How to check / R&R final drive breather?

rbernie

Member
Joined
Apr 30, 2014
Messages
57
Location
McKinney, Texas
My final drive is weeping diff oil from the axle / cush drive and also misting oil around the gasket that holds the two halves of the drive housing together. If it was just weeping from the cush drive area, I'd assume that it's a simple oil seal replacement - the bike's a 2013 with 45K miles on it and the leak isn't catastrophic yet, so no worries. But the misting around the housing gasket bothers me, and leads me to wonder if I don't have a clogged vent that is building up pressure in the housing and forcing the oil past the seal and gaskets.

How do I check or replace the vent? It almost looks, from the fiche, as if it's a press fit?
 

EricV

Riding, farkling, riding...
2011 Site Supporter
2012 Site Supporter
2013 Site Supporter
2014 Site Supporter
Joined
May 22, 2011
Messages
8,227
Location
Tupelo, MS
You're talking about P/N 2H7-17590-00-00, I assume? Revzilla claims to have (1) in stock for $12.17 - LINK Partshark for $10.84. You know the shipping will kill the low price though. :(
Here are some pics I found indicating that you are correct, it's a slip fit part. Yamaha has been using this same part for a long time.
breather.jpg
breather2.jpg
Not very complicated. Seems unlikely that it would clog, unless you've got some really ugly crud in the diff.

Have you drained the oil and re-filled it? If so, what condition was the oil? And when you re-filled it, did you just pour oil in the fill hole until it started to come out? Or did you spin the wheel and try to get more in?

The "gasket" between the two halves is an O-ring, which makes me think that's very odd that it's misting around that area.

Pictures?

Edit - Some others have done seal replacement - LINK 1 Pinion seal VID Old thread with some interesting reading - LINK 2
 
Last edited:

tntmo

Well-Known Member
Joined
Nov 10, 2017
Messages
649
Location
San Diego, CA
My bike is doing a similar thing, getting a bit of oil film around the gasket. I just drained and refilled the oil, it was perfectly clean. If it keeps leaking I'm just going to order all the gaskets and seals and do a refresh. My bike has 50k miles and started doing this a few thousand miles ago.
 

Cycledude

Well-Known Member
Joined
Jan 29, 2016
Messages
3,997
Location
Rib lake wi
What Eric mentions about over filling the final drive is a very likely cause of the leak, I learned that lesson on my very first shaft drive bike way back in the 80s, drained and refilled it to the proper level and it never leaked again. A little under full is better than over full.
 

jrusell

Well-Known Member
Joined
Aug 23, 2017
Messages
460
Location
Dartmouth, Nova Scotia, Canada
I have never done it myself, but if I was concerned of a pugged vent I would first drain the oil. Using a small hand pump or even a compressor carefully apply a little air up through the drain hole. Should be able to hear air escape through the vent. A little tissue paper around the vent may allow you to see the air flow if you can't hear it. Don't go nuts.

If you ride in dirt/mud a lot I suppose some could be plugging the vent. Spray it with wd40 or some light oil to loosen the crud if you find any. Wiggle a small wire up the seam to dislodge and buildup.

As others have mentioned I doubt it is clogged. Unfortunately seals need to be replaced eventually.
 

Squibb

Well-Known Member
Joined
Aug 10, 2014
Messages
1,064
Location
Bedford, UK
Sounds like a new seal is needed - best not delay IMHO. The law of sod always dictates that the leak will worsen right at the most inconvenient moment.

The breather is easily checked; when you next drain down the FD blow through from the drain point with compressed air along the lines suggested in #5. Then you don't risk crud going the wrong way.
 

rbernie

Member
Joined
Apr 30, 2014
Messages
57
Location
McKinney, Texas
Update: The breather was fine, and replacing the seal was pretty trivial.

I wanted to check the breather because the bike's seen some pretty crappy conditions over its lifetime and I've seen more than one clogged breather from too much road grime and water crossings. But it was pretty spotless, so all good there. One note - you can't really remove it without destroying it (the mushroom cap will pull off the body), so be sure to have the spare on hand first.

Getting the oil seal out was the most fraught part, and even that wasn't bad. The new seal pushed in easily (lubed first all the way around) but I used the mason jar approach to make sure that it was fully seated.
 
Top