Fork seal leak

mjd

mjd

mjd

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Joined
21 Oct 2002
Posts
1,074
Location
Llanelli, S.Wales
Hi chaps,

Hoping someone can give me some guidance with what I assume is a leaking fork seal. I noticed a puddle around the front wheel of my CB125f a few days ago. I just assumed it was rainwater as there had been a downpour the night before, but on checking this morning can see it's clearly oil and seems to be the left hand fork. From the videos I have watched most leaks look relatively minor when they are caught, however my fork appears to have dumped the lot.
Does the fact that so much oil has escaped whilst not actually being ridden mean this is any more serious than just replacing the fork seal?
 
It can't dump "the lot" from the fork seal whilst not being used, since on "right way up" forks the majority of the oil is held in the lower fork leg which is below the level of the seal. Is it obvious the oil has come from the seal area? If it's leaked from this area then it's probably just the seal, but damaged (e.g. rusty) fork tubes or worn bushes will exacerbate things.

It's also possible (though fairly unusual) for oil to leak from a bolt in the wheel end of the fork that holds the damper rod in place. In this case it will dump everything.

Also check it's not brake fluid; is the brake reservoir still full?
 
Hi,

Its a late 2015 bike. On inspection, the oil appears to have come out through the top of the dust cover. I noticed a small amount of dirty liquid on the mudguard when I rode the bike earlier in the week, but put this down to having just washed it and didn't think anything of it.

Dumping the lot is probably an exaggeration on my part, but it was a noticeable puddle and definitely oil.

n1hcGpr.jpg


The bike was on the side stand, so the bulk of the residue that hadn't made it to the floor was on the inside/top of the fork closest to the wheel with a noticeable build up on one side of the dust cover.

As for brake fluid, that was my first thought, but all fine with the resevoir and checked all around the caliper and hoses and its all clean.
 
Yeah, that brake disc is gonna need a massive clean/binning, and I'd just straight out bin the pads too, they'll be covered in fork oil.

Fitting new fork seals is a maintenance job, if you ride more than a couple of thousand miles a year it's a case of when, not if. With the correct tools it's a pretty easy job tbh, I've done a few on my own bikes.
 
I 'might' have been lucky with the calipers and disc. As the bike wasn't moving when the fork spontaneosly combusted, and apart from a small amount on the rim and tyre, I can't find a trace. I've ordered new oil and seals and will check the brakes more thoroughly when the forks come off. Still can't understand how this happened with the bike stationery though.
 
I can't actually understand how it would happen at all without more than just the weight of the bike going through the fork at the time unless they've been massively overfilled with oil possibly but you'd have noticed that when the front end was solid.
 
Yep, certainly doesn't make any sense. There was no load (as such) on that fork at all and it just seemed to happen overnight. Will be interesting to see if there is any oil left in there
 
Lift up the dust seal and make sure the oil seal is fully seated. There is typically a wire clip to prevent the oil seal coming out, if that hasn't been fitted or fitted badly then pressure within the fork whilst compressed can pop the seal out.
 
Okay, forks are all off and dismantled. The leaking fork looked fine visually, but there was hardly any oil in it.

The other fork actually looked the tattier of the two. The retaining clip for the seal on this one is pretty rusty and thin in places, presumably the leaking oil on the iffy fork prevented this from happening.

I want to replace the dust seals and retaining clips on both just for piece of mind. I cant seem to find anything (in stock at least) online, can I pick up bike parts through a Honda car dealer?If anyone has any tips for getting the cost down that would be great too. Over £5.00 for a metal clip seems ludicrous.
 
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Thanks. Prices on these things are insane for what they are, but still cheaper than paying somebody else to do it I suppose :)
 
I use David silver online parts for all my genuine Honda bits and bobs, Wemoto also do some genuine parts and good pattern parts.

It's quite common for fork seals to go suddenly like that, I've had a few spring leaks over the winter whilst sat in the garage.

Don't bother changing the spring clips unless they're rusty, isn't necessary. Edit: just seen it is rusty :D
 
All sorted now, including giving them a quick respray. Someone had clearly had them apart before, and had 'cleverly' used silicon instead of crush washers at the bottom bolts. I stripped them down entirely, gave them a thorough clean and so far not a glimpse of oil to be found
 
mjd said:
All sorted now, including giving them a quick respray. Someone had clearly had them apart before, and had 'cleverly' used silicon instead of crush washers at the bottom bolts. I stripped them down entirely, gave them a thorough clean and so far not a glimpse of oil to be found
Click to expand...

Nothing worse than stumbling across a bodge job on your bike
 
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