Final Drive Output seal - leaking or not

[azazica]

I am not sure if the seal is actually leaking.

I went on a long trip 300 miles and it was half rainy half dry. At the end of the trip i checked the plastic cover on the final drive and looked as it had a little oil on it but nothing under... just some dust on the final drive paint. I was sure that i have a leak. I cleaned up everything and after returning home... 300 miles again ..... i checked the plastic cover again -- no oil on it... i removed the plastic cover and since the weather was really bad .... 300 miles of heavy rain .. i found some water under the cover with an oily feel in it... and with a smell of onion ... but again nothing on the paint... so is it normal? a tiny amount of oil under the cover...

I dont understand .. is it leaking or not... should i change it before the oil change?

This is my first time im doing this... the bike has 13 k miles and i want to change the oil to put around 200 ml ( not 180 or 220 ) because im not sure how the previous owner did the FD.

What do you think?

 

[Bendy toy]

Onion smell hints at FD oil. Just change it and see how it goes.

I put 220ml in mine. There have been no problems and I have a (within tolerance) side play in the bearing.

 

[azazica]

Onion smell hints at FD oil. Just change it and see how it goes.

I put 220ml in mine. There have been no problems and I have a (within tolerance) side play in the bearing.

ok thanks a lot

 

[Bendy toy]

I was prepared to take a risk on the excess oil causing a seepage at the seal. It's been fine for 10K miles. Check the wheel for lateral play. Too much movement in the main wheel bearing could affect the seal.

 

[Sgt Bilco]

The outer seal will leak if it's very hot or at high altitude in my experience but I'm guessing your trip was neither!! It's not a leak as such but more of a misting which looks far worse than it is.

On my trips, we've had a few outer seals which will leak one minute and be fine the next so I do not worry about it too much.

I've only had this once and had to do 4000 miles before I could source a seal and do the job but it never worried me. I fill mine with 180ml which is more than enough to do the job and I've had no issue in the last 75,000 miles so I must have been doing something right. I change it at every service.

 

[azazica]

The outer seal will leak if it's very hot or at high altitude in my experience but I'm guessing your trip was neither!! It's not a leak as such but more of a misting which looks far worse than it is.

On my trips, we've had a few outer seals which will leak one minute and be fine the next so I do not worry about it too much.

I've only had this once and had to do 4000 miles before I could source a seal and do the job but it never worried me. I fill mine with 180ml which is more than enough to do the job and I've had no issue in the last 75,000 miles so I must have been doing something right. I change it at every service.

I guess ill just leave it as it is... change the oil and see. I already have a new one so no problem there.

 

[Bendy toy]

As said, mine is "horrendously" over filled and has had some side play in the bearing for at least the last year. After my last ride (this morning) there was still no sign of any oil leak.

 

[Bobbin-Man]

Change the seal or wipe down and leave alone ......?

 

[Bendy toy]

Mine HAS now started to leak but it's had "within tolerance" side play for about 10K miles.

I could change the seal (it's done 50K) but the wheel bearing isn't totally smooth so it's def past it's best.
I'm sending the whole FD and prop shaft to Mikeyboy. If one bearing is failing the others are likely to be heading the same way.
It also needs a new needle roller on the inside bottom pivot.
Swing arm bearings feel fine but as it's all apart I may change them anyway.
The prop shaft gearbox end (the one with the biggest angular change) is as smooth as. The FD end is not knotchy but is stiff outside it's middle range of travel.

 

[Bendy toy]

That is more than enough to have me at least change the seal. It's on the verge of dangerous with that much oil on the tyre not to mention the brake pads.

Whip the wheel off. Remove the brake caliper and speed sensor, disconnect the top link and let the FD droop down. Dont go too far unless you want the oil to leak out of the speed sensor hole. This free's up the gearbox so you can see how the bearing feels. Mine was not exactly rough but sort of lumpy. Next stage for mine will be the roller cage letting go so best to change the main wheel bearing and seal. As said above, I decided to have the whole thing rebuilt then it should be good for at least another 50K.

 

[Bobbin-Man]

Erm, the bike's currently in Spain .... and I'm not!

I spotted this as I was getting ready to leave for the flight home It had been on its' side stand and the oil had leaked down onto the wheel but avoiding the brake disc. I'm heading out early October to complete my tour, I've had Motorworks send me a new cover and seal and I should have enough tools already with the bike to do the swap if I need to. Does anyone happen to know what the Torx size of the drain/fill plug is?

The FD oil was changed the week before going so I suspect it was maybe over-filled slightly, should be easy enough to just drop a little out. There's minimal play in the bearings and they still feel sweet to rotate so not overly concerned in that respect.

 

[Bendy toy]

A pocket set of torx keys should have one to fit the drain plug. Not much option but to just change the seal.

Mine was filled last year with at least 200ml. The 2013 MOT shortly after cautioned the wheel side play was high but within limits. Its since done at least 10,000 miles with "excessive" oil content and no leaks until this week when I spotted the seal leaking and decided to get the FD overhauled.

It should get you home but I'm not convinced just a little too much oil will do any harm.

 

[Bendy toy]

Mickey has just come back with the news about my FD.

The wheel bearing is shot but the pinion bearing is heading south as well so none of the bearings can be trusted. Total rebuild cost including new bottom trunnions and return post is £450. Used FDs (mostly) cost less on eBay but are they any good?

I'm now very glad I didn't simply get a new wheel bearing fitted. The trunnions should have been regreased, but its a pig of a job to even get the bolt out** so it never got done. As I often moan, it's poor design with needle rollers that cant be greased in-situ.

** Mine was heated to 110C (2KW heat gun and IR thermometer) and lubed with "Plus Gas" but the thread felt all the while like it was close to galling. Its come out OK but no fun at all. Its really not a saturday morning fettling job so gets "forgotten". I very much doubt if mine has ever had any grease since it left the factory.

The bottom UJ is also failing so that's another £90 and I need a new brake disc.

 

[bikemad]

Bloody hell bendy your rear ends well gone by the sound of it lol,cought it in good time mikey will sort it for ya though.
My bike has receipt for shaft rebuild,also had a s/h FD fitted all looked in vgc last week when I had swing arm off,I got given the old one by previous owner too just has leaky input seal ideal for a rebuild if I ever need to

 

[Bendy toy]

I thought about getting a used FD. But eBay sellers don't know what they have and how could anyone challenge the advert mileage claims.
So I've bitten the bullet. Mikey is also going to see about having the case powder coated (£60). It's not bad at all but while it's in bits may as well get it done.

It looks like the back end UJ has a harder time than the top one in spite of the bigger drive angle up top. Or maybe it's the small angle that duffs it up.