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Discussion Starter · #1 ·
Looking for some assistance from anyone that has replaced the transmission rear output shaft oil seal. This would be the one that exits the transmission and goes into the rear diff. See the attached photo. I am pretty mechanically inclined in terms of drive train, suspension, brakes and so on. Basically the only thing that I never actually dived into is tearing an entire 4-stroke motor apart and rebuilding it. I have done top end and know how to check valve lash and shim. So I feel tackling this is within my ability I am just looking for some guidance from anyone that has done this. Below I have outlined my main concerns/questions.

  • Can it be done with the transmission left mounted in the frame?

  • Do you need to completely remove the rear diff from the frame in order to get the shaft out?

  • There is a special tool that it calls for in order to get the nut off so that you can remove the coupler, but the tool appears to be very hard to find available for purchase. I have an impact so I am not worried about getting it off, it’s the torque spec when reinstalling it that I am worried about. Any advice on this?

  • When installing the new seal, how did you press it in? On seals like this for wheel bearings I always used a socket that is just slightly smaller than the seal, then place a rag in between the seal and the socket and then tap it in with a hammer. Can this same process still be used? Also should some oil be rubbed around the perimeter of the seal before pressing it in?

  • Lastly, when I purchased the replacement seal I found that the original was superseded. That being said was this seal specifically replaced with an updated one to address this oil leak issue? Anyone that has replaced theirs did you find the new seal held up much better/longer? I have a 2016 that I purchased a year ago with 300 miles, currently it has just over 1000 miles on it and this seal is leaking really bad. I know that this oil seal leaking was pretty common on the earlier models. Just hoping that the updated seal has been improved and I won’t be dealing with the same issue in another 500-1000 miles.

Thank you in advance for any help and advice that you can supply.


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I have done this job twice. You can definitely do it with the tranny in place in the machine. I did remove the rear end to allow the shaft to be removed and reinstalled. I own the special Yamaha tool and it does make it pretty easy. Without it, I probably would have just used a pipe wrench on the outside of the coupler that goes into the tranny to hold it while torquing. I don't think it is a real heavy torque as I recall. As for seal installation, nothing fancy and an appropriate sized socket or seal installer works just fine. I have not used the new seal as I had some spares of the old version. I think I got about 8k miles out of the second one before it started to leak. I think that the recently replaced seal is already seeping lightly with low miles, so I highly recommend trying the new seal part number. Good luck.
 
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Discussion Starter · #3 ·
Thank you for the knowledge @fortrdb . I will be sure to let you know how I make out with the new seal. I like to run’er hard when I’m driving her, but it gets cleaned up immediately following a riding trip and I like to keep up with the maintenance on my toys.
 

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After fighting 8 hours to remove drive shaft . We did simple bend on 2 rear diff brackets . To move diff extra 1 1/2 back easy then to pull shaft. This is one stupid set up shame on Yamaha.
 

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Did you change out your seal yet? if so, any further pointers you could pass along?
I have a 2016 that finally started leaking as well. I pulled off the skid plate today to see what would be entailed.
 

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Did you change out your seal yet? if so, any further pointers you could pass along?
I have a 2016 that finally started leaking as well. I pulled off the skid plate today to see what would be entailed.
It only takes about an hour or so to get the rear diff out if you just give into the fact that it needs to be removed to get the driveshaft out. Once you get the rear diff out, it is a cake walk from there. My method for rear diff removal process is:
1. Drain rear diff and remove bolts securing rear brake lines to the upper rear a-arm. Remove the calipers from both sides and tie them up out of the way.
2. Remove the rear shock bolts. Remove the outer bolt on the upper rear a-arm at the rear spindle. This will make removing the shocks easier. Remove the shocks. Pivot the upper rear a-arms up and tie them up out of the way.
3. At this point the rear spindles are free to pivot down and allow you to pull the half-shafts out of the rear diff. No need to undo the outer axle nut on the half-shafts, just let them point to the sky.
4. Remove the parking brake assembly. Remove the Weller rear frame brace if installed.
5. Remove the rear mounting bracket from the rear diff to get it out of the way. Remove the upper two bolts holding the rear diff in place. Remove the vent tube and let the rear diff come out.

Now the driveshaft can be pulled and the seal replaced. This is an excellent time to install the Alba hardened coupler and improved grease boot. Hope this helps.
 
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