My 05 spung a leak at the rear drive seal

[vrodb]

I am new to this forum but am checking to see if anyone has had the main drive shaft seal go out on the rear of the engine where it exits the motor and accepts the universal joint?

I ride an 05 FJR with 9,000 miles. This leak happened suddenly and created a huge puddle of motor oil in about one hours time.

This seal is on the motor side of the universal joint and is under the thin sheet metal u-joint shroud held in place by 3 bolts which are a pain to reach and actually two of them hit the main frame of the bike before they come out all the way.

I had to grind part of the shroud at the holes to get it off in order to remove this seal otherwise it is drop the motor from the frame time.

When I got this leaking output shaft seal pried out of the housing I found a large gland nut (which is about 36mm and tightens against the inner race of a large ball bearing) completely backed off of the threads of the shaft inboard of the seal and in so doing chewed the lip of the seal and the tiny spring all to little pieces. No wonder it was gushing motor oil.

I would like to know why this nut would back off and what will keep it from happening again?

There is a non-threaded lip on the nut, which was bent down into a recess in the threaded shaft to keep the nut tight. This obviously didn’t work out well.

What would generate the counter rotational force necessary to back this nut all the way off the threads and what damage might have occurred by having no loading on the ball bearing?

I will try to get some answers from my Yamaha dealer and the Yamaha Company about this and torque specs for the nut etc. but was just wondering if this is rare for the 05 FJR or a common thing. I often get a blank stare from the dealership about anything FJR as they have little or no experience working on this model.

Any input would help as this would be a drag on a trip or out in the middle of nowhere USA.

In spite of this issue I still love the bike.

Thanks

 

[user 213]

Never heard of that problem before. I have read about a few rear drive seal leaks, but at the diff, not the engine.

So, no YES for you then?

Its probable that the nut was not installed correctly the first time. You might need to get a new nut, or perhaps it will be fine with proper torque and installation.

Good luck.

 

[Constant Mesh]

Service manual shows Loctite for that nut. Also mentions using a 'drift punch' on that nut. I think a drift punch is what ironworkers use to align the holes in two pieces of steel so that a threaded bolt can be installed.

 

[user 213]

vrodb said: "There is a non-threaded lip on the nut, which was bent down into a recess in the threaded shaft to keep the nut tight. "

To me this implies that the drift punch is used to indent the edge of the nut into the shaft. Pretty common way to lock a nut down on a shaft. It may be that it wasn't done hard enough to do the job on the first install.

Your description of a drift punch is not wrong, any form of drift will do that. The "punch" part is more about the notch. A center punch has a point which can go too deep, or damage the nut excessivly. A drift punch has a flat tip, so less damage when crimping the nut in.

 

[vrodb]

Service manual shows Loctite for that nut. Also mentions using a 'drift punch' on that nut. I think a drift punch is what ironworkers use to align the holes in two pieces of steel so that a threaded bolt can be installed.

Thanks for the input. Would you have the torque spec on this nut?

 

[Constant Mesh]

80 ft-lbs, 110 N-m with Loctite.

Manual shows tightening this nut with the shaft removed from the engine. Using a vise to hold the shaft while the nut is tightened and torqued. It may be difficult to properly torque using the engine to secure the shaft. Also the spring damper on the middle drive shaft will allow the shaft to rotate some as you torque the nut.

Not sure you can torque the nut properly without removing the shaft from the engine.

If you have warranty remaining I'd let a professional tackle this problem.

 

[vrodb]

80 ft-lbs, 110 N-m with Loctite.
Manual shows tightening this nut with the shaft removed from the engine. Using a vise to hold the shaft while the nut is tightened and torqued. It may be difficult to properly torque using the engine to secure the shaft. Also the spring damper on the middle drive shaft will allow the shaft to rotate some as you torque the nut.

Not sure you can torque the nut properly without removing the shaft from the engine.

If you have warranty remaining I'd let a professional tackle this problem.

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Thanks for your input Constant Mesh.

I think if I modify the 36mm socket by opening the drive hole in the end so the u-joint will slip through and engage the splines and weld a handle onto the side of the socket I will be able to hold the output shaft from rotating. I will just need some sort of scale that goes to 80 lbs or so hooked 12 inches from the shaft center for the torque setting. I sure don't want to disassemble the motor if I don't need to.

 

[dcarver]

Hit it with a 'calibrated' impact gun and call it good!

 

[FlyingLow]

Hit it with a 'calibrated' impact gun and call it good!

Yeah, that's what I was thinking. This sure sounds like a fluke occurence.

 

[vrodb]

Hit it with a 'calibrated' impact gun and call it good!

Yeah, that's what I was thinking. This sure sounds like a fluke occurence.

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This might be a fluke but the book fix is to drop the motor and dissasemble the out put shaft assebly.

I am a tool and die maker and have built the tools neccessary to torque the thing to 80 ft lbs by holding the splined end thats withen reach with the motor still in the frame. If all goes well the bike will be back on the road tomarrow.

If any one runs into this problem I might be of help so they won't have to resort to the calibrated impact method which would just destroy the drive unit and no room to get into it anyway.