Is there anything wrong with using stainless steel fasteners?

[Kroggers]

I am in the process of reconditioning and replacing a lot of parts on the car (winter project), including front suspension, bumpers etc. A lot of the nuts and bolts that I have removed from the car are rather rusted, and I was considering replacing most of them with ss fasteners - they do not rust, but I know they are not as strong as other materials. What is the general consensus on using ss attachments on our cars??

[FLATTOP]

Paul

Rather than going for Stainless Steel fasteners I would suggest either Nickel Plated or Zinc Coated bolts. If I am not mistaken you retain the strength of the steel bolts but have an added feature of being rust resistant. I have also found that the stainless bolts are not as dimensionally accurate as the steel ones.

I am going through the same process with my track car where all the factory bolts have been replaced by cap screws (black). Despite my stoutest efforts rust (oxidisation) eventually forms on protruding bolt heads. Hence the move to replace the bolts with zinc plated bolts.

Maybe a nut & bolt expert can cast more light.

Regards


Johan

[Kroggers]

Thank you for the info Johan, are plated bolts available from shops, or only special order??

[Chocaholic]

No expert here but...be very cautious about replacing suspension hardware with anything that does not meet the hardness and durability characteristics of the originals.

[Kroggers]

Originally posted by Chocaholic
No expert here but...be very cautious about replacing suspension hardware with anything that does not meet the hardness and durability characteristics of the originals.

I was more interested in replacing the fasteners for the bumpers, oil cooler, horn bracket etc - you know general stuff, rather than the core suspension hardware. For the suspension and other parts that my safety depends on I will only use original Porsche parts

But thank you for the warning

[RoninLB]

SS can be ok.. it depends

I wouldn't use SS on suspension though. SS is great for fan shroud strap, engine shroud nuts and side bolts, threaded rivet bolts, etc. I mostly use marine grade. Those I bought from McMaster were a lower quality but doable for the rivets.

[Kroggers]

So Ronin, would the ss stuff you can get in a bag on ebay be ok for the stuff I was talking about (bumpers, oil cooler, horn bracket etc) or not?
Or should I get the zinc plated stuff instead and forget about ss fixings on my 911

[RoninLB]

Originally posted by Kroggers
get in a bag on ebay be ok for the stuff I was talking about (bumpers, oil cooler, horn bracket etc) or not?

Or should I get the zinc plated stuff instead and forget about ss fixings on my 911

SS cheap grades may rust?

I'd say check out McMaster for your metric items as SS w/anti-seize is real nice to work with after many yrs. For instance I'd be nervous to disassemble rusty bolts from threaded rivets after it sitting around many years. Same goes for what you mentioned. It also stays hard so you won't be rounding off any bolts or nuts.

I also use them on head stud nuts and mufflers but that requires technique or they'll come loose.

did I say I live on a sandbar, 1,000' from the ocean and 200' from a large channel?

[Kroggers]

Great, thank you Ronin, then I will order in some general ss fasteners and not bother with the zinc plated stuff

[oneblueyedog]

The main problem I'm having with SSteel is that the bolts loosen over time and I can't fish them out with a magnet. I'm using them for the engine sheetmetal. I think the heat cycling of the engine does this. When I drop the engine, I'm going back to ferrous.

[RoninLB]

Originally posted by oneblueyedog

bolts loosen over time

I think the heat cycling of the engine does this.

what I do is re-torque clockwise only after a few heat cycles.. then again after many cycles for exhaust and other heat cycling areas.

they never come loose after that.

[oldE]

One more thing to be cautious of: If you live in a corrosive environment, perhaps with salt on the roads in winter, there will be galvanic action where dissimilar metals are in contact. If you are using plated fasteners, the plating usually corrodes first. If your fasteners are stainless, there is a good chance whatever mild steel parts they are holding together will be the first to go.

Les

[jcwolff]

I wouldn't use stainless fasteners on any exhaust or engine part. Besides not having the same characteristics as mentioned above, stainless fasteners tend to gall when they get hot and overtightened.

Thread galling is most prevalent with fasteners that are made of Stainless Steel, Titanium and other alloys which self-generate an oxide surface film for corrosion resistance.

Thread galling is also referred to as “Cold Welding” as during fastener tightening, pressure builds between the contacting thread surfaces and protective oxides are broken. The interface metal high points then shear or lock together. This cumulative clogging action causes additional adhesion and increases the severity of the galling.

In extreme cases the galling effect leads to complete thread seizing and if tightening is continued the fastener can be twisted off or its thread stripped.

To help reduce the amount of galling produced, slowing down the RPM of screw tools will frequently reduce and in some cases solve the problem completely. As the screw tool RPM increases, the heat generated during tightening increases. As the speed and inevitably the heat increases so does the tendency for the occurrence of thread galling.

Lubricating the internal and/or external threads frequently eliminates thread galling. The proposed lubricant should contain substantial amounts of Molybdenum disulfide (Moly), graphite, mica or talc. Some proprietary, extreme pressure waxes may also be effective. Lubricants can be applied at the point of assembly or pre-applied as a batch process similar to plating. Several chemical companies offer anti-galling lubricants.

[David]

If you're having corrosion problems and switch to stainless bolts the corrosion on the non-stainless parts will increase.

[Gunter]

Good stuff mentioned here, especially the lube-stuff.
For the non-essential fasteners, SS is o.k. with lube.
I use Moly-graphite anti-seize on pretty well all of the nuts and bolts, SS and steel.

[fastpat]

What the others have said here, plus, stainless will "cold weld" itself together in a high vibration environment. So anything threaded stainless on stainless must be put together with anti-seize compound, as should anything put into aluminum.

The best are yellow zinc plated, or cadmium plated. Second best is silver zinc plating, no third best coating. Also, you never want a lower strength piece of fastener hardware, unless it's strictly decorative, and I'd be careful there.

[RoninLB]

fwiw.. I have been using SS successfully in my act for over 40yrs.

and with all due respect.

[Cordts]

I have rebuilt many british cars and use SS & grade 8 alot.. no problems with the SS.. SS for show Grade 8 for strength

[Wil Ferch]

Grade 8 ( or 5, whatever)...does not compute and does not apply to metric fasteners. There is no "grade" for metric...only "property class".

Reference...US Grade 5 ~ property class 8.8

- Wil

[Cordts]

Will .. I was simply saying that have used 8's for the British work that we have done and also used SS extensively,, with no negative's.. there is another stronger value.. 10. something.. available here in NC on special order..