I have just bought some new A65 crankcase studs. On tightening one stripped with virtually no effort. What grade material should they be made from? I suspect the ones I bought were very soft mild steel.
Any thoughts?
normal fastners would be mild steel, some situations demand a higher tensile steel.
many chose to change chrome plated mild steel for stainless steel on engine cases. Stainless is a harder material and can strip threads in cases, the disadvantage with stainless is it cant be used in high shear applications as it can shear as opposed to bend.
I did have a mx based road bike that someone had fitted aluminium bolts into the rear sprocket. they sheared (7 out of 8) and had to call the AA in to recover.
as for yours , I would question the supplier. I would only expect the thread to strip if wrong pitch or nut used or the stud had been gunned down. In which case I would have thought the casing threads would strip first being alluminium.
just thinking after posting, I suppose if someone picked up some wrought steel it could be softer otherwise steel supplied from China!
Hi,
I know from 1968 they were EN15, stepped stud EN14B. From 1971 both were EN16.
If using the steel I would use the EN16 which is the top of the medium carbon grade. However, I used stainless extended studs to use a thicker washer with a 1 1/2 thickness nut to ensure best fixing. To do this I had to power file a section of the lower cylinder fin for clearance.
Best wishes..
the thing to remember is that, in the eyes of some manufacturers steel is steel, aluminium is ally and brass is brass.
look through the British Standards Materials handbook there are hundreds of different grades and strengths and mixturers for materials .
today, there are not as many foundries, rolling mills etc to make the different grades. A back street machine shop or 50p wonder on ebay wont have all the stock bar to make the different grades. My stock is running low and wont be buying any more especially as suppliers like Woodbery want minimum orders.
As an example, at work we had a requirement for a component, min order was 1 metre for a 20mm component. a year later we had to order more, each time we bought a metre. in the end we didnt buy 3 metres,, we bought 9 metres BUT presumably it all came from the original 3m bar.
Brass, Muntz, bronze, phosphor bronze all acceptable for bushing but only the phos has the best oil retaining ability.
people order stainless steel case screws instead of chrome nickle plated mild steel, but I know some stainless actually rusts and reacts with water and aluminium cases.