T120V 5 Speed - Indexing, False Neutrals Etc

[scottholl]

Hi Scottoil, I fear I also broke my main shaft or did some kinda damage in my tranny. T120v 5 speed. I first thought the clutch locked up but have the primary side taken down all the way to the 20 tooth front drive sprocket, chain and rear wheel and sprocket still on. The clutch and everything there looks great. Yes the big nut is off the front sprocket and was tight. The main shaft itself and the drive sprocket seem disjointed only catching each other intermittently when moving rear wheel and chain therefore the front drive sprocket back and forth. So this is where I am. Any advice going forward before I pull the front sprocket and start on the Tranny.

Amer14; It's a little difficult to visualize the condition of these parts as you have described, "The main shaft itself and the drive sprocket seem disjointed only catching each other intermittently when moving rear wheel". have the splines on the main shaft's outer diameter and or the drive sprockets INTERNAL splines, have these had their respective materials worn away or have been "machined away" (due to rotation and contact interference? Can you take some photos and send? Regards Scott

 

[amer14]

Amer14; It's a little difficult to visualize the condition of these parts as you have described, "The main shaft itself and the drive sprocket seem disjointed only catching each other intermittently when moving rear wheel". have the splines on the main shaft's outer diameter and or the drive sprockets INTERNAL splines, have these had their respective materials worn away or have been "machined away" (due to rotation and contact interference? Can you take some photos and send? Regards Scott

 

[amer14]

Shaft moves in and out less than 1/4 inch. Maybe nut is loose other end. When I pull it towards me it will engage the sprocket. Teeth on inner sprocket and the gear end with the threads for the big nut all look real good. Time to pull kicker cover tranny side ? Thinking tranny or main shaft in tranny teeth now more than broken main shaft cause I the shaft feels whole to the other side. False neutrals abound cause when I do find a gear all seem fine with shaft rotating with some play like from 10 o'clock to 12 before full engage of sprocket.

 

[amer14]

Main shaft is Broken . Nut was almost off on tranny side. Damn such an easy fix should have checked it got Allen bolts on it cover off in 2 min. Now any advise on best way to pull it ?

 

[scottholl]

Main shaft is Broken . Nut was almost a long time ago was it exits out of the tranny case but I could be mistaken and it might exit from primary case side.

I know when I did. This was the first time I ever attempted such a disassembly and for withdrawal of transmission gears and dogs and forks (and main shaft and lay shaft) I primarily resorted to following the steps and instructions as written in workshop manual. Do you have a WSM? I believe a WSM can be downloaded from the site.

 

[amer14]

Thank you Scott, yup I need the shop manual and you tube. 5 speed has 3 dogs .Found a NOS on eBay just bot it didn't even haggle $150 delivered. 2 gears are jammed on it too hope I can salvage both of them. But case looks good as do all teeth

 

[scottholl]

View attachment 51078

I have ordered a replacement. Will try hylomar along the threads as an attempt at sealing it rather than risk the same happening to me

You may have some luck if you can thread the switch in as well as it can engage the broken area. Then use the low temperature aluminum welding rod (melts with a torch's flame) and it can use the exposed threads as a pattern that the low temperature welding material can mold around the threads, essentially creating new threads in the exposed threads. I hope you can understand my suggestion. Regards

 

[amer14]

Hi Scottoil, I fear I also broke my main shaft or did some kinda damage in my tranny. T120v 5 speed. I first thought the clutch locked up but have the primary side taken down all the way to the 20 tooth front drive sprocket, chain and rear wheel and sprocket still on. The clutch and everything there looks great. Yes the big nut is off the front sprocket and was tight. The main shaft itself and the drive sprocket seem disjointed only catching each other intermittently when moving rear wheel and chain therefore the front drive sprocket back and forth. So this is where I am. Any advice going forward before I pull the front sprocket and start on the Tranny.

Broke mainshaft between 2nd and 3rd. Kickstarter nut worked it's way loose. My advice is if your shifting feels funny or you get false neutrals pull the kick starter cover and check that nut and shift rod on that right first before opening the primary side and before anything breaks.