Author Topic: Oil leak at front wheel  (Read 1960 times)

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Phil C

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Oil leak at front wheel
« on: 29 November, 2021, 14:01:25 »
Please have a look at this photo (1965 B40F.) Clearly there's somehow an oil leak.  What's that all about? Could anyone advise please?   Thanks in advance.   Phil

Derek996

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Re: Oil leak at front wheel
« Reply #1 on: 29 November, 2021, 14:09:30 »
Possibly too much grease in the bearings that has melted and leaked out
1948 B32 Competition
2015 Ducati Scrambler Classic
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Phil C

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Re: Oil leak at front wheel
« Reply #2 on: 29 November, 2021, 14:13:30 »
Hasn't happened before. Could it be grease coming from the brake?  I'm guessing not.  Phil

JulianS

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Re: Oil leak at front wheel
« Reply #3 on: 29 November, 2021, 14:26:05 »
I think the brake would need to get very hot to melt the grease in the bearings and I think it would run into the drum rather than onto the outside of the brake plate and you would notice a lack of brake.

Check for a leak from the fork oil seal.

Phil C

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Re: Oil leak at front wheel
« Reply #4 on: 29 November, 2021, 14:43:21 »
Just been out to see if it's been running down the fork slider. It's a little bit oily but I don't think so. Looks like it can only be, as Derek said, grease from the bearings? I guess it's nothing to worry about and if it's an excess of grease then it will stop of it's own accord?   Phil

Editor

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Re: Oil leak at front wheel
« Reply #5 on: 29 November, 2021, 14:50:20 »
I'm not familiar with these forks so a bit of a longshot but, do your B40F forks have the tapered peg pointing skywards inside the slider at the bottom. This is the standard way of damping the forks on compression.
If so, the peg is bolted in from the bottom and should have a fibre washer in there to stop oil leaking - for life. If said fibre washer is missing or perished then oil can seep through.
Again I might be talking through my backside but maybe worth taking the wheel out and seeing if oil is coming from the recess in the slider?
Chris

JulianS

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Re: Oil leak at front wheel
« Reply #6 on: 29 November, 2021, 15:21:02 »
If you think it is grease then I suggest that you check the brake for contamination.

Phil C

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Re: Oil leak at front wheel
« Reply #7 on: 29 November, 2021, 15:32:33 »
Chris, l'm not familiar with forks atall. So far in my "apprenticeship" in this hobby I've done nothing with forks except drain and renew the oil. I guess at some stage I need to commit to taking them to bits in order to learn. I don't even know where the recess in the slider is.  Phil

Phil C

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Re: Oil leak at front wheel
« Reply #8 on: 29 November, 2021, 15:33:34 »
If you think it is grease then I suggest that you check the brake for contamination.

Brakes worked okay this morning when I was out.

DAVE BRADY

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Re: Oil leak at front wheel
« Reply #9 on: 29 November, 2021, 16:04:10 »
Hi,

I would suggest cleaning it all off the brake plate and anything on the fork leg right up to the top.  Pump the forks quite vigorously to simulate riding and see if anything is coming out of the fork seal.  If not go for a ride and then see where it starts to come from.  For the grease to melt you would have be riding along with the brake held partly on to generate the heat needed.  I have only ever seen the grease melt once and that was in a rear hub after an enthusiastic decent of the Ballon d'Alsace.  The brake will usually fade before getting this hot.
It surprising how a very small amount of oil will gather at a drip point and look like a lot.
Have you topped up or changed the fork oil recently?  Just a bit too much will need to escape.  If you determine that it is wheel bearing grease do as suggested by Julian and strip the brake out.  The brake may have been working this morning but you really do not want to find out when it does not.  Better safe than sorry and think about the potential damage to your B40.

Dave.

AdrianS

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Re: Oil leak at front wheel
« Reply #10 on: 29 November, 2021, 16:54:57 »
Melted grease during this cold weather - I think not.
Wash and clean everything from the fork seal holders downwards as suggested and keep an eye for future traces of oil.
All 3 of my BSAs suffered from fork oil leaks and if itís not the drain screw fibre washer leaking itís usually a fork seal or a poor seal between the seal holder and lower fork leg.
Before you can do anything, you must diagnose the problem!

Mike40M

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Re: Oil leak at front wheel
« Reply #11 on: 29 November, 2021, 17:04:28 »
Adrians advice seems a good starting point. If cleaned, you might be able to find where the leak is.
The drain plug washer or the damper washer as likely source of the leak. Not unusual with drain plug leaks if reusing the old one.
It should be easy to find out if fork seals are  source of the leak as described in earlier posts.
Checking the single side sealed wheel bearing can be done when you take off the wheel.
« Last Edit: 29 November, 2021, 17:28:44 by Mike40M »

chaz

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Re: Oil leak at front wheel
« Reply #12 on: 29 November, 2021, 18:18:39 »
same as the forks on the B40 Im working on.
one drain screw has sprung a leak , no pressure on it as bike on a stand with wheel off the ground, new washers, it just happened one weekend.
the fork leg seems to be a welded assembly , a seam might have sprung a leak, or another possibility, being split caps is that a tapped hole may be too deep and broken through into the fork oil chamber. Both of these could be aggrevated by movement  and vibration.

Phil C

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Re: Oil leak at front wheel
« Reply #13 on: 29 November, 2021, 18:31:59 »


Phil
same as the forks on the B40 Im working on.
one drain screw has sprung a leak , no pressure on it as bike on a stand with wheel off the ground, new washers, it just happened one weekend.
the fork leg seems to be a welded assembly , a seam might have sprung a leak, or another possibility, being split caps is that a tapped hole may be too deep and broken through into the fork oil chamber. Both of these could be aggrevated by movement  and vibration.

Split caps? What, and where, are they?   Phil

idie

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Re: Oil leak at front wheel
« Reply #14 on: 30 November, 2021, 13:48:00 »
He means the caps that hold the spindle to the bottom of the forks on full width hubs.