Rear drive spinning ??

[888GoldDragon]

I have a problem and don’t know where to go next??
I do not think it’s the clutch, I could be in gear and crank the throttle and something spins there’s a slight grinding noise at the rear, something is spinning my RPMs go up, and I have no acceleration, I can back off a little bit it’ll grab it I can get acceleration.
It does not happen during deceleration. Only acceleration.
My u- joint boot is cracked I’m going to put a new boot on however there are no metal shavings in the boot.
I have not taken the u-joint out yet, so I don’t know the condition on the rear of the U joint I need to get a 17mm hex drive first.
The rear engine shaft splines look good
Front u-joint splines look good
Front driveshaft spines look good
Axle splines look good.

My main question I guess is due I take apart the rear end housing to check the splines on the rear of the driveshaft could that be the culprit, or should I definitely remove and change the U joint, or were there be another cause I’m not aware of??

[Andy Cote]

Why are you eliminating the clutch from the discussion?

[888GoldDragon]

Because it happens without the clutch. I can be in the same gear and crank the throttle and it happens. But I have been known to be wrong a few times. That is why I’m asking. Should I be looking at the clutch also,

[Rambozo]

With it running on the center stand and the rear brake locked, put it in gear let out the clutch and see what is moving and what isn't.

[joecoolsuncle]

With it running on the center stand and the rear brake locked, put it in gear let out the clutch and see what is moving and what isn't.

this! put it in 5th gear and see if you can stall the motor at 5k rpm. note: only do this test for a few seconds, as the clutch will heat quickly.

[Earl43P]

Have you disconnected the drive shaft from the final drive?
That will expose the pinion cup and drive shaft coupling, which is what I suspect has failed.
You mentioned a bad u-joint boot; that lets rain/water into the swingarm and if the drive shaft seal to pinion cup is bad, water enters the pinion cup and it'll rust and fail over time.

You should be able to just PULL hard and separate that last joint (pinion cup). None of your photos show that.

[888GoldDragon]

No I have not separated driveshaft pinion cup yet. If the rear of the driveshaft to the final drive is bad, do I replace final drive also or can I rebuild?

[Earl43P]

You can just replace the pinion cup.
Once you access it and determine if it is the problem, clean out the pinion cup and you can see one nut in the center.
Use an electric IMPACT on that nut, both taking it off and installing the new.
Expect to replace the drive shaft and install a new seal as well.

IF that joint is the problem.

[888GoldDragon]

Yes, it looks like that was the problem, pinion gear. It was worn on the edge and no grease left only a thick paste that likes my magnet. Replacement parts on order. Thankyou everyone for the help and input. Hopefully I will be riding again before winter sets in.

[MikeB]

Yes, it looks like that was the problem, pinion gear. It was worn on the edge and no grease left only a thick paste that likes my magnet. Replacement parts on order. Thankyou everyone for the help and input. Hopefully I will be riding again before winter sets in.

This is what my pinion and cup looked like in 2002 on a 1999 GL1500 with a little over 94,000 miles on it.

Back then I didn't know that the pinion and cup needed to be lubed with Moly Grease every 16,000 miles.

[888GoldDragon]

My looks very similar, not as bad. And I have 110 000 miles on mine. Thanks for tip I didn’t know hay had to greased that often.

[joecoolsuncle]

Yes, it looks like that was the problem, pinion gear. It was worn on the edge and no grease left only a thick paste that likes my magnet. Replacement parts on order. Thankyou everyone for the help and input. Hopefully I will be riding again before winter sets in.

pinion gear is inside the final drive, are you referring to the pinion cup?

[888GoldDragon]

Yes. Pinion cup. I checked final drive. It’s looks pristine. As well as pinion gear.

[joecoolsuncle]

k. info like tat helps us common folk. good luck with the repair!

[888GoldDragon]

Thankyou all for your help, Andy you were right. It was a combination of both, pinion cup gear and the slave cylinder. The major problem was the slave cylinder, but when I had all the u-joint, drive shaft and final gear apart it was good to have a good inspection on all of it. The pinion cup gears were worn bad, glad I changed it before it was crucial, and greased everything. Hopefully get some good long rides in before the cold sets in.