drive train vibration during deceleration

[Gary Lich]

Halfway through a ride last weekend on my GS1100GK I noticed a distinct vibration/buzzing/growling noise. It was only apparent during deceleration at ~40+ when the thottle is closed ....When I pull in the clutch the noise quickly fades away. It seams to be coming from the left side near the final drive but it was difficut to pinpoint. I pulled the rear wheel to check the splines in the hub. The splines were not completely dry (greased about 5K ago) and there was some wear visible on both the hub splines and drive ouput splines but not excessive. (I replaced the hub spline after it failed ~8K ago) I searched the posts and couldn't find too much else that was related. Anyone else experience this or have some throughts on the cause???

 

[bwringer]

Check the secondary bevel gear. This is the doohickey on the back of the engine that bolts to the driveshaft.

Peel the rubber boot back a bit with your fingers and see if any of the metal bits are wiggly.

 

[willie]

I lean towards it being a secondary trans output shaft problem. I hope I'm wrong. While you have the boot peeled back....see if you can move the u-joint/coupling front to back AT ALL. If you can, you're output shaft has snapped at the base of the threads. I'm in the midst of replacing the one on my GK now.
Oh yeah, drain your secondary trans oil into a clean container and examine what comes out. It may give you another clue. Mine was black as coal.
Good luck and post a followup re: what you find.
Willie in TN

 

[TheCafeKid]

Having just reinstalled a set of bevel gears in a GK, one with 140K on it, and finding its NOT at hard as I thought it would be (dont even have to split the case partially at all..) I would suggest checking those as well. The bearings in the bevel housings are more than likely the problem over the gears themselves. In MY case, they failed completely, allowing the gears to waller around in the housing, and sufficiantly destroying them. The shop manual shows how to replace the bearings themselves, but i think you'd spend more money and time doing that than simply replacing the whole set up (sold as a set, for around 200 or so i think, still available thru Zook) Its my Roomates bike, Ed was nice enough to sell him a set of gears from a 1000G, and we popped em in and the mighty Grandpa GK is back on the road and running like a top. The sounds you describe are exactly what i was hearing from the GK before it crapped out completely. I was thinking tranny, but it was in fact the secondary that was making the racket...

 

[Grandpa]

Having just reinstalled a set of bevel gears in a GK, one with 140K on it, and finding its NOT at hard as I thought it would be (dont even have to split the case partially at all..) I would suggest checking those as well. The bearings in the bevel housings are more than likely the problem over the gears themselves. In MY case, they failed completely, allowing the gears to waller around in the housing, and sufficiantly destroying them. The shop manual shows how to replace the bearings themselves, but i think you'd spend more money and time doing that than simply replacing the whole set up (sold as a set, for around 200 or so i think, still available thru Zook) Its my Roomates bike, Ed was nice enough to sell him a set of gears from a 1000G, and we popped em in and the mighty Grandpa GK is back on the road and running like a top. The sounds you describe are exactly what i was hearing from the GK before it crapped out completely. I was thinking tranny, but it was in fact the secondary that was making the racket...

That makes me a very happy Grandpa! So good to hear "my" mighty GK is running again.

Nick Diaz
Middletown, MD

 

[Gary Lich]

Thanks to all for the insight....I will update when I have tracked this issue down....

 

[willie]

Another, easier test, to see if its the secondary transmission bearings is to examine whats left after you drain the secondary trans oil. I have my clusters out in preperation of changing them. I stuffed a rag into the cavity thinking I'd get every last bit of dirty oil out of there. When I pulled the rag out it had a bunch of metal flakes on it. So.....a thought that came to mind...after draining the oil...stuff a cotton swab in the drain hole and give it swab. Take a look at what's on it. That should tell you if the bearing(s) is worn out.
Good luck,
Willie in TN
PS
Please post your findings on the poll I started re: shaft drive problems. I think it'll help others who have or are considering a G model.

 

[propflux01]

Mine snapped just forward of the nut that holds the bearings in. I did the same thing as you describe, vibration when decelerating. I rode it like that for quite some time before pulling off the back tire for replacing, and then while all that was out of the way removed the rubber cover to check the u-joint/drive shaft and there it was. Got another set from EBAY and 20K later still going.

 

[Gary Lich]

No obvious culprits yet...I peeled back the rubber drive shaft boot and poked around. nothing felt loose, no front to back movement, not broken parts apparent. Drained the secondary oil and it looked ok (no metal shavings or discoloration). However, when I drained the final drive oil there where some metal shavings on the magnetic drain plug and in the oil. With the tranny in 1st there is about 30-40 degrees rotation of backlash (slop) in the drive system..Is this amount normal ? (I also should have mentioned the bike only has 28K on it)..

 

[rustybronco]

Time to pull the rear wheel and look at the splines.

you could peel the boot back, hold the drive shaft yoke stationary and rock the rear wheel back and forth. that should show the play in the shaft/final drive/spline areas.

 

[TheCafeKid]

No obvious culprits yet...I peeled back the rubber drive shaft boot and poked around. nothing felt loose, no front to back movement, not broken parts apparent. Drained the secondary oil and it looked ok (no metal shavings or discoloration). However, when I drained the final drive oil there where some metal shavings on the magnetic drain plug and in the oil. With the tranny in 1st there is about 30-40 degrees rotation of backlash (slop) in the drive system..Is this amount normal ? (I also should have mentioned the bike only has 28K on it)..

Im pretty sure you said you replaced that inner hub spline on your wheel...or maybe that was a different thread? Either way, that bike is an 82...the stock spline is garbage...I blew one out that was probably well on its way when i bought my now ex 82 1100G last spring almost immediately. I changed it out...with another 82 spline...7K miles later, It blew out on me again! I changed it out...with a black spline from a 79 850...never had the problem again... Pull your rear wheel...clean the grease out of the hub spline, and pull the spline...From the front it may look ok, cause the very front of the teeth that you will see never make contact with the drive gears in the pumpkin...But just behind that, bout an eighth inch or so, you may find the teeth are stripped clean off....

 

[Zooks]

It's backlash. Mine whines like that all the time (exactly as you described). I put it back together and never got around to adjusting it (I really should do that). If it's never been apart though it may be that something has come loose.

If the shaft is broken as described (in propflux's post above) then have a look at how I fixed mine on BassCliffs website. It's a fairly easy and quite common way of fixing a broken shaft - http://members.dslextreme.com/users/storagecliff/images/bevel_gear_shaft_repair_zooks.pdf

 

[Gary Lich]

The vibration problem was definately in the final drive....major front/inuput bearing failure and the end of the final drive drive gear shaft had actualluy snapped off where it passes through the drive gear coupling ....I was about 40 miles from home when the vibration suddenly started (that must had been when the shaft broke). I am amazed I made it home. Anyhow, a with a replacement final drive unit (and a black spline off of 79 GS1000) from ebay, the GS in now back on the road !!!

 

[TheCafeKid]

Yanno, ive heard of spraining your shaft, but Im pretty sure you cant break it...

Glad to hear its back on the road!! Congrats! The shafties are GREAT when they work, but when they have problems, they can be a WAY bigger PITA than a simple chain and sprockets...

Speaking of Broken Shafts...I was listening to Love Line with Dr Drew not too awfully long ago on the way home from work. A guy called in asking if you COULD in fact break your...ahem...shaft. Dr Drew told him it can be bruised, and even sprained, as there is a tendon in there, but no bones, so no, you CANT break it. Why did he ask though?? Well apparently this gent and his girlfriend were having a wee bout of co-ed naked wrestling in the livingroom...like ya do. She took off running down the hall, and he lit out after her, only to have her slam the door on his...uh...business....Not only did it get slammed, she, thinking he was trying to push it open, kept leaning on it till it actually LATCHED :-& No BS...well, at least thats what i HEARD..i dunno if he was BSing or not... Totally off subject really, but it KINDA related...

Now back to your regularly scheduled thread

 

[tkent02]

Speaking of Broken Shafts...I was listening to Love Line with Dr Drew not too awfully long ago on the way home from work. A guy called in asking if you COULD in fact break your...ahem...shaft. Dr Drew told him it can be bruised, and even sprained, as there is a tendon in there, but no bones, so no, you CANT break it. Why did he ask though?? Well apparently this gent and his girlfriend were having a wee bout of co-ed naked wrestling in the livingroom...like ya do. She took off running down the hall, and he lit out after her, only to have her slam the door on his...uh...business....Not only did it get slammed, she, thinking he was trying to push it open, kept leaning on it till it actually LATCHED :-& No BS...well, at least thats what i HEARD..i dunno if he was BSing or not... Totally off subject really, but it KINDA related...

Now back to your regularly scheduled thread

That reminds me of the time we were trying to get my neighbor's orange cat Tang out of the Garage, he finally ran through the door into the house, Scott slammed the door, the entire cat got through except for his testicles.....

 

[Guest]

Jeez, I laughed so hard at that one the tears nearly streamed