M732/5 Thumbies & Mech - 8 speed?

[Once A Hero]

Quick question, can M732/5(?) thumbies and an M735 rear mech be set up to run indexed 8 speed? Or just by friction? Or not at all?

I have the thumbies and mech, and was planning on going 7 speed, but I have an 8 speed freewheel / block which would save me sourcing a 7 speed item is all.

 

[hamster]

The spacing on 7-speed is 5.0mm, on 8-speed it's 4.8. So even with everything set up perfectly, there will be a mismatch. Apologies if I am teaching you to suck eggs.

Yes, you can get it to work, especially if you set the middle gears up first and accumulate the errors each side using the floating top jockey in the mech. But it will always be fussy and rattly in a couple of gears in my experience. When cable outers get tired it then becomes annoying.