1200 gearbox parts

Z

Zakredridge

Junior member
Location
United Kingdom
Hi All
My gearbox is stuck in first gear, on closer inspection the internal gear that meshes with the external gear ( outer gearbox cover) is not for rotation.
Does anyone have any spare gear box selectors, cam plate or main Shaft lay shaft parts available?
Cheers
 
You don't need spares, the mechanism just needs proper adjustment/alignment. Unless you've broken something internally, which is highly unlikely.

This topic has been done to death here, use the search function for selector mechanism.

piet
 
sfcpiet said:
You don't need spares, the mechanism just needs proper adjustment/alignment. Unless you've broken something internally, which is highly unlikely.

This topic has been done to death here, use the search function for selector mechanism.

piet
Click to expand...
The selector plate will not move on the gear tho!
I have been having issues previously, missed gears ,and laboriously long changes
 
More input required... pics?

Sprocket cover mis-aligned? Loosen the 4 screws a bit and the selector shaft will most probably miraculously loosen itself. The "sweet spot" then needs to be found. Warped sprocket covers are now fairly common, having often suffered from decades of abuse. These can be a royal pita...

Sprocket cover not fitted? New neutral switch installed? Switch needs to be shimmed for smooth selector drum operation.

Was the engine/gearbox apart? Gears, shafts and selector forks should be checked for proper clearance and movement. These may be pretty simple boxes, but that doesn't mean they can be thrown together in a hurry. They hold quite a few pitfalls.

All sorts of possibilities. These boxes rarely break, but when they do, you'll certainly notice it. The entire shift mechanism often needs quite a bit of TLC to work properly.

piet
 
sfcpiet said:
More input required... pics?

Sprocket cover mis-aligned? Loosen the 4 screws a bit and the selector shaft will most probably miraculously loosen itself. The "sweet spot" then needs to be found. Warped sprocket covers are now fairly common, having often suffered from decades of abuse. These can be a royal pita...

Sprocket cover not fitted? New neutral switch installed? Switch needs to be shimmed for smooth selector drum operation.

Was the engine/gearbox apart? Gears, shafts and selector forks should be checked for proper clearance and movement. These may be pretty simple boxes, but that doesn't mean they can be thrown together in a hurry. They hold quite a few pitfalls.

All sorts of possibilities. These boxes rarely break, but when they do, you'll certainly notice it. The entire shift mechanism often needs quite a bit of TLC to work properly.

piet
Click to expand...
Ok thanks I'll check those points out .
 
Like Piet, can't possibly point to a cause without more info. Did the problem suddenly occur? ie Was the bike running ok then the gearbox suddenly started playing up? Or is it a 2nd hand purchase that wasn't running?

It should be easy enough to trace the cause. The outer selector shaft with the pins can easily be checked by doing what Piet suggests, or simply removing it - you'll quickly know whether it's moving freely once it's off the bike. Once off, see if you can use a large flat blade screwdriver to turn the inner gear (that operates the internal selector drum/plate - you need to be turning the rear wheel backwards and forwards to have any hope of selecting gears (so if the chain is not fitted, you'll need to find some way of rotating the gearbox sprocket).

I've never seen a selector shaft seize on a Laverda in over 50 years working on them. Doesn't mean to say there isn't something broken inside, but you would never split the cases based simply on what you've described before doing every possible check with the thing assembled.
 
maybe a broken cam chain tensioner is lying under the slector drum and has jammed it, no good looking at the tensioner blade and guide (front and back) it might have broken and been left inside when new blades where fitted, only to have the broken one move around causing the current difficulty, but of course, take the tensioner and blade out and if they are both complete??????? or have a portion missing..... bingo.
CLEM
 
piranha-bro2 said:
Like Piet, can't possibly point to a cause without more info. Did the problem suddenly occur? ie Was the bike running ok then the gearbox suddenly started playing up? Or is it a 2nd hand purchase that wasn't running?

It should be easy enough to trace the cause. The outer selector shaft with the pins can easily be checked by doing what Piet suggests, or simply removing it - you'll quickly know whether it's moving freely once it's off the bike. Once off, see if you can use a large flat blade screwdriver to turn the inner gear (that operates the internal selector drum/plate - you need to be turning the rear wheel backwards and forwards to have any hope of selecting gears (so if the chain is not fitted, you'll need to find some way of rotating the gearbox sprocket).

I've never seen a selector shaft seize on a Laverda in over 50 years working on them. Doesn't mean to say there isn't something broken inside, but you would never split the cases based simply on what you've described before doing every possible check with the thing assembled.
Click to expand...
The bike has had numerous faults since I got it.
The selector shaft is solid, no movement in it at all.
The gearbox has been terrible trying to get a positive change.
I've been through all previous processes to end up at this point.
I'm half way to removing the engine.
Just going to take bottom crankcase off and have a look.
The centre stand mounts are completely knackered, they need heat to position and then welding.
This has just brought it forward.
 
Bear in mind the 'selector plate' is held in certain positions by the internal detent mechanism - in my experience it never just moves "with fingertips". Also, if the dogs are not in alignment when stationary, it will feel like it's locked, but in normal operation things are all spinning and the dogs can find their mating slot in the respective gear.
But if you're rotating the clutch or countershaft and have some leverage on the gear of the selector shaft, yes, it should move pretty freely between the detents.
Bottom case off sounds like a good idea for a bike you're still sorting out and has many unknowns.
Double check there is the retaining pin in the selector fork shaft - sometimes overlooked by those not familiar and/or who have received the bike in bits.
Piet had the great tip of reassembling the gearbox shafts into the bottom case and securing them snugly into the bottom case with an extremely long cable tie down through the neutral switch hole. Bottom case + gearbox can then be lowered onto the assembled top end quite easily, bolt it up and then snip the cable tie and extract.
 
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