Oil Leaking out of front fork. Advice please

Discussion in 'Mechanics Garage' started by melectrok, May 22, 2016.

  1. melectrok

    melectrok New Member

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    I have oil leaking out of my front fork on my '99. It is from the fork as you bonce the front end the shiny part of the shaft start to get more and more oil on it. It runs down the fork and drips off where the axle goes through. Can someone give me the jist of what is involved in fixing this? The approximate steps, time and difficulty in fixing this myself. I don't want to wait on a repair shop if this is somewhat easy. Also what parts should I expect to want to get ordered before starting. Any information is helpful. Thanks.
     
  2. Terry Smith

    Terry Smith Member

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    You have a classic blown fork seal. Replacement is not hard but there's a fair amount of disassembly required. I can do this in about 90 minutes but I've had some practice. Lay out lots of newspaper as the job is impossible to do without spilling oil!

    It is a lot easier to loosen (but not remove) the fork caps before you start, ditto for tight fasteners like the axle bolt.
    Remove mudguard, undo and move brake calipers off the discs, free up the brake lines off the fork legs. Chock up the front of the bike ( a jack under the headers plus the centrestand), remove axle bolt and loosen bottom clamps, remove axle and pull out the front wheel.
    Loosen the handlebar clamps and the top and bottom triple clamps, pull off the small circlip on top of the forks, and slide the fork legs out.
    Before you go any further loosen the hex head bolt at the bottom of the forks, these are the one part that causes grief due to previously used threadlock. An impact driver is really handy sometimes.
    Back off any spring preload, then unscrew the fork cap (24mm, watch for spring tension), then loosen the locknut (14mm) under the fork cap and remove the cap. The spring, spacer and washers can now come out and you can drain the oil. Remove the hex bolt+copper washer from the fork bottom and slide the damper and oil lock piece out of the fork. The oil lock piece (shiny alloy cup about 1" high) sometimes stays in the fork or sometimes stays jammed on the end of the damper.

    Remove the upper dust seal by prying gently with a fine screwdriver and remove.
    Extract the circlip on top of the oil seal with a pick.
    Time to get a bit medieval, you now need to drive the seal out of the fork leg by extending the leg hard, causing the top bushing to drive up on the seal, repeat until it comes out.
    You should now have a lower fork leg in one hand, and the fork stanchion in the other. Give all components a good clean with kerosene or similar.


    If the bike has done a few miles, it might be a good idea to replace the bushings as a set, the dust seal is usually OK to re-use, and likewise the copper washer on the hex bolt should be OK for a re-use. You will need new fork seals of course, OEM are a reliable choice. Make sure you pay very close attention to which way up the seal is meant to sit when installed.

    You should take a close look at the stanchion to see whether a rock ding has caused the seal failure, and polish off any high spots with a fine file/fine sandpaper.

    Start reassembly with the new fork tube bushing, then slip on the the slider bushing, then back-up ring, then the new seal. When you reinstall the seal, put the cut-off corner of a plastic bag over the end of the fork tube so the seal does not tear on the tube.

    You can use the old fork seal on top of the new one, to protect it when you are driving it in. You need a fork seal driver, I use a length of PVC pipe + rubber mallet just big enough to slip over the 41mm fork, small enough to slip inside the lower fork outer, long enough to reach up over the fork leg. Pound the seal in until you feel it bottom out. A bit of rubber grease or fork oil to lube the process does no harm. Refit the circlip (should slip in easily if the seal is pushed in properly) then move the dust seal back into place, use the seal driver to get it home.

    Once the fork is reassembled with the damper bolted in place ( I use a lick of Loctite on the hex bolt threads), you can refill the fork with a good quality 5W oil to 130mm from the top of the fork leg. Before setting the final level, pump the fork up and down to expel air, and do the same with the damper until you get even, consistent damping feel through the full stroke. Now install the spring (tight end down), washer, spacer, another washer, then the cup washer under the lock nut. Wind the lock nut down on the damper rod, then screw on the fork cap till it just bottoms, then nip up the lock nut to that. Screw the fork cap onto the fork tube.

    Install the forks back up through the triple and handlebar clamps, fit the circlips and pull the forks back down so everything is snug. Tighten all those clamps (use a torque wrench!). Install the wheel and axle, tighten the axle bolt and right side pinch bolts. Install the brake calipers and connect the hoses to the forks. Install the mudguard. Pump the brakes, then take the bike off the stand and pump the forks a few times to settle everything, then tighten the left side clamps. Lastly, nip up the fork caps.

    My shopping list would be:
    New fork seals
    New bushings
    New copper washers (as insurance)
    1 litre of 5W oil

    Tools required:
    Torque wrench
    Fork seal driver (or PVC pipe)
    Long 6mm hex driver
    Usual assortment of metric sockets
    Bucket (for oil)
    Rags (ditto)

    Torque settings
    Brake bolts 31 N-m
    Bottom triple clamp (14mm bolt) 49 N-m
    Top triple clamp (6mm hex) 23 N-m
    Axle clamps (12mm) 22 N-m
    Axle (22mm) 59 N-m
    Handlebar clamp 26 N-m
    Damper hex bolt (6mm) 20 N-m
     
  3. melectrok

    melectrok New Member

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    Thank you for the quick response.

    How would you suggest supporting the bike during all this. I do not have any special stand or jack. Just the build in service stand.

    What type and size PVC pipe do you use?

    My brake calipers were installed with red Loctite on the 2 bolts on each side holding the calipers in place. How would you suggest removing these bolts knowing the Loctite is there?

    What other service do you recommend knowing what I have to take a part besides seals on the other side. The bike currently has 19,000.
     
  4. Terry Smith

    Terry Smith Member

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    I use a block of wood under the headers that I cut to a specific height after some measurement. With a helper leaning on the back of the bike just keep packing wood under there until you get the wheel high enough. With my special block, I can do this on my own with my foot.

    [​IMG][​IMG]

    I think 50mm PVC is the right size but get out a measuring tape, you need to clear 41mm of fork diameter. And length would be about 600mm.

    Whether Loctite is present or not, use the right size tools in good condition so you don't round-off a fastener, and a breaker bar if needed.
     

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  5. RVFR

    RVFR Member

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    As an extra thought if available. I hung mine from the ceiling By sliding an eye bolt long enough to go up through the steering head then using a motor cycle tie down hooking it up to a large eye screw I placed in a truss in the ceiling. It worked for me and comes in handy for hanging other objects as well. on another subject..... You Dog Terry, you got me going with that SH brake up grade even more :sneakiness:

    [​IMG]

    [​IMG]
     
  6. V4toTour

    V4toTour New Member

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    Try cleaning the seal before you rip everything apart.
     
  7. Badbilly

    Badbilly Official VFRWorld Troll Of The Year!

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    Another question..

    The mach 1 91 has been in a marine environment since it arrived in the Port of Seattle in 1991. The forks are Gold Valved. The upper tubes have pitted to the point they have cut the seals.

    Finding replacement parts is a bitch. Got a few responses from wreckers but "sorry no pix" but we can fix you up for 400 bucks and shipping.. I can do the work and would mostly like to find an alternative method to effect a fix. New hard chroming comes to mind..
     
  8. melectrok

    melectrok New Member

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    I am being told that the fork spring still remains under some tension even with the preload turned all the way back and that a compressor or press will be required to get the shock back together once taking apart. If this is incorrect say so but if not how do you push the cap down hard enough to start it threading if there is tension?
     
  9. NorcalBoy

    NorcalBoy Member

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    Springs are listed in ratings of 0.90, 0.95, 1.0, etc. This number equates to how many kilograms it takes to compress the fork spring 1 mm. So even if you have a 1.0 kg spring....it only takes 2.2 pounds of force to compress it 1 mm. I doubt you will need a compressor to push the cap down and get the threads started. Now, If you're talking compressing a shock spring it might be a little tougher if backing off the preload adjusting ring doesn't put the spring at full slack before you run out of threads on the shock body.

    Here are some calculations you can use to determine if you might need one....

    Pounds per inch - or kg/mm * 55.88 or N/mm * 5.71
    Kilograms per mm - or lb/in / 55.88 or N/mm / 9.79
    Newtons per mm - or lb/in / 5.71 or kg/mm * 9.79

    If you are just removing the fork cap to change the oil, my experience has been that you don't need a compressor.
     
  10. Terry Smith

    Terry Smith Member

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    I just push down on the fork cap with a socket and ratchet driver. As Norcal says, there isn't a huge amount of spring tension in the fork. Nothing can fly off as the cap is held down by the damper rod, but the cap's thread might get a little damage if you don't control it's exit from the tube nicely.
     
  11. squirrelman

    squirrelman Member

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    You'll need to de-grease the front rotors and fit new brake pads. :stung:
     
  12. Allyance

    Allyance Insider

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    I used a couple of deep sockets to loosen and restart caps by hand, they have ample gripping area. Also, used 1 1/2' PVC pipe trimmed square on a chop saw to tamp seal in. Don't know if you have a good set of snap ring pliers, the best I found were sold at Sears, I got the larger size. they have integral points, not the cheap Chinese kind with removable points, also they have to be thin enough to get down in slider. If you are going to do both, then do one at a time! Parts are different, at least on my 83.
     
  13. jerritt

    jerritt New Member

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    What timing I went out to my bike this morning and what do I see but a small puddle of oil below my left fork
     
  14. melectrok

    melectrok New Member

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    Okay, so I have removed the forks and pulled the dust seals. I have to barrow some snap ring pliers from my dad tommarow. It sounds like you just snap the shocks in and out hard to remove the seal. I have purchased new seals, bushings and the copper washers for the bottom. The Honda dealer here hooked me up with 7w oil. Its a shock oil, they said it is what the use when they replace the factory oil. Sounds like stock Honda is 5.7 or 7.5. Don't remember which one.

    Here in the states we don't have metric pvc pipe. We have 1.5 and 2 inch. The 1.5 measures at 38.5 mm id. Od is fine. I purchased it anyways and it is way to snug of a fit. Sounds like someone here has used 1.5inch pipe for this. Can you tell me the brand as that may make a difference. Also the schedule. The pipe I have is schedule 40. Schedule 20 in theory has a larger ID but I can find sch 20 under 3 inch. Else does anyone else have an idea. I wasn't going to slam these seals out of there until I have a way to put them back in.
     
  15. Terry Smith

    Terry Smith Member

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    The tube I have is Marley electrical conduit with 43mm id and 50mm od. [​IMG]

    If you are absolutely unable to find some pipe you can tap the new seal in carefully with a screwdriver, I would definitely put the old seal on top to protect the new one if you do that.


    Sent from my iPhone using Tapatalk
     
  16. Badbilly

    Badbilly Official VFRWorld Troll Of The Year!

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    Talked to Nils the vapor blasting guy about this problem. There is a sort of fix using abrasives and a special solder on the pitted area.. Very pricy. Nobody on a way to fix my forks?

    If the cost is out of line for the actual worth of the bike I may have some parts for sale
     
  17. Terry Smith

    Terry Smith Member

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    Billy I would have thought that if you just file off any high spots and polish up with fine sandpaper, you could use a cold metal filler in any remaining pits to get a surface that would be kind to the seals. Maybe you could post a photo of the fork tubes?
     
  18. sunofwolf

    sunofwolf New Member

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    I here BB and Duccman have a Motorcycle graveyard -just go there and get another fork. You may have to pay a toll however to BB.:vfrshorty:
     
  19. Voided76

    Voided76 New Member

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    I had a blown seal on the 07, and MotionPro fork seal cleaners worked a charm. I didn't have to do anything but remove the first dust cover.

    follow the instructions, work the cleaner's tab in, hook the grime and contaminants that have fouled the seal out, clean the surface very well, and bounce the forks and clean the surface until it cleans up, or you move on to the next spot. it took about an hour of working the lil plastic tool, then the bounce/clean/repeat but my left seal is sealed, and I didn't have to tear my shock apart.
     
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