Weird Shimano FD-6400 adjustment problem
 

Hi all.

I am installing a front derailleur, a shimano fd-6400 (aka 600) braze-on, paired to a dura-ace brake/shifter from the same year. the cranks are also shimano 600. I'm running 8-speeds in the back, and front is a double ring. I'm putting them on a new-ish scattante frame.

Here is the problem I've run into. It seems that the shifter isn't pulling enough cable to fully move the derailleur.

I started by having the chain on the small front, and large rear cogs, then adjusted the lower limiter on the FD to be 1mm clearance. Then tightened the cable, and used the downtube adjuster screw to take up any slack. Then I moved the outer limiter screw way past where it should be (so it shouldn't allow the maximum amount of cage movement). Then I shift the chain to the large front/smallest rear cogs, and the front cage is rubbing the chain. I can pull on the cable and the FD has plenty more room to move, but the shifter just isn't pulling that amount of cable in one full shift.

The shifter came off of a bike that was paired with the same crankset but a FD-6401 clamp version of the FD. and the fd-6400 is a slightly different design, with the parallelogram at an angle, instead of being perpendicular to the seattube. Would this account for it? seems odd, since why would they have a different shifter for a braze-on vs. clamp type FD?

How is this possible? is there something wrong with my shifter?

what am i missing?

please help.

Probably nothing wrong with the derailleur or shifter. Simply shift the brifter into the small chainring setting (clicking the smaller button behind the lever several times, while pulling lightly on the cable with your hand if you have to), loosen the cable locknut, take up the slack, and re-engage the cable locknut. The main thing you want to remember is to leave a little more slack in the cable than your intuition tells you.
I made the mistake of making the cable too taut not once, but twice. :(
It may be that you had the brifter in the big chainring position when you engaged the derailleur's cable lockring, but it is more likely that the cable just needs a little more slack.
Good luck and let us know how it turns out! :)

Sounds familiar, I had the same issue with a Shimano 3403, I thought my shifting lever had gone bad. Cleaned everything, put back together twice, and still did not work right. Finally found that the cable routing/attachment was not right and causing incorrect tension. Fixed the way the cable attached to the FD, it fixed the routing problem, tension problem, and it is back shifting. Those little things can sometimes drive you crazy.

Check out where the cable attaches to your derailleur. Many Shimano front derailleurs have a little L-shape arm. The shift cable goes OVER that arm.

+100. This is a very common mistake. If you route the cable under the "arm" ( a little tab) so it goes betwween the tab and the bolt it will not pull sufficient cable. The cable must go outside the tab and attach over the top of the bolt. Shimano's installation sheet shows the proper routing but doesn't emphasize it enough.

Thanks, Calamarichris,

are you saying that if the cable is too tight, it won't drop into the small chain ring?

the problem I'm experiencing is that it will shift to the big chainring, but not enough so that the chain rubs when the cog is on the lowest gear. And it's not the the limiter screw, because i've checked that.

I'll take a photo of how the cable is routed. But I'm pretty sure I have it right. I have it going over the little tab, and under the locknut where the little grove is. the cable sort of bends over the top of the FD.

any other ideas?

Thanks everyone...

okay, just checked it again.

It seems the cable is routed fine. the nut inside the shifter is seated right. the BB routing is right, the cable over the locknut is right.

but the problem is still there. the cage doesn't move enough. From the lower limit to the upper limit, it rubs on the lowest gear (big chainring, little cog).

when the cage is at the lower limit, the FD stops at the limiter screw, and there is very little cable slack, if i touch the cable at all, it moves the cage. (small chainring, biggest cog, 1mm clearance)

When I shift to the big chainring and the smallest cog, the FD cage rubs, and there is still more room for the FD Cage to go before hitting the upper limit screw. When I just pull the cable more (from the downtube), it moves the cage to the upper limit screw, and it's set to 1mm of clearance.

So is this a problem because the FD-6400 is really designed for 7-speed?

could it be a problem with the type of cable housing?

maybe it always rubbed and I just always ignored it? Since I seldom use the lowest gear?

thanks,

The FD-6400 was originally meant for 7-speed, but, I've never had any issues mixing 7 and 8 speed components. The problems occur when you move up to 9/10 speed. The chain you should use is an 8-speed, which is nearly the same width as the 7-speed, which is the determining factor.

BTW, I don't understand why you're adjusting anything while you're in the smallest cog/chainring combination front and rear. That's technically an "illegal" gear combination in 8-speed systems, you should get unpredictable results since the chain is really way far off the limits of chainline goodness.

Thanks Anixi,

I am infact using an 8 speed sachs chain. (maybe that has something to do with it. not being hyper glide.)

The issue of crossing the chain...
What I mean to say is that I put the chain furthest right, then furthest left. Not crossing the chain. I only use the first 2/3rd of the gears for each chain ring, keeping the chain line straight. Sorry I wasn't very clear or got it mixed up. I'm adjusting the FD to the furthest right (big chainring/small cog) and furthest left (small chainring/big cog).

So that said, any other ideas as to why the cable pull is insufficient?

Thanks,

It sounds like you're not getting all of the cable out of the shifter before attaching the cable to the derailleur.
With the chain on the smallest chainring and largest cassette cog flip the small shift lever several times while pulling the cable out of the shifter. Confirm that the low limit screw is properly set. Pull all of the slack out of the cable while attaching the cable to the derailleur.

I checked that. but the cable end is seated properly in the shifter, and the shifter is down all the way. (made sure no more clicks were left).

I measured the amount of cable pull, it's pulling 3/8th inch. and it really needs to pull about 1/2 in to get the proper cage movement.

is the FD-6400 suppose to go with the brake/shifters? or are they only for downtube shifter?

I used to have a FD-6401, and it works fine. but had couldn't use it on the new frame cause of the seattube diameter mismatched the clamp. So bought this FD-6400 thinking it should be the same. but I suppose the difference is making itself known.

Will buy another FD-6401 to try, maybe it'll solve the problem.

Anyone have any ideas how much cable a brake/shifter suppose to pull and which FD match which shifter?

Thanks,
Thomas