high tensile stainless steel

[clogsParticipant @clogs]

Frank in France

Good morning, well it is. the sun's up and the bird's are singing…just has to goodstart to the day….

My question……I need to make some thru studding for a motor cycle engine, (I have only one for a sample) these thread into the cranck-case, thru the cylinder barrel's (4) and then hold the head down…..reason for stainless they are highly visual and u can't get cadmium done any more !!……so what would be the best grade to use…they are 250mm x 10mm long….also..This same engine, 1/2 of the big end nut's are missing…the same question as above but can I buy the hex bar the correct grade so I only have to thread and part it off ? where can it be bought ?….thread size 8mm x 0.75….

This engine has a max RPM of 4000, so it's a little important to get this one correct…

Well thanks in advance…..I find this a liitle embarrasing to keep asking question's, I hope one day I can help someone else……as alway's u guy's are a mind full of info…….what a great forum…..

thanks Frank

[clogsParticipant @clogs]

[GoCreateParticipant @gocreate]

Hi Frank

British spec 431S29T (En57T) is a high tensile Martensitic st st and easy enough to machine. Strength is similar to En24T alloy steel. I bought some from M-Machine a while ago.

Also ASTM 654-630 17/4 PH available in various grades is high strength but may be difficult to find in small sizes and qty.

I can't say for sure if these would have any issues with you application.

Nigel

[Bob Brown 1Participant @bobbrown1]

I can see some issues with using stainless steel for head studding.

The strength of 304/316 stainless steel is probably going to be lower than the original stud and it is susceptible to corrosion when used to fasten aluminium components.

The torque settings for a stainless stud/bolt is going to be different due to the different properties of the original material and stainless steel to get the same clamp load if indeed this can be obtained.

Both 304 and 316 grades of stainless steel are available in both round bar and hex bar, 304 is not too bad to machine but 316 can be tricky as it is prone to work hardening and you will need good quality taps and dies specific to stainless steel to get good clean threads particularly on 316.

Have you considered nickel plating?

[Bob YouldonParticipant @bobyouldon45599]

Good Morning Frank,

Why not use monel? strength wise would it would probably meet your requirements.

Regards,

Bob

[Involute CurveParticipant @involutecurve]

Stainless can setup an electrolytic reaction with Aluminium, do you know the original material spec, rate of expansion might be an issue, more info is required to give good advice, out of interest what engine are these for?

Shaun

[Russell EberhardtParticipant @russelleberhardt48058]

Head studs aren't so critical as they can easily be replaced. Big end bolts are a different matter. I would stick to EN24 as suggested above. It is worth making an extra one and tightening it in stages increasing the torque a little at a time releasing it and measuring the length with a mike. When you reach a torque that has permanently stretched it you can use about 10% under that figure for the others.

Russell.

[Tim StevensParticipant @timstevens64731]

Stainless fastenings have been used on motorcycles (and aeroplanes) with light alloy engines for over 60 years – both factory fit and rebuilds. First on the Vincent HRD, from memory. And I know of no serious corrosion difficulties. Many motorcycles – especially older ones that only rev to 4000 – tend to have oily surfaces, which helps, of course.

I would not recommend a home made big-end nut, never mind a bolt. They are the most highly stressed, and fatigue susceptible, parts of an engine. Modern big end bolts are usually rolled threads and sometimes ground, neither of which is easy on an old Myford.

Cheers, Tim

[ChrisHParticipant @chrish]

Stainless steel and aluminium can 'weld' together in the right situation, a sort of corrosion I think between the two, the two bits end up 'solid' anyway – ask anyone who has a boat with stainless fittings on an aluminium mast! You can buy from yacht chandlers some grunge in a tube to protect the bits in question, but best avoid the situation arising in the first place if at all possible.

Also, stainless can be brittle – hence you never hammer test it; hence, another point to bear in mind when in material selection mode.

Chris

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