Author Topic: Metal shavings in oil  (Read 1078 times)

Offline owain

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Metal shavings in oil
« on: 21.07. 2019 22:11 »
Hi all,

I've just drained the oil from my A10 and noticed a thick layer of metal shavings on the magnetic sump plug. Does anyone experience this? I removed the timing and chaincase covers and noticed that the clutch was a bit wobbly see video: https://www.youtube.com/watch?v=6bR5odP63GU ) with slight signs of abrasion on the inner chaincase wall.

The clutch hub nut was pretty loose, so my first thought was to just tighten it really damn tight to eliminate the wobble. The odd thing is that there aren't many metal shavings in the chaincase but quite a bit on the sump plug... Haven't experienced any engine knocking or odd sounds from the engine otherwise.

I'm planning on riding my A10 to France and Belgium in 3 weeks. So I'm wondering whether I should remove the top-end to inspect the pistons/inside the crankcases...or just tighten up the clutch hub nut and go...or perhaps, stick one of those fancy inspect cameras through the sump?
Sweden & North Wales
'50 BSA A10
'69 BSA A75R

Online ironhead

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Re: Metal shavings in oil
« Reply #1 on: 21.07. 2019 23:07 »
Hi Owain.

How long since the last rebore? During the first 500 miles or so there will be a build up of very fine metal dust coming off the cylinder walls & rings.
If the engine has done a lot of miles with regular oil changes & your getting noticeable flakes of steel on the magnet My first guess would be cam & or follower problems. Constantly having to adjust valve clearances will indicate this. Could also be crank shims disintergrating, hows the end float?
With the clutch nut coming loose, I would remove it completely & check both tapers as running it loose for a while can damage both & just tightening the nut may not work. There is always a bit of wobble on these clutches due to the narrow bearing set up used.
SA

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Re: Metal shavings in oil
« Reply #2 on: 21.07. 2019 23:43 »

 
Quote
.........With the clutch nut coming loose, I would remove it completely & check both tapers as running it loose for a while can damage both & just tightening the nut may not work. There is always a bit of wobble on these clutches due to the narrow bearing set up used.

 If I recall owain has a Plunger model so the clutch is on a spline= no taper
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
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Online ironhead

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Re: Metal shavings in oil
« Reply #3 on: 22.07. 2019 00:57 »
Yep, different scenario then. Maybe need to check the 2 x1/2 clips at the back of the clutch & not REALLY tight on the nut & make sure the tab washer is in good nick & folded over. ( as the drum has been rubbing on the case)
SA

Offline owain

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Re: Metal shavings in oil
« Reply #4 on: 22.07. 2019 08:43 »
Thanks for quick replies. It has definitely no more than 200 miles since it's last rebore. I'll check the end-float later this evening. I've completely removed the clutch now, can't find anything amiss. Just the loose hub nut.
Sweden & North Wales
'50 BSA A10
'69 BSA A75R

Offline Swarfcut

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Re: Metal shavings in oil
« Reply #5 on: 22.07. 2019 09:05 »
Owain.. Engine and chaincase are completely separate, so there is no mixing of the oils. All engines produce varying quantities of metallic debris, and without knowing its previous history it is difficult to tell whether this material is "old stuff" being washed out or a new problem. In the absence of any major catastrophic impending doom noises I would be inclined to wash out the tank and sump as best you can, remove muck and sediment from nooks and crannies in the timing case, refill with fresh oil and remove the sump plate from time to time to see if the situation continues. That way you can plan for remedial work, and get a firm idea whether a problem exists. As it has been recently bored, I would expect some nice new shiny bits in the oil.

 Clutch Chainwheel...They all rock a little bit, the design relies on a single row of rollers, so not much stability even when new.  Remove the clutch for inspection, you should find the gearbox input shaft has no lateral movement. This is controlled by a ball race at the kickstart ratchet end of the mainshaft. A large circular flat thrust washer locates the clutch, this fits over two semi circular steel half rings (abutment ring in the parts book). The gearbox input shaft is splined, not tapered, so all this just pulls off. Loss or failure of this thrust arrangement will allow the chainwheel to contact the inner chaincase and allow the centre retaining nut to loosen. The groove in the mainshaft for the two half rings is shallow, so pay close attention to their correct fitment.

  Damage and wear on the roller "tracks" means new parts, but short term a set of new rollers will offer a small improvement. Grease the rollers on assembly.

  Give the big clutch retaining  nut some Loctite, even though there is a tab washer, inner shaped to fit the input shaft splines. Give it a good tighten with the old "put in top gear, brake on" trick.

 Make a nice tubular peg spanner for the cush drive crank nut, it needs to be well tight, 60-70 Ft/lbs is suggested. Most are butchered by hammer and drift.

 Swarfy.


 Additional. See you have the clutch off now, have a good look at the abutment rings as they  have to support the whole clutch, a bit like hanging on with just fingertips. the groove is less than 1.5mm deep. Turn them over to put an undamaged inner edge towards the gearbox. Stick them to the shaft with a dab of grease, then carefully place the thrust washer over them. Originally this washer came in varying thicknesses to assist in chain alignment. When I first got my bike the half rings were missing, the thrust washer happily running on the three rivet heads that hold the oilseal carrier!

Online Greybeard

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Re: Metal shavings in oil
« Reply #6 on: 22.07. 2019 11:11 »
You can buy a special tool for the cush nut on the crank.

Offline coater87

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Re: Metal shavings in oil
« Reply #7 on: 22.07. 2019 11:40 »
200 miles sinse rebore and new rings?

 Run it like you stole it Owen, that metalic smeary stuff is what happens when rings and bore are breaking in together.

 Most of it probably happened in the first 100 miles, and it will continue to taper off.

 Hope Teddy is still enjoying the bike too!

 Lee
Central Wisconsin in the U.S.

Online chaterlea25

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Re: Metal shavings in oil
« Reply #8 on: 22.07. 2019 19:50 »
Hi Owain
It would have been nice to hear how or what resolved your last issue with the ignition so that you now feel confident to head off across to Europe  *????*
Feedback to problems solved serves as an information bank for others who may run into the same or similar issues

Check that the oil tank is clean, and change the oil before you head off on your trip
On newly built engines I change the oil at approx 300 miles, then at 800 and again at 1500

John
1961 Super Rocket
1963 RGS (ongoing)

Offline owain

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Re: Metal shavings in oil
« Reply #9 on: 23.07. 2019 22:20 »
Still haven't got around to checking the end-float (too busy with work this week!). Yeah, it had new pistons and new rings fitted during it's last rebore. So far it seems the most likely culprit.

Tonne-up Teddy is still loving the wind in his beard. I've replaced the crusty old twin exhausts with a new siamese exhaust to reduce the noise for him. I'm wondering whether adding wraps to the exhaust header would also help reduce noise  *dunno2*
Sweden & North Wales
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'69 BSA A75R

Offline metalflake11

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Re: Metal shavings in oil
« Reply #10 on: 24.07. 2019 08:36 »
Hi Owain
It would have been nice to hear how or what resolved your last issue with the ignition so that you now feel confident to head off across to Europe  *????*
Feedback to problems solved serves as an information bank for others who may run into the same or similar issues.

Check that the oil tank is clean, and change the oil before you head off on your trip
On newly built engines I change the oil at approx 300 miles, then at 800 and again at 1500

John

Could agree more John.

Otherwise it's just problems with possible solutions that may or may not have worked, and the same questions being asked over and over.
England N.W
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Online RDfella

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Re: Metal shavings in oil
« Reply #11 on: 24.07. 2019 11:11 »
Have to say I'd be rather concerned about 'shavings'. Can't be the rebore settling in, that'll produce a thin grey sludge from the cast iron barrel. And cast iron isn't shiny. Basically just makes the oil a little black. And these shavings are steel, not alloy, to stick to a magnet. If the bike were staying at home, I'd ride it gently keeping a watchful eye on it. I wouldn't consider taking it away as whatever this is can only get worse. Unless, of course, this is swarf left in the engine at build time.
'49 B31, '49 M21, '53 DOT, '58 Flash, '00 Firestorm, Weslake sprint bike.

Online raindodger

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Re: Metal shavings in oil
« Reply #12 on: 24.07. 2019 18:49 »
Gentlemen.
            'Shavings' suggests shims breaking up, check crank endfloat as a priority.

Regards.
Tim.

Offline owain

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Re: Metal shavings in oil
« Reply #13 on: 25.07. 2019 08:26 »
Righto, I checked the crank end float this morning and there appears to be a huge endfloat of 0.021" (0.54mm). Way more than the 0.003" maximum I've seen suggested https://www.a7a10.net/forum/index.php?topic=1758.msg11713#msg11713. I'll do an engine tear down later today :(

PS: I also tied off the thread about the ignition issues I was having.
Sweden & North Wales
'50 BSA A10
'69 BSA A75R

Offline Swarfcut

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Re: Metal shavings in oil
« Reply #14 on: 25.07. 2019 08:53 »
What a shame that you have a bit more hassle. Still, an ideal excuse for cleaning out that little old sludge trap. Budget for a set of sludge trap plugs, the crank shims and possibly a new main bearing. Taking the inner race on and off the crank can result in damage to the rollers. Alternative types of bearing are now available, NJ or NUP which leave the rollers in the crankcase, but are more complex and expensive. Some folks have used a simple and cheaper deep groove ball race as on the very early Longstroke A7, and this is an easy way to eliminate float entirely.  Lots of debate on the Forum as to the relative merits of these bearing choices.

 Swarfy.