Campagnolo 8 speed shifting issues

[RibbleRoad]

Hi all, hoping for some advice. I have bought a set of Campagnolo 8 speed Avanti ergo shifters and a Chorus 8 speed rear derailluer to replace some Shimano 7 speed downtube shifters and Shimano 600 rear derailleur, but cannot get it to shift anywhere close to being useable. It will shift the first couple of gears okay but then will either skip gears or be trying to overshift, as though the shifter is pulling too much cable.

I have an 8 speed Miche 13-26 cassette fitted which shifted perfectly with the 7 speed Shimano downtube shifters (obviously not using one of the cogs). Previously I had a 12-21 Campagnolo cassette which also shifted pefectly with Shimano downtube shifter. I have also tried putting the Shimano 600 rear derailleur back on with the Campagnolo shifters and it does actually shift slightly better that with the Chorus derailleur, but still not what I would consider acceptable.

I'm confused as to why an 8 speed Campagnolo shifter is not able to correctly shift an 8 speed Campagnolo derailleur when used with a Miche cassette which is designed to be compatible. Does anyone have any ideas on this?

This is all mounted to an old Ribble road bike if that makes any difference and I have checked hanger alignment and all seems okay.

 

[pigman]

Campag 8 speed is a different spacing to Shimano 8 speed. So if your cassette has Shimano 8 speeed compatibility it won't work with your 8 spd campag shifters. Check whether your cassette is 8 speed campag or 8 speed Shimano. That's the root of your problem

 

[RibbleRoad]

Thanks for the reply. The cassette is a Miche one designed to replace a Campag one. Just to be sure I have put the old 7 speed Campag cassette back on to try and have the same problem with overshooting. I understand that 7 and 8 speed campag cassettes have the same 5mm spacing so this setup should work. It seems that there must be some compatibility issue between the Avanti ergo shifters and the Chorus cassette...

 

[Frankenorange]

Are you sure the campag derailleur is 8 speed?

If you have 8 speed shifters, the right chain, and the right cog spacing, then the mech is surely the problem.

 

[RibbleRoad]

Thanks for the responses all. I ended up messaging the seller I bought the derailleur from and he admitted he made a mistake in the listing and it was actually a 7 speed.