G'day All, I need some advice from more knowledgeable forumers than myself. Have recently installed a new clutch plate into the recently acquired 75S. Installed the gear box, started it up to check for any untoward noises going through the gears - none. Then installed the swingarm, drive shaft and final drive. Started the bike up and there is a rumbling noise from the uni. joint area through all gears. Remove drive shaft, no rumbles. I suspect it is the uni. joint. Any advice welcome and thank you in advance. Cheers Tom

With the driveshaft in your hands, what does the UJ feel like when you flex the coupling?  Is it smooth or rough/clicky?

Al

Thanks Al, I'll let you know once the drive shaft has been taken out and the UJ flexed.

Tom Grabau wrote:G'day All, I need some advice from more knowledgeable forumers than myself. Have recently installed a new clutch plate into the recently acquired 75S. Installed the gear box, started it up to check for any untoward noises going through the gears - none. Then installed the swingarm, drive shaft and final drive. Started the bike up and there is a rumbling noise from the uni. joint area through all gears. Remove drive shaft, no rumbles. I suspect it is the uni. joint. Any advice welcome and thank you in advance. Cheers Tom  

If you tested the rear drive with the bike on the center stand, it could just be the top uni rubbing on the d/s tunnel (swing arm) Jack the rear of swing up just in front of F/D till wheel is off the ground  & test again
PJ

Thanks PJ, The bike was started while on stands at rear ( not centre stand) with shockie fixed but no wheel on. I'm guessing the SA is probably in the normal position. Today the DS is coming out so the UJ can be checked. It does sound as though the DS is making contact inside the DS tunnel. I'll keep you posted. Cheers Tom

Tom Grabau wrote:Thanks PJ, The bike was started while on stands at rear ( not centre stand) with shockie fixed but no wheel on. I'm guessing the SA is probably in the normal position. Today the DS is coming out so the UJ can be checked. It does sound as though the DS is making contact inside the DS tunnel. I'll keep you posted. Cheers Tom

Have you ever replaced the shockie ? it only needs to be 5mm longer then normal for the D/S to rub inside the SA
PJ

Thanks PJ, No, the shock. has not been replaced. I will change over shocks and let you know the result. Cheers Tom

Hi All, just a quick progress report on this issue. In short, there has been no progress. So far, the following has been done:-
- changed shockie with a known good one but rumbling noise still there
- removed DS and checked UJ which seemed OK - no clicking noises or untoward movement
- removed swing arm and checked Gearbox output shaft for movement - none felt.
- started bike without swing arm etc. and no rumbling noises
- fitted final drive from a spare bike (condition of this FD unknown)
- fitted DS from spare bike and rumbling noises reappeared.
The DS does not seem the make contact with swing arm tunnel because there are no visible score marks on the DS.

I'm guessing it is the UJ or the FD so I'll do a swap from the good 75 and I'll keep you posted.
Tom

wonder if its an gearbox output shaft bearing tom ?

it may run fine unloaded ?

from what I have seen from my last gearbox change ..if the gearbox has been sitting idle for a very long time . could corrosion have set in ?

I have issues changing gears on that box ...and suspect that the cam gear and pressure roller on the gear change drum are gummed up with corrosion , and the retaining pin of the cam gear is now loose as anything , and the gear selector pins channel is corroded as well
I also noticed a fair bit of grumble whilst under way till at least a few thousand ks were rolled on ...but I guess the damage is already done and the oil is disguising the noise to a fair degree now  

ill be pulling this one apart soon enough

Thanks Charlie, did some more testing ( with Gaz 80 assistance) and established the gearbox rumbled in 3rd, 4th and 5th Gears. Bugger...... Will now swap out gearbox from spare bike. Thanks heaps for all advice. Tom