Unless you were lucky enough to either buy the bike new, or buy it used from someone who kept every record of service, you don't know what shape your splines are in until you see them for yourself. And for you riders who have older bikes and are thinking you don't need to worry about this...Probably the most ignored and overlooked service item on a shaft drive bike is lubing the splines.
The Background: The VN750 is a great bike as we all know, but there is this "spline" issue that can be a real problem if it goes too long without lube. The problem is many bikes as they were being assembled were not properly lubed. The job was to lube the spline where it slides into the collar on the drive shaft, an area that gets lots of movement in and out as the rear suspension goes up and down, creating a ton of heat and potential wear of the teeth on the spline and collar. Well, apparently, someone was sleeping at the factory between about 2000 and 2006 as the largest sampling of our bikes that were discovered with dry splines were during those years. However, many older bikes have been found with the same dry splines, so it apparently had been missed here and there for the duration of the VN750 run. If the splines are left dry for very long, what you will find is not pretty. You'll find rusty nubs where the spline teeth are supposed to be as well as nubs inside the collar, and instead of a glob of grease when you pull them apart, you'll likely get a pile of red dust, which is the rusty, ground up bits of the teeth that are supposed to be there. If you are one of the "lucky ones", you will find some grease and perfect teeth. Either way, you can't let this go for too long, and checking and lubing them is really not that hard. Plus, once you have them lubed, you have almost zero chance of a failure back there as long as you re-lube them about every 10-12 thousand miles. If you are like me, you may find the teeth are already chewed off and you will need to find a replacement final drive and drive shaft collar. The collar you can order if you have to, for a decent price, but the final drive you will pay dearly for unless you can find one from a 750 that's being parted out. The final drive on my 02 is from an 86 model, so keep that in mind. They are all interchangeable from year to year. So, that's the story behind the spline lube problem... I don't really know for sure that it was a farm boy that did all this, but I'll betcha the real story would go something like that...
I'm going into this for the second time, this time replacing the final drive and the drive shaft coupling, but the procedure will be the same if you're only in there to check and lube your splines. You will see by the photos below, mine were shot and needed replacement, so I found a drive shaft with coupling, and a final drive on Ebay for around $100.
There are several excellent write ups on the 750 site and elsewhere, and I used them to go into mine the first time, but I really could have used photos of the steps to make me feel a little more comfortable. I'm certainly not taking anything away from those who posted writeups on this procedure, because they helped me tons, and now I'm hoping to give back by helping someone else. So this is for the guys and gals, like me, who need the photos!
I would suggest that before you start this procedure you order some replacement O-ring's KAW part # 92055-1044. This is the o-ring that seals in the moly and keeps it from gushing out and all over your final drive and back wheel. You could choose to remove your final drive, remove the o-ring and go to ACE hardware and see if you can match it up from the huge cabinet they have full of o-rings in the plumbing section. Either way, be prepared to replace it and keep a couple extras on hand.
Pliers, Metric Socket set (long sockets needed) or Metric Wrenches (ratcheting wrenches would be cool), 27mm socket (not usually included in a normal set, bought mine at Lowes) good quality Torque Wrench, breaker bar (I use my floor jack handle slipped over my 1/2" Craftsman socket wrench) and Circlip Pliers if you are replacing the drive shaft coupling.
Charlie sent this pic of his tools he used on the lube job. Yeah, that's his cell phone. Email me and I'll give you my number and be glad to help you during the process!
1. Put the bike up on the center stand, with the center stand on a 2x12 or similar size block of wood. This will raise the bike high enough to be able to remove the rear tire and wheel without deflating it. It's a good idea to use a ratchet strap to tie the center stand to the front forks to keep the bike from rolling forward and off the center stand when you are loosening the axel nut. You don't need to tighten the strap too tight, just enough to keep a little pressure on the center stand. Keep an eye on things as you loosen the axel nut to make sure you're not rolling the bike forward.
1A. There have been several suggestions from members on VN750.com that it is easier to first put the bike on the center stand, then have two 2x6's handy and tilt the bike to one side and slip the 2x6 under the center stand leg that is up, then tilt the bike to the other side and slip the other 2x6 under the other leg. If that works better for you, that's the way I'd do it. It certainly isn't easy doing it my way, but I'm used to it. Now we have options!
1B. Another option that has been suggested is to compress the front forks using a ratchet strap through the front wheel and over the handlebars while someone sits on the bike and forces the front forks to compress. Again, if that works for you, and you'd rather do it that way, I'm all for what works!
2. Remove the license plate. This will make more room for removing the tire.
3. Using a 10mm socket, remove the four bolts from the Right passenger foot peg mount. This will give you just a little wiggle room for your right exhaust pipe so you can remove the lower right shock nut.
4. Remove the cotter pin holding the brake drum torque rod nut (B), and then the nut, using a 14mm socket. Then remove the brake rod adjusting nut (A). To make sure I got this adjustment close when re-assembling, I counted the threads showing behind the nut, and made sure the same amount of threads were showing when I put it back on.
5. Remove both lower shock mount bolts with 17mm socket or wrench. Remove the shocks from their bottom mounts and let them hang. You may have to put your foot or leg under the tire to support it as you remove the shocks from their mounts. Then let the wheel hang low.
6. You can see that with the lower shock mounts off, the tire hangs plenty low to reach the axel nut with a socket wrench.
Here is where you need to be careful not to lurch the bike forward and off the center stand. Remove the cotter pin holding the axel nut.
Using your 27mm socket and breaker bar, loosen the axel nut and remove it. Lightly tap on the end of the axel with the plastic end of a screwdriver, or a piece of wood and it should pop loose. You can pull it from the right side and remove it along with the spacer. I laid out a shop towel on the floor to put these and all the nuts and bolts on. I especially wanted to keep the axel and spacer clean. Make note of what order things go here. From the right side, your axel goes through the frame, through a spacer, through the wheel hub and final drive (which has a spacer inside it) out the left side of the final drive, through a washer and then the axel nut. Remember this for re-installation!
7. From the rear, grab the wheel and rock it slightly to the right and it should come off the final drive. Keep a hand on the brake drum so it doesn't fall out, and put the wheel to the side.
NOTE: We've had one 750 owner that had the large circular ring clip come loose when he removed the wheel from the final drive. This ring clip is shown in this exploded view below. (OlHoss's edit 25 May 2013) It holds the drive coupling plate that covers the drive damper
, has the 7 holes in it in the left side of the wheel hub. He didn't get it snapped back in tight and it fell loose again when he put the wheel back on the final drive, and when everything was tightened back up, it was pinched between the final drive and hub, locking the back wheel. Just something to be aware of! (Added 6-22-2011: Discovered by Wib714 in the KAW manual, this area is supposed to be cleaned and lubed, which he took photos of and I've added a link to his post of the photos and description near the bottom of the procedure, so make a mental note to come back here and look at the diagram below and you'll see the large snap ring that has to come off and the parts you need to remove, clean and what needs to be lubed and how it goes back together! Thanks again Wib!)
(Hope you don't mind me making the clarification of what the big snap ring holds in fergy. I can't believe I found even a small mistake in this thread after it being read by virtually every new member who checked in, and re-read several times by those performing the procedure on their own scoots!)
8. Remove the 4 nuts where the final drive is mounted to the swingarm/driveshaft housing and remove the final drive. Note the teeth on the spline of the final drive and the teeth inside of the drive shaft coupling. This is where the grease should be. Mine, unfortunately was dry, rusty, and full of rust powder the first time I went in here, which is why I'm replacing the final drive and drive shaft coupling, as well as lubing everything. You should also replace the o-ring that goes on the spline behind the teeth in this process.
(You don't get to see my rusty splines cause when I found them, I cleaned it up and greased them and put it back together so I could squeeze a few more rides out of it while I waited for my replacement parts to arrive.That was before I did this write-up with photos.)
You can see in the side by side photo, my old one on the left has nearly all the teeth worn off, and the o-ring is pretty flat. You can see that it was letting the grease out into the area around the spline. You can see the replacement final drive on the right and the fatter o-ring, and good teeth.
Because of the 10 image limit on postings, this is continued in Part 2...