Warp11XX Posted August 10, 2009 Share Posted August 10, 2009 I finally got around to doing the swap on my leaky rear differential, and replacing the swingarm to trans boot and u-joint. I've had a small but persistant problem ever since I've owned the bike. It is a '92 Aspy if that matters. The problem seemed related to the wear condition of the Dunlop tires I was running. At least it became much more noticable and intense, seemingly related to how much the rear tire was worn and cupped. The problem appears when I let off throttle and try to hold it in a "null" position while riding. At that throttle position, a vibration becomes apparent that feels as if something in the driveline is not quite running or spinning "true". As long as I have power to the wheel driving forward, or am at throttle off position while using the engine to slow down under compression, there is not the slightest vibration that I can feel. Only when coasting at neutral throttle (which I actually do a lot more than I ever noticed before) does the vibration become noticable. I found out by accident this weekend that it also does it at a significantly noticable level if I'm running 70+ and simply pull the clutch in to just coast in gear, but not being under power at all. The faster I'm going, the worse the vibration seems to be. I'm thinking at this point that it must be something in the final transmission drive such as the output shaft bearing being really badly worn. I did a lot of work and made several changes at one time...a different (used) differential and driveshaft, a new u-joint, and changing to new Michelin Pilot GT tires. It used to seem that the problem did not get to the noticable level it is now on brand new tires until the tire got significant mileage and started to show the first signs of cupping, and at least the first small sign of higher mile center flat spotting. It's annoying as all hell since it "walks" in and out of this vibration in normal riding conditions up and down hills and such as I adjust throttle. What do you guys think? Quote Link to comment Share on other sites More sharing options...
Skull Posted August 14, 2009 Share Posted August 14, 2009 Did you moly-grease the driveshaft splines? Quote Link to comment Share on other sites More sharing options...
Warp11XX Posted August 14, 2009 Author Share Posted August 14, 2009 Yes and no.... I used a red flavored, hi-pressure grease, but not moly. Was this possibly an "oops, my bad" moment? Quote Link to comment Share on other sites More sharing options...
Skull Posted August 14, 2009 Share Posted August 14, 2009 Yes and no.... I used a red flavored, hi-pressure grease, but not moly. Was this possibly an "oops, my bad" moment? Molybdenum is best. What did they look like? The splines are where all of the Valkyries eat their drivetrain over time, mostly because most dealers don't even bother to check them. I'd look at the cush drive, as well. The little rubber bumpers dry and split. After that, I'd check the u-joint and the output shaft for play. After that... Look at the rear shocks -- I know a couple folks that bent the shocks and didn't know it. The rubber top shock mount inserts also go bad. Both conditions manifested themselves as weird vibrations. Most of my off-the-top-of-my-head knowledge about 1500 machines is from Valkyries, but they're not that different. Quote Link to comment Share on other sites More sharing options...
Warp11XX Posted August 14, 2009 Author Share Posted August 14, 2009 Yes and no.... I used a red flavored, hi-pressure grease, but not moly. Was this possibly an "oops, my bad" moment? Molybdenum is best. What did they look like? The splines are where all of the Valkyries eat their drivetrain over time, mostly because most dealers don't even bother to check them. I'd look at the cush drive, as well. The little rubber bumpers dry and split. Splines on the output shaft looked good, u-joint is brand new OEM. Driveshaft and final diff is replacement in used, good condition. Same problem before and after changing these components. After that, I'd check the u-joint and the output shaft for play. After that... None present. Does have very slight runout by observation of the front section of the u-joint while spinning/running on centerstand. Can't confirm yet if runout is in the acceptable/normal range and haven't indicated it yet. I estimate a few thousandths by observation and feel. No luck so far finding a stated tolerance for this dimension. Bearing on output shaft seems good with no discernable side play. Suspect a possibility of micro-bent output shaft at this point. Requires engine pull to service that area. Look at the rear shocks -- I know a couple folks that bent the shocks and didn't know it. The rubber top shock mount inserts also go bad. Both conditions manifested themselves as weird vibrations. Good suggestion and haven't addressed that possibility yet. Since it is a repeatable problem on the centerstand, that almost eliminates suspension doesn't it? Most of my off-the-top-of-my-head knowledge about 1500 machines is from Valkyries, but they're not that different. Not really....just a bit lighter weight maybe... Quote Link to comment Share on other sites More sharing options...
beestoys Posted August 18, 2009 Share Posted August 18, 2009 Yes and no.... I used a red flavored, hi-pressure grease, but not moly. Was this possibly an "oops, my bad" moment? Molybdenum is best. What did they look like? The splines are where all of the Valkyries eat their drivetrain over time, mostly because most dealers don't even bother to check them. I'd look at the cush drive, as well. The little rubber bumpers dry and split. Splines on the output shaft looked good, u-joint is brand new OEM. Driveshaft and final diff is replacement in used, good condition. Same problem before and after changing these components. After that, I'd check the u-joint and the output shaft for play. After that... None present. Does have very slight runout by observation of the front section of the u-joint while spinning/running on centerstand. Can't confirm yet if runout is in the acceptable/normal range and haven't indicated it yet. I estimate a few thousandths by observation and feel. No luck so far finding a stated tolerance for this dimension. Bearing on output shaft seems good with no discernable side play. Suspect a possibility of micro-bent output shaft at this point. Requires engine pull to service that area. Look at the rear shocks -- I know a couple folks that bent the shocks and didn't know it. The rubber top shock mount inserts also go bad. Both conditions manifested themselves as weird vibrations. Good suggestion and haven't addressed that possibility yet. Since it is a repeatable problem on the centerstand, that almost eliminates suspension doesn't it? Most of my off-the-top-of-my-head knowledge about 1500 machines is from Valkyries, but they're not that different. Not really....just a bit lighter weight maybe... Ahhh if you can see runout with your naked eye I bet its more than a few thousandts. And that would be your primary culprit. The vibration your describing usually comes from a worn u joint. When under power or decelerating the looseness is taken up by the laoding and the joint play is taken out. When you coast or get up in speed and the load comes off the shaft it will pick up the slack and start to harmonically oscilate giving you the feeling your describing. The other thing I have seen cause this is Phasing of the joints. Joints are designed to be off set originally to counter the above condition I described. This phasing keeps the joint partially loaded. You may also want to check out the goldwing site if you changed the rear diff. There is a proceedure to tightening up the 3 bolts and rear wheel. It is a sequence that helps with the alighnment. You can get the diff cocked on the shaft when you tighhten it down. It can give a funcky tracking and it may also cause a missalignment that your feeling as a vibration as well. If you have access to a copy of the factory manual it explains the install and alignment proceedure there. Quote Link to comment Share on other sites More sharing options...
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