Primary chain noise?

I was in the workshop a few minutes ago. The Jota is still on the bike lift with the primary cover off and both chains removed. As I was walking past, I gave the clutch an idle spin and noticed there was no clicking noise. The bike was in neutral at the time, so I stuck it in gear, gave the clutch a spin and the noise was there loud and clear. That indicates to me that the problem doesn't lie in any part of the gearbox that spins when it's in neutral. I assume the countershaft is permanently engaged so that only leaves the final drive end of the main shaft that doesn't spin in neutral.

Furthermore, the number of "clunks" per revolution of the clutch drum varies depending on the gear selected, from about 2 clunks per rev of the clutch in 1st gear to 5 or 6 clunks in 5th gear. That's roughly proportional to the 1st and 5th gear ratios, which is further evidence against the final drive bearing. The prosecution rests its case m'lud.

I've also decided it's more of a solid clunk rather than a light click, and I can actually feel it as I turn the clutch. So probably not just a bunch of un-caged balls flopping about. More likely a totally fucked bearing.  I hope it hasn't done anything nasty like spun the outer bearing race in the case, or spread bits of shrapnel through the engine.

I guess I'll find out when I get in there ...
 
Cam,

I take it you have given the output shaft a good wobble at the sprocket end to feel if there any free-play?

As regards not just a bunch of un-caged balls, if the balls all congregate on one side of the bearing in the absence of a cage then the shaft may rattle around all over the place.
 
Broken main shaft?  Not sure if it tallies with the symptoms but it's about the only internal gearbox issue that's vaguely common.  They break up where the diameter steps right down for the sleeve gear don't they?  I've never come across one as yet.
 
breganzane said:
Broken main shaft?  Not sure if it tallies with the symptoms but it's about the only internal gearbox issue that's vaguely common.  They break up where the diameter steps right down for the sleeve gear don't they?  I've never come across one as yet.
Click to expand...

I have... ::)

Gearbox output bearing often gives up as well, can usually be put down to excessive chain tension.  Next step is the shaft snapping!

piet
 
mainshaft breaks where the lubrication holes have been drilled in the stepped down area, seen 4 so far
is actually what I thought last night as well when I read this thread

the other thought I had was the perceived issue was being over analysed by a qualified engineer  :D
just pull the damn thing apart, is only 45 minutes for a complete engine strip and all is clear
you have already wasted 65 mins counting the different clunks and clicks at different gear ratios and then using your slide ruler to calculate gear ratios

:D


 
Ha, very easy for you to say from the depths of Laverda heaven Red, 45 minutes for a full engine strip indeed!
The rest of us mere mortals reserve the right to perform the following when we think something is amiss with our beloved steeds:
Ripping of hair,
Rending of vestments,
Shooting the dog, and
Over-indulging in strong drink.
When all the above fails to fix the problem, we resort to the following:
Ask for advice on the forum,
Contact Red and ask how much. :D :D
 
redax5 said:
mainshaft breaks where the lubrication holes have been drilled in the stepped down area, seen 4 so far
is actually what I thought last night as well when I read this thread
Click to expand...

With everything in line, no great forces are applied to the shaft at this point.  Once the drive chain is over-tensioned, the output shaft will tilt, bugger up the bearing and bend the end of the mainshaft exactly around the point of the lube bores.  Have seen one snapped at the step, it blocked itself before even more harm was done, rider luckily did not fall off. 

Bit over 1 1/2 hours to get the lump out of the frame and into bits on the workbench, normal rate without getting into a sweat. :D

Usually takes at least 4 hours to get everything spotless... ::)

piet
 
redax5 said:
you have already wasted 65 mins counting the different clunks and clicks at different gear ratios and then using your slide ruler to calculate gear ratios
Click to expand...

And you've just wasted 10 minutes reading this thread  :D

It might take you 45 minutes Red, but I reckon it'll take me the best part of a day. It'll be the first time I've delved that far into a Laverda engine.

I'd be very surprised if the output shaft is busted. The chain tension was OK and the bike was still running normally as I rode it the 60km back home after I first heard the strange noise.

I'd prefer not to turn the engine upside down in case there are little slivers of bearing lying in the bottom of the case that could end up elsewhere in the works.
The head gasket is weeping a bit of oil too, so a gasket replacement was on the to-do list anyway. Just another reason to strip the engine from the top down.
Cash flow is a bit tight at present, so I'll try to avoid any other stuff on the "while I'm in there" wish list.
 
Dellortoman said:
And you've just wasted 10 minutes reading this thread  :D

It might take you 45 minutes Red, but I reckon it'll take me the best part of a day. It'll be the first time I've delved that far into a Laverda engine.

I'd be very surprised if the output shaft is busted. The chain tension was OK and the bike was still running normally as I rode it the 60km back home after I first heard the strange noise.

I'd prefer not to turn the engine upside down in case there are little slivers of bearing lying in the bottom of the case that could end up elsewhere in the works.
The head gasket is weeping a bit of oil too, so a gasket replacement was on the to-do list anyway. Just another reason to strip the engine from the top down.
Cash flow is a bit tight at present, so I'll try to avoid any other stuff on the "while I'm in there" wish list.

Good luck with that  you have heard the old opening a can of worms?????
Click to expand...
 
Terry Dymond said:
Ha, very easy for you to say from the depths of Laverda heaven Red, 45 minutes for a full engine strip indeed!
The rest of us mere mortals reserve the right to perform the following when we think something is amiss with our beloved steeds:
Ripping of hair,
Rending of vestments,
Shooting the dog, and
Over-indulging in strong drink.
When all the above fails to fix the problem, we resort to the following:
Ask for advice on the forum,
Contact Red and ask how much. :D :D
Click to expand...

Leave the poor old dog alone, shoot the misses.... oops, sorry Oscar.... :-X
 
Agreed.  When your Laverda is a pile of oily bits on the floor and the rebuild bill is skyrocketing out of control the dog is the only one who will come along and lick your ear.
 
Hi Cam,
Give me a call and I will come around and give you a hand getting it out of the frame. Bit of a juggling act. We can tilt it on it's rear end to get the bottom half off if you are worried about loose bits. I will bring beer and humour too. It is probably just a bearing and we will have it going in 2 sessions.
Cheers
Russ
 
Dellortoman said:
I'd prefer not to turn the engine upside down in case there are little slivers of bearing lying in the bottom of the case that could end up elsewhere in the works.
Click to expand...

Rarely do, they are normally trapped in the sludge that has accumulated on the casing floor. :D

piet
 
Hey Cam why not put up an ad for a spare engine to slip in whilst you fix yours.
On second thoughts maybe not, I believe a 750 owner tried that and that didn't go well. >:( :D

                                                                              Dave
 
Dellortoman said:
And you've just wasted 10 minutes reading this thread  :D

It might take you 45 minutes Red, but I reckon it'll take me the best part of a day. It'll be the first time I've delved that far into a Laverda engine.

I'd be very surprised if the output shaft is busted. The chain tension was OK and the bike was still running normally as I rode it the 60km back home after I first heard the strange noise.

I'd prefer not to turn the engine upside down in case there are little slivers of bearing lying in the bottom of the case that could end up elsewhere in the works.
The head gasket is weeping a bit of oil too, so a gasket replacement was on the to-do list anyway. Just another reason to strip the engine from the top down.
Cash flow is a bit tight at present, so I'll try to avoid any other stuff on the "while I'm in there" wish list.
Click to expand...

If you open the engine upside down, there's nothing going anywhere unless it falls "down" the camchain tunnel which is "a" very unlikely, and "b" of no importance whatsoever, you can retrieve the muck easily.
Just do it.
Paul
 
Thanks for the offer Russ. I dunno when I'll get to it, but I'll let you know.
Getting it out of the frame is no problem. I'll yank it out with the chain hoist like I did with Tim's 3C. But beer and humour are always welcome.  :D
 
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