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Fork seal leak

Discussion in 'Biker's Cafe' started by mjd, Jul 26, 2018.

  1. mjd

    Wise Guy

    Joined: Oct 21, 2002

    Posts: 1,066

    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?
     
  2. Dogbreath

    Capodecina

    Joined: Oct 18, 2002

    Posts: 16,650

    Location: Devon

    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?
     
  3. Diddums

    Capodecina

    Joined: Oct 24, 2012

    Posts: 19,382

    Location: London

  4. mjd

    Wise Guy

    Joined: Oct 21, 2002

    Posts: 1,066

    Location: Llanelli, S.Wales

    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.

    [​IMG]

    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.
     
  5. TallPaul_S

    Soldato

    Joined: Mar 24, 2011

    Posts: 5,778

    Location: Kent

    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.
     
  6. mjd

    Wise Guy

    Joined: Oct 21, 2002

    Posts: 1,066

    Location: Llanelli, S.Wales

    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.
     
  7. tom_e

    Man of Honour

    Joined: Dec 26, 2003

    Posts: 26,824

    Location: West mids

    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.
     
  8. mjd

    Wise Guy

    Joined: Oct 21, 2002

    Posts: 1,066

    Location: Llanelli, S.Wales

    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
     
  9. Dogbreath

    Capodecina

    Joined: Oct 18, 2002

    Posts: 16,650

    Location: Devon

    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.
     
  10. mjd

    Wise Guy

    Joined: Oct 21, 2002

    Posts: 1,066

    Location: Llanelli, S.Wales

    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.
     
    Last edited: Jul 28, 2018
  11. tom_e

    Man of Honour

    Joined: Dec 26, 2003

    Posts: 26,824

    Location: West mids

  12. mjd

    Wise Guy

    Joined: Oct 21, 2002

    Posts: 1,066

    Location: Llanelli, S.Wales

    Thanks. Prices on these things are insane for what they are, but still cheaper than paying somebody else to do it I suppose :)
     
  13. Foghorn Leghorn

    Wise Guy

    Joined: Jul 5, 2003

    Posts: 2,383

    Location: Cheshire

    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
     
  14. Dogbreath

    Capodecina

    Joined: Oct 18, 2002

    Posts: 16,650

    Location: Devon

    When new seals and clips are in, a generous quantity of grease around the clip will prevent future corrosion.
     
  15. mjd

    Wise Guy

    Joined: Oct 21, 2002

    Posts: 1,066

    Location: Llanelli, S.Wales

    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
     
  16. agnes

    Capodecina

    Joined: Dec 1, 2006

    Posts: 15,814

    Location: San Francisco, CA

    Nothing worse than stumbling across a bodge job on your bike