Lotus Elan

Elan S2 rear hub carrier outer a-arm bolts dimensions

PostPost by: DaveJ » Thu Jan 18, 2018 12:13 am

While working on my Elan S2's rear suspension, I noticed the previous owner used the wrong bolts to put it back together.

The area where the bolts go through the hub carriers are threaded and the threads are quite demolished. It seems they should have a longer unthreaded shank so that the hub material rests on that part and not the threaded bit.

Can anyone give me the proper length of the bolts and how much should be unthreaded?

I had to reassemble the rear suspension just to get the car going and don't have access to these dimensions but need to order the correct bolts to fix the problem.

The manual only says they are 7/16" with no other dimensions.

thanks, DaveJ
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PostPost by: alan.barker » Thu Jan 18, 2018 7:05 am

A "Bolt" has a plain unthreaded section.
A Screw or "Set Screw" is threaded the full length.
When you order i would suggest you make sure they are "HT" high tensile for the Suspension.
Alan
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PostPost by: oldelanman » Thu Jan 18, 2018 7:28 am

They are "special" bolts with thin heads. S J Sportscars have them in the UK .....

https://www.sjsportscars.com/parts-and- ... rchresults

Pt No's SJ604 (long) and SJ605 (short)

Dave Bean will probably have them in your part of the world...

http://davebean.com/

455202sj604.jpg and
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PostPost by: DaveJ » Thu Jan 18, 2018 9:33 am

Thanks guys for your quick responses. And a special thanks to oldelanman for the part numbers for the two bolts.

I'll order them Thursday from Dave Bean.

Dave
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PostPost by: oldelanman » Thu Jan 18, 2018 9:39 am

Dave,
Those part no's are from the SJ Sportscars catalogue so not Lotus numbers and Dave Bean won't recognise them but they should know what you're after.
Regards,
Roger
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PostPost by: alan.barker » Thu Jan 18, 2018 10:06 am

Lotus part nos forward/front bolt wishbone to bearing housing A036D0190
rear/back bolt wishbone to bearing housing A036D0191
Alan
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PostPost by: knockoffnut » Thu Jan 18, 2018 3:28 pm

Alan, In engineering school they taught us that a bolt is fastened with a nut, while a screw is threaded into the parent material of the joint. The same fastener can be either a bolt or a screw depending on what it threads into. Wikipedia has a correct detailed description and it refers to the Machinery's Handbook which toolmakers and engineers often consider to be the bible for this type of topic. Virtually all long screws and bolts have unthreaded sections. When you get past screw length around of 4 to 6 times its diameter you always get a unthreaded shank section. This is partially due to designed use and partially due to manufacturing constraints. When you roll a thread there is an internal force trying to stretch the length of the shaft and there is a practical limit to this "stretch". (Yes, threaded rod is rollformed but that's a whole different discussion...) Cut threads are typically not strong enough to meet high load requirements, and too expensive to make in volume. (vintage Bugattis had all cut-thread fasteners)

alan.barker wrote:A "Bolt" has a plain unthreaded section.
A Screw or "Set Screw" is threaded the full length.
When you order i would suggest you make sure they are "HT" high tensile for the Suspension.
Alan
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PostPost by: alan.barker » Thu Jan 18, 2018 3:40 pm

Well there seems be to be more than one school of thought.
I'm just repeating what i learned during my Engine Fitter and Turner Apprenticeship in HM Royal Dockyard Portsmouth :wink:
Alan
ps. Maybe my memory is playing up it was back in the 60's
Last edited by alan.barker on Thu Jan 18, 2018 3:59 pm, edited 1 time in total.
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PostPost by: john.p.clegg » Thu Jan 18, 2018 5:59 pm

If you can remember the '60s you weren't there...

John :wink:
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PostPost by: JonB » Fri Jan 19, 2018 10:39 am

I have to agree with Alan here. I've seen the term "Set Screw" to refer to a bolt with a thread going from head to tip, many times.
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PostPost by: knockoffnut » Sun Jan 21, 2018 5:09 pm

You are correct in that a fully threaded screw with a head can be a set screw, if it is used to clamp the fine adjustment of a machine component. "Set screw" describes how a screw is used rather than its shape (in the same way that a "border spade" describes a type of spade used for gardening in a border, not a spade which is shaped like a border). A "set screw" is used for "setting" an adjustment on a machine. It can have a hex head, or square head, or no head and a hex (Allen) wrench socket, or a slot.
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