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Fork Oil leak

fleetingyouth

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I noticed this morning that the rear fender and underneath the tail had a thin black oil sprayed across it as if it was flicked up from the tire. I checked the underside and chain and couldn't find any evidence of a leak. then I noticed what looked like the fork oil leaking and the front break caliber was covered in oil. Could the fork leak enough oil for the rear tire to kick it up on the fender?

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670cc

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You may have a fork seal leak that explains the brake caliper mess. Raise the dust cap on the fork and check for oil wetness on the seal itself. These leaks are usually caused by debris in the seal, and can often be fixed with a seal cleaner tool.

As for oil on the rear end, check under the countershaft cover for a gross accumulation of old chain lube. Check the engine oil pan for signs of an engine oil leak (which I think you did). Especially check the rear shock for oil leaking out of it’s seal. My stock NC rear shock was done when all it’s oil leaked out at 29,000 miles. Or maybe you just rode through some black liquid.
 

fleetingyouth

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I washed the bike today and took it for a short ride to heat it up and see what happened. I inspected the underneath, no sign the rear shock leaked or anywhere oil might leak. ill check under the covers tomorrow but I didnt see any sign of a leak or build-up of chain lube.

When I got home no sign of any oil on the rear. The front right fork did have a thin coat of oil on the fork so I'll pull the dust cover and clean/inspect it tomorrow. It definitely did leak enough to coat the front caliper but doest feel like it drained all the oil out.

I picked up a complete cogent dynamics suspension and will do that sooner than later. I guess I'll replace the seals when I do that. Does anyone have a link to a good deal on seals? Also is it good practice to replace dust covers at the same time?
This will be my first time doing my own suspension overhaul.

Here is a pic of how much oil was on the rear fender area. I does seem like a lot more than I would expect from the front fork so maybe I did ride through some oil though I can't imagine how I wouldn't notice. I'll keep an eye on it.
 

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fleetingyouth

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OK I'm going to order some new seals, has anyone ever used these All Balls Racing seals?

Also, I read on some other suspension threads and in the Cogent Dynamics instructions to use a thinner oil with the DDC kit. Is the Honda Pro Fork Oil the right stuff to use? It says it is 5w but I know fork oil doesn't really play nice with that standard.

Thanks for any tips
 

670cc

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OK I'm going to order some new seals, has anyone ever used these All Balls Racing seals?

Also, I read on some other suspension threads and in the Cogent Dynamics instructions to use a thinner oil with the DDC kit. Is the Honda Pro Fork Oil the right stuff to use? It says it is 5w but I know fork oil doesn't really play nice with that standard.

Thanks for any tips
The majority of the time I have had a fork seal leak oil, the remedy was to clean out the seal with a tool made for that purpose. Other than raising up the dust seal, no other disassembly was required. Maybe you just want to replace the seals anyway, but if not and you want a possibly easier fix, it might be worth a try.
 

halfSpinDoctor

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OK I'm going to order some new seals, has anyone ever used these All Balls Racing seals?
I've used the All Balls ones on my Ninja 250 and they were totally fine. That being said, I think the Honda OEM (Showa) seal set can be purchased for $20 per fork ($40 total), so for $8 bucks or so more it may be worth just going OEM. I think either is probably fine.
 

fleetingyouth

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The majority of the time I have had a fork seal leak oil, the remedy was to clean out the seal with a tool made for that purpose. Other than raising up the dust seal, no other disassembly was required. Maybe you just want to replace the seals anyway, but if not and you want a possibly easier fix, it might be worth a try.
I guess my thinking was, and tell me if you think I am wrong. That since I would have to pull the forks apart to install the new components and change the oil, it just made sense to install new seals at the same time.
They have 20k miles on them and the bike is 9 years old.
 

670cc

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I guess my thinking was, and tell me if you think I am wrong. That since I would have to pull the forks apart to install the new components and change the oil, it just made sense to install new seals at the same time.
They have 20k miles on them and the bike is 9 years old.
I’m not sure what exactly you mean when you say you need to “pull the forks apart”, since I don’t know what all components you want to change or modify. I have not installed a Cogent fork modification. I have installed the Racetech Gold Valve Emulator kit. You have to remove the forks from the bike, remove the oil, springs, and the damper tube, drill the damper tubes, reinstall everything with the additional emulator valves, and new oil. To install the emulators, at no time is there any need to separate the inner and outer fork tubes, but if you wanted new seals, then would be the time to take those extra steps to get to them.

If you want to be absolutely sure the fork oil leak is fixed, it does make sense to inspect the fork tubes for nicks or damaged surfaces, and change the seals.
 
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MZ5

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I guess my thinking was, and tell me if you think I am wrong. That since I would have to pull the forks apart to install the new components and change the oil, it just made sense to install new seals at the same time.
They have 20k miles on them and the bike is 9 years old.
If you’re pulling the forks apart and replacing seals, with 20k I’d replace the bushings, too. They’re about 5 bucks apiece or so, and they’re a wear item.

For my 2012 they’re item numbers 7 and 8 in the diagram here:


Do inspect the polished fork tubes very closely. If there are scratches or gouges or pits that have damaged the seal, the same will happen again. It’s not really likely, but it happens. I had some scratches on mine that a local shop thought were too significant, so they polished them a bit.
 

showkey

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As mentioned in prior posts……….Before replacing the seals. I would clean the seal with a device like “seal mate”. Debris and bugs guts get trapped in the sealing surfaces…..even a small amount can cause a leak. Cleaning the seal will not fix a damaged seal or damaged fork surface.


14E77778-3BC5-434A-875F-385BFF8E5800.png
 
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Griff

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The majority of the time I have had a fork seal leak oil, the remedy was to clean out the seal with a tool made for that purpose. Other than raising up the dust seal, no other disassembly was required. Maybe you just want to replace the seals anyway, but if not and you want a possibly easier fix, it might be worth a try.
Thats exactly what I did also. I fabricated a tool from a section of an old Xray negative. It immediately sorted the leak and I think that was over 20,000 kms ago. I will shortly get the forks serviced with new seals and bushings as theyu are well overdue by now at 42,000 kms.

One thing I always do after every dirty or wet ride is clean the fork leg lowers and apply a very light coating of lube so the seals are not coming in contact with dried dirt later which can work underneath the seals. That alone has served me well with my other bikes also.
 

fleetingyouth

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Hey all thanks for the info and tips. I went to try and clean the seal and noticed the dust cover had signs of cracking so decided to just replace the seals. I'm going to be installing my suspension upgrade parts tomorrow and just replace the seals and bushings as recommended above. for $50 it just seemed worth the peace of mind so I don't have to take the forks off anytime soon.

I also noticed some light rust pitting assuming from rock hits on the higher portion of the tube right below the clamp. can this be cleaned up with a Scotch-Brite pad or do you think it should be filled in?

PXL_20220530_163156420.MP.jpgPXL_20220530_163219812.jpg
 

showkey

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Not sure what product would be used or even work to fill in the pits.


The good news the seal does not travel that far up the tube.
 

dduelin

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Once the chrome finish has pits in it the carbon steel fork tube underneath is exposed and the rust will quickly return. A very close look at the pit reveals a tiny crater with a raised edge where the chrome is lifting and that sharp edge will damage new seals. A brisk rub with an extra fine Scotchbrite pad or 000 or 0000 bronze wool wetted with WD40 will clean up the pit's loose chrome that the rust underneath lifts up to form the edge of the crater. In the clean-up process microscopic bits of bronze wool will break off and lodge in the cracks and fissures of lifting chrome. If we use steel wool instead of bronze that steel debris rusts rapidly and the problem's return is accelerated. However, as Showkey said, I am unaware of of anything that will provide a successful long term repair.

Here is a picture of my bike with "analog" data acquisition devices I installed that record maximum fork travel during a ride. The upper zip tie is the limit of fork travel (137 mm for 2012-2020 models) and the lower one recorded the max travel attained during last Saturday's ride. About 10 mm was left in reserve before bottoming out. Messing around with preload and fork oil level determines how much travel is routinely used when you ride. You can extrapolate the travel recorded on my bike to your pictures and see the pits are probably going to damage new seals. You could lift the front wheel clear of the ground with a jack under the engine and measure 137 mm up from the top edge of the dust seal and see if any pits are in the wiped area.

IMG_2212.jpg
 

fleetingyouth

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Thanks guys I ended up just cleaning them up. I saw a bunch of videos and articles talking about filling pits in with epoxy to extend the like of forks.

I dont think I have as much travel as you dave as when I pushed the fork tube down till it hit the bottom it was well below where the pitting is.

I'm terrible about understanding suspension stuff but got the new fork parts all installed. I will probably start a new thread with questions on sag, adjusting, and whether I measured is all out correctly haha. Just going to take it for a few more rides to feel it out. Next is the rear shock maybe this weekend.
 
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