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Final Drive Leak

gr8scott

gr8scott

Member
Member
I noticed some oil drops on the garage floor the other day coming from the final drive. Actually dripped onto the tire then to the floor.

Clymer says it's either clogged breather hole or failed seals. The breather appears to be clear, but the drive looks pretty nasty. I'm pretty sure it's the seals, but wanted to ask your thoughts. See potos.

Should I just replace the final drive entirely?

Scott

20201212_122621.jpg20201212_122545.jpg20201212_122521.jpg
 
Mine started leaking a few years ago I bought the seals (3 of them if I recall) and the leak stopped. It's a pretty involved job to change one of the seals. You can buy the whole unit used on Ebay for $40-$60. Another trick might be to add some brake fluid to the gear oil and see if that swells and softens the seals enough to stop the leak.
 
I think it can leak with an overfill condition. It's not supposed to be filled to the fill hole. I beleive it takes 220 ml if my memory is correct but look it up.
 
bobct said:
I think it can leak with an overfill condition. It's not supposed to be filled to the fill hole. I beleive it takes 220 ml if my memory is correct but look it up.
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It hasn't leaked in over a year (last fluid change), so it wasn't an overfill situation.
 
A few years ago Steve (from sunny Florida) wrote a good article about leaks
from the final drive and how to repair. It was in the Concourer. You should
be able to find it in the archives.
 
I believe that Steve also made a video that is available on you tube.

I watched that and have just replaced the seal that was broken, it fits into the drive shaft, and can cause it to leak there according to his video.

I haven't put it back on the bike yet to see, I had a spare final drive that I put on instead. I also have the other seals just in case, but know that they are a bit more difficult to replace.
 
Ended up getting a reasonably priced used drive that is 6 years newer and has 80k fewer miles on it.
 
I have a similar problem. After watching Steve’s video, I’m likely leaking from the o-ring around the pinion gear. In his video he shows a small hole than allows the final drive oil to pass through to lubricate that part of the driveshaft. Anyone replaced that seal? The Clymer manual says the final gear case disassembly requires special tools. Here’s his video:
 
ghabel said:
I have a similar problem. After watching Steve’s video, I’m likely leaking from the o-ring around the pinion gear. In his video he shows a small hole than allows the final drive oil to pass through to lubricate that part of the driveshaft. Anyone replaced that seal? The Clymer manual says the final gear case disassembly requires special tools. Here’s his video:
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Funny you mention those small holes.

UPS delivered my replacement unit with a damaged box. They dropped or mishandled it in shipment, then affixed a sticker saying they opened the box, inspected it for damage, found none, and resealed the box. The studs were protruding from the box on arrival. I have no idea how the could tell if it wasn't damaged internally. Only visible problem was the box and interior packaging were oil soaked.

So to check, I cleaned the unit, affixed some washers and nuts to the studs to simulate mounting on the bike, filled it with fresh gear oil, and tipped it up a bit (see photo). The holes on the shaft were originally up and down. After it dripped I turned the shaft 90 deg to see that the lower hole was filled with oil that wasn't there earlier. I surmised these were passage holes for the shaft or bearing lube. Clymer makes no mention of the holes.

After wiping up again, I set the unit level for an entire day with the holes horizontal and there were no more leaks. Figured all was well and good and mounted it up to the bike.

No idea when my next ride will be. I have the brake disk off the wheel and am waiting on wheel bearings to come in as a preemptive strike. I needed front wheel bearings this summer as I approached 100k miles, so replacing the rears seemed cheap and prudent at this point as long as the wheel was off. Also replacing the brake disk.

Scott
 

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mgoodrich said:
I believe that Steve also made a video that is available on you tube.

I watched that and have just replaced the seal that was broken, it fits into the drive shaft, and can cause it to leak there according to his video.

I haven't put it back on the bike yet to see, I had a spare final drive that I put on instead. I also have the other seals just in case, but know that they are a bit more difficult to replace.
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How hard was it to remove the old seal and did you need special tools? I think that’s my issue too!
 
No special tools needed on this seal that goes around the pinion gear.

As soon as I pulled the drive unit out of the shaft itself the seal fell out. It had broke into 3 pieces and was very brittle.

So, that one is the easiest to get to and replace. The other 2 you have to disassemble the drive unit, so they are a bit more difficult to replace.
 
mgoodrich said:
No special tools needed on this seal that goes around the pinion gear.

As soon as I pulled the drive unit out of the shaft itself the seal fell out. It had broke into 3 pieces and was very brittle.

So, that one is the easiest to get to and replace. The other 2 you have to disassemble the drive unit, so they are a bit more difficult to replace.
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Thanks!
 
This kind of goes along with, "do you remove the drive to replace a tire". If you do, you have the opportunity to inspect and replace the seal. It moves back and forth with the rise and fall of the suspension, and wears. Downside is you can cut the seal as you put the drive back on.
On the Vulcan 750 (also a 20 year production run) Kawasaki didn't use a seal and drive oil for lube. The manual said to remove and lubricate at every tire change. Many don't and then they wear out the drive splines. Ma K forgot to lube many on the assembly of the bikes also. My brother in law/ now my son's lasted 50,000 miles. All tire changes done a dealership's. Not a bit of lube when I replaced it.
 
I think the label on the drive says to use SAE80 below 5 deg C and SAE90 above 5 ded C, so I'm using Lucas Oil Heavy Duty High Performance 80W-90 Gear Oil. I'm not an oil expert, and correct me if I'm wrong, but I think Roadrunner's 75W-90 would be a wee too thin in winter. Also he said 75W-90 but pictured 75W-140, which would be too thick when warm. I see no reason to doubt Mama K.
 

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gr8scott said:
I think the label on the drive says to use SAE80 below 5 deg C and SAE90 above 5 ded C, so I'm using Lucas Oil Heavy Duty High Performance 80W-90 Gear Oil. I'm not an oil expert, and correct me if I'm wrong, but I think Roadrunner's 75W-90 would be a wee too thin in winter. Also he said 75W-90 but pictured 75W-140, which would be too thick when warm. I see no reason to doubt Mama K.
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Ah, ha, thanks for the correction regarding my discrepancy (between what I wrote and the pic I grabbed). I use 75W-90, year-round, but it would depend on where you live as what may work better for you.
 
Road Runner said:
Ah, ha, thanks for the correction regarding my discrepancy (between what I wrote and the pic I grabbed). I use 75W-90, year-round, but it would depend on where you live as what may work better for you.
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Agreed, you can probably get away with 75W-90 if it never gets below 5 deg C where (or when) you ride. I'm in Maine, so, well, you know. We have summer, fall, winter, and three months of bad snowmobiling.
 
gr8scott said:
Agreed, you can probably get away with 75W-90 if it never gets below 5 deg C where (or when) you ride. I'm in Maine, so, well, you know. We have summer, fall, winter, and three months of bad snowmobiling.
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Understood. Snowmobiling is awesome, if on the right vehicle. Living in north AL it's rare if we get in the teens Fahrenheit more than once or twice in the winter.
 
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