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Drive shaft noise ??
- Thread starter 40427
- Start date
bikerfish1100
New member
personally, for the ~$20 savings over the rebuild, i'd have avoided the gamble and opted for a "better than new" rebuilt shaft.
barron_williams
Monza Blue 1974 R90/6
What about just loosening the clamps so you can get the boot out of the way and check for loose bolts, play in the u-joint, or the joint hitting the swing arm?
That should either confirm or eliminate some highly probable causes and you haven't really done too much you can't easily reassemble?
Then, if no fault found, drain the oil to see if anything else comes out and report back.
Barron
I'll chime in here since I had a similar posted problem last week. (posted under "u-joint inspection") Mr Williams above is giving excellent advice. I chased a knock from a suspected bad u-joint for a week, before I discovered it was the u-joint hitting the side of the opening on the swing arm. I should add that I had to reassemble the swing arm in the frame and attach the drive shaft to the transmission, without the rubber boot in order to see this. Then by turning the drive shaft slowly I could see it hit. I hope your problem is as easy to fix.
This may be just personal but I view the use of locktite on the driveshaft screws as a bad idea.
In the life of a machine one must/should remove the transmission at reasonable intervals to clean and lube the splines and to clean or replace clutch disks and other problems that may crop up with the trans or driveshaft.
The job of removing and replacing the screws is made unnecessarily difficult with this thread goop preventing the easy turning of the screws by fingers alone after loosening with a wrench.
Although I have found loose or missing screws on junkers I have dissassembled for parts I have never had a loose screw on one I assembled reusing screws dry cleaned screw and thread it enters with spray carb cleaner and tightened in pattern of opposites with original tool kit box wrench finished with a light/moderate blow with a hammer on each. If the screw will turn out with fingers after loosening there is no stretch and I see no reason not to reuse it. Since almost all screws I have removed from many salvage machines will screw out with fingers I assume no thread goop was used by factory and none is necessary on assembly.
In the life of a machine one must/should remove the transmission at reasonable intervals to clean and lube the splines and to clean or replace clutch disks and other problems that may crop up with the trans or driveshaft.
The job of removing and replacing the screws is made unnecessarily difficult with this thread goop preventing the easy turning of the screws by fingers alone after loosening with a wrench.
Although I have found loose or missing screws on junkers I have dissassembled for parts I have never had a loose screw on one I assembled reusing screws dry cleaned screw and thread it enters with spray carb cleaner and tightened in pattern of opposites with original tool kit box wrench finished with a light/moderate blow with a hammer on each. If the screw will turn out with fingers after loosening there is no stretch and I see no reason not to reuse it. Since almost all screws I have removed from many salvage machines will screw out with fingers I assume no thread goop was used by factory and none is necessary on assembly.
krpntr
New member
another source of noise
Are the rivets in the rear wheel intact? The ones that unite the spline assembly to the wheel. They can work their way loose ya know. Please don't ask how I know this.
I bought a new swing arm/drive shaft for about $150. Simple to install, just be careful when centering it in the frame or it will knock.
Are the rivets in the rear wheel intact? The ones that unite the spline assembly to the wheel. They can work their way loose ya know. Please don't ask how I know this.
I bought a new swing arm/drive shaft for about $150. Simple to install, just be careful when centering it in the frame or it will knock.original
Why couldn't the original U joint just be pressed out and a new one pressed in.I realize that they are staked but that could be ground off and re done instead of that gargoyle welding of the washers.I can see on my bike where the U joint started to move,the tube was damaged a bit and braised but the U joint was pressed back and restaked.???
Why couldn't the original U joint just be pressed out and a new one pressed in.I realize that they are staked but that could be ground off and re done instead of that gargoyle welding of the washers.I can see on my bike where the U joint started to move,the tube was damaged a bit and braised but the U joint was pressed back and restaked.???
bikerfish1100
New member
i agree with your assessment of the threads and screws being good if easy to turn by hand.
the reason loctite is now recommended (certainly by mechanics, if not officially by BMW) is that original setup used bolts with lock washers to hold them in place. However, over time, BMW saw that the washers were cracking, splitting apart, and ending up in the bottom of the boot, with a now loose bolt trying unsuccessfully to hold things together. thus, a new length bolt was spec'd, along with application of loctite.
do as you wish, but i like blue loctite for this application. a few more spins with the wrench vs fingers is no big effort, especially as compared to what happens if the bolts start backing out.
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Yesterday I bought a mechanic's stethoscope to get a better listen to the drive line.
Rotating the wheel now , the klunk is gone ??
I think i scared the poor old thing threatened to sell it and get a Honda
Any way, we pulled the boot back checked the U Joint for slop = none
Bolts were all tight.
Tried rotating the wheel in all 5 gears , no klunk.
Started the engine and ran it through all the gears on the center stand ( no lectures please) the only noise we got was some clutch chatter.
Held the rear brake on tight and put it in gear , let out the clutch in all 5 gears trying duplicate the noise. = no joy.
At this point it has been suggested the spring in the rear may be broken so a complete dissasembley is on order for Monday.
Will report findings then.
Rotating the wheel now , the klunk is gone ??
I think i scared the poor old thing threatened to sell it and get a Honda
Any way, we pulled the boot back checked the U Joint for slop = none
Bolts were all tight.
Tried rotating the wheel in all 5 gears , no klunk.
Started the engine and ran it through all the gears on the center stand ( no lectures please) the only noise we got was some clutch chatter.
Held the rear brake on tight and put it in gear , let out the clutch in all 5 gears trying duplicate the noise. = no joy.
At this point it has been suggested the spring in the rear may be broken so a complete dissasembley is on order for Monday.
Will report findings then.
"Tried rotating the wheel in all 5 gears , no klunk.
Started the engine and ran it through all the gears on the center stand ( no lectures please) the only noise we got was some clutch chatter.
Held the rear brake on tight and put it in gear , let out the clutch in all 5 gears trying duplicate the noise. = no joy."
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If all these tests were conducted with bike on centerstand and no clunk that might indicate clunk is a load related problem.
Roll the bike around on its wheels while listening and report.
If clunk only while on wheels then probably related to rear wheel cup splines being stepped from wear or wheel bearing problem.
Started the engine and ran it through all the gears on the center stand ( no lectures please) the only noise we got was some clutch chatter.
Held the rear brake on tight and put it in gear , let out the clutch in all 5 gears trying duplicate the noise. = no joy."
==================================
If all these tests were conducted with bike on centerstand and no clunk that might indicate clunk is a load related problem.
Roll the bike around on its wheels while listening and report.
If clunk only while on wheels then probably related to rear wheel cup splines being stepped from wear or wheel bearing problem.
44006/ we did roll it around the garage and did not hear anything.
Fired it up and rode in the neighborhood also.
We still feel a catch or a bump when rotating the wheel , no noise, just a slight catch /bump.
Plan to take it to my friends shop and rip the back end off the bloody thing Monday. Something is not right back there and by jinkies i'll find it !
Fired it up and rode in the neighborhood also.
We still feel a catch or a bump when rotating the wheel , no noise, just a slight catch /bump.
Plan to take it to my friends shop and rip the back end off the bloody thing Monday. Something is not right back there and by jinkies i'll find it !
helmut_head
New member
That catch/bump is likely inside your transmission. How does your trans magnet look?
One good test would be to remove your FD and with the trans in neutral, rotate your driveshaft. If it clunks, and there are no witness marks on the universal or shaft housing, likely it's in the trans. Then if you are still not convinced, pull the driveshaft from your trans and spin the output shaft and you will likely feel it inside the trans.
I was skeptical that I needed to spend $$ on a rebuild until I did all this. Now with the trans rebuild, that hanging up, bump sensation is eliminated.
One good test would be to remove your FD and with the trans in neutral, rotate your driveshaft. If it clunks, and there are no witness marks on the universal or shaft housing, likely it's in the trans. Then if you are still not convinced, pull the driveshaft from your trans and spin the output shaft and you will likely feel it inside the trans.
I was skeptical that I needed to spend $$ on a rebuild until I did all this. Now with the trans rebuild, that hanging up, bump sensation is eliminated.
I doubt it's a weight issue, I am holding at a pretty steady 173lbs ( that's down 15 lbs thank you very much)
I travel fairly light and am pretty sure the bags were not overloaded.
The rear mono shock is original and on the list for replacement any way.
If it is a transmission problem I may sell the bike and let someone else deal with it.
I changed the transmission, rear end and drive shaft fluids less than 1500 miles ago and they all came out clean as new, no swarf on any of the drain plugs.
Not sure i want to commit that much money in to a 27 year old motorcycle.
I travel fairly light and am pretty sure the bags were not overloaded.
The rear mono shock is original and on the list for replacement any way.
If it is a transmission problem I may sell the bike and let someone else deal with it.
I changed the transmission, rear end and drive shaft fluids less than 1500 miles ago and they all came out clean as new, no swarf on any of the drain plugs.
Not sure i want to commit that much money in to a 27 year old motorcycle.
ISAMEMON
Grammarian no, Rider yes
I doubt it's a weight issue, I am holding at a pretty steady 173lbs ( that's down 15 lbs thank you very much)
I travel fairly light and am pretty sure the bags were not overloaded.
The rear mono shock is original and on the list for replacement any way.
If it is a transmission problem I may sell the bike and let someone else deal with it.
I changed the transmission, rear end and drive shaft fluids less than 1500 miles ago and they all came out clean as new, no swarf on any of the drain plugs.
Not sure i want to commit that much money in to a 27 year old motorcycle.
I too have an 85 R80Rt adn love it, the best airhead I have owned. So yes at times it is hard to put money into a 27 year old bike
nope does not sound like a weight issue on your end, thtas a good healthy weight. the oem rear monos dont have a very good life span. I had to rpelace mine when I got the bike. at 51k
however it is a model with the famous tranny circlip missing, and it just very well might be the tranny bearings moving around since the circlip is not there to hold stuff in place. Tha is another issue I had to deal with shortly after getting the bike, works rear shock, tranny overhau at 60k
If you can make the catch/bump happen at will by rolling the bike or rotating the wheel the stethescope should tell you where it is coming from - trans - shaft - rear drive.
Something described as a catch or crunch that gets better with time is often part of a bearing cage going through the works of trans or rear drive but looking at the oil should confirm or rule this out. It is surprising how far one of these things will run with a bearing coming apart before final damaging failure as long as there is gear oil present.
Something described as a catch or crunch that gets better with time is often part of a bearing cage going through the works of trans or rear drive but looking at the oil should confirm or rule this out. It is surprising how far one of these things will run with a bearing coming apart before final damaging failure as long as there is gear oil present.
