sluge trap screw

[edboy]

hello. i ve just slaughtered both sludge trap screws out of a small journal a10 crank. it cost me 2 impavt driver heads. trap totally blocked so more than necessary. now i need to know what size thread they are to clean them up. they look bsc but what size? any experts out there?

[duTch]

Dunno ' bout the small ones, but the LJ ones are 11 tpi - BSF, I think 7/8".
I expect the small crank ones will also be BSF..?

 Get some replacement ones first (socket hex ones from SRM), to be sure, and ask them for confirmation..

[wardleybob]

Can't be sure but I think they are 9/16 cycle thread .

[The Artful Bodger]

They're cycle thread, I bought a tap to do mine last year but can't put my hands on it right now to give you the size.
Colin

[trevinoz]

If they are available, it would be a good idea to use Allen head plugs when you are putting things back together.

Trev.

[edboy]

thanks for replys but i think they are larger than 9/16" but suspect they are bsc. i need a tap to clean up the thread before replacing them with the allen key ones. i realise now , too late, that i should have heated them up before removal.

[bsa-bill]

now is the time for caution, I'd be 100 % certain of the size and thread before putting a tap anywhere near ( ask when you purchase new ones)
the wrong tap is going to be expensive

[edboy]

come on the artfull bodger.  find that tap . is it 5/8"bsc?  i m dying with suspense here.  the pressure is on and i may have to pick up the phone to srm as a last resort.

[The Artful Bodger]

Sorry I haven't been looking at the forum for a few days. I dug out my box of cycle taps and found an almost new 5/8" 20 tpi, 99% sure this is the one I bought for the sludge traps.
 Colin

[duTch]

 Might be best to pick up the phone and make sure.....?

[edboy]

thanks  artfall dodger , i ve ordered taps that size. obviously a oneoff size but i guess used elsewhere on the bike. i havealso looked up better methods for removal such as drilling through the centre and welding a bolt to the plug which would also burn off any locktight.i wish i had known that before.

[The Artful Bodger]

You're in the UK, I don't know if you've bought from "Tracy" before, I get most of my taps and dies from them www.tracytools.com
    If I'm going to use them a lot I buy tool steel, but for occasional use I buy their carbon steel which are very good quality. The one I bought for the sludge trap was carbon steel and worked fine despite mine being in a similar state to yours (hence the need for a tap!)
  I can highly recommend their helpful service and quality of tools.
Colin

[edboy]

thanks for recommendation bodger. i remember tracy tools when they were in brentford years ago when we also had manufacturing factorys in london, and plenty of jobs, labour party, page 3 , clocking in and clocking out. asbestos everywhere , yes those were the days.