MT804 Gearbox missing 3rd and 4th

[jim.mt10]

Hello.

I recently split my MT10/36 gearbox to fit a new selector plate as the neutral sensor earth tag was missing.

Everything looked ok in there i.e. bearing etc, so I just replaced the seals. Before I put the cover back on, I checked several times that I could change up and down the gears and everything seemed ok, so I put it back together, put it back in the bike and when I took it for a test ride it selects first and second gears smoothly but won't allow me to shift into 3rd or 4th. The gear pedal just moves to the end of its travel with no resistance.

Anybody have any ideas what I've done wrong. I did have a washer(i.d. 20mm o.d. 50mm approx) left over and I couldn't remember where it came from.

Thanks for any suggestions.

[dneprlover]

Does reverse work ok? was everything set back into the neutral position before the case was refitted? Not sure about the washer, it could be from under the spring at the cover end of the kickstart shaft, or a shim to set the float of the output shaft. It does sound a bit large for either though. Have a look in the parts book on www.goodkarmaproductions.com to see if you can identify where it goes. Internals for mt10/10-36/11/12 and 16 are all the same so any parts book will do, only the main casting differs due to the air filter shape or leccy foot.

 

Sorry, sounds like you need to go inside it again

[jim.mt10]

Thanks, DL.

Yes, reverse is still working. I've already resigned myself to splitting it again, was just

fishing for ideas. I guess I'll soon find out. Cheers

[DneprCossack]

Hello.

I recently split my MT10/36 gearbox to fit a new selector plate as the neutral sensor earth tag was missing.

Everything looked ok in there i.e. bearing etc, so I just replaced the seals. Before I put the cover back on, I checked several times that I could change up and down the gears and everything seemed ok, so I put it back together, put it back in the bike and when I took it for a test ride it selects first and second gears smoothly but won't allow me to shift into 3rd or 4th. The gear pedal just moves to the end of its travel with no resistance.

Anybody have any ideas what I've done wrong. I did have a washer(i.d. 20mm o.d. 50mm approx) left over and I couldn't remember where it came from.

Thanks for any suggestions.

Be aware that the selector plate is matched with the selector forks. If you look at the new and ols selector plate, they will probaly be different! I think it comes from (to large) production tolerances.

[jim.mt10]

That thought had occurred to me and in fact, I was looking for a piece of spring steel to make a replacement

for the neutral earthing tab so that I could use the original selector plate but as the part is 13euros

and I was wasting time looking for suitable material, I just went ahead and ordered it. The thing is, before I put the gearbox cover back on, I was

able to change up and down all 4 gears smoothly, but I suppose with the cover bolted up everything is that bit tighter and any variations in the selector plate

might cause problems.

Anyway, I'll be splitting the box again in the next few days and soon find out.

Thanks for the reply.

[temppu]

I think i have to give warning to everyone who is rebuilding gearbox.

There are lot of chinese stuff, and those are really soft iron.

 

Here is example of one part what shoud test before installation:

 

In that picture part number 272.

If you got chinese version you can try to scratch that and you will see good marks in there.

If you got real old NOS part, you can't scratch it. It's best to try with file (not sure is that right word).

 

Those chines part takes maybe 300 km and that's it. Rebuild again... not funny.

So if old part is ok, DONT change that.

[jim.mt10]

Got to the cause of my gearbox problem. The first problem was an error on my part. As I stated above, i checked to see if I could go up and down the gears before I bolted up the gearbox cover, the Problem was, I was concentrating on the gear changing function and didn't verify that the Primary shaft was driving the driveshaft in all the gears..this I only discovered when the engine was running. After Splitting the gearbox again and checking drive in all the gears, I discovered the Primary shaft wasn't driving 3rd and 4th gears...the reason being that the woodruff key (part no, MT804425) is missing. As there is no sign of key fragments and the keyway itself is in good condition, I can only assume that someone has stripped the gearbox and reassembled it without the woodruff key and then given up on the bike (or ridden it around in 1st and 2nd!). I hope this is useful to somebody...