Can a novice Mechanic remove and service the Driveshaft/Gear Coupling/Final Drive? Constant puddles of drive oil under the drive shaft

[SurvivorGuy]

Constant puddles of drive gear oil pouring out of the weep hole, sometimes huge puddles, yet when I check the level of fluid in the read differential it's at the level. I am baffled by what is occurring. I have run low on gear oil but, not what one would think considering the amount pours on the ground.

Thinking I need to service the final drive. I found this thread on this site. I'm a novice mechanic..

http://www.bikes-n-spikes.org/maint/spline/SkooterG/coupling101.html
I would hate to start the process and not finish it

What are the parts needed to fix these issues

Apologies ahead of time as it appears there have been a lot of threads on leak driveshafts

 

[infrared]

SurvivorGuy,

Before doing anything else, engage first gear and put the bike up on the center stand. Remove the upper (filler) plug from the Final Drive and put an oil catch pan on the floor under the rear drive. Go and do non-bike other stuff for half an hour. When you return, see if any hypoid oil has come out of the Final Drive filler hole. If so, then relax; the Final Drive was overfilled, and your "leak" was just excess oil escaping at the FD assembly vent. Wipe away any oil at the filler hole. Replace the filler plug, and all will be good.

It is very easy to overfill the Final Drive with hypoid oil. Just rotate the rear wheel as (or before) you fill the Final Drive, and an overfill is guaranteed, with oil "leaking" as a result. You did put the bike into gear before the check, to avoid turning the rear wheel while making make this check.

If no hypoid oil comes out of the filler hole after half an hour, and you know the FD was filled correctly lately, see how much hypoid oil it takes to refill the FD correctly. If the FD needs more than an ounce or two, then you have a leak. Clean away any oil on the outside of anything, and spray the area with aerosol body powder spray. Monitor the powder on these surfaces closely, and the powder will show you where the oil is leaking, before oil can get all over everywhere. Repeat the clean-and-powder trick as needed to nail down the location.

 

[mshrout]

ditto what infrared suggested. if you determine it is a leak, appears most likely the input shaft seal to the rearend. in auto terms, this would be the pinion seal. its easy to get to and make additional inspection. remove rear wheel and unbolt those 4 nuts, and very gently remove the rear end off the shaft. now you can make a further inspection on the rear end alone. if the seal is wet, then you can either replace the seal yourself or take the unit to a bike shop with part and they can install for you. don’t forget to drain rear end and refill . check the parts fiche on any bike internet site. I usually use RMATV for my go to parts, it will be under OEM Parts. good luck.

 

[rbentnail]

I have replaced the final drive input shaft seal. It is NOT a novice job.

 

[Bounce]

Several Write Ups here from several people. Specifally check the stuff about Final Drive 101 and Servicing of the driven splines, the drive shaft, and the U-joint.

https://www.fjr-tips.org/maint/maint.html

 

[SkooterG]

A leak of the FJR final drive of your magnitude is very rare. But it can happen and there are a lot of different seals that can be causing it. But most likely, the driveshaft seal that you linked to. It is very rare for the final drive fluid to leak enough to form a puddle so I think you have an issue. What is your schedule like? If you ride it over here to my place in near northeast Phoenix I can help remove the final drive to take a look at it. I have a lift!!! Unfortunately, I am about to be busy and gone for a week over the holidays.

 

[RossKean]

Is that, by any chance, a crack in the casting? If so, your problems may be more than a rubber seal.
Hard to tell for sure and it doesn't especially look like lube has come out in the area I highlighted but perhaps elsewhere?
If that is the case, look on ebay for used final drive units...

 

[SurvivorGuy]

SurvivorGuy,

Before doing anything else, engage first gear and put the bike up on the center stand. Remove the upper (filler) plug from the Final Drive and put an oil catch pan on the floor under the rear drive. Go and do non-bike other stuff for half an hour. When you return, see if any hypoid oil has come out of the Final Drive filler hole. If so, then relax; the Final Drive was overfilled, and your "leak" was just excess oil escaping at the FD assembly vent. Wipe away any oil at the filler hole. Replace the filler plug, and all will be good.

It is very easy to overfill the Final Drive with hypoid oil. Just rotate the rear wheel as (or before) you fill the Final Drive, and an overfill is guaranteed, with oil "leaking" as a result. You did put the bike into gear before the check, to avoid turning the rear wheel while making make this check.

If no hypoid oil comes out of the filler hole after half an hour, and you know the FD was filled correctly lately, see how much hypoid oil it takes to refill the FD correctly. If the FD needs more than an ounce or two, then you have a leak. Clean away any oil on the outside of anything, and spray the area with aerosol body powder spray. Monitor the powder on these surfaces closely, and the powder will show you where the oil is leaking, before oil can get all over everywhere. Repeat the clean-and-powder trick as needed to nail down the location.

Hi Infrared.

I followed your steps, my FJR is an AE. I put the bike on the center stand, put it in 1st gear, and let the tires spin for a few rotations. I turned off the motor with it in 1st gear. I removed the rear fill plug on the RD and let it sit for an hour and when I returned there was no gear oil on the pan below. I let it sit for a day and nothing came out.

It only took less than a few ounces to fill it back up.

The leak always appears to come from the weep hole or the overflow at the bottom of the drive shaft. Could there be an internal issue that would cause the oil to flow out of the overflow? I can not imagine this is normal as it leaves massive puddles, way more than what I am putting in.

How often does the rear differential fluid need to be topped off?
Are puddles of drive oil common under our machines?

I appreciate your in-depth response. thank you very much!

 

[SurvivorGuy]

A leak of the FJR final drive of your magnitude is very rare. But it can happen and there are a lot of different seals that can be causing it. But most likely, the driveshaft seal that you linked to. It is very rare for the final drive fluid to leak enough to form a puddle so I think you have an issue. What is your schedule like? If you ride it over here to my place in near northeast Phoenix I can help remove the final drive to take a look at it. I have a lift!!! Unfortunately, I am about to be busy and gone for a week over the holidays.

SkooterG: I know there is something wrong. There are constant puddles. I would greatly appreciate your help in repairing this issue. I will PM your my number and am stoked to work with you and around your schedule. I was also thinking the universal joint should be replaced.

 

[RossKean]

How often does the rear differential fluid need to be topped off?
Are puddles of drive oil common under our machines?

There should NEVER be a need to top off the rear drive fluid. Level simply DOES NOT drop a measureable amount in tens of thousands of miles.
There should NEVER be puddles (or even occasional drips) under the bike - from any source.

It only took less than a few ounces to fill it back up.

A few ounces is a lot. It really doesn't hold a lot.

 

[SurvivorGuy]

There should NEVER be a need to top off the rear drive fluid. Level simply DOES NOT drop a measureable amount in tens of thousands of miles.
There should NEVER be puddles (or even occasional drips) under the bike - from any source.


A few ounces is a lot. It really doesn't hold a lot.

It is obvious, I have an issue.
I just topped it off and it started flowing out of the overflow. Looking forward to meeting up with ScootG to pull it apart and repair whatever it is..

 

[juniorfjr]

If Skooter can't get it fixed, take one of his. I think he's got 6 or 7 laying around.

 

[infrared]

It is obvious, I have an issue. I just topped it off and it started flowing out of the overflow. Looking forward to meeting up with ScootG to pull it apart and repair whatever it is..

SurviverGuy,

I am curious about the results you see with the aerosol body powder spray process. Where is the leak, really? Oil should not be coming from the vent, unless the Final Drive was over-filled. You already know how to prevent that mistake. An actual oil leak from the Final Drive is a very rare occurrence with the FJR.

As mentioned in an earlier post, it may be worthwhile to get a good used Final Drive from eBay or similar sources. Search by Part Number. If nothing appears, then Search by Part Name. I would purchase a Gift Card to make any payments, with no more money deposited to the Gift Card than the purchase price, but even then, only if you trust the seller to deliver on the sale or use PayPal. Swap the good FD into your bike. No need for a lift; this is all a center-stand job. Ride on.

You can tear down and repair the leaking FD that you have (if any repair is possible) at your convenience. A cracked housing would probably be a total loss failure, but that loss can be more tolerable to you if your bike still rides like new. If you can repair the original FD, then you can keep it as a spare, use it again, or sell one FD as you wish.
My US$ .02 worth . . .

 

[infrared]

SurvivorGuy,

The only other cause that I can imagine for a "leak" may be caused by the type of gear oil that you use. Yamaha makes a special gear oil for the FJR Final Drive, specifically to resist the shearing action of the hypoid gears. Other oils may possibly cause foaming, or other problems, but we can't say that for sure. You need very little FD oil for each FD oil change, so I suggest using the Yamaha product, if you are not using it already.
https://www.amazon.com/Yamaha-ACC-SHFTD-EX-00-Yamalube-Shaft-Exclusive/dp/B0081837YO

 

[RossKean]

The Yamaha gear lube is stupid expensive but, as infrared mentioned, it doesn't take very much so it amounts to a totally insignificant maintenance cost. On the other hand, many (most?) people use the Mobil 1 75W90 synthetic gear lube (or equivalent) without issue. I change my rear drive fluid once per year or so using a non-Yamaha synthetic gear lube and haven't had a problem in more than a dozen years and 450,000 kilometers on two different Gen II FJRs. Never had a leaky seal.

Did you have a look for a possible crack in the casting as I highlighted, above?

I just topped it off and it started flowing out of the overflow.

When you say "overflow" are you referring to the fill hole (where plug #25 goes) or the vent on the top of the drive (#27)? Or is it flowing out elsewhere?

(Should be filled via #25 without turning the wheel. Fill to the brim of the filler hole - requires just 0.21 US qt. or 6.7 fluid ounces from empty.)

 

[Ignacio]

I just topped it off and it started flowing out of the overflow.

Thanks Rosskean for the picture to reference....because I'm confused too.

It sounds like SurvivorGuy is saying they filled it in the #25 and #26 hole to where it's just at the top of the threads and it immediately started overlfowing out of #27 that's 2 or 3 inches higher......without ever turning the wheel.

Something still doesn't compute here.....

 

[RossKean]

It sounds like SurvivorGuy is saying they filled it in the #25 and #26 hole to where it's just at the top of the threads and it immediately started overlfowing out of #27 that's 2 or 3 inches higher......without ever turning the wheel.

Yeah, I'm definitely not understanding something. Although #27 is a separate part, it is a vent that is not designed to be easily removed. (Freeze fit, I think)

 

[BigOgre]

Isn't there a weep hole underneath near the acorns?

 

[SkooterG]

No, he said the leak always comes from the 'weephole', or 'the overflow at the bottom of the driveshaft'. He is talking about the weephole on the bottom of the swingarm near where the FD bolts on. As he shows in the photos above. If that is the case, that narrows down the problem root causes quite a bit. I may not be able to repair it, but I can help properly diagnose it if nothing else.

Choice of gear oil has nothing to do with it. Nor a cracked case. It is leaking past a seal. Plain and simple. And while you can remove the wheel and FD assembly on the C-Stand, let me tell you it is a hell of a lot easier on the back when on a lift!

 

[Ignacio]

No, he said the leak always comes from the 'weephole', or 'the overflow at the bottom of the driveshaft'. He is talking about the weephole on the bottom of the swingarm near where the FD bolts on.

Thanks for the pointing out. I didn't study the pictures in detail enough.

To the OP, Skooterg is one smart fella! I'd listen to him.