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Discussion Starter · #1 ·
will a sprocket for a 36-79 4spd fit a 80-85 4spd trans ? from the pictures it looks like the only difference is that the later sprockets have tapped holes in them for a lock plate ?
 

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Discussion Starter · #3 ·
Gerry said:
I guess so. At least it works the other way round. But why do you want to use it that way?

Greetings!
Gerry
i need to get more clearance between my chain and starter housing so I want to try using a 21 tooth sprocket instead of the 23. I've already got a 21 but it's the old style. i've already put a 49 tooth sprocket on the back so I'm hoping i'll still have some top end left.
 

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lilbill said:
i need to get more clearance between my chain and starter housing so I want to try using a 21 tooth sprocket instead of the 23. I've already got a 21 but it's the old style. i've already put a 49 tooth sprocket on the back so I'm hoping i'll still have some top end left.
I think the rule of thumb is for every tooth on the tranny it's 3 on the rear, so if you increase the tranny by 1 you would have to DECREASE the rear by 3 to end up with the same gearing.
-Jesse
 

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jesse said:
I think the rule of thumb is for every tooth on the tranny it's 3 on the rear, so if you increase the tranny by 1 you would have to DECREASE the rear by 3 to end up with the same gearing.
This is one of those cases where the actual math is no more difficult than the rule of thumb.

It's a simple ratio between the teeth on the trans sprocket and the teeth on the rear sprocket.

Running a 21f, 49r combo . . . the rule of thumb is significantly off. Two and a third teeth changed on the rear equals a single tooth change on the front.

Just divide your rear tooth count by your front to get your present ratio. Do the same for any proposed changes to see where you stand.

Respectfully,
Jason
 
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