Baldini Posted March 16, 2012 Share Posted March 16, 2012 Scura just under 28,000 miles & front UJ exploded rather spectacularly. Possible contributors: Lazy maintenance on my part - hadn't touched front UJ grease nipple for probably last 20k cos it's a bugger to get to & thinking I'll get round to it... Not long before, I had found on of the s/a mount peg locknuts had backed off & the peg had backed out of the sideplate a far way. I just screwed it back in to right feel, centred side to side, tightened locknuts & carried on, hoping for the best... I found the front & back UJ's to be way out of alignment when shaft is assembled according to the factory paint marks. I had always gone by the paintmarks & had never checked alignment. It is possible to align them better by turning relative to each other by one spline but UJ's are still misaligned. The new complete driveshaft is, by comparison, bang-on. See attached photos. Link to comment Share on other sites More sharing options...
Baldini Posted March 16, 2012 Author Share Posted March 16, 2012 Old & new driveshafts aligned according to factory paintmarks. Old one can be aligned better by rotating one end by one spline. Worth checking yourself rather than relying on factory marks. Link to comment Share on other sites More sharing options...
guzzimeister Posted March 16, 2012 Share Posted March 16, 2012 Hi Keith, that did go bang, didn't it? Nice to see the safety cage works though to prevent shrapnel going through your leg.... Re possible causes for failure. In my experience,mis alignment of the two shaft halves is the biggest killer. I have seen other V11s where the paint marks do not indicate alignment, in once case 90 degrees out. This puts a massive strain on the joints, surprised you got to 28K. Lubrication seems to be less critical, I do mine about 10 to 15k apart and they have lasted to 64k so far. Grease is not critical, just make sure it's squelching out of the bearing. I hear somewhere the the UJs should be slightly stiff, and that if they strat getting floppy the bearings are on the way out. Personally I prefer to take th ebike to 30 mph, pull the clutch in, kill the engine and coast. If it feels harsh or vibratory, I would look at the UJs. Drive line slack is not an indication as it is made up of the wear in the bevel box pivot, the shock absorber in the gearbox and the cush drive (not much). Somewhere on this forum, someone has identified that the UJ is a standard one and can be had for a lot less than MG charge for it. Alternatively try Stein Dinse, who seem to be very reasonable. Going to the V Twin? Cheers Guzz (JW) Link to comment Share on other sites More sharing options...
Baldini Posted March 16, 2012 Author Share Posted March 16, 2012 Hi Guzzimeister, how you keeping/ Yes, when it went I thought the motor, clutch or gbox had blown, plenty smoke & noise. Shield was toast but as you note it did it's job! Below photo to show how I could have got better alignment had I just ignored factory paintmarks & checked it myself. It's just turned by one spline. Oh well - live & learn. To anyone else hasn't checked - I'd recommend it! Couple questions: 1. Output shaft seal in gearbox endcover. appears to be replacable with box in situ. Any comments? 2. I've heard of people sourcing uj's for V11 other than from Guzzi. I don't understand cos the uj's are integral with splined collars, are they available from non-Guzzi sources like that or are people cutting & welding collars to non-Guzzi ujs? KB PS: Guzzimeister, no I'm not going to V-Twin - don't really do rallies. Have a good one! Link to comment Share on other sites More sharing options...
Paulsmartv11 Posted March 16, 2012 Share Posted March 16, 2012 Why does shaft need to align??? its only turning the back wheel - whats the reason? Paul Link to comment Share on other sites More sharing options...
guzzi323 Posted March 16, 2012 Share Posted March 16, 2012 Scura just under 28,000 miles & front UJ exploded rather spectacularly. Hello again. Our shared Scura curse strikes again. In case you didn't see it a while back I had a different failure traced back to the un-alignable driveshaft thoughtfully provided by Moto Guzzi. http://www.v11lemans.com/forums/index.php?showtopic=15638 In mine the transmission went. The u-joints were fine and I had the drivehsaft yokes aligned by an automotive machine shop that deals with driveshafts all day long. I haven't been riding much the past year or so but the bike now has over 70K on that original, re-aligned shaft and it's still fine. For the record, I only lube the driveshaft when replacing the rear tire (and I think I may have forgotten to get it once or twice) but that seems to be sufficient to keep things happy. Glad you're alright. johnk Link to comment Share on other sites More sharing options...
guzzi323 Posted March 16, 2012 Share Posted March 16, 2012 I was just looking at your driveshaft pics. They are a little small to be able to see everything clearly. I wanted to mention that on my driveshaft the mis-alignment was not obvious (like your original shaft). I'd recommend a very close examination of the new driveshaft. johnk Link to comment Share on other sites More sharing options...
gstallons Posted March 16, 2012 Share Posted March 16, 2012 Why does shaft need to align??? its only turning the back wheel - whats the reason? Paul You would have to understand the need for the alignment.......... Google it for a thorough understanding.......... Link to comment Share on other sites More sharing options...
guzzimeister Posted March 16, 2012 Share Posted March 16, 2012 Hi Guzzimeister, how you keeping/ Yes, when it went I thought the motor, clutch or gbox had blown, plenty smoke & noise. Shield was toast but as you note it did it's job! Below photo to show how I could have got better alignment had I just ignored factory paintmarks & checked it myself. It's just turned by one spline. Oh well - live & learn. To anyone else hasn't checked - I'd recommend it! Couple questions: 1. Output shaft seal in gearbox endcover. appears to be replacable with box in situ. Any comments? 2. I've heard of people sourcing uj's for V11 other than from Guzzi. I don't understand cos the uj's are integral with splined collars, are they available from non-Guzzi sources like that or are people cutting & welding collars to non-Guzzi ujs? KB PS: Guzzimeister, no I'm not going to V-Twin - don't really do rallies. Have a good one! Hi g/box seal is replaceable in situ, drive two woodscrews in and yank it out! Guzz Link to comment Share on other sites More sharing options...
stefano Posted March 16, 2012 Share Posted March 16, 2012 Why does shaft need to align??? its only turning the back wheel - whats the reason? Paul our u-joints need to be in plane with each other, meaning that the cross's need to be in the same position relative to each other so that when our wheel works up & down the u-joints can move up & down without binding each other. that said, the driveshafts can be assembled in four different arrangements relative to each other that will be fine,(0,90,180,270) degrees. the cross's will be in the same position relative to each other in any of these positions, although the paint marks will not line up at 90, 180, 270. i don't remember the # of splines in the center of the driveshaft, but it is possible to align one or more splines off, the worse case being 45 degrees off. when i bought my V11, i noticed the driveshaft paint lines didn't line up. on further inspection i noticed that my cross's actually were aligned, but the trunnions were off by 90 degrees. as the cross's were aligned i didn't worry about it 'til i changed tires, then i aligned the paint marks, just for the hell of it, i could have left them 90 degrees off, no problem, but anything other than 0-90-180-270 apart would be unacceptable. i've heard of paint lines put on wrong from the factory(i haven't seen any personally) but as long as the cross's line up you're good. standard disclaimer, this is my personal opinion, possibly the only opinion like this in the the whole universe. cheers, stef 1 Link to comment Share on other sites More sharing options...
68C Posted March 16, 2012 Share Posted March 16, 2012 Universal joints are normally used in pairs the cross bearings at each end of the shaft assembly must not only be in line with each other but must also be a mirror image, the centre shaft must have each end at the same angle. If the drive shaft assembly is not in a straight line, and ours is not as the suspension moves up and down, a phenomena known as Hookes Joint Effect or the Conservation of Angular Momentum causes the output from the first joint to move in a jerking action - fortunately the second joint turns this back into a smooth action. This is most noticeable on an unladen large truck, as it pulls away the drive shaft can be seen to rotate in a jerking fashion althogh the input to the rear axle is smooth, when loaded the designer will have arranged the system to be almost in line reducing this effect. If the joints are not aligned this jerking action will occour even when the shaft assembly is almost straight with consequent wear to the transmission and vibration. Altering the ride height of a shaft drive bike by jacking up the rear or overloading the bike can mean the shaft asssembly is no longer straight which can increase wear also. The out of phase jerking action will someday destroy the U/J. 1 Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now