1971 R50/5 Whine

[daz]

The whine is NOT coming from the bike but from the owner. I took the bike to AMA Vintage Days in MidOhio. I want to sell or trade the bike for a later R65. I've put only about 50 miles on it since I bought it. And all new fluids, filters, and throttle cables. It ran fine until I took it for a ride there. A terrible grinding, crunching sound coming from the rear! Out of nowhere, all of a sudden. Fact: The speedo quit working. Other facts probably more to the point: The rear drive fluid was totally clear. The transmission fluid was totally clear. The drive shaft fluid was dark and contained some small ferrous particles.

As I move the wheel forward and rearward, there seems to be a clanking from the transmission area. (Which may be normal?) And from the shaft area.

So how do I start the trouble shooting process? Or do these symptoms ring any bells?

[Deleted User 62]

First check if the bolts connecting the u-joint to the transmission output flange are intact. You don't have to remove the boot to do this, just rotate the rear wheel and feel for them through the boot.

[Kurt in S.A.]

Are the four bolts that hold the driveshaft to the back of the transmission still attached? Pull the clamp off the rubber bellows at the back of the tranny and pull the edge back to expose the four bolts.

Kurt in S.A.

[daz]

Tim and Kurt, thank you, I am in your debt. However I don't foresee any ocean voyages in the near future so I can reciprocate and buy you guys some exotic beverage.

One bolt was still partially in. One bolt I found, two not yet.

SO...What's next? The thing is that the bike was advertised as 3500 original miles. The guy who prepared the bike for sale to the bar tending college student from whom I bought the bike was THE MAESTRO, the Leonardo De Vinci of bike prep for sale. Judicial gray spray painting. Everything, as advertised, is original except for the two into one exhaust and the handlebars. Well, as far as I can see. The brake linings were OK. Original air filter, etc. Wavy washers where they should be. However, all the drain bolts, although not rounded off, are rust colored. The fork springs were rusted! I can't figure this thing yet. I've not pulled the cylinders and measured ring end gap yet. I guess that's coming up.

Suggestions?

[Deleted User 62]

Did the last remaining u-joint bolt have a lock washer under it? If so, they are the early longer kind and were prone to coming loose. Replace with the shorter version, no lock washers. I hate to say it, but that noise you heard may have been the loose bolts getting spun around inside the swing arm tube. If they are not in the bottom of the boot, they have probably migrated down the shaft near the rear drive. You'll have to pull the rear drive off to fish them out of the tube if they can't be snagged from the front... All my "original" bikes have come to me with rusty drain plugs, not to worry. I'd just fix what needs to keep it running, don't go too deep in the engine just yet. It may be fine.

[daz]

Thanks. I needed a word of encouragement and a pat on the head. And I figured those u-joint bolts didn't just disappear. No, the whine was from me leaving that huge event with a broken heart from not making some kind of deal. But there was a glimmer of hope because I was free to shoot a National Rifle Association Civilian Marksmanship event the next morning. U.S. Service Weapons. But that was rained out. So until I heard from you guys I was really bummed out. True to human nature, I now see a light at the end of the tunnel. Edit: No lock washer. So...............has that u-joint been tampered with in the past? My gut feeling is that this really cool looking bike has many more miles that I was told. Really not too much of a concern other than I got screwed moneywise. I easily could live with the situation if the po said it had ________miles rather than 3500 original miles.

[Kurt in S.A.]

If the bike was that "all original", wouldn't it have the long bolts with lock washers? I think that was OEM well into the '70s. The service bulletin for this came out in June 1983 and mentions "Lock washers are not needed when repairing motorcycles prior to 1981." That leads me to think that the lock washer arrangement was used into 1980. If that's anywhere true, then someone was into the rear drive before you got the bike.

Kurt in S.A.

[Major Softie]

If the bike REALLY has only 3500 hundred miles, things like rusty fork springs and bolts are still totally possible (since it would have to have just sat for years), but there should be other signs.

A bike with that few miles should show pretty much no wear on any of the rubber parts: foot pegs, shifter rubber, grips, etc.. They may well be rotted and even crumbly, but they shouldn't show "wear."

[daz]

Bad information. I was incorrect about the washers. At first glance the washer appeared to be part of the bolt. So it does have washers.

Also, related to the Major's rubber comment, the handle bars and grips have been replaced. However, the foot pegs both front and back are not overly worn. To compound the enigma, resistor caps, plug wires and coils are original. It's missing the battery hold down. Someone has messed with the wiring in the headlight and disconnected the horn. I suspect the odometer has been replaced. The tachometer and speedometer and dash lights WERE all working. So thanks for all the help fellas. No real proof of anything yet.

[Duane Ausherman]

The whine is NOT coming from the bike but from the owner. I took the bike to AMA Vintage Days in MidOhio. I want to sell or trade the bike for a later R65. I've put only about 50 miles on it since I bought it. And all new fluids, filters, and throttle cables. It ran fine until I took it for a ride there. A terrible grinding, crunching sound coming from the rear! Out of nowhere, all of a sudden. Fact: The speedo quit working. Other facts probably more to the point: The rear drive fluid was totally clear. The transmission fluid was totally clear. The drive shaft fluid was dark and contained some small ferrous particles.

As I move the wheel forward and rearward, there seems to be a clanking from the transmission area. (Which may be normal?) And from the shaft area.

So how do I start the trouble shooting process? Or do these symptoms ring any bells?

When you first found the ferrous particles in the swing arm fluid, this was the notice to you to check the bolts. In any case, those bolts should be checked before you even ride it and now you know why. They were prone to fall out in few miles from the factory. When we prepped a bike for sale, it was standard procedure to pull the boot back and tighten them.

Now you must remove the final drive and clean out the swing arm very well, as it is full of ground up bolt particles.

This is a minor problem and you just need a new set of bolts, gasket and of course oil. Put in a measured amount and don't try to fill so some level that you have heard about. There is no such thing as an "oil level" for the swing arm.

All of this is on the web, so you should read and read more before jumping in. My website includes this info and more.