I've got the dreaded leak...

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Mad German

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I noticed a tiny amount of fluid on the weep hole on the swingarmast night. It's the same color as the final drive fluid, so I'm assuming that one of the seals is on its way out. The bike is a 2008 with only 10K miles on it but I'm not sure of the maintenance history before I got it. Even though the miles are low, it's s till a 7 year d bike with 7 year old parts.

I'm hoping it's the seal that's held in place with the circlip and washer (I forget the name of that seal). Does that seal spin with the driveshaft, or does the driveshaft spin on that seal?

Also, I've read the threads about replacing this seal, it seems very straight forward, but I recall one gentleman having issues getting the new seal on the shaft without damaging it. Are there any tricks to getting this seal in place without nicking it or compromising it?

Thanks guys. If you have any tips to pass along, I'm all ears.

Cheers,

Scott

 
That leak can occur with an overfilled final drive. With bike on center stand and level, gear oil should be at the bottom brim of the filler hole below the threads. Remember, the plug only requires 17 ft-lbs of torque.

 
Thanks for the tip Tom. I'll have a look at the level tonight. I didn't think it was possible to overfill the differential. If I overfilled it, how would the fluid make it out through the weep hole? How does the vent in the top of the differential work? Is that cap screwed on or is it pressed on?

This is my first shaft driven bike, so apologies upfront for the questions.

 
I think the main thing is that it seems unlikely that you'd have a leak after only 10k miles. Sure, there could be a freak instance, but given the FJR's record of general reliability with regards to the final drive in this forum, it would be very unusual to see something that early.

 
Mine has signs of a slight seep. I'm not going to worry about it.

If it ever turns into a drip, I'll open it up.

(To be honest, I never looked until you posted this.)

 
Scott,

I would not panic yet. Keep an eye on the final drive fluid level for a while, and see if the "leak" stabilizes. This problem could be just a matter of over-filling the last time, or possibly oil foam, if the rear drive fluid is not quite all it should be. Worst case, at least before I got out all the tools, would be to drain the drive assembly and refill with Yamaha's new magic rear drive oil (the factory now admits the OEM gear lube, which my 2008 came with new, was not the best stuff for the FJR). That rear drive needs gear oil that has the best of anti-shearing qualities. You may be seeing "worn-out" oil (for lack of a better term) that is passing a good seal, where the right new oil would not. Now I am no oil expert, but my opinion comes from Yamaha's explanation of some rear drive failures, which they blamed on oil shearing. They do have a new oil formula (so I am tempted to believe it was needed) for the rear drive. A quart bottle was pricey, but it's enough for several changes. That time interval is so long, I think the price was not a major concern.

Cheers,

Infrared

 
I drained and refilled the diff after I got the bike. However, now that I think of it, when filling it, I filled it until the fluid was pouring out of the full hole, then put the plug in. Is it possible that by doing so I put in a little more than I should have? I assumed the level was correct, but maybe I need to drain a little out and fill it til it barely touches the full hole threads?

Your thoughts?

 
I drained and refilled the diff after I got the bike. However, now that I think of it, when filling it, I filled it until the fluid was pouring out of the full hole, then put the plug in. Is it possible that by doing so I put in a little more than I should have? I assumed the level was correct, but maybe I need to drain a little out and fill it til it barely touches the full hole threads?
Your thoughts?
In the words of many here, "Ride more, worry less." ;)

You probably just overfilled it a bit. If it starts actively dripping, I'd be concerned, but otherwise, no.

 
If you filled it while (or just after) rotating the rear wheel, it will be over-filled. the level drops as the wheel is rotated since the lube gets distributed over all of the gears. An overfilled rear drive unit will leak.

 
Scott,

Found it. The factory's "new and improved" rear gear lube is this:

Yamaha ACC-SHFTD-EX-00 Yamalube Shaft Drive Oil Excl 32Oz; ACCSHFTDEX00

If you COPY and PASTE that line into the Amazon.com website, they will have it. with free shipping.

Cheers,

Infrared

 
Thx for the help so far, guys. So, if I did overfill it (I'll check later tonight), how could that cause a leak at the weep hole? Would it be from too much pressure against the oil seal, thus causing a little to slip by?

The oil seal looks like it has a spiral molded into it. I'm assuming that's to allow any fluid that might get behind the seal to be "pushed back" towards the differential?

 
That weep hole is a vent. Heat causes expansion, and too much fluid expands beyond the vent...thus a "leak." From what you posted, yes, you overfilled it, and what you're seeing is normal.

 
OMG, just use the Valvoline synthetic 75W-90. It is GL5 gear lube and is about $28/quart. It'll last like 4 changes.
HRZ,

Exactly the right stuff, one quart from Yamaha costs US$26.88 through Amazon, and you don't even need to leave the house. Shipping is free. Your choice, of course.

Cheers,

Infrared

 
That weep hole is a vent. Heat causes expansion, and too much fluid expands beyond the vent...thus a "leak." From what you posted, yes, you overfilled it, and what you're seeing is normal.
Yet another way to say, "Stress less, ride more." Maybe the OP will heed the cluster of sage advice he keeps being gifted.

 
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Well, I didn't know the Yamaha official **** is only $26.88 per bottle. Learn something every day. However, I don't remember what I paid for my Valvoline.

 
I drained and refilled the diff after I got the bike. However, now that I think of it, when filling it, I filled it until the fluid was pouring out of the full hole, then put the plug in. Is it possible that by doing so I put in a little more than I should have? I assumed the level was correct, but maybe I need to drain a little out and fill it til it barely touches the full hole threads?
Your thoughts?
Yes. As I said above, just fill it to the bottom of the threads while on the center stand. I also use the Valvoline, or Mobile 1 synthetic 75-90. Doesn't really matter, the vent is there to solve the problem you created. Soap and water will solve the symptoms.

 
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