Excessive Crankshaft End Play

[groucho]

On thrust bearing longevity:

With a manual transmission, does sitting at traffic lights with the clutch pushed in for minutes at a time wear the thrust bearing? Enough to worry about it?

It'll wear it and the TO bearing. How much exactly? Dunno. I let my clutch out at all stops on my stick cars

[CDMBill]

On thrust bearing longevity:

With a manual transmission, does sitting at traffic lights with the clutch pushed in for minutes at a time wear the thrust bearing? Enough to worry about it?

Not enough to worry about if the clearances and thrust are set correctly, even with a pretty big clutch pressure wise. Most diaphragm style clutches go over center or close to it when fully depressed and exert less thrust pressure as a result when dis-engaged.