BSA Owners' Club Forum

The BSA Workshop => Twins => Topic started by: Charles R on 01 November, 2017, 12:35:08

Title: A65L Crankshaft welded sludge trap access
Post by: Charles R on 01 November, 2017, 12:35:08
A65L 1970 (last of oil-in-tank)

Has anyone seen this before?  See photo of welded up sludge trap access (yes I know, it's a bit rusty too, but one thing at a time!).
I can't understand why anyone would wish to weld up the entry point when it could simply have a threaded cap fitted (loctited if thought necessary).
Now I've got the problem of what to do about it.

There are three obvious options:
1. buy a replacement crankshaft - not easy & quite expensive even as a used item (would need regrinding, new shells, etc)
2. re-machine the hole and tap it (difficult alignment problem) - also quite expensive as expect it to take about 3 hours
3. ignore the weld and fit it as it is!  (I will be fitting a cartridge oil filter, so sludge should not be an issue.)

Any comments or suggestions?

Cheers, Charles
Title: Re: A65L Crankshaft welded sludge trap access
Post by: JulianS on 01 November, 2017, 13:30:37
I would not advise option 3 - firstly you do not know what is already contained in the sludge trap and secondly you do not know if the oilway from the main bearing journal has not been blocked or restricted by the welding.
Title: Re: A65L Crankshaft welded sludge trap access
Post by: Charles R on 01 November, 2017, 15:58:01
Thanks for the reply Julian.

I was intending to use a compressed air line to give it a good blow through after putting in some scavenging oil and letting it rest for a day or two.
After that I was going to set up a feed to the bushed bearing feed hole and see how freely the oil moves through to each big end.

BUT before all that I'm going to try and drill through the weld using tools in my shed.  I need to jury rig my bench drill press so it hangs over the bench then set up a solid table under it to give me the necessary clearance to hold the crankshaft under the drill bit.  Setting up will not be simple!

I still don't know why it was welded!

Cheers Charles
Title: Re: A65L Crankshaft welded sludge trap access
Post by: JulianS on 01 November, 2017, 16:51:37
Sometimes the sludge build up is so hard it needs a drill or other mechanical means to move it, or so I have found. I would not rely on any solvent to loosen it or the small oil holes in the journal to allow the all effluent to escape.

The plugs were often removed with a hammer and cold chisel which often destroyed them and sometimes resulted in damage to the edges of the hole in the crankweb.
Title: Re: A65L Crankshaft welded sludge trap access
Post by: Mike Farmer on 01 November, 2017, 19:17:53
Hi

Do you know anyone with about a 3' pillar drill. You would then only have to align the crank. Where are you.

Mike 8)
Title: Re: A65L Crankshaft welded sludge trap access
Post by: Charles R on 02 November, 2017, 11:41:36
Mike

I don't know anyone locally with a floor standing pillar drill or anything approaching it.
I live near Halesworth/Harleston on the Suffolk/Norfolk border.

I'm still intrigued as to why it was welded.  This would have been done about 40 years ago and the motor has never been used since.  Perhaps there was a school of opinion that the sludge trap was not useful if an external filter was fitted but, even so, why weld the hole up?

Cheers, Charles
Title: Re: A65L Crankshaft welded sludge trap access
Post by: Mike Farmer on 02 November, 2017, 11:54:32
 :)

I discussed this with a local machinist today complete with piktur etc. Prob not a cheap job.

My thoughts for what its worth and what I would most likely do, and if this is frowned upon I understand.

Figuring that you're unlikely to need to do this again.

I would drill the weld, clean it completely and then weld it up again. Even suggesting this goes a bit against the grain but it would sort any faults inside the hole as well. Duff threads etc,

Finally please don't anybody threaten to lynch  for this suggestion.

Mike 8) 8) 8)
Title: Re: A65L Crankshaft welded sludge trap access
Post by: JulianS on 02 November, 2017, 12:51:57
Even with an external filter there will still be some build up in the sludge trap.

I would think that it was welded as a bodge job, because the original plug was wrecked when removed and/or the face of the crankweb was damaged during removal and/or plug removed by drilling and the threads in the crankshaft were damaged in the process.

The plugs were secured by centre punching the edge and these marks often needed drilling to allow the plug to be unscrewed.
Title: Re: A65L Crankshaft welded sludge trap access
Post by: Mike Farmer on 02 November, 2017, 16:17:18
hi.

yep definitely a bodge job. cant see any other reason. some clown welded the locknut on the oil drive worm on my A50 prob they had tried to turn the nut the wrong way. Tuff really but that's life with something that's changed hands a zillion times.

Mike 8) 8) 8) 8) 8
Title: Re: A65L Crankshaft welded sludge trap access
Post by: Bess on 02 November, 2017, 16:29:52
Hi Mike,
            If after removing the welded section and you cant salvage the threads, my suggestion would be to make up a blank and braze it back. It could be removed easily removed if needed next rebuild.

Best wishes...
Title: Re: A65L Crankshaft welded sludge trap access
Post by: Charles R on 02 November, 2017, 16:50:12
Thank you all for your thoughts.

I would like to drill through and discover what's lurking:
 a. have they left the sludge trap still in there?
 b. is it clean in there?
 c. can the thread be reinstated?  (By the way, anyone know the thread size & type?)

Depending on what's found, ideally I'd like to reinstate the thread and fit a sludge trap plus plug.  Otherwise, as has been mentioned, seal it up again without a sludge trap so as to allow an external cartridge filter to do its job.

Cheers, Charles
Title: Re: A65L Crankshaft welded sludge trap access
Post by: JulianS on 02 November, 2017, 17:00:37
7/8 x 20tpi.
Title: Re: A65L Crankshaft welded sludge trap access
Post by: Charles R on 02 November, 2017, 17:05:08
Thanks Julian

Which thread type?  Whitworth?

Cheers, Charles
Title: Re: A65L Crankshaft welded sludge trap access
Post by: JulianS on 02 November, 2017, 17:07:26
Think it is cycle.
Title: Re: A65L Crankshaft welded sludge trap access
Post by: Mike Farmer on 02 November, 2017, 19:28:35
Hi

Yep if it becomes necessary then I agree Brazing would be better than welding.

Mike 8)
Title: Re: A65L Crankshaft welded sludge trap access
Post by: Editor on 03 November, 2017, 18:11:26
I would take it to a machine shop - probably a local engine reborer etc. and ask them to set it up on a vertical milling machine and using a 1" plus slot drill, remove as much of the welded area as poss, exposing the original bore to see if the sludge trap is still there or not. I would then get them to sleeve it with a 7/8" cycle thread internal thread sleeve and a larger thread on the o/d. Thoroughly swilled out afterwards it will be as good as new! Even at 80 /hr, it shouldnt take longer than a couple of hours so certainly cheaper than getting a replacement.
Chris
Title: Re: A65L Crankshaft welded sludge trap access
Post by: Charles R on 07 November, 2017, 12:47:40
Chris

Thanks for your suggestion.

I live quite close to Draganfly so took it to them for their view.  They were very reluctant to commit to how long it would take, but their view was a minimum of 2 hours and no certainty of success in being able to reinstate it.  I could then be back to square "minus one" with a hole in the crankshaft and another one in my pocket!  I know they are quite busy, so it could be that they didn't really want to do it (though they certainly didn't say so)!

I think the answer (as recommended by you) may be to seek out another machine-shop and get their view to see what sort of process they could carry out to get into the sludge trap area to see what's in there  After inspection I could then decide what's best to do regarding making it good again or simply blanking it off (see later).

With an external cartridge filter and frequently changed modern oils, I can't see that a sludge trap would be necessary - but I'm no expert on this matter.  It seems to me that BSA put the sludge trap in the crankshaft to make use of the centrifugal effect to remove the heavier deposits in the oil but only because the filtration system was so poor.  Any thoughts on simply not bothering with the sludge trap after opening the hole to check everything is good and clean inside the crankshaft?

Cheers, Charles
Title: Re: A65L Crankshaft welded sludge trap access
Post by: Editor on 07 November, 2017, 15:46:55
I agree that with a cartridge type oil filter the sludge trap will need cleaning out a lot less often. However, the type of deposits I've found in them when I've cleaned them out has been very fine, compacted matter. In my opinion, this will build up over a long period, how long is anyone's guess, and will need cleaning eventually.
However, I last cleaned my A65 sludge trap out about 10 years and 11,000 miles ago. It has had a cartridge type filter all this time and I don't intend to split the cases to clean it out again anytime soon. I will probably do it as it approaches 20,000 miles since the last time. I will note how much clag comes out and let everyone know, but that's likely to be in 3-4 years time so watch this space.
In the mean-time ask yourself how long you want to keep the bike and more importantly how many miles you expect to do on it in that period. After a clean out I wouldn't worry for 15-20,000 miles with a filter and that would be 7-10 years at 2000 miles a year!!
Hope this helps put it in perspective.
Chris
Title: Re: A65L Crankshaft welded sludge trap access
Post by: Charles R on 07 November, 2017, 17:51:34
Chris

I am not intending to do any great or numerous journeys on my A65L (when eventually resuscitated) so that's part of the reasoning for not worrying unduly about the sludge trap.  I'll be very surprised if I manage more than 1000 miles a year - there could be peaks but there'll also be troughs in my use.

I also wonder whether the sludge would be fine enough and in small enough quantities to pass through the crankshaft journals without affecting them, as I would expect the filter to deal with them fairly well as they go round the oil loop.

I suppose I'm looking through rose tinted spectacles and hoping to "cure" the crankshaft block without spending a fortune or tearing out what little hair I've got left.

Hopefully my bike will be back on the road before you are able to report on how much gunge your trap has been filled with!

Thanks again for the help.

Cheers, Charles