G80 1957 oil coming from back of the clutch housing

Information relating to the Matchless G80 or AJS Model 18 500cc Heavyweight.
sdillon
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G80 1957 oil coming from back of the clutch housing

Post by sdillon »

Hi folks, re 1957 G80S
I have filled the primary drive casing to recommend level just above the chain to the bottom of the inspection hole with engine oil. When I take the bike for test run lots of oil is escaping from the hole at the back of clutch casing onto the chain back wheel and everywhere, it's dripping and scarey dangerous.. :o
Can anyone suggest how to stop this please.
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Joker_Bones
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Re: G80 1957 oil coming from back of the clutch housing

Post by Joker_Bones »

The recommendation I see most often is to only fill the chaincase so that the oil is just touching the bottom of the chain. I would try that first.
1957... Alloy chaincase? There is more to be said if the problem persists.
sdillon
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Re: G80 1957 oil coming from back of the clutch housing

Post by sdillon »

Cheers for quick reply, I will try that.. Yes it's 1957 aluminium chaincase. Managed to seal that bit but the large whole behind clutch is a bit worrying. I have seen a felt washers and rivet plate on spares website wondered if that's worth a go.. Cheers
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dave16mct
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Re: G80 1957 oil coming from back of the clutch housing

Post by dave16mct »

Lower the oil level as JB says, barely touching the very bottom of the chain is enough. The whip of the chain will fling it around. Check that it is coming from the primary cases. It could be from the main seal in the gearbox or the crankcase breather.
Dave.
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Joker_Bones
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Re: G80 1957 oil coming from back of the clutch housing

Post by Joker_Bones »

Is the sliding plate not fitted? It would be a large hole without it!
This is a replacement sliding plate, the two halves can be riveted or bolted together. A felt seal or an o ring can be sandwiched between the two halves.
IMG_20230923_121733.jpg
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sdillon
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Re: G80 1957 oil coming from back of the clutch housing

Post by sdillon »

Many thanks, plates missing that explains things..
Many thanks for all the quick replies I only joined the club last night and it's been a super experience on the forum... Cheers Mr Bones
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Joker_Bones
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Re: G80 1957 oil coming from back of the clutch housing

Post by Joker_Bones »

I've never tried running a alloy chaincase without the sliding shield so cannot suggest how much oil would find its way out.
I don't think the earlier steel chaincases (except on the competition models) have the sliding shield, maybe they have a drip ledge above the hole, my bikes have alloy chaincase I'm not that familiar with the steel ones.
If lowering the oil level/fitting a shield doesn't sort the problem then, as Dave says, gearbox mainshaft oil seal or engine breather are possible causes. I've had the amount of oil you describe, all over the swing arm and back wheel, when an already leaking gearbox oil seal finally let go.
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clive
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Re: G80 1957 oil coming from back of the clutch housing

Post by clive »

The steel cases have a drip ledge but they tend to leak a bit anyway!
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sdillon
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Re: G80 1957 oil coming from back of the clutch housing

Post by sdillon »

Thanks all got a plate and felt seal to fit so hopefully that will stem the worst of it..
Cheers to Jampot spares guys. Will report back re effectiveness 😊
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Re: G80 1957 oil coming from back of the clutch housing

Post by Eamonn »

Have you had chance to check this?
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