Oil leak around final gear drive?

Grape_salad

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I've noticed that I've got a bit of an oil leak around the final drive. It's not too bad - no oil dripping on the floor under it, but it is seeping out. I've noticed there's a hole on the underside which seems to be the source of a lot of it - anyone have any clues as to what is causing this? Anything to be concerned about? I just got back from a ~1000km trip and there is noticeable more oil on the underside than there was before I left.

I did change the final drive oil about 6 months ago - I don't think it's related as it didn't start happening immediately after i did that.

IMG_4284.jpegIMG_4283.jpeg
 

bimota

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its probably the seal on the inside of the pumpkin alot on here have had to change it, few threads on here about it, if you take the wheel off and look at the inside of the pumkin you can see the seal about £18 easy job the usually pull the old seal out with a sel tapper screw

rob
 

holligl

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If it is coming out the weep hole, which is what it looks like to me, it maybe the front seal which is harder to replace. A special socket is needed to remove the bearing retainer nut. Clean it up and try to determine which side the oil is coming from. If it is a slow leak, you can keep riding, just check the level now and then. If it starts leaving oil on the ground, then you need to do something. Like Rob said the side seal is quick at easy.
 

Cycledude

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Or maybe you over filled it ? Definitely don’t rotate the wheel while filling because that will load the gears with oil so it will be over filled.
Or used synthetic oil ? Synthetic is much more likely to leak than regular oil.
 

Scott F

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Or maybe you over filled it ? Definitely don’t rotate the wheel while filling because that will load the gears with oil so it will be over filled.
Or used synthetic oil ? Synthetic is much more likely to leak than regular oil.
Why is synthetic more likely to leak? This is interesting; I am not questioning you, just asking a question.

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Grape_salad

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its probably the seal on the inside of the pumpkin alot on here have had to change it, few threads on here about it, if you take the wheel off and look at the inside of the pumkin you can see the seal about £18 easy job the usually pull the old seal out with a sel tapper screw

rob
Thanks, that was an incredibly useful video. I'm not seeing any leaks around the axle though, so I don't think it's the output side seal on the pumpkin. I'm leaning more towards what @holligl said about the seals on the drive shaft:

1711056559350.png

@Cycledude - I don't think I overfilled it, but can't rule it out. Wouldn't the gears though be filled with oil when checking the level and topping off as part of regular inspection? I saw no signs of leakage around the breather.

I used Castrol Axle EPX 80W-90, which is API GL-5 spec. Unclear if it's mineral or synthetic, but since it isn't advertised as synthetic, I'm inclined to think it is mineral based. I too am curious as to why synthetic oils are more prone to leaks?
 

holligl

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Here is the thread for the front seal and o-ring. I did not replace the flexible shaft seal as it looked OK. If you have many miles you probably have a groove worn in the coupler gear. Some don't worry about it. I replaced mine. One on here was able to replace the seal without removing the bearing retainer nut. Mine was a bear to get out, and @eemsreno had the tool.

 

V-rider

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I was riding from Detroit to Seattle last summer, and after I went thru the mountains in Montana, I noticed some drips on my wheel and on the ground at a rest stop. I checked it and it wasn't low enough to add. I bought some lube to carry and worried about it all the way to Seattle. It never dripped anymore after coming down out of the mountains. I rode home thru WA, ID, NV, UT, AZ, NM, TX.... 4000 more miles and never leaked again. I'm guessing I over-filled it when I changed it before I left on my trip. It seemed to have purged what it didn't need and never another drop. :)
 

simmons1

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It's my turn. Got a pretty good mess coming out the weep hole It went from dry to splatters on the wheel and a drip this afternoon. I am on a trip and currently 500 miles from home. Hope to buy a quart of gear lube and check it frequently to get me home.
 

scott123007

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It's my turn. Got a pretty good mess coming out the weep hole It went from dry to splatters on the wheel and a drip this afternoon. I am on a trip and currently 500 miles from home. Hope to buy a quart of gear lube and check it frequently to get me home.
Mine did that too a few years ago. I bought a quart because I had 1200 miles to get home. I cleaned the wheel, to see how badly it was leaking, and then checked the level in the pumpkin. It still looked full so I didn't add any. The wheel had more drips on it a couple hundred miles later, but the oil level still looked full. I cleaned the wheel again, but it never leaked again. 30,000 miles since then and still dry. You might get lucky like I did by the time you're home.
 

simmons1

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Mine did that too a few years ago. I bought a quart because I had 1200 miles to get home. I cleaned the wheel, to see how badly it was leaking, and then checked the level in the pumpkin. It still looked full so I didn't add any. The wheel had more drips on it a couple hundred miles later, but the oil level still looked full. I cleaned the wheel again, but it never leaked again. 30,000 miles since then and still dry. You might get lucky like I did by the time you're home.
Wasn't yours leaking on the big seal by the wheel and not the input seal where the drive shaft goes in?

If you were the guy at the Super Tenere Rally at the Hub, I was the guy that loaned you the allen wrench to check the level in the pumpkin.
 
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Cycledude

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I believe high temperature is another reason they sometimes leak, mine leaked while riding home from Colorado a couple months ago, temperature was 80-100 degrees for most of the 1,300+ mile ride home with cruise control set at 80-83 mph, after I got home I drained the oil and refilled it while parked on sidestand, leaned over like that oil comes out the overflow hole a little sooner so there’s less oil in it, I haven’t noticed any leak since. The bike now has 82,000+ miles showing on odometer.
 

simmons1

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Follow up. I got home fine on Saturday. When I drained final drive it was down roughly an once and a half. Pulled it a part Sunday, new input seal arrived today. It is installed and all back together.

Pretty much followed this procedure by @SkunkWorks for changing the seal including making a tool to go across the cush drive lugs. I didn't have a great way to hold the final drive doing the 108 ft-lb torque on the coupling nut so I improvised and held the final drive in the clamps from my Derek Weaver Tire changer. LOL

 
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