Author Topic: Oil leak at front wheel  (Read 1970 times)

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chaz

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Re: Oil leak at front wheel
« Reply #15 on: 30 November, 2021, 16:07:38 »
It  looks like the bottom of the fork leg has a pair of bolts holding the axle in, other B40;s from 1965 have full diameter holes with a clamp bolt behind, so the bottom half of the leg is called a cap or clamp. on my A50 and more modern bikes with conventional forks the damper assembly is is fitted in the bottom of the fork leg with a bolt which is removed by the aid of the bottom cap.
my eldest bought a modern KTM with the old style single bolt clamp and it wasnt until we were cleaning the bike one day that we noticed the clamp was split and held in with superglue, he bought the bike from someone who worked at Heathrow airport.
if one of the cap bolts is too deep, it might break through into the leg where the fork oil sits.

Phil C

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Re: Oil leak at front wheel
« Reply #16 on: 06 December, 2021, 14:35:26 »
Afternoon everyone,

Just an update, to keep you interested :)  -   just been out to the garage, cleaned off the brake plate and the fork leg, and pumped the forks about a dozen times. No sign of any oil.

Next step is to go for a (careful) ride and see what I can see then.

Given that no oil was evident after pumping the forks just now, maybe it is wheel bearing grease, as Derek996 suggested. It does look like that's where it's coming from on the photo, don't you think?

Any thoughts appreciated!

Phil

JulianS

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Re: Oil leak at front wheel
« Reply #17 on: 07 December, 2021, 10:39:01 »
Phil

I have already suggested a way forward and other members have offered opinions and nothing appears to have changed since then. I do not for one minute think that the oil on the brake plate is melted grease from the hub.

If you look at the cross section diagram of the iron full width hub setup below you can see that if the bearing grease has melted it would drip into the hub, not squeeze out along the wheel spindle and leak over the outside of the brake plate.

If you think it is bearing grease then you have a duty of care to other road users to check that your brake is safe and not contaminated.

It is easy enough  to remove the wheel and detach the brake plate to check.

Colin SS90

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Re: Oil leak at front wheel
« Reply #18 on: 07 December, 2021, 11:14:12 »
I agree with the opinion that it is not melted grease.
I would further investigate a fork leak as just pumping the forks does not simulate the forces from riding which induce much more fork travel and can maintain fork compression forces under braking. Also if the fork oil level was too high initially the excess may have already leaked out resulting in a leak free level.
1964 SS90

BEESY

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Re: Oil leak at front wheel
« Reply #19 on: 07 December, 2021, 11:54:28 »
Have you taken the wheel off and had a good look at the forks?

That and taking the brake plate off the wheel would be the 1st things I would do.

AdrianS

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Re: Oil leak at front wheel
« Reply #20 on: 08 December, 2021, 10:17:15 »
Do as I suggested in an earlier post. Whether you take the front wheel off is up to you. As I said it is highly unlikely to be bearing grease.
Clean everything off properly and see if a leak appears. If ok take the bike for a run and recheck.
It is very easy to overfill the forks. If you drain them through a drain plug, quite a fair amount remains within the fork even after pumping.
If you have a genuine leak, the main places are the drain plug, the fork seal holder and I suppose even from above the seal holder if the seal fails and a large excess of oil is put into the fork.

Pete Gill

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Re: Oil leak at front wheel
« Reply #21 on: 09 December, 2021, 14:47:36 »
Hi Phil

I can not see how that could be grease. From what i can see from the tracks and the way its run its got to be oil. I would be convinced by the way it feels to touch under your finger.
At these temperatures (? 5 deg C ) in the garage this time of year grease would feel very waxy and firm under the finger but oil will still run and actually look like oil and glisten on the finger.
It looks like oil from the fork to me.

Phil C

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Re: Oil leak at front wheel
« Reply #22 on: 10 December, 2021, 14:06:10 »
Hello all,

It didn't seem runny enough to be oil, but maybe it was dried by the passing air on the ride, and/or the coldness of the air - dunno. Maybe it had been there a while and I'd not noticed. But anyway, general consensus seems to be oil rather than grease. Fair enough, I expect that's right.  Went for a short run this morning - just two or three miles - and there was little if any on the brake plate when I got home, maybe a little bit, and some around the brake plate nut - hard to tell much very precisely because of raindrops all over the place (unexpected shower, but actually, living in South West Devon, not all that unexpected.) I'll look into it further as soon as I get time (moving house next week so a bit pushed for time at the moment), including taking the wheel off and having a look at the brake. Looking forward to that, and maybe also then taking the forks apart to learn about them. If and when I do that you can expect a flurry of dim questions.

Phil

Pete Gill

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Re: Oil leak at front wheel
« Reply #23 on: 11 December, 2021, 17:21:45 »
I look forward to hearing your findings Phil, we all learn from these things.
Pete

chaz

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Re: Oil leak at front wheel
« Reply #24 on: 11 December, 2021, 19:35:36 »
trouble with fluid, is it collects dust. this then solidifies, more dust and more oil ends up like grease.
left long enough it will stain, especially if old and contaminated with brass and aluminium that is inside the forks.

Phil C

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Re: Oil leak at front wheel
« Reply #25 on: 20 December, 2021, 22:03:02 »
I needed to ride the bike yesterday, in order to get it to the house I'm moving to. The distance I travelled was about the same as I had gone when I noticed the oil which started this discussion. This time there was no sign of any oil streaked down the brake plate. And btw the brakes seemed to work okay.
Maybe the trouble was that when I drained and renewed the fork oil a few months ago I put in a touch too much oil, which then found its way out until the level was correct. But I was pretty careful in measuring it out, so I'd be surprised if that's the case. I guess there's no way of checking the fork oil level other than draining it and renewing with a measured amount. If there's been a leak then I imagine there might be no oil now left in the forks, so maybe I should remove the drain plugs to see, drain any that's in there, then put in the right amount, and see what happens. All advice/thoughts appreciated as always.   Phil

AdrianS

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Re: Oil leak at front wheel
« Reply #26 on: 22 December, 2021, 09:50:56 »
The problem is that just opening the drain screw does not drain all the oil out. Iíve left the screw out and pumped the forks before removing them for a rebuild only to find quite a bit of oil still inside.

DAVE BRADY

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Re: Oil leak at front wheel
« Reply #27 on: 22 December, 2021, 09:59:54 »
Hi,

Even with the top nut removed some oil will remain.  I have found the best way is to leave the top nuts in place and with the drain screws removed pump the forks until no more oil comes out.  Beware though the oil will squirt a good way so drip tray rather than a jar is essential.

Dave.

Phil C

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Re: Oil leak at front wheel
« Reply #28 on: 22 December, 2021, 10:00:15 »
So, after I drained the forks a few months ago, including pumping, I might have still had some oil in there when I put in the measured amount, and the two together added up to too much, which then found a way out.  OR, I might simply have a leak and there's now no oil left in there at all. I don't see any way of checking the latter without opening the drain screws.  Phil

TTJOHN

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Re: Oil leak at front wheel
« Reply #29 on: 22 December, 2021, 10:35:31 »
Phil.
Sorry only just picked up this thread. Have you check the shuttle valve stud at the bottom of the forks? this is usually where the trouble lies, the drain plug on the forks has a turned down bit at the end which fits into the shuttle valve recess of the shuttle valve stem to stop it from turning sometimes these are badly damaged, from tightening up the stem, the stud at the bottom is a small hex head stud with a 1/2"BSF thread, this should have a fibre & a plain washer on it. HTH

Regards TTJohn