Condition Monitoring the Timing Chain

[StephenB]

If that was possible you could get twice the miles out of those expensive sprockets. Run a single chain on one row until it's warn down....then put a chain on the other row the next time.

I like THAT thought!

[Rapid Dog]

I just replaced the chain and crank sprocket on my '81RS (55K). The timing mark was very wiggly.
Wrench told me it probably wouldn't change the mark.
He was wrong.
The timing mark is now very easy to see!

[Garnet]

If that was possible you could get twice the miles out of those expensive sprockets. Run a single chain on one row until it's warn down....then put a chain on the other row the next time.

I like THAT thought!

My unproven and half baked theory as to why the sinlge row chain lasts longer is:

The double row sprockets must be made to a much closer tolerance and mounted absolutly in line with one another so that the load on both rows of the chain is identical. If there is a tiny bit more load on one side of the chain it will begin to wear quicker, wearing the sprockets unevanly makeing things worse. As well the mass of the cam sprocket is half on a single row set up. As soon as there is a tiny bit of play in the chain, the snatching back and forth is less strain with the lighter weight single row. For that reason, I don't see a single row chain lasting as long on a double sprocket as it would on the single.

That being said, it is so easy to change just the chain, you could get a much longer sprocket life useing a singlechain on a new double sprocket. But the single sprockets are much cheaper.

As stated above, just theory, as sound as cold fusion.

[mattcfish]

If that was possible you could get twice the miles out of those expensive sprockets. Run a single chain on one row until it's warn down....then put a chain on the other row the next time.

I like THAT thought!

My unproven and half baked theory as to why the sinlge row chain lasts longer is:

The double row sprockets must be made to a much closer tolerance and mounted absolutly in line with one another so that the load on both rows of the chain is identical. If there is a tiny bit more load on one side of the chain it will begin to wear quicker, wearing the sprockets unevanly makeing things worse. As well the mass of the cam sprocket is half on a single row set up. As soon as there is a tiny bit of play in the chain, the snatching back and forth is less strain with the lighter weight single row. For that reason, I don't see a single row chain lasting as long on a double sprocket as it would on the single.

That being said, it is so easy to change just the chain, you could get a much longer sprocket life useing a singlechain on a new double sprocket. But the single sprockets are much cheaper.

As stated above, just theory, as sound as cold fusion.

The only sprocket you would have a play issue with would be the lower cam sprocket. It can be lightened substantially by drilling more or larger holes, just like the old flywheels. The single chain has less mass, so play from it is going to be less of an issue.

[DanielMc]

I'm still trying to understand why a double row chain would wear quicker than a single row - in power transmission terms it should be at least 50% stronger, no?

[ME 109]

I'm still trying to understand why a double row chain would wear quicker than a single row - in power transmission terms it should be at least 50% stronger, no?

Do the joining pins go through both chains?
A longer pin would be more susceptible to any misalignment, no matter how slight.
Just a thought.

[StephenB]

It is a dual-row chain, one piece, with the masterlink going through both "halves" ... but ... there are no halves, it is a dual-row chain.