Sludge trap Tube Plug Removal Q&A (BSA and Triumph Twins)
Q: Can you offer a little advice on BSA A65L
"sludge trap plug" removal? I've stripped and rebuilt a number of motors in the
past, not too unsuccessfully, but have never tackled this job before. It's the
last serious dismantling job to do before I start the rebuild.
(1) Firstly, I had read the articles, and the book, and knew before starting that they could be beastly things to remove.
(2) The plug has been replaced once before. I see two "original" diametrically-opposed centre-punch marks, outboard of the plug thread line, probably done at the factory, together with four extra indentations around the plug thread, probably done at a later bottom-end service. Sure, we don't want a thing like this to come adrift at 5000rpm, but I thought this a bit over-zealous. I drilled these four out lightly, and as far in as I dared.
A:USE THE SMALLEST DRILL YOU CAN THAT WILL REMOVE THE CENTREPUNCHING COMPLETELY. WHEN YOU PUT THE NEW ONE IN, ONLY CENTREPUNCH IT LIGHTLY
Q: (3) I tried at first with my largest, widest screwdriver, coupled with a monkey wrench, (or "cle anglaise" as they say somewhat derogatorily here in Quebec). No luck before I chickened out, not wanting to burr it up too much. I guess everyone tries this first.
(4) Next, I resigned myself to forking out for an impact screwdriver, just as they recommend. I had always managed "stuck-in bolt" jobs like this before without resorting to this device. I found one with the widest screwdriver-blade bit. I mounted the crank on top of a hefty bit of steel pipe, cushioned the other end of the crank with a piece of alloy so as to get maximum force throughput, protected the right-hand shaft end against any inadvertent knocks, then proceeded to "give the thing some gip with an 'ammer" - my heaviest - bearing down, and being very careful not to damage or bend anything. No luck. I welted it as much as I dared.
(5) Now I'm thinking of the next escalation. I saw in Canadian Tire a hefty "screw extractor" with a 7/16" shaft. I thought that this, and a "cle anglaise" (plus 3-foot pipe extension) should give enough purchase. I would have to drill a 5/16 hole through the plug in order to insert the extractor (a reverse-spiral thing which bites harder into a stuck-in screw as you turn anticlockwise.) I assume there is air-space behind the plug.
A: DON'T USE THE EXTRACTOR ON THE PLUG, USE IT ON THE SLUDGE TRAP TUBE IF NECC AFTER REMOVING THE PLUG AND THE FLYWHEEL BOLT CLOSEST TO THE TRAP.
Q:(6) Is this a worthwhile pursuit, or must I now think of turning it over to an expert to machine the screw out?
(7) I had also thought of getting a special "screwdriver-slot" 1/2" socket ($18.00), grinding it down a little so it's a good fit in the plug-slot, then making a clamp arrangement to somehow lock the socket into (against) the plug-slot whilst still being able to give it some useful torque with a socket wrench.
A: THIS IS THE TRICK, AND USE A REALLY GOOD LONG T HANDLE. IF THE SLOT IS TOO BUGGERED TO DO ANYTHING, YOU CAN ARCWELD AN OLD BROKEN SOCKET TO THE PLUG AND TURN THAT WITH THE T HANDLE, BUT TRY NOT TO GET THE CRANK TOO HOT WHEN DOING THIS. THIS IS A LAST RESORT. ALTERNATIVELY, YOU CAN ALWAYS PUT THE CRANK IN A DRILL PRESS AND USING PROGRESSIVELY LARGER BITS, DRILL IT OUT. I HAVE ALWAYS FOUND THE SECRET TO BE REMOVING ALL DISTORTION FROM THE CENTREPUNCHING, AND THEY THEN COME OUT EASILY.
Q"(8) When it's out, the new one I put in will be a hex-slot type, so that the next person to do this won't have so much trouble.
A: GOOD MOVE!! Mark
Thanks for your tips on sludge-trap plug removal. I managed it in the end, with no damage, and send you this to share my final fix with you.
- I protected any bearing surfaces with foam and tape, in case of a "slip-graunch" accident, in particular the right-side crankshaft bearing surface.
- Carefully, with ever-increasing drill sizes, I drilled right through the centre of the plug, out to a final 3/8" diameter. Because of the slot, you have to watch against breaking the smaller drill bits.
- With a 1/4" square file, I opened out the round 3/8" hole to make a 3/8" square one. The plug is fairly soft, and files easily.
- Then I took my Craftsman 3/8" socket wrench, whose square drive-peg now fits nicely into the filed plug-hole. The head diameter of the wrench is such that it fits quite well, doesn't foul the crank bearing surface when turned, and, most importantly, fits right up close against the plug.
- With this set up, and the whole show clamped in a vice, it's easy to apply useful and persuasive torque to the plug, both via impact and lever-extension without fear of anything slipping off or out.
- A few grunts, and a few confident smacks later, the plug surrendered and was withdrawn, exposing the expected grey-black grimness and corruption within!
(Since I've clouted the impact screwdriver that I bought from Canadian Tire several times now in attempts to do this job, I can no longer take it back for refund. I guess I'll find a use for it one day!)