GT380 plastic timing gear replacement

[Komo1]

I'm trying to replace the plastic timing gear on my 1972 380 and I can't seem to be able to break the nut free that's holding it. I've tried holding the shaft with vice grips but don't want to damage the shaft and have tried an air wrench to see if it would break it free but no luck. Any suggestions?

[yeadon_m]

Please don't hold the points cam with gripper - it will marr the surface and your timing will be no good any longer, nor properly settable!

take the clutch cover off, then there is a 14mm nut on both sides, one on the points cam outside, and one on the plastic gear inside. Two spanners, no need for grippers

I did this in 2013 on my 380, the gear had lasted ~42000 miles.

You may wish to change out the twin bearings while you're in there, if there is even the slightest side play on the points shaft. That play even if seemingly tiny is distorting the ignition timing so if in doubt, its worth the few bucks.

Mike

[Komo1]

Thanks Mike. I have the cover off but the nut on the points side is loose therefore when trying to remove the nut on the plastic gear side, it just spins. Is it a left handed thread.

[yeadon_m]

Ah, OK. Well, you might try removing the points cam, then the 3 legged timing plate, then pull out the small, pressed-in pin retaining the points shaft, then tap the shaft backwards back out of of the clutch cover. You could then grip the threaded part of the shaft in a vice, after protecting the threads, and that should enable you to undo the nut retaining the plastic gear (it might be possible to do this with the points shaft in situ but would be easier when out). Or, just go as far as removing the points cam and then put two nuts on that shaft separated by a sprung washer, and use the inner nut as a locked nut to give traction with a spanner for the nut on the plastic gear.
I don't think the plastic gear nut will be on very tightly - its probably not been moved in 40 years
Good luck,
Mike

[Suzukidave]

Not sure if this helps http://www.oldjapanesebikes.com/mraxl_G ... index.html" onclick="window.open(this.href);return false;

[2strokedGT]

Komo1
The 1972 nylon gears were only made for that year and in 1973 the nylon gear and steel drive gear
were updated to a different style.See the service bulletin 119 http://www.ozebook.com/compendium/techb ... 0mc119.pdf

I installed a later 1973 nylon gear in my !972 GT380 before I found this out it works fine but i'm worried about it wearing out prematurely.

[Komo1]

Thanks guys, good info. I finally got the cracked plastic gear off and the new one installed. Now its off to install the electronic ignition. Good to hear a metal gear is being used instead of nylon.

[yeadon_m]

Just to be clear in case this is found later, Suzuki never made a metal driven gear, these were always plastic (nylon) and this is what we think of when we mentioned the plastic timing gear. Its the drive gear that was metal (of course).

There was an aftermarket driven gear made of metal. I've not heard one running, but I understand that with one fitted, the system is noisy, perhaps why Suzuki chose plastic? (though it might have been cost, since its a low-loaded component).

Cheers,
Mike