Author Topic: Need some 2 3/4 big end bolts n nuts  (Read 569 times)

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Offline Scomoto

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Need some 2 3/4 big end bolts n nuts
« on: 23 Jan 2023 at 09:48 »
Hi all

I'm in need of new big end nuts and bolts for my 1920 2 3/4 Model W

 The pre war spares section of the club is currently suspended and this will now impact the progress of my rebuild.

Does anyone have a spare set that they would sell to me or is there another way of getting some or is there an alternative ?

Thanks

Offline SunbeamS7

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Re: Need some 2 3/4 big end bolts n nuts
« Reply #1 on: 24 Jan 2023 at 20:12 »
As i understand it, per older article on rebuilding Douglas 2 3/4 TS Flat Tank, by Ken Terry (1986)  you can use "1/4 inch BSF (26TPI) Allen Head Cap screws, with Locktite (Red)...and reuse the old Douglas lock nuts (again with Locktite)".
Happy to scan the article to you.
Regards
bryan

Offline Marcus

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Re: Need some 2 3/4 big end bolts n nuts
« Reply #2 on: 24 Jan 2023 at 21:28 »
Hi Bryan,

As I am about to start rebuilding my 1920 engine I would be very grateful to get a copy, or if you are happy could you post it to the Technical Articles section then it would be available for anyone in future.

Many Thanks
Kind Regards

Marcus

Offline eddie

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Re: Need some 2 3/4 big end bolts n nuts
« Reply #3 on: 25 Jan 2023 at 09:19 »
WARNING!!
   In reply to SunbeamS7's posting - the bigend bolts on 2¾hp engines are 17/64"dia x 25tpi (not ¼" bsf)(another of Mr Douglas's odd threads!). The original set up relies on a good fitting thread to align the cap with the rod - if these have become worn, it pays to open the threads out to 7mm x 1mm pitch and use Allen Screws for the bolts. Allen Screws have a rolled thread, so are much stronger than bolts with a cut thread. Also, some modern CNC produced bolts have threads that end in a continuous groove right around the bolt - leaving a reduced section at the point of maximum loading (I have heard of several modern bolts failing in use!).

  Regards,
                Eddie.

Offline Scomoto

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Re: Need some 2 3/4 big end bolts n nuts
« Reply #4 on: 25 Jan 2023 at 09:52 »
Hi Bryan,

That's good info,

yes please can you scan that article for me ?

mike@m-techtraining.com

Cheers

Offline SunbeamS7

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Re: Need some 2 3/4 big end bolts n nuts
« Reply #5 on: 25 Jan 2023 at 20:35 »
Greetings,
I have (hopefully) attached/posted the article by Ken Terry (Rebuilding the Douglas TS) under the Technical Section. If any dramas opening the article please let me know.
Regards
bryan

Links added - Dave (Admin), 27Jan2023
« Last Edit: 26 Jan 2023 at 17:31 by Dave »

Offline Marcus

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Re: Need some 2 3/4 big end bolts n nuts
« Reply #6 on: 26 Jan 2023 at 20:29 »
Hi Bryan,

Thank you very much for posting this, do you happen to have the piston drawing that is referred to in the text.

Many Thanks

Marcus

Offline SunbeamS7

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Re: Need some 2 3/4 big end bolts n nuts
« Reply #7 on: 27 Jan 2023 at 19:24 »
I have tried to send the diagram of piston modifications as was part of Ken Terry's article on rebuilding the Douglas TS Flat Tank, however it keeps getting declined as "file is too big". Happy to scan it to anyone interested via their email, maybe that'll work? (i'm not overly tech-no-logically minded).
Regards,
bryan

Offline Marcus

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Re: Need some 2 3/4 big end bolts n nuts
« Reply #8 on: 27 Jan 2023 at 19:48 »
Hi Bryan,

Thank you very much, if you wouldn't mind scanning it and email it to me, that would be great. My email address is;

marcusjling@outlook.com

Cheers
Marcus

Offline Dave

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Re: Need some 2 3/4 big end bolts n nuts
« Reply #9 on: 27 Jan 2023 at 19:54 »
Quote from: Bryan
... it keeps getting declined as "file is too big"

Hi Bryan,
if you would like to email the file to the email address shown in this topic, we can add it to your post so it will be available for everyone.
Dave
Admin

Offline Dave

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Re: Need some 2 3/4 big end bolts n nuts
« Reply #10 on: 29 Jan 2023 at 07:03 »
Thanks very much to Bryan for sending in his diagram of piston modifications.



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Offline Ian

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Re: Need some 2 3/4 big end bolts n nuts
« Reply #11 on: 30 Jan 2023 at 02:49 »
I am a bit out of touch for the last couple of months and had not noticed that the pre war spares scheme is suspended ! I also need a set of big end bolts after a major blowup last year. There is a news item on the LDMCC website that the spares scheme should be up and running again from 1 March. To get up and running for the Australian rally I am thinking of using a used set of bolts with suitable loctite then replacing when I can source new ones.

Offline Scomoto

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Re: Need some 2 3/4 big end bolts n nuts
« Reply #12 on: 30 Jan 2023 at 07:33 »
The spares scheme will be up and running in March. Details in the next mag

 

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