Will an 84 gl1200 differential and drive shaft work in an 86?

[jcall22000]

I bought an 84 gl1200 differential and drive shaft thinking that it would fit in an 86. Running the engine in 1st gear, the rear wheel won't turn.

Three questions: is the 84 drive shaft the same as the 86?
Is the differential the same? I'm assuming yes, since the 86 wheel spline fits correctly and turns the differential.

If everything is correct, what am I doing wrong? This is the first time I've changed out the differential on a GW.

Thanks for any help.

[HALBUDD]

Im not sure about the match up from 84 to 86 but my question is this are you sure that you have the drive shaft inserted in the u joint? If you can pull back the rubber boot and look to see if the drive shaft is in the u joint. It can be a little hard to get the drive shaft to go in to the u joint even if you have it all back together the shaft could be out of the u joint.If you put the bike in 1st gear and try turning the rear tire while on the center stand if she moves freely then it tells me that the wheel is not hooked to the transmission. Im guessing that the drive shaft coming out of the rear of the motor is turning when you put it in gear. I have replaced my drive shaft and rear drive off of an 84 into an 85 without any problems. Good Luck-----------------Hal

[jcall22000]

Quick question:

This is the first time I've replaced a differential. Do I need to drop the swingarm to see the boot?

Looking at the final drive schematic, don't get how I can see the boot without doing this.

Thanks for walking a newbie through this...

[HALBUDD]

You dont need to drop the swing arm to get to the boot.If you look on the right side of the bike you will see the rubber boot at the rear of the motor. It is attached to the drive shaft guard,you can pull it back to expose the u joint and see if the drive shaft is inserted into the u joint.If it is not then you will need to pull the wheel and drive off and try it again.-----------Hal

[jcall22000]

I pulled the boot back, and, yup, the ujoint wasn't attached to the engine spline. I pushed it on with a piece of pipe through the swingarm, put the boot back on, and am reassembling. BTW, on an 86 GW, there's a welded piece of metal inside the swingarm pipe that doesn't allow the ujoint to come through the swingarm. You have to put the driveshaft onto the attached ujoint...

Thanks much for the advice...don't know that I could have done the job without it.

[HALBUDD]

Glad to be of help just make sure you get the drive shaft into the u joint when you put it back together. It can be a **** to get the shaft in to the joint. Good luck--------------------Hal

[jcall22000]

Now that I've done this once, I'll summarize for everyone out there. If you another method, please list it.

Hopefully this helps the repair with minimum pain.

For all gl1100s, gl1200s, use Honda Moly 77 assembly grease to grease the FD spline, the wheel spline, and drive shaft splines during reassembly:

1) Take the wheel off, check the wheel spline and FD spline for wear. Replace the FD and/or wheel spline as necessary.
2) Remove the FD, remove the drive shaft, check the splines at each end. Replace as necessary.
3) To reassemble, on an 86 where the ujoint is blocked from moving down the swingarm tunnel:
a) put the transmission in gear,
b) raise the swingarm until it's level (it makes the attachment to the ujoint easier)
c) open the drive shaft boot between the swingarm and the rear of the engine, on the right side of the bike.
d) the ujoint should be on the engine/transmission spline, flush with the rear of the transmission.
e) if the ujoint is off the spline, center the ujoint and start the ujoint onto the spline.
f) grease the drive shaft splines, input it into the swingarm tunnel, and start it into the other side of the ujoint. You can raise the ujoint/ds spline by inputting a flat blade screwdriver and moving it up/down. You'll know it's in the proper position when pushing the drive shaft to the spring detent causes the shaft to rebound.
g) double check that the ujoint is still centered on the transmission spline. If not, center and start it.
h) on the FD side of the drive shaft, hit it with a rubber mallet to drive the ujoint onto the transmission spline. Youll know when you check the ujoint which is now flush against the transmission case.
i) Reattach the boot, bolt on the FD
j) Grease the wheel spline, attach the wheel and brake calipers , and reassemble the back side of the bike.

[jcall22000]

I just put an 84 differential into an 86. The drive shafts are the same; the ebay seller included the 84 shaft; comparing to the 86 shaft, no difference. However, on an 86, the wheel spline is larger than the 84 differential spline. You NEED an 84 wheel spline, or it won't work. And the 84 wheel spline will fit on an 86 wheel.