ST4B Front Chain Driven Gear

[Loneoutrider]

My Snowmaster has been breaking off teeth on the front chain driven gear. The parts list show shows the gear complete as part ST7489. Is there any difference between an ST4 and an ST4B in part number. The chain complete is shown as part ST7123. Does anyone have the specs on that chain ie: sae or metric dimensions, number of links, etc? I believe it will be best to change the drive gear on the variator at the same time, so will have to figure out correct tooth count there also.
I don’t know if the parts list from Goldmine Corp differentiates between the ST4 and ST4B. I believe there are some gearing differences due to wider tracks on 4B. I am using the snowcat between 6500 and 7500 above sea level so don’t want mess up gearing. Don’t have any extra performance as it is!
I haven’t started taking apart yet. The county just plowed my road April 10, so now it is time to put snowcat and snowmobiles away.
Thanks ahead of time for any guidance!
Loneoutrider

 

[Cidertom]

The chain is 16B "metric". It has the same pitch distance ( 1 inch) as SAE 80 however the width is larger and SAE 80 will damage the sprockets. it wont sit down all the way in the sprocket and will load the tips harder. I have been told, but have not seen, that some folk have ground the edge of the sprocket to make SAE 80 work.

 

[redsqwrl]

The chain is 16B "metric". It has the same pitch distance ( 1 inch) as SAE 80 however the width is larger and SAE 80 will damage the sprockets. it wont sit down all the way in the sprocket and will load the tips harder. I have been told, but have not seen, that some folk have ground the edge of the sprocket to make SAE 80 work.

this is absolutely the best and clearest explaination of the chain pitch ever, Put that in the book of snow trac!

and yes masters and tracs are typically different. Just in tooth count. if you change them in pairs you are fine. get your sae chain gone. metric is the same price and availability