There are so many things that need to be checked when rebuilding one of these boxes it's hard to know where to start....
To begin with check the selector fork arms for excessive wear and/or discolouration caused by overheating...also the grooves in the selector dogs that the selector forks fit into...The forks should be a reasonable fit in the grooves and the walls of the grooves should be smooth...
Look at the cam tracks that the pins run in on the selector fork shaft...The pins and track should be unworn...If you have more play between the pin and track at the point where the track changes direction they may need replacing...
Check the splines on the mainshaft where it runs against the sleeve gear (top gear)..If the splines are worn back on the ends and discoloured the mainshaft may need to be replaced. Wear here will affect the position of the mainshaft within the box when it is shimmed to take up end float and can affect gear selection....
Check the teeth of the ratchet plate and ends of the pawls of the gear change assembly for damage...Replace if damaged. Replace both gearchange return springs if they are stretched/rusty/distorted....
It is likely the majority of the bushes will be outside of tolerance...However, check the shafts for wear before ordering new bushes...
The shafts can be cleaned up as they are through hardened but if that means they are then undersize it is better to make, or have made, new bushes toleranced to suit the shafts...
The layshaft cannot be removed from the inner cover until the speedo drive is extracted......
Slacken the nut at the upper end the speedo drive (on top of the inner cover) and give the end of the brass drive housing a light tap with a hide mallet BEFORE attempting to undo the grub screw that holds the drive outer into the casing...The end of the screw is extended and fits into a groove in the speedo drive outer. The outer is pulled against that screw and locks it in place when the nut at the top is tightened, effectively making it impossible to get the screw undone without the nut being loosened first....
Ask more questions here as you go along...that will usually get an answer...and make sure you have the factory worksheets for the gearbox....
If you mail me off forum I will send you some information that will be useful...Ian
email (option): ian@wright52.plus.com
... And have a look at the Technical Section on the website...
email (option): viaconsu [at] planet [dot] nl
Hi Gary,
Also look for wear on the teeth, specially the ones on the sleeve gear and its corresponding one on the layshaft (the set most to the driveside of the bike), this set is the most under power.
And of course the condition of the bronze bush in the sleeve gear, in most cases worn. probably caused by a low oil level.
But also think that the wear out of the bronze bush could be caused by a too tight front chain. The 2 bolts which have to hold the gearbox fixed between the plates are rather small so can't be tightend too much without stripping the threads. I have found that the box has the tendency to be pulled back by the rearchain and causing extreme pressure on the front chain and subsequently the bronze bush.... I now adapt the construction by putting in longer bolts with big serrated washers on both sides of both of the bolts. And also using higher nuts which can be tightend more.
You might be lucky as, unlike the WD boxes, your box has a oil seal on the driveside.
Good luck, Michiel / NL
['I now adapt the construction by putting in longer bolts with big serrated washers on both sides of both of the bolts. And also using higher nuts which can be tightend more.']
I have made the same modification....Ian
email (option): ian@wright52.plus.com
To begin with check the selector fork arms for excessive wear and/or discolouration caused by overheating...also the grooves in the selector dogs that the selector forks fit into...The forks should be a reasonable fit in the grooves and the walls of the grooves should be smooth...
Look at the cam tracks that the pins run in on the selector fork shaft...The pins and track should be unworn...If you have more play between the pin and track at the point where the track changes direction they may need replacing...
Check the splines on the mainshaft where it runs against the sleeve gear (top gear)..If the splines are worn back on the ends and discoloured the mainshaft may need to be replaced. Wear here will affect the position of the mainshaft within the box when it is shimmed to take up end float and can affect gear selection....
Check the teeth of the ratchet plate and ends of the pawls of the gear change assembly for damage...Replace if damaged. Replace both gearchange return springs if they are stretched/rusty/distorted....
It is likely the majority of the bushes will be outside of tolerance...However, check the shafts for wear before ordering new bushes...
The shafts can be cleaned up as they are through hardened but if that means they are then undersize it is better to make, or have made, new bushes toleranced to suit the shafts...
The layshaft cannot be removed from the inner cover until the speedo drive is extracted......
Slacken the nut at the upper end the speedo drive (on top of the inner cover) and give the end of the brass drive housing a light tap with a hide mallet BEFORE attempting to undo the grub screw that holds the drive outer into the casing...The end of the screw is extended and fits into a groove in the speedo drive outer. The outer is pulled against that screw and locks it in place when the nut at the top is tightened, effectively making it impossible to get the screw undone without the nut being loosened first....
Ask more questions here as you go along...that will usually get an answer...and make sure you have the factory worksheets for the gearbox....
If you mail me off forum I will send you some information that will be useful...Ian
Thanks Ian - email sent.
Gary
email (option): gj.owen@hotmail.co.uk
Thanks Hans, found these and they look really helpful.
Gary.
email (option): gj.owen@hotmail.co.uk