Struggling get my 8 speed brake/shifters to index correctly.. HELP!
 

I'm having some serious difficulty with my Ultegra 8sp brifters combined with my DuraAce 7402 8sp rear derailleur. It's shift throws are just a tad long, so if I adjust properly on 1st, by the time it's down to the 5th or 6th cog it's getting noisy, then will skip 7th entirely and jump down to 8th. This all worked perfect with my 8sp downtube shifters, so I know the rest of the system is fine.

Thinking my Ultegra units were bad, I purchased some cheap Shimano sora 8sp brifters, and this gave the same result.

I'm confused why this 8sp dura ace derailleur would be incompatible??

Thanks for any suggestions!

Bill

IIRC the 8 speed DA used a different cable spec then the rest of the Shimano line. The cable was a 1.6mm diameter, just about all other Index systems use a 1.2mm (well 1.1 also) cable diameter. So mixing the shifters and or the cable will upset the amount of cable that is pulled and in turn the amount of dérailleur movement. This difference will be noticed as you shift through more gears, just one shift is not enough build up to show the miss match yet. What i don't remember is if the actuation ratio is also different (how far the dérailleur moves for a unit of cable movement.) If you were to change out the DA 7402 to a 9 speed one and use the new shifters with a 1.2 cable all will play nice. Andy.

The cable pull of the Dura-Ace 7400 series is different than all other Shimano. You need either Dura-Ace 8-speed shifters or any Shimano 9-speed shifters to shift the Dura-Ace 7402 RD for Shimano 8-speed spacing. See this table http://sheldonbrown.com/dura-ace.html#indexing .

Or as Andrew says, get a new rear derailer - any Shimano except Dura-Ace 7400 series.

Your 8-speed downtube shifters must have been Dura-Ace.

Ok, that makes sense, of course Dura Ace would be different.. :( I did have Dura ace downtube shifters, so that answers that.

Thanks!

I just realized something. I was fixing up a K2 road bike frame and put some 8 speed brifters on it and set it up. The rest of the components are RX100. I was having a devil of a time getting the 8 speed brifters to index with the rear cassette. I looked at the brifters and they are Dura Ace. Do the Dura Ace 8 speed brifters use that same odd pull that is only usable with the Dura Ace rear derailleurs?

+1 to above. You either need different shifters, or more sensibly, a different RD.

Yes. Dura Ace 8-speed shifters actually pull the same amount of cable as all Shimano 9-speed, but with one less click of course. See Gonzo Bob's link above.

Now the real question - why were you putting DA STI on an RX-100 bike??? :P

I have them? I don't know what to do with them. I honestly don't like doubles all that much because I'm so big (350+) so I like to have the option of a bail out granny gear. The bike was built up with the RX100 stuff a while back using a double crankset but I used a 9 speed cassette and a pair of 3x9 Ultegra shifters. Worked fine but I robbed the 3x9 shifters and cassette for another bike I just finished (an old Rockhopper drop bar conversion). I had the Dura Ace 2x8 shifters in my junk bin so I threw them on it but now they don't shift well until it dawned on me that well they are one of the odd ball models.

So I'm kind of back to square one now.

I have the a set of the Shimano SL-BS77 Dura Ace Double/Triple Bar End Shifters (9-Speed). One of the confusing aspects was a sentence in the service instructions that warn, "This shifting lever can not be used with any rear derailleur other than Dura Ace". Apparently this was some hold over from the proprietary DA days, as starting with 9 speed, DA derailleurs and shifters became cross compatible with the rest of the Shimano line. As mentioned, the combination of the new 9 speed shifters (all, not just DA) and the old 8 speed DA derailleur, shifts the same as an 8 speed DA shifter and DA derailleur; the 8th index click is just adjusted out. Further as a 9 speed index shifter it will work with the whole of the Shimano line (Yes, I'm sure there are some limitations here, but the cable pull length/ derailleur movement will be the same).
It is also possible the OP had one of these 8/9 speed bar end shifters.

What I find amusing is there are still a lot of LBS wrenches and posters that will tell you that the SL-BS77 will only work with Dura Ace because of that warning, even though it's only validity is with the 8 speed index mode.