Driveshaft noise?

I bought my first Airhead a few years ago ('76 R60/6) and it's been a joy to own and work on. I've put a few thousand miles on the bike (now at 65K). One thing I noticed is that when I am pushing the bike around in the garage (especially in reverse) there is a clunk, clunk noise coming from the rear/final drive area. It also happens when I rotate the rear wheel by hand. There is also a bit of a rubbing(?) noise coming from the rear when I take sharp turns slowly. At first I thought it was just the nature of the beast, never having owned a shaft drive bike before. Well, I've since learned that they don't all do that. I'm planning a cross country trip next summer and would like to know if this is a big deal. Bike seems to run and handle just fine and I'm on a bit of a budget so I'm not really interested in fixing what is not broken, but I don't want it to leave me on the side of the road either. As always, any advice is much appreciated.

u-joint? only time i notice it is when rotating the rear wheel while adjusting valves. It's more through feel than sound.

as for rubbing, is the tire hitting the swing-arm? any scuffs on the tire?

Tire doesn't seem to be rubbing. Maybe rubbing is not the best way to describe the noise. More of a rrrrrr, rrrrrrrr, rrrrrrr sound coming from the rear end when turning.

When I spin the rear wheel by hand I get a clack, clack, clack. Please excuse my ignorance and the cryptic way of describing the sounds but I don't know how else to describe it! Only thing I've done back there is replace wheel bearings. Didn't help...

Prolly no big thang if it's not doin' it when the bike's goin' down the road...with the swing arm unloaded, it's prolly a different angle...I'll bet that's it...

I would be sure that the splines are cleaned and lubed in the final drive. But there is a certain amount of clunk on the u-joints and it is amplified by what YD said...the angle while sitting on the stand versus going down the road.

Photorider, one of the "gurus" will come along eventually and address your question, but for now, let me give you my thoughts.

If I was planning on riding a bike across the country, before leaving, I'd investigate any noise that made me uncomfortable. Its not that hard to pull things apart and have a "look see" at the u-joints. My drive shaft was beginning to "click", and on my bike, they are a known problem. I pulled it and had it rebuilt for peace of mind. Besides, its always more expensive to make repairs on the road rather than in the comfort of your garage.

Tom

I don't think it is normal. I would check it out. It could be a damaged U joint. It could be loose flange bolts. It could be play in the transmission output shaft. Although very rare in an oiled wet shaft housing, it could be a problem with the splined coupling at the final drive.

Peel back the boot and verify that the flange is tight and that the universal joint has NO play. While there, push, pull, and tug to feel for any radial or axial play in the output shaft.

As always, thanks for the replies. I've never pulled the drive shaft but you've given me the courage to have a look!

Take Paul"s response one step further..if you're planning a long trip and never touched the mechanics, this is a good place to learn.

To check for the non-standard "clunk" takes maybe 4 hours, about $70 of parts and fluids, and one special socket for the swing arm lock nuts.

Find the local AirHead chapter and see if they have a Tech Day coming up. You'll very likely find someone who's BTDT and has the right tools..espcially if you have the Air Marshall put out the message before hand.

This is where you watch and learn. You see how to set the valves, balance the carbs, fix some electrical problems, etc. These can be very hands on learning experiences..and a way to make new friends.

My guess would be either the U joint or the drive shaft bolts...but that's why you take it apart...to find out for sure. From your description, we can't tell if the "clunk" is associated with something rubbing metal to metal or from something that came apart and it hitting the inside.

Another test..bike on centerstand..wheel spins freely. Does the sound/vibration from sound come from the front or rear of the drive shaft? Top or Bottom? Grab the top and bottom of the rear tire and try to twist it on all its axis..any movement or solidly mounted? Simple tests can narrow it down.

Using a tip from another member, I went to Lowe's and got their Kobalt 27mm 1/2" drive socket for the swing arm nut...worked great with no modification...just make sure you put some oomph on it when you pull the trigger on your zip gun...

You are smart to solve anything that makes you nervous before heading out on a long trip. You can take things apart, clean up, lube, and check clearances without spending a lot of money. And if you find something wrong, you can either fix it yourself, or take the ailing assembly to someone who can do the job. That will turn out much cheaper than having to rent a car and U-haul trailer to get you home.

If the U-joint bolts are snug and nothing in the U-joint area is loose, I suggest other places to look:

1. There is a spline at the rear of the driveshaft. The male side is a removable part on the final drive. You can access this by pulling the final drive off the swingarm. These rarely go bad, assuming there is lube in the swingarm.

2. The splines on the output of the final drive wear with a step, and often a burr at the inside end of the male splines. As the wheel rotates, the spline can jerk around a bit, especially if the wheel bearings allow any lateral play. If the splines are worn more than halfway through, it's time for a spline rebuild. You remove the crown gear and send it off to one of the repair shops who do spline rebuilds. While you're waiting, you get the female spline and change it on the wheel so that the new parts will match.

3. The bearings in the rear wheel must have correct preload, so that there is no lateral or radial play, and no excess drag. Remember that the bearings control the position of the drive splines.

The correct way to do this is to cut a spacer (a straight piece of handlebar is about right) and use the spacer to snug up the bearings on the axle. Then heat the wheel hub with torches until the bearing pack can be driven out the left side with a rubber mallet. With the bearings out and still snug with the axle in place, see if you can move the outer spacer. It should be just finger tight. If it's too snug that means the inner spacers are too thin. If it easily slides back and forth, it means the inner spacers are too thick. There are a variety of different shims available for adjusting the pack. Then, disassemble, clean, regrease, heat the hub again and drive the whole pack back in from the left.

Obviously, if you find any bearing damage, you'll need to snug them up on the axle to check the play before greasing and inserting the pack.

Note that the outer bearing races must fit snugly into the lands in the aluminum hub. I've had a wheel or two on my sidecar rig where the outer bearing races have pounded out the aluminum lands. That allows the rear wheel to flop around, which not only makes a clunk but also allows the driven spline on the wheel hub to flop around on the final drive splines. The tire can rub on the swingarm.

The fix for pounded out lands is to have a machinist install a steel insert. If it's the RH bearing, that will require some clever machining. I unspoked the hub and took mine to a machinist who inserted a steel sleeve all the way through the hub to give support for both bearings. The other option is to replace the wheel.

So, do a little disassembly, clean, wiggle, and fiddle, and you'll eventually discover the issue. That's the joy of owning an airhead.

pmdave

Driveshaft noise

Not sure where you are in Chicago, but if you decide to have a professional look at it, both ACE Motorcycles & Scooters on Jackson St. and Motorworks on Weatern Ave. Are good shops. I have found especially found Chad at Ace to be especially knowledgeable and reasonable.

I have a 1979 R65 that I bought in Jan 2009 and put on nearly 6000 miles between April and November. Longest ride was 2700 miles between Evanston and New Orleans and back. While I'm mechanically minded, I'm still learning Airheads and I felt much better having an expert look over the bike initially, tuning it, and giving me a baseline from which to compare any changes to. The peace of mind was well worth the $250 ~ $300 or so that was spent.

Randy