The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => A7 & A10 Engine => Topic started by: Guy Wilson on 06.10. 2015 11:52
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I'm drilling out the sludge traps on my large journal Crank. Can anyone tell me how thick they are? I'm using an 8mm drill roughly 5/16 equivalent and have so far drilled about 12mm deep . Does the sludge trap cover a chamber of sorts and should I keep drilling until I get through? I'm getting nervous...
Thanks.
Guy
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One end is thicker than the other, LHS I think (by logic tells me that engages the tube to hold it centre) has like a spigot on the end of it *conf*;- you should be getting close rhs (I think) at that depth they about that or so
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Thanks Dutch, I've drilled them both now. they are not shifting yet. I'll put some heat on them later. No access to gas now...
Guy
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According to the hex-key method, you should be able to drive an 8mm (or, maybe, 5/16) hex key into the hole and use it as a wrench to remove the plug. Have you drilled out the punch dimples around the circumference?
Richard L.
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I've drilled out the punch holes. They are just very tight..I may have an engineer put the crank on a lathe and take them out that way. I get nervous putting too much force on things as it often ends in blood and tears.. I'll have a cup off coffee and then have another look at them.
I'm assuming they're not left hand thread?
Guy
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They are not left-hand thread.
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thank you, re-assuring!
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Success...It was almost completely full of crap..(this is not the crank that seized) so I'm very glad I took all your advice and checked them.
Also there's a tube or a sleeve inside the crank that I've crewed the end up a bit getting one trip out. What's that for?
Guy
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You're going to need a new tube, and they are readily available. As I understand it, the tube distributes the oil across the width of the crankshaft while centrifugal force throws the sludge into the gap between the tube and the crank. If the tube itself was full of sludge it was really overdue for cleaning. I'm looking forward to going to the dunce corner when my explanation of sludge-trap theory gets shut down.
So, how did you eventually get it done?
Richard L.
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I tried to used a stud extractor, the type you drill a small pilot hole and the then screw in antilock wise etc. I'm guessing but it didn't have enough grip and was possibly expanding the plug making it grip harder etc.
Eventually, I did what was suggested and hammered first a size 10 hex that wouldn't grip .So I had another go with a size 10 star - they look like a small gear cog head on -. That gripped and with enough pressure on the T bar they came out. I damaged the tube with the drill..
Thanks again, another job done in a day that otherwise could have taken weeks or stalled the rebuild!
Guy
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So worth the effort when you found it full of shyte! *smile*
The Plunger does not have the inner tube, at least mine doesn't
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The bike i had the con rod failure with is a 54 / 55 swinging arm model with the smaller end journals, So I'm not expecting to find a tube in that one. The sludge trap plugs I took off today were from the spare engineI have, which is a 58 engine.
I'll tackle the original, small journal engine now I know what I'm in for.
Having removed the sludge traps I can completely see how essential it is to do so. Based on how daunting it first looked I'd probably have not bothered...however, based on what everyone has said about how important it is and more more importantly how to do it, i have no sludge in my sludge trap..
Do you, or anyone know where I can get a new tube for the large journal crank? Is it something I can make?
Guy
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Easiest place to find one will be eBay. Here is one from SRM. Make sure it looks like yours or drop SRM a line. there are many more on eBay to look at. I searched "BSA A10 sludge trap tube".
http://www.ebay.com/itm/BSA-A65-and-late-A10-crankshaft-sludge-trap-tube-67-1220-/271967399347?hash=item3f52852db3&vxp=mtr
Richard L.
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As I understand it, the tube distributes the oil across the width of the crankshaft while centrifugal force throws the sludge into the gap between the tube and the crank.
That's the way I see it too, but in addition, the way I see it is that's partly why the holes in the journals are at 90˚ to vertical (when at T/BDC), and the oil feed holes in the tube are inwards towards the crank centre, so the oil is pumped against the centrifugal force into the outer gallery- but I'm inclined to think that a certain amount of sludge would still build up inside the tube (maybe with non-detergent oils, but we woN'T go there *ex*)...I spent too much time figuring out which way the tube went back in *conf*
Now, Richard- pass me that pointy hat that you don't have exclusive rights to, or even have *smile*
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How is the sludge trap tube secured? Is it by the bolt on the outside of the crank or is it a push fit and held in place by the sludge trap plugs? I've tapped it about half way out although it now seems to stuck..
Thanks
Guy
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The bolt. The attached photo shows it, but is a bit weird because the flywheel isn't shown.
Richard L.
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Thanks Richard, It makes sense I couldn't find any information on the parts catalogue I have, so I was roughly measuring the distance, which was when the thought occurred....
Guy
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I just Googled "BSA A10 sludge trap" to find that picture.
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I just Googled "BSA A10 sludge trap" to find that picture.
OK Richard, no need to show off! :!
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Rest assured Richard, It helped. I removed the crank bolt and out came the tube all be it a bit battered..
I'd better give SRM a call now...
Guy
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OK, so the one I showed in the previous link seems incorrect. Here's one that looks like yours:
http://www.ebay.com/itm/70-3903-BSA-A10-TRIUMPH-T120-T140-TR6-TR7-BONNEVILLE-CRANKSHAFT-SLUDGE-TUBE-/321868392696?hash=item4af0d9e8f8&vxp=mtr
Not from SRM but I'm rather sure they will have the correct one. Just describe yours.
Richard L.
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I just Googled "BSA A10 sludge trap" to find that picture.
OK Richard, no need to show off! :!
Well, I was actually trying to show that I did nothing special. *smile*
Richard L.
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Hi, just my 2p worth, but back in the 60's I had a rather hot roadrocket. And what we used to do was use 20/50 duckhams and then used flushing oil eveey few 1000 miles and never had any trouble at all regards blocked oilways, big end bearings and main bearings.
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Hi all - glad Graybeard doesn't have a sludge tube in his plunger crank. Mine doesn't either and even though one isn't shown in the parts manual I was a bit worried when I built the engine. I did of course take the plug out and clean all the crap out!
John.