Nightmare

Won’t need a helmet for a bit. I was starting the Norton on my rollers this afternoon and it wouldn’t start probably because one plug lead was off. Anyway after a prod of the kickstart there was no drive through the box and the clutch was all floppy. Going through the gears revealed a stoppage so I didn’t push it too far and thought that the kickstart pawl must have broken and was maybe jamming something. Took off the outer cover, nothing. took off the inner cover and forgot that you would normally have to undo the nut on the end of the mainshaft (which is under the clutch release mech.) Not necessary in my case because the mainshaft is now in two bits and second gear (mainshaft) has two teeth missing. (Well not missing because I found them in the bottom of the case.)
This is my theory that is all mine. starting on rollers in second gear has shock loaded the gears, breaking off one or two teeth, they had jammed the gearbox, deflecting the mainshaft far enough to snap it. BOLLOCKS Anybody want a set of start rollers? Cheap.

Is the gearbox shell damaged at all ,cos if it's not ,I think it's not as bad as it could have been. Still pretty shit though.

Jg

Shell looks ok but totting up the cost of parts, it's going to be bread and dripping for a while :cry:

There are ALWAYS people looking for starter rollers...

Has it not been started in a while, Was the clutch plates free or stuck together with gear oil ?

gripper said:

Shell looks ok but totting up the cost of parts, it's going to be bread and dripping for a while :cry:

Click to expand...

Good fortune on that one. It was porridge for me when my box popped.

The problem that caused that is starting it in 2nd gear, to much shock, when some low life theived my kick starter off my Norton back in late 1979 I couldn't get a new kicker at the time so had to clutch start it all the time, doing it in 2nd or 3rd gear all it did was to lock the back wheel, but clutch starting it in 4th was so easy but you had to be quick with the clutch lever when it fired up with out snuffing it, so if you fired it up in 4th gear on the rollers will put less strain on you gear box, a friend of mine starts his race Triton on rollers and he always does it in top gear, he learned a long time ago from a few breaks from starting in low gears, since doing it in top gear he hasn't broke nothing.

Ashley

Naughty. Naughty. The only way to crash start any engine is in the highest gear. Everyone now knows what happens when you disregard common sense. Shame.

Dereck

Crap, hasn't been assembled with a mismatch of late and early second gears by any chance, mine was when I got it and the lay shaft snapped

You don't say what year this is, but Nortons put out a bulletin at some point (early 850 ?), warning that the mainshaft should be checked for straightness.
The implication being that some weren't, and that they could snap.

Ain't old bikes fun....

Mainshaft second gear has an oil hole through it, the two teeth that went astray are either side of that hole. 1970 750 probably original shaft, I've only had it 42 years. I've always bump started in second gear but I suppose a higher gear would make sense

The clutch was free before the start attempt and the gears are the correct 18:24 pairing. I notice that the break in the mainshaft is where there is an undercut, reducing the overall diameter. Mind you I wouldn't expect a full diameter to survive that sort of damage.
I'm wary of undercuts on shafts. In 1990 the tail rotor pitch change mechanism on my Puma chopper featured a splined shaft that was undercut where the splines ended. That reduced the diameter of the shaft wall and it let go at a most inopportune moment. (loss of tail rotor control is always inopportune) the resultant ditching in the English Channel was an experience to say the least. Still any landing you can walk away from, or in this case swim, is a good one.

They Do That ! ( dont ask how I know ) . Youve probably bent the layshaft , too .

Once people realised you waited untill the temperatures were up before standing on it .

BUt , if ' youve always ' bump started it in second gear ' , did you run / roll start it , in neutral AND shift into second . :twisted:

Cold Oil / baulkey shift . Forced ! .

Had someone ride mine with ex plod boots ( WW1 DR in NZ ! ) My delicate sensitivities were jarred on every graunched shift ,
whicxh was most of them .
The things these Triumph Riders do as a matter of course ! You can clutchless shift a Triumph , forcefully .

A Knorton , it is a matter of timing and dexterity , learnt by driving crash box tractors , Straight Cut truck boxes etc .

A toe on the shift , and itll go in when it wants to - delicately . Any More Force is force & forces it .
I recomend you equip yourself with winklepickers .
And check the Mainshaft output bearing housing .



Dommie bits'll fit .
A new mainshaft in NZ was $ 80 in NZ about 81 , and they ( someone ) had one ' on the shelf ' . Wonder multiplication on price now .

Er , cool day And not using clutch , or even with the clutch , drag & cold oil may result in such uncalledfor consequences . As the large Boot forces gears out of kilter .
Check the Clutch Drum spins true on the bearing , too .

Spot on Matt, bent layshaft 0.018" out

Matt
'Dommie bits'll fit .
A new mainshaft in NZ was $ 80 in NZ about 81 , and they ( someone ) had one ' on the shelf ' . Wonder multiplication on price now . '

The Commando mainshaft is about 6mm longer than the Dommie mainshaft.

gripper said:

I'm wary of undercuts on shafts. In 1990 the tail rotor pitch change mechanism on my Puma chopper featured a splined shaft that was undercut where the splines ended. That reduced the diameter of the shaft wall and it let go at a most inopportune moment. (loss of tail rotor control is always inopportune) the resultant ditching in the English Channel was an experience to say the least. Still any landing you can walk away from, or in this case swim, is a good one.

Click to expand...

Very low airspeed? Immediate AR?

140kts, couldn't maintain heading, autorotate into the sea etc etc. The Commando is back on the road and running better than ever. I've just removed 9kg of rack and abus granit lock from the tail end and it feels much better for it, In fact it's going so well I'm wondering if it's trying to tell me something. Total cost of mainshaft, layshaft a couple of bushes and new mainshaft 1st and 2nd gears £406 bargain :roll:

Good to see you are back on the road, are you still using the rollers to start up and if so have you been doing it in top gear, I like my gearbox it always just click in gear, have a very light clutch and the friends that have ridden my Norton always say how well it changes gear, its been like that ever since buying it new all them years ago, the only work I have done on my gearbox is lay shaft bearing and 4 kick start pawls, not bad for a everyday bike for the first 37 years.

Ashley