Joined: Jun 2018 Posts: 527 Threads: 91
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The pins on my front spring shackles are worn beyond redemption. I plan to make some replacement pins , but wonder what grade of steel would be best. I was considering case hardening some silver steel, but would welcome advice.
Regards,
Jamie.
Joined: Aug 2017 Posts: 32 Threads: 4
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Jamie,
The short answer: I wouldn't even think about making them, why would you when they are readily available from the Seven Workshop. By the time you made them and heat treated them they would cost you way more. From memory they are about £60 an axle set. Not worth the time hassle and risk of getting it wrong.
The longer answer: Spring pins like that can be safely made using EN24T to run in phosphor bronze bushes. It has the advantage of being machinable with a decent lathe. The problem is that the spring shackle isn't a simple pin.
Do not think about using silver steel for this application, it is often not a brilliantly controlled material with batch variance, and not to be used for safety critical applications. The heat treatment also adds to a degree of uncertainty adding to risk. Although not high tech Austin Sevens were not "over engineered" so the room for error on materials is less than on some other vehicles.
Sorry if you know all of this. I just didn't want someone else to read the post and then go off and make bits in silver steel they have lying around and think everything will be OK.
Exact manufacturing process of the front shackles and pins, I could not tell you, but I would expect the suppliers to know if you really wanted to know. However there is no way you could make them for the cost that they do them for.
All the best
Tom
Joined: Aug 2017 Posts: 2,748 Threads: 31
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Location: Auckland, NZ
i guess can be made in a multi section style partly pressed together. Silver steel is through hardening not case hardening and very prone to cracking when quenched. It is sold in a medium hard state and would probably wear for years in modern well greased useage. Or with nylon bushes. Lester Reader notable NZ specvial builder and rubber duck owner used plain silver steel as kingpins in his Seven based special as less prone to fracture.
There are probably many moderately worn about which could be reground by the patient.
Joined: Aug 2017 Posts: 1,808 Threads: 99
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ive not made shackle replacement pins for a wile as suggested new shackles are available. or at least they usually are.
but when i made them they were in EN24T.
there are pitfalls though.
its a strong steel for getting a small grease hole that far down the shaft.
oversize the hole, and it weekens the shaft.
to much undercut for the thread, and it will weeken the shaft.
tony
Joined: Jun 2018 Posts: 527 Threads: 91
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Thank you for the replies, advice and suggestions, especially about the appropriate grade of steel to use. A set of replacement shackles is about £80.00 to £100, depending upon the supplier, although there are some duff used ones on e-bay for £38.99 each.... I shall have to think about what to do.
Regards,
Jamie.
Joined: Aug 2017 Posts: 3,448 Threads: 108
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Location: Darkest Bedfordshire
Perhaps one of our traders can sell you a better used pair Jamie.
Joined: Jun 2018 Posts: 527 Threads: 91
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Tony: I have sent you a PM.
Regards,
Jamie.