Author Topic: Sludge trap end caps / plugs thread size  (Read 361 times)

Offline spottycat

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Sludge trap end caps / plugs thread size
« on: 05.06. 2024 11:18 »
Hi - I have tried to remove the sludge trap plugs from my 1961 A10 using all the techniques people talk about in the forum. Alas, I can not budge them. My local engineering shop can bore them out for me but they want to know the thread size before doing so. I have searched the forums but not found the answer. Can anyone tell me if the size and if it is a whit or BSF thread please? Cheers, Chris
61 A10

Online berger

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Re: Sludge trap end caps / plugs thread size
« Reply #1 on: 05.06. 2024 11:26 »
i seem to think they are 7/8ths 11 tpi someone will be along to correct me if this is wrong.

Offline spottycat

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Re: Sludge trap end caps / plugs thread size
« Reply #2 on: 05.06. 2024 11:30 »
Many thanks
61 A10

Offline Swarfcut

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Re: Sludge trap end caps / plugs thread size
« Reply #3 on: 05.06. 2024 12:44 »
  Plenty on the Forum to see how other folks do it. New plugs are available, sacrificing the originals is a shame but If you need to be a bit brutal after pussyfooting with.....

    Drilling the plugs, not the crank, to remove the factory punch locking pips....

    Using a well fitting driver with a wide blade (slot type) or hex key.......and an impact driver set to undo!

    Giving the driver a good smack with the lump hammer.....to shock the thread.

    Applying heat with a blowtorch......to soften any locking compound, expand the metal, get even!!!!

    Welding a nut onto the plug......

   Still stuck?  Best sharp drills at the ready, time to show who's boss, start  by drilling a hole accurately into the plug centre, then increasing the hole diameter until you are left with just a defeated threaded cylinder which can be collapsed inwards leaving the original crank threads to receive new plugs.

   I would have thought for initial professional assessment the size of the plug core was clear to anyone familiar with nuts, bolts and threads. Nor would I expect them to machine away the existing crank thread so no aftermarket plug would fit.

 Swarfy.

Offline limeyrob

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Re: Sludge trap end caps / plugs thread size
« Reply #4 on: 05.06. 2024 13:16 »
7/8 BSF. I got a tap off e-bay for about £5.  They may have one.
Oddly BSF is 11 tpi and BSW is 9 which hardly seems worth the bother *conf*

The sludge trap tube is probably jammed in so order one of those if you haven't, one plain plug and one with a spigot and double and treble check you put them in round the right way...  Locktite is fine, no need for huge centre punch marks.  The A65 is locktite and (correct me guys) no one in the history of man has has one undo.

Worth getting three flywheel bolts while you are there.  Yes it all adds up *smile*
Slough 59 GF/SR

Offline muskrat

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Re: Sludge trap end caps / plugs thread size
« Reply #5 on: 05.06. 2024 20:02 »
G'day Spotty.
When ordering new plugs get the ones with the hex. Makes the job next time so much easier DAMHIK! https://draganfly.co.uk/shop/55405/sludge-plug-hex-socket-large-journal-78-bsf/#10404-58A
https://draganfly.co.uk/shop/74560/sludge-plug-hex-socket/#67-1212A
Pitty they don't make them for the small journal cranks.
Cheers
'51 A7 plunger, '57 A7SS racer now a A10CR, '78 XT500, '83 CB1100F, 88 HD FXST, 2000 CBR929RR ex Honda Australia Superbike .
Australia
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Offline BVSR

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Markku
A7 1961    A10GF 1954    A10GF 1960    A10GF 1961 sidecar    A10SR 1958    A10SR 1959 
A10SR 1960   A10SR -61  A10SR 1963    A10SR 1963   A65T 1968    A65L 1968   B25SS 1971    B31 1952  
B31 1952   B33 1947  B33 1951   DBD34 GS 1958    NSU Supermax 1962    Husqvarna 510TE 1984
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