Forum

[Gwilly]

Colin the torque figure for the sprocket nut is 47 lb/ft or 6.5 Kg/m but in all honesty put your boot down hard on the rear brake and use a Two foot breaker bar to a measure of 1.5 grunts.
bloody tight but i don't mean jump on it..

[Gwilly]

John i've had this discussion before and i'm with Tim.

Remove the inner seal from each bearing and use the gearbox oil to lube and cool the bearings..

True there may be some swarf from wear even in a now sealed box but remember this swarf comes from the gears and pawl and if theres enough to bugger a bearing then your going back into the box anyway, and after 30,000 miles who cares? bearings are cheap..

[papasmurf]

Gwilly you don't need a 2 foot bar to achieved 47Ft/lbs. The rear wheel bolts on my BMW have to be torqued up to 78ft lbs and I manage that (just,) with a shortish torque wrench, and I have weak hands.

[mauri]

the motioned figure of 6,5kg/m is for the main shaft nut, not for the sprocket nut.











for the sprocket nut there is no mention of torque but a figure of 8kg/m(80,0Nm) would be more correct.

[John R]

We'll having mulled this one over I'm keeping both seals on the bearings. I may be right, I may be wrong but I don't think the bearings get hot enough to worry about cooling. The mains are sealed and I think they run hotter. We shall see...

[John R]

Ok the mains aren't sealed. Also the actual answer to my original question is that the new seals are for the LH bearing and the sprocket. Just a final word; I do have trust in Hitchcocks and the products they supply. If they send me sealed bearings for a given application then on balance I will assume they are fit for purpose; they always have been up to now.

[Colin F]

Thanks Gwilly,it's just that i have doubt's about tightening this nut at all,as i assembled
the bearing,sprocket onto the m/s sleeve before fitting to the gearbox just to see how it goes together and was suprised to see that it is the chamfer of the inner race that engages against the sleeve,there's not a proper shoulder for it to butt against.So all i can see is that applying torque to the sprocket nut tends to push the inner race along and up on the chamfer.
I wonder what an engineers view point on this would be.
cheers
colin

[Revband]

On most bikes the gearbox sprocket should only be just nipped up and then the nut locked with the tab washer/locking screw/ETC, this will give the rear chain an easier life allowing the sprocket to run true in the chain.

[Tim NZ]

The Countershaft nut for the gear box sprocket must be fully tighten if it is to be located inside the bearing, and the housing. IF the sprocket nut is loose to any degree, or the sprocket not fully pulled-up and seated, it can allow the sleeve gear to float, and in turn eventually the bearing spins in the case. In extreme case this will result in the bearing drifting inwards and its outer race making contact with the layshaft 1st gear.


(Shiny silver metal flakes in the oil)


Finger tight DOES NOT do the job. Tapped up tight with a drift/pin punch and Hammer DOES NOT do the job. Relying on the sprocket nut Tab washer as fitted to the Indian gear-box is not 100% reliable.

[John R]

Yes, tightening the sprocket nut lightly will not let it float in order to comply with chain movement as revband suggested- that would not happen unless it was quite loose on the shaft.
Nobody has a recommended torque for that nut as far as i am aware, but I know that the other, left hand thread mainshaft nut is supposed to be about 45 ft pounds, which is a lot less than it was when I dismantled my box. So was the sprocket nut, but that was my fault. Like, I suspect, many of us, I don't have a proper spanner for the sprocket nut and will probably end up using a pipe-wrench.
Incidentally, the cause of my gearbox problems turned out to be a totally knackered left-side layshaft bush, worn right through to the casing, now replaced with a deluxe bronze job.