Crankshaft sprocket alignment

Something is seriously wrong with the chaincase rubbing on the swing arm. Is this why the chaincase has cracked? I would check that thecrankshaft andgearbox mainshaft are parallel to each other in two planes as a starting point. Not the easiest thing to do unless you have access to surface plates and squares.

Try alteringthe gearbox adjusters to see if you can achieve parallel alignment in the vertical plane of the engine and clutch sprockets. The front isolastic (glad to see you refer to it correctly as adjustable, a vernier is the movable scale on micrometers etc) will have no effect on engine/clutch sprocket alignment as this is dependent on the gearbox/engine cradle.

It is important to measure the clearance between the back of the inner chaincase and the central mounting stud when the three crankcase to inner chaincasenuts are correctly torqued and then fit a spacer as required.

Hope this is of help, Simon.

Hi Simon,

I too used to feel the same way about the wordvernier, but one day I looked it up and found that itactuallymeans "fine adjustment", like vernier rifle sights, vernier throttle on aircraft, etc. I wassurprised at the definition as I used to be a machinist and was familiar with verniermeasuringtools & didn't know theactualdefinitionof the word. I guess Norton was right & I was wrong, Vernier adjustment means fine adjustment. Its good to learn new things!

Skip Brolund

Has the bike been dropped heavily on the lhs? Perhaps the chaincase was knocked inwards by the footrest, causing it to be mis-shaped and giving rise to the cracked mounting screw boss. It's difficult to imagine the engine being so far out of alignment since the bike was firstbuilt (or is that wishful thinking....)

I know this might sound daft but have you got the spacer fitted to the top gearbox mounting bolt, on the left hand side inside the cradle? It is possible, with a little perseverance, to fit it on the right, or even leave it out. (Don't ask me how I know) this will throw your gearbox well out of line and give you some interesting primary chain alignment problems.

Hi Paul

Iâd put my money on the spacer on the central mounting stud Simon mentioned being missing or too thin. My inner chaincase has marks where the swingarm pivot has rubbed sometime in the past. When I had it apart I fixed the chaincase to the crankcase, thenmeasured and fitted a spacer of the correct size to the stud. There was then plenty of clearance at the back.

Cheers

Jeff

Hi Paul

I've just re-read your post, and something does seem to be out of alignment. Perhaps there was no spacer behind the central stud which caused the swinging arm to rub, and somebody put too thick a spacer in to correct the fault later, which allowed the primary chain to catch the case?

Cheers

Jeff

Previously wrote:

Hi Simon,

I too used to feel the same way about the wordvernier, but one day I looked it up and found that itactuallymeans "fine adjustment", like vernier rifle sights, vernier throttle on aircraft, etc. I wassurprised at the definition as I used to be a machinist and was familiar with verniermeasuringtools & didn't know theactualdefinitionof the word. I guess Norton was right & I was wrong, Vernier adjustment means fine adjustment. Its good to learn new things!

Skip Brolund

Hi Skip,

the Vernier scale was the invention of Paul Vernier a French mathematician. One definition I founddescribes the scale found on precision measuring instruments, another as an auxiliary device for making fine adjustment to an instrument usually by means of a fine screw thread.

I don't think either of the above definitions describes thethreaded collar found on Mk3 isolastics.Don'tthink I'm being pedantic but whilst we're on the subject there's also no such thing as 'superblend' main bearings.FAG NJ306E are parallel roller bearings within acage. FAG do a barrelled rollerbearing intended for misalignment of shafts of upto 2 or 3 degrees. Neither of these are listed as superblend.

Simon.