Stainless Steel Fasteners

[phantom lunger]

Im currently in the middle of a winter rebuild on a Formula Ford. One thing I want to do is replace all of the nuts and bolts rather than get them all cleaned and re plated. I am considering using stainless steel fasteners as a replacement, due to the fact that they will not corrode. Are there any downsides to using SS rather than plated Mild Steel? i.e will it add much more weight?

Thanks

[ianpearson]

Stainless Steel bolts are weaker than high tensile bolts so not really recomended for areas under high stress i.e holding your suspension or roll hoop on. some areas would be fine

[GORDON STREETER]

Stainless steel is harder than mild steel but is not tactile (elastic)

[Dave Brand]

In non-critical applications, there's no problem. As you only intend using them where you're currently using MS, you'll be fine - as Ian says, don't use them where HT fasteners are required.

By the way, Gordon, the word you're looking for is 'ductile', not 'tactile'!

[SidewaysFeltham]

Thee is always a temptation to make race cars "Pretty".

Normally not a good move with critical bits!

I well remember a dear chum who was focused on making his Special Saloon look pretty: even to the extent of having all the brake pipes chrome plated.

It was exciting for both him and the spectators when they failed.................

HT steel fasteners whould at best be chemically dipped and no bright finish; it weakens the part.

In the late sixties many suspension failures, in particular wishbones, were attributed to the chrome plating: thereafter they were nickel plated only.

There are a range of treatments available to prevent corrosion, such as cadmium plating.

However, always be cautious and seek advice on how any finishing process can weaken mission-critical parts.

Always preferrable to have a straight dull car than an attractive bent car!

[GORDON STREETER]

Sorry Dave to many San Miguel's

[Leighton Irwin]

Back in the dark ages when I was an Atlantic crew chief we replaced all grade 5 bolts (automotive quality) with aircraft quality, grades 8 to 10. They are precision made and not likely to be either over or undersized. They are also stronger. All Indy cars used aircraft quality nuts and bolts and yes I worked on Indy cars too.
If you buy from a aircraft supply house the cost is high but if you can find a military or aircraft surplus store they are quite reasonable. We used to pay by the pound! $500 or $600 worth of nuts and bolts would cost $30 to $40.

I would suggest that you read Carroll Smith's book 'Prepare to Win.' His series of books used to be the race mechanics' bible.
His method of setting brake bias is a trick I taught him. Mind you he taught me one heck of a lot more!

[djinvicta]

Sorry guys; Cant resist this thresd.
Having supplied Fasteners for 25 years, I can disagree with some bits here. HT Bolts are High Tensile or Grade 8.8. If Zinc plated they still retain all tensile strength. If Socket Screws with an Allen key head, only available in Grade 10 or Grade 12 strength, if zinced or chromed they become Grade 5. If, as they should be, dembrittled too in the process, they lose no tensile strength, and can still be used with confidence.
As is the saying; Ya only get what ya pay for!
There are people out there selling EU or Chinese fasteners with no tensile strength.
Buy from a reputable UK distributor, ask for certificates of conformity, and you will have no problem.
AND! Somone did produce me a cert for A2 stainless showing it had more tensile strength than HT bolts. Hmmmmmm. Not sure.
Stainless is produced for its stubborness to salt and all corrosive products, not for its strength in a ding.
All stainless fasteners will produce massive varieties in their tensile strength.
So; without giving out a phone number......
Look. Pete Thurston hit Paddock Bend armco at 120mph in a Mk1 Escort and lived! My fasteners survived too!

[GORDON STREETER]

My cousin worked as a "mechanic" (or whatever the posh name is) on airliners and used to supply me with nuts and bolts, that to my surprise were half the weight of the normal motor trade stuff that we are supplied with. I never had anything break or bend in years, but I would think they were pretty expensive !

[djinvicta]

Aviation spec is a totally different spec to every day fasteners, for obvious reasons!! We cannot sell them without a licence.

[Dave Brand]

Originally Posted by djinvicta

AND! Somone did produce me a cert for A2 stainless showing it had more tensile strength than HT bolts. Hmmmmmm. Not sure.

Tensile strength is only part of the equation - modulus of elasticity is equally, if not more, important in high-stress applications.

[tristancliffe]

Most bolts aren't installed with tension in mind anyway, but [double] shear, and I believe that Stainless is worse in this condition as well.

[phantom lunger]

Thanks for all your responses...Im really glad I asked the question now! I have definatley fell into the trap of making it look "pretty". I think I'll throw away that zinc plating kit I bought now...by the time I've finished trying to get a nice finish there will be no strength left in the bolts.

djinvicta,

You mention there are people selling inferior strength fasteners, would you say this also applies to Rod ends? I am planning to replace these too but I am overwhelmed by the choices out there. There is a company on a well known auction site selling rose joints for a very attractive price, but makes me wonder if they are any good compared to the likes of NMB etc?

[tristancliffe]

Again with rod ends, you get what you pay for. Cheap ones will fair or wear out (or even have play when new) far quicker than a more expensive one. Depending on how long you plan to run a certain car, lots of cheap ones might be better than a couple of expensive ones.

Personally, I prefer to go for middle-range items. Nor bargin-bin cheap, but not NASA quality either.

[djinvicta]

Since the demise of the UK manufacturing base, fasteners are now imported from India, Poland, China, and all other countries you care to choose. If buying any component, just ask for a Certificate of Conformity to any grade the distributor may state. Try and get one from Poland!

[Dave Brand]

Originally Posted by tristancliffe

Again with rod ends, you get what you pay for. Cheap ones will fair or wear out (or even have play when new) far quicker than a more expensive one.

I've seen a few single-seaters with suspension damage after impacts where the failure has been in a rod end - what looks like a brittle fracture in the body of the joint, not the joint itself. Not the sort of failure mode I'd expect from a good quality component. (Not a professional judgement, just the opinion of a marshal who happens to be an engineeer - or vice-versa!)