Stainless steel swaps

Post by **irish.david** » 02 Sep 2007, 22:56

I'm currently pulling my 2.1DJ apart for a bit of an overhaul and have spent the day going mano a mano with every sort of rusted up screw,bolt and nut that VW has to offer. Instead of putting back a selection of regular steel fittings that'll just go crumbly again i was thinking of replacing most of the bolts and nuts with their stainless steel equivalents. I recently got a load of stainless stuff as a job lot on ebay so parts are not a problem.

Can anyone think of any reason not to use stainless bits? My knowledge of metals is a bit rusty (har har) but i have a feeling that stainless doesn't have the tensile strength of the regular stuff and i'm also worried about the reaction between the different metals stainless stuff and the block into which they're screwed. Has anyone else tried this?

Dave

Post by **VWCamperfan** » 03 Sep 2007, 10:10

Morning!
Right, stainless is an alloy but due to the low carbon content, stainless steel can not be hardened. Therefore when compared with regular steel it is stronger than mild steel fastener but weaker than hardened steel.
As for the reaction with other metals, this can happen but if used with an anti-binding lubricant eg. copperease grease, then these problems shouldnt occur.

Post by **irish.david** » 03 Sep 2007, 10:33

Cheers,

Sounds like stainless will be ok for fastening things down but a no-no for anything that uses a compressible gasket or needs torquing.

Dave

Post by **toomanytoys** » 03 Sep 2007, 10:37

You cant use ordinary nuts for the head studs.. but I cant see anything else that would cause a problem Although exhaust studs might not work too well...

Use plenty of copperslip and lock washers

Post by **trickydicky** » 04 Sep 2007, 15:37

They can be prone to snapping in high stress area's.

Post by **Ruby** » 04 Sep 2007, 18:50

SS has lower tensile strength than high tensile fasteners so may be prone to shear in higher stress areas.

All materials have different coefficients of expansion so in high heat areas fasteners may work loose.

Dismaterials in contact can suffer from electrolytic corrosion, this should only be a real problem between SS and aluminium though.