Final Drive Oil Leak.

[Ken]

Hi

My D9 has started to leak a few spots of oil from around the swinging arm when on its side stand.
It’s coming from the final drive gator and I’m sure it is gear oil. The diff is loosing about an eggcup of oil every 100 miles.

The Haynes manual says there are no serviceable parts in the diff but it does show a replaceable seal on the driveshaft.

Here
www.piaggiospares.co.uk/spares/epc2.asp?ModelID=9534&pageID=25&m=YAMAHA+XJ900S+DIVERSION+DRIVE+SHAFT&uid=0

It appears to show at least two seals

Which seal do you think will be the problem?
Will I need special tools?
Would it be easier to just buy a new diff from fleabay?
Maybe I could just put up with it!

Thanks for any help.

Regards

Ken

[DahDit]

Have you changed the oil in the final drive recently?

[Ken]

Hi Neil, Thanks for your reply.

I did find a thread where changing the oil cured a leak from the breather but the oil in my bike has done less than 2000 miles and is still clean.
Could this still be the problem?

I cannot find another thread on the internet with this problem (D9), surely it would be common if it was just the oil?
Maybe my breather is blocked, is there a way to check this?

I will change the oil this weekend and see if the problem goes away.

Regards

Ken

[HRHpenfold]

It's not a common problem, so uncommon that I suspect that no one will know, I don't,
have you used special oil in it?

maybe getting a used is the answer, then you can have a look at the old one at your leisure

[DahDit]

Hello Ken, reason I mentioned it was I changed the final drive oil once and used synthetic gear oil, thinking I'd be doing the best thing. The seal started leaking, changing back to mineral based gear oil cured the leak.

It may not be the same in your case, but might be worth considering before going through the expense and time spent changing the seal.

[Ken]

Trust me to get the unusual problems

BMW’s seem prone to the problem but I can’t find any reports of this happening to a D9.
I did not use special oil, just standard Comma 80’s gear oil, although it had sat on the shelf for a couple of years.

I’ve bought some fresh Wilkinson gear oil today so I’ll drain the old oil and try new oil this weekend. I’ll let you know if the leak improves.

Thanks

Ken

[CD]

BMWs suffer from collapsed wheel bearings but they dont have an axle spindle so everything pretty much goes through one large diameter bearing. The type used on Diversions is less pretty but a stronger design.

To take off the drive box tie a zip tie around the back end of the drive shaft UJ and loop some string through. Undo the four M8 bolts on the drive case and pull it off the swing arm. If the input bearing feels good with no slack the seal is probably ok as well. When putting the shaft back use the zip tie and string to hold the UJ up while you slide the shaft in place.

The Yamaha service manual (section 6) shows how to rebuild the gear case. Haynes couldn't be *rsed.

[Ken]

Hi.

Thanks Dave, Some very useful tips in there. I do have the Yamaha service manual.pdf and found the instructions for stripping the diff but special tools do need to be made so it will probably be easier to just buy another diff from Ebay.

May 12, 2013 15:33:24 GMT CD said:

If the input bearing feels good with no slack the seal is probably ok as well.

I had the whole swinging arm out 2000 miles ago to change the swinging arm bearings and I did check for play in the diff at the time, - everything seemed OK then.


Today I put some new oil in the diff. I also checked the breather was working correctly.
Took it for a blast and its still leaking.

I stopped to check the temperature of the diff and it’s not getting too hot, it just felt warm after about 20 miles.

I glanced at the mileage while I stopped and it was all 4’s, - Took a piccy
www.dropbox.com/s/bmcw2mz440djwoe/2013-05-14%2015.57.35.jpg

Thanks

Ken

[CD]

The input seal is quite probably a standard size. Its worth measuring it up to see.