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Pitted fork

Discussion in 'Maintenance and Servicing' at netrider.net.au started by bazz, Nov 10, 2014.

  1. Hi everyone,
    This is my first net rider entry. Thanks in advance its a long one.
    I started riding around the 1st September 2014. I'm still on my L's. I ride a 2009 Honda CB400. I purchased it second hand for 5300 with 12 months rego. At the time it only had 9300km on the clock. Now it has more than 14000[emoji5]

    I recently took it to the mechanic for the 12000 km service, had new tires put on, spark plugs changed, oil filters, oil change and so on. That cost $1140 (ouch, two new expensive tryes n major service)
    A few weeks later I heard a winding down noise from the front brake as I bring the bike to a halt. I took it back to the mechanic and he confirmed the front disks are a little bit bent, but will be useable until the 18000km service. Fine.
    Then he noticed that the left fork suspension is leaking oil. The cause of this is that the stantion has pitts that get beneath the seal, damage it, and allow oils to leak via the pitts.
    Has anyone ever had pitted forks? What is the best and cheapest solution to this problem in your opinions?
    I've been watching YouTube clips on how to change the oil seal in a suspension fork, and suspension fork assembly/disassembly in general, and from what I can observe, while the job is straightforward, its extremely labour intensive. As I don't have a garage or tools at my disposal right now (have been travelling for the last few years for work) the reality is that I'm going to have to pay a mechanic to do this job.
    The cost of a whole fork assembly part is $570. I figure its going to be better if I replace both forks (there is minor pitting on the right folk but no oil leak yet) that's $1140 . the labour in replacing two complete forks should be minimal: unscrew four bolts on the fork braces slide out the suspension and slip in the new ones. This could be done when the front brake disks are being changed.
    On the other hand that's $1140 just in parts! And im going to need new disks too!That a lot of doe.
    So I wonder if I should ask the mechanic to change the two pitted stantions and oil seals only (at about $400 parts), not the whole suspension My gut says no, as by the time he's finished pulling out the suspension forks, draining the oil, changing the seals , replacing the stantions, reassembling suspension, filling with oil etc... He will have done many hours labour, for a less quality outcome than option one, where the whole suspension is new. And knowing mechanical repairs, isn't it also true that when he opens up the suspension he might find that the springs are gone too? Pah!
    Pitted forks, what a painful learning!
    Im going to keep the bike for my Lam's perio of another year. i need to fix the problem, as I can't sell it to someone else in good conscience with pitted forks either. Can anyone help to shed some light, check my logic, give any helpful suggestions around this topic. Where is good to source parts too?
    I'd be most grateful Thanks very much.
    PS I tried to attach images of the Pitts but for dome reason I don't have permission[emoji102]

  2. There's no problem with changing the stanchions only. In fact they can be re-chromed. It needs to be hard-chrome, not many do it anymore, and I'm not sure it will be cheaper than new parts. Worth checking out however.

    You will change the seals at the same time and inspect the bushes. At those ks I doubt the bushes will need work. Obviously you replace the oil too.

    The whole lot is a medium difficulty job so it might not be a good idea to do yourself.
  3. It's unlikely that you'd find a hard chromer in Australia who can do the job for less than the cost of a complete replacement fork leg. It's really only an option for reclaiming rare components where no replacements are available. The cost lies less in the chroming than in the precision grinding of the reclaimed surface back to spec.

    Other than replacement with new, there are a couple of options. Good used legs from a wrecker would work. Trouble is, many late model bikes end up in wreckers as a result of front end impacts which, of course, kancker the forks. Those which don't are in high demand to repair bikes which have, so there won't be many bargains to be had.

    The old bodge, very popular in the time and place that I cut my biking teeth, is to clean out the pits as well as possible, removing all traces of oil, and then to smooth in a layer of Araldite or similar. Once set, the "repair" is polished with fine wet & dry paper. It covers up/removes the sharp edges, thus protecting the seals and allowing them to work. Sometimes it works, sometimes it doesn't, but if the fork leg's scrap anyway it can be worth a shot.

    I find it interesting that a low mileage, 5 year old bike has warped discs and pitted forks. So much for Honda's much vaunted "quality".
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  5. Hey guys, thanks very much for your insights. Both are helpful.
    I've been talking to wreckers without any luck at all.
    The hard chrome ides is clever, especially for bike restoration, but I'm not sure I'll get it cheaper than new parts. For the time being,I may just attempt the araldite option. What grade wet n dry do you recommend, 1000?
    If that doesn't work, I guess I need to talk with several mechanics and try and lock in a realistic estimate for replacing the stantions vs the whole forks
    I'll keep you updated
  6. one of the metal repair epoxies would likely be better than the "5 minute" Araldites.
    ie JB weld or Permapoxy or similar

    need to really clean out the pits, and flush with a couple of solvents to get any oil and crap out.. eg metho and then acetone

    need to be careful to not sand too much of the original chrome.. or use a softer grit material to reduce wear on the chrome