5 speed ribbed tranny rebuild

[ME 109]

Thanks Jean, In the freezer they'll go.

Steve, I'm just a wee bit familiar with this shift kit business. I read about it somewhere some time ago and as you say I might be lucky enough to have it already.

I'll prolly at least change the nylon roller for a ball bearing.

Can't say that I've suffered from a clunky shift tho'

[ME 109]

Tranny housing is empty and thoroughly cleaned.

Suprisingly, the gear clusters took several 'baths' to flush out all of the micro and not so micro particles that were caught up in all the nooks and crannies.

I thought the clusters were clean enough until I bathed them. And then bathed them again......and again.

After the third time there was very little that had settled on the bottom of the wash tub.

Lesson, these parts require serious flood cleaning before reassembly. What I found recently on the magnetic plug was no more than 25% of what was in there.

There's a little oil seal in the rear end of the input shaft. Haven't seen that mentioned as requiring change, but it would make sense to do so I 'spose.

[dougie]

There is a small seal that the clutch pushrod slides through every time you use the clutch.
That's like 10000000000000000000000000000000000000 times.

[chasbmw]

And that little seal is a right bugger to fit

[dougie]

And that little seal is a right bugger to fit

Yes I buggered the first attempt, then I did it with a length of threaded rod, washers, and nuts. And the warm/cold thing.

[ME 109]

This is the only wear that I can see on any of the gears.
It is on the end of the output shaft.
Not sure if this means that I need both gears, or just the worn one....
Edit, the pitting varies in amount from tooth to tooth, and only affects less than half of the circumference of the gear.

[robert]

This is the only wear that I can see on any of the gears.
It is on the end of the output shaft.
Not sure if this means that I need both gears, or just the worn one....
Edit, the pitting varies in amount from tooth to tooth, and only affects less than half of the circumference of the gear.

If the mating gear is without pitting, just replace the 5th gear output pictured and you're good to go. That is pretty common.

[ME 109]

If the mating gear is without pitting, just replace the 5th gear output pictured and you're good to go. That is pretty common.

Thanks Robert, I hadn't had the time to even find out what gear it was.........

So, I just looked at Motobins......taller 5th??? Do I need any other gears if I want to go the taller 5th? As in layshaft?
I wonder what the rev difference is @160kph.
I think 5th gear was replaced (second hand?) about 13 years ago.

Appears to be 21 teeth on the normal 5th and 20 on the taller 5th.

And what is the centre spot on the gear? I haven't read that far yet but I'd assume it has to do with assembly.

I'll need to pull the gear off and check for an 'X' My bike is 9/81 so it should be 15 degree without an X

[Major Softie]

No, you do not need another gear, you can just replace that one for a taller 5th.

We have speculated about this here before and no one has, to my memory, explained how you can change the tooth count of just one of two meshing gears without changing their distance apart, but apparently you can.

[Jean]

MS, If the number of teeth is not TOO different, the teeth can be made taller with a slightly fatter root and you can get away with changing the tooth count. I'd look hard at some sort of heavy-duty additive for this gearbox as the pitting suggests either it sat a long time and some of the teeth got rusty, or the oil wasn't as good as it should have been or maybe not filled properly.
PS to ME109. Running 5th gear without being at high speed and RPM can eat up gears pretty fast. What RPM are you currently running at 160KPH?