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Forks leaking oil

Posted: Mon Nov 04, 2019 9:30 pm
by MauriceSanders

I have recently got my 1948 Ariel NG from the back of the garage. It’s a lovely bike and I want to start using it more. But I found a patch of oil on the floor not directly under the forks but adjacent to the bottom of the mudguard. It looks like oil has leaked from the fork leg and it has run down the mudguard. There’s plenty of oil on the leg itself. At first I thought that it might be the plugs but on investigation I couldn’t find any. Is it possible that this early model (first with telescopic forks?) didn’t have them?

Some advice on this would be welcome. Clearly the forks need to be fettled. I’ve never done this on an Ariel before so any tips, advice, things to look out for etc would also be welcome. And do I need any special tools? All that kind of information. Thanks in advance.


Maurice Sanders

PS registered May 1948, engine number BK5541, frame number BP13204

Re: Forks leaking oil

Posted: Tue Nov 05, 2019 1:47 am
by nevhunter
It either leaks from the seals which are at the top of the bottom (slider) part or MAY leak from where you add the oil Hexagons at the top of each fork. (Never had that happen myself.) The actual seals are in the bit that's usually chromed (Not chromed on the early model) which unscrews from the top of each slider and that allows the stauncheon and top bush to come out and requires a special spanner that fits inside it to undo without damaging the part. You do need a manual or download something from the net rather than go blind into it. You can remove one or both sides from the steering head section with a stand under the engine/ bike but watch for it tipping over as it's close to the balance point. If stauncheons are worn /rusted you need new ones or the seals won't do much , They are a bit tricky to get the fine threads sealed when retightening the seal holders.. Nev

Re: Forks leaking oil

Posted: Tue Nov 05, 2019 5:55 pm
by JohnnyBeckett
can it been over filled with to much oil in the forks

Re: Forks leaking oil

Posted: Tue Nov 05, 2019 10:01 pm
by nevhunter
Quite possibly. I use fairly thick hydraulic oil in ARIEL forks and usually include drain screws at the bottom. Otherwise you can only drain them by removing the fork ( each side separately,) to tip the oil out.. If the bikes been sitting for ages it might be better to change( empty) the oil and add the specified amount which some clever chap will no doubt know. Nev

Re: Forks leaking oil

Posted: Sat Nov 09, 2019 6:39 pm
by jj.palmer
Maurice, I am having a similar problem, if you goto the 4 stroke secton on this forum and then goto "Front fork oil leak" dated Fri Oct 18th you may find some helpful information.

John P.