteners.

[Tilar]

I think inside trim would be the ONLY place I might even remotely consider using them. Aluminum corrodes and even though your old bolts are 40 years old they are still a lot stronger than new aluminum ones.

[b5blue]

Your begging for corrosion issues over time... How about stainless?

[bakerhillpins]

You would need to be very careful about not over torquing them as AL isn't very forgiving to being bent back. As stated above Galvanic corrosion.

[Old Moparz]

There is a reaction between aluminum & steel that takes place, but I forget what it's called. If you have contact between the two, they fuse together & it's just as bad as two pieces of steel rusting together. I had this happen on two later model cars with aluminum distributor housings where the caps were held down with steel screws. All the screws broke & had to be drilled out.  

[471_Magnum]

generally speaking, bad idea

[68X426]

I think inside trim would be the ONLY place I might even remotely consider using them. Aluminum corrodes and even though your old bolts are 40 years old they are still a lot stronger than new aluminum ones.

Stainless is the choice.

[BigBlockSam]

Stainless is the choice

[greenpigs]

I guess the best thing to do is forget this idea. I even had a class on metallurgy in college but forgot about the fusing thing, this happens when your a C student.

[bobs66440]

I guess the best thing to do is forget this idea. I even had a class on metallurgy in college but forgot about the fusing thing, this happens when your a C student.

It's called electrolysis and using aluminum is not recommended for this reason (not to mention the weakness).  I wouldn't use stainless for anything important as it has a strength rating about equal to grade 2. Very weak, but it's common for engine fasteners that don't require much torque and would be excellent for interior fasteners.

[bull]

I wouldn't use stainless for anything important as it has a strength rating about equal to grade 2. Very weak, but it's common for engine fasteners that don't require much torque and would be excellent for interior fasteners.

What about stainless nuts on steel zinc bolts?

[HPP]

If our doing it for weight concerns, why not titanium?

http://www.speedwaymotors.com/ProductSummary.aspx?free_text|3/4/2011%208:04:33%20AM=titanium+bolts&deptId=0

[greenpigs]

Not in the scope of my build as they are not cost effective for my wallet, aluminum would have been.

[bobs66440]

I wouldn't use stainless for anything important as it has a strength rating about equal to grade 2. Very weak, but it's common for engine fasteners that don't require much torque and would be excellent for interior fasteners.

What about stainless nuts on steel zinc bolts?

I don't know what the benefit would be, but I suppose it would work, though you would still be working with a weaker nut.

[Domino]

Warning! scientific content: To avoid galvanic corrosion due to dissimilar metals, stick with metals that are close together on the galvanic scale (just google it if you care) and strong enough for your application.  The further up the scale will corrode metals further down and the further apart they are the worse it is.  You can see on the scale that SS is not too friendly to regular steel and even less friendly to zinc.  Luckily zinc forms a layer of zinc oxide that insulates the metal and slows the reaction.  What you'd see with stainless bolts and zinc plated nuts together is a build up of white chalky substance on the zinc, similar to corroded battery terminals.

some ideas:
up size your fasteners if you feel the SS is too weak.
apply anti-seize to prevent future disassembly issues.
insulate dissimilar metals with non conductive materials or coatings
get a small parts blaster and clean up your factory bolts.

[bull]

Okay. Thanks for the info.