Stainless bolts into Steel, cast Iron and Aluminium Alloy?
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What are the true, accurate implications of the above scenarios?

I seem to hear different stories on the above, so if anyone can clarify each material in regard to mating with a stainless thread form I'd be appreciative :)

well...in theory you arent supposed to use stainless/Alu, as there will be electrolitic corrosion or some poo like that..

But in reality, most people use them anyway, and have no problems.

The only downside about stainless/stainless......sometimes the threads lock up for no reason.

I think stainless and other materials are ok though.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

" some poo like that" LOL!

I use stainless fasteners on my thermostat housing and can always remove it - a significant difference from when i ran standard studs...
Maybe its never in place for long enough to get electolytik'd up however?


I'm still interested in the 'book' theory however...

Edited by turbodave16v on 7th Sep, 2007.

well most outboard engines all use stainless into ally, the worst is brass into ally and steel into ally, but stainless into steel or cast is ok.

always looking for them bigger bunches of bannanas

i had to look into this for work a while ago. most office building use steel pipe for the heating system but some use copper and some galvanised steel. basically when copper and galvanised are used togother you get that electrolitik crap happening, in that the galvanised pipe gets eaten away.

the solution for the plumbing world is DZT couplers, these have some sacrificial thing going on.

if you look deeper into things it all depends on the metals. apparenty Ally is a one end of the scale with copper below it and at the other end of the scale is zinc and galvanised steel. materials at either end of the scale have the largest reactions so something middle of the road like steel against ally is not so bad.

the reaction also depends on enviroment (wet is not good) and the two need to touch (so sealant and gaskets stop/reduce the reaction)

my conclusion

unless your planning to build a submarine out of galvanised steel and ally, dont worry about it.

Stainless will not cause electrolysis corrosion, steel and alloy touching eachother will

Paul

I seriously doubt it!

We have stainless screws going into aluminium at work. Where our equipment is hottest threads tend to bind up (this is normally over a few years). If you use plenty of never-seaze on assembly there never seems a problem!

I think when theres heat involved, especially alot of heating and cooling this causes the aluminium to 'creep' which kind of amplifies the whole reaction.

Saying that im going to be using stainless bolts on my ally back plate so bollox to it...lol

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1/4mile in 13.2sec @ 111 terminal on 15psi

worked with them for years in all metals and no problems whatsoever dave

just use say copper slip as well is bad enviroments

only thing that are not so strong as say an 8.8 steel fastner

for max strength! situations they are not advisable

"Turbo's make torque, and torque makes fun"

"did you know you can toast potato waffles?"

can't give a full answer Dave

but certainly stainless bolted into steel will result in corrosion, this is by electrolitic process that has already been mentioned, from memory the stainless pulls any chromium from the steel making it more prone to oxidising

i think the alloy situation is that it would oxidise regardless, although some metals would react alter the corrosion process

there are some good products out there to prevent the corrosion on thread forms

I've heard that Copaslip is a big nono in aluminium. Can anyone confirm this?

I heard the same Vegard,

but I also heard from the same source that copper tubing should not be used in the cooling system of an imp due to the ally head/block.....

what about the copper rad though? lol

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

We always use a nickle based anti-seaze compound on aluminium.

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1/4mile in 13.2sec @ 111 terminal on 15psi

With Matty on that .... Moly grease also seems to help, no idea why!

Every day is a school day ...........

How fast and how expensive ...... the same question...

Hi,
Moly Grease used to be supplied with head gasket sets on Citroens as the use ali blocks...
Cheers,
Gavin :)

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Yup, copper slip is banned on our stuff.

we use a graphite based anti-seize, a rocol one. seems to do the trick most of the time.