Stainless Steel

[steve.n]

Anyone know of any conflicts between stainless and aluminium ie using stainless bolts for steering pump bracket, lifting eyes, carb elbows etc

Steve

[marshman]

Not recommended in a marine environment. The two metals are quite a long way apart on the "nobility" table. But to be honest in the "dry" confines of your engine bay it will probably be OK .

see this extract from t'interweb:

https://www.bssa.org.uk/topics.php?article=89

Corrosion risks with aluminium and stainless steel in contact

Aluminium and stainless steel together also appears to be a bi-metallic corrosion risk, from the 'nobility' table.
With this combination the affect of relative surface area on corrosion is important.

A large area of 'cathode' relative to 'anode' will accelerate the anodic corrosion. Although aluminium is anodic to stainless steel, large relative surface areas of aluminium to stainless steel can be acceptable, dependant on local conditions.
Stainless steel fasteners in aluminium plates or sheets are normally considered safe, whereas aluminium rivets or bolts holding stainless steel parts together is an unwise combination, as there is a practical risk of corrosion.

An example of the safe use of stainless steel and aluminium together is where stainless steel fasteners and hold down bolts are used to secure aluminium roadway or bridge parapet guards.
Even with no insulation between the metals, there should be little risk of corrosion.

In contrast, in a marine environment, severe localised pitting corrosion to the aluminium treads has been observed where un-insulated stainless steel bolts were used to secure the treads in place.
On the same ladder however, bolts with sound insulating washers did not show any pitting on the surrounding aluminium.

This illustrates the beneficial effect of breaking the corrosion cell by isolating the two 'dissimilar' metals in marginal cases.

[steve.n]

thanks for the info marshman
Steve

[Phil S]

l used stainless bolts and fixings on my last kit car..all was still good after 10 years as l always used a grease on assembly.
Phil

[mjheathcote]

I've used stainless steel fasteners throughout my rebuild, including the aluminium heads, no problem 25+ years and counting!