Adding additive to XJ650 final drive.

Hi all,
A few months back I had a problem with my taking off at the lights. When I released the clutch I got this knock thru my seat. Was advised to check for brake delamination. It was definitely coming from the final drive. I was told by the wizards here that most likely its the spring on the shaft has lost some of it tension and hence the knock when I take off. Since I have adjusted the clutch correctly it doesn't seem to happen as much. My question is after all that rambling. Is there any product that you can add to the final gear oil to quieten and smoothen out the action.? I am about to drop the old gear oil and was recommended an American product called Lucas Oil Transmission Fix.
Has anyone used this before on a final drive and would it do any harm.? I wouldn't dream of putting it in the engine due to clutch and starter slip but in the final drive I figure it would be ok.?
As always...thanks all.
Morg.

 

The "spring" that's in the driveline is located inside the rear engine case on the final jackshaft, and it tensions a cam mechanism that absorbs harshness - bad shifts. If this spring actually broke, driveline impacts might be felt/noticed at the rear.

A pinion bearing going bad would make some unusual noises. (and you would stop riding the bike)

Try to check "lash" between the "U" joint and rear wheel,(should feel very tight) then with the engine in gear, see if you can rotate the joint a quarter turn without turning the motor. (that would be the broken spring)

No oil is going to fix either of these 2.

 

Thanks TIMEtoRIDE.
Funny thing is...I had the bike off the road for a number of years and when I got her back on the road I kept messing with the clutch adjustment at the lever end.Wasn't happy with it..
To be honest I wasn't too sure what I was doing. Is it possible that the clutch incorrectly adjusted contributed to the knock in the drive shaft.? Reason I ask is that since I got the clutch adjusted perfectly over the weekend the knock hasn't happened. And it is normal for the lever to be almost out fully before the gears engage.?
Thanks again.
Morg.

 

A worn and sticky clutch cable can cause problems.
You can drip motor oil thru it using the bag-and-tape method.