Slack drive chain?

[RedBlazer]

I'v got my new treads, wheels are on their way, and now I'm trying to figure out how much chain slack is acceptable??? There is no hook forming on the teeth, but the chain sags, not enough to hit the tub, how much is too much? Is there a dimension from a straight edge or any "rule of thumb" to use?
There are no tensioners on this ole'girl and there doesn't seem to be any type of adjustment as the bearing and axles seem to be bolted in the rails.
Any advice or a point in the right direction would be much appreciated.
Being a 79, and new to this, should I just replace everything?
Thought of replacing axles with the 5 bolt pattern axle/hubs as it has the old 3 bolt on it. Might be a waste of money though as I will for now just make the adapters...so many questions???
Doug

[JohnF]

Hey Doug,

Hard to say on the axle swap what I would do. Sounds like you have a pretty good handle on it.

As for the chain: if we assume that the chain is tight enough that it meshes properly in the sprocket, wear of the sprockets happens when the pitch of the chain changes due wear. The sprockets will wear to match the new chain pitch. You can check this and use this as your guide to whether you should replace the chains. Measure center pin to center pin for as many as you can get lined up - say have a helper stretch the top of the chain tight - and divide by the number of pins. (More pins reduces percentage error) This is the chains pitch. I don't remember exactly the number we are looking for but it is something like 1/16 and their shot. (1/16 is 10% of 5/8, the pitch of my chain, 50-2)

For the slack on good chain, and assuming it bothered me, I would then start looking at adapting a tensioner.