jdave5917

I want to remove the large lever/housing, hoping that I'll be able to see what might be causing the shifting mechanism to not fully return to the small ring (downshifted) position. Trust me - I've tried every penetrant and lube that has ever been suggested for freeing up stuck shifters and that is definitely not going anywhere. I'm hoping that it's something obvious like a small piece of frayed cable that is fouling the mech rather than a broken spring or other part, but there's no way of knowing without getting the housing off. With other brifters that I've worked on, removing the small screw near the top/inside of the levers would let you slide the housing off but that doesn't seem to be the case with this one. I'm guessing I need to remove the notched, round nut on the back (first photo) of the shift assembly which requires a special tool, but don't want to go there if that is not the correct step, or worse - springs and small parts will fly everywhere. I can probably make the required tool by modifying an appropriate size socket, but if anyone has a better/simpler suggestion, please let me know.
I picked this left shifter up recently at a swap to match a working right DA 7400 shifter, gambling that it would be a simple matter of using some spray lube to get it working. The bike already has a working non-DA left brifter but I was hoping this would result in a matching set.

morri869 

I know the dura ace versions are a little different than the other brifters made in this time period but I am pretty sure you have everything right. The little screw on the back of the lever is usually all you need to remove. Are you sure it isn't just jammed on something?

Could you take a picture of the front of the shifter? Maybe that has a clue.

jdave5917

Yes, this Dura Ace 7400 definitely different than the Ultegra 6400 and the 9 speed 6500. Don't know why I omitted the front photo in my original post but here it is with the name plate cap removed
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dddd

I've used a very small, slim Vise-Grip plier to loosen the castle nut on several occasions. It is slow going but will inch the nut along until you can grip it with needle-nose pliers and turn the nut a little further with each re-position of the jaws (because the needle-nose plier jaws are thinner). From there, it comes right off.

Oh, one more thing, apply a bit of penetrant first.

I would start taking notes, in order, as to how each piece fits, in which orientation.

I have found levers where the tip of the small lever had sheared off, just above the pivot (where it is now still not visible). Usually this is on the right lever however.

Keep an eye out for any tiny broken-off bits that are part of the rotating plates inside.

Good news (if you can't fix this one) is that left levers should be much easier to source.

morri869 

Ok, after seeing this I think you may need to pry off that front metal? Washer with a thin screwdriver if possible. It doesn't look like you got the return spring for the big lever off yet, it is usually just behind the face plate of the shifter. In this case it may be behind that big washer.


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jdave5917

Good suggestion on the needle nose pliers. I did get the large lever/housing off last evening. With the small screw at the inside/top of the levers already removed, it was a matter of slipping a thin/sharp putty knife under that back plastic disc on the front of the assembly (shown in last photo immediately above) and vary carefully prying it off. It's held on by a very tight friction-fit and it took some time to gradually work it off to prevent damaging it. You definitely do't want it to pop off suddenly since that tiny brass ring (I moved it slightly off center of the mounting hole in the disc so that it's easier to see in this new photo - I think it's just a bushing since it seems far too delicate to serve as a retainer for the black disc). Once that is off, you can pull the shifting assembly back through the lever/housing part. Expect some small parts to fall out from near where the small screw was removed at the back/top of the small lever.
In looking at the shifting mech, I can see a very thin shim that was apparently jammed and got deformed, but I think the actual problem is deeper inside where all the gears/pawls/springs are. Debating if I want to go there since I know how you reach a point where you remove something and all of a sudden a lot of tiny parts unexpectedly fall out. On the other hand, it's not worth anything the way it is other than for parts, so not much to lose. A project better left for a bad-weather day because I know it won't be quick.

dddd

Ok, at this point you want to be sure that you have all reassembly steps documented, in order.

Then we need to see what the pivot end of the small lever looks like, removed.

I'm suspecting there might be no reason to take the "barrel" assembly apart.

easyupbug 

Ugly but works:

repechage

I have One DuraAce 8 speed integrated lever that flops.
got the bike that way.
I have not yet bothered to take it apart as I figure something is broken, and parts? Not like Campagnolo that for a good chunk of time had replacement parts.

jdave5917

I've temporarily reassembled the springs, small lever, hold-down plate and screw to the large lever just to have fewer loose parts laying around while I decide where to go next. The top of the small lever looks fine as does the retaining plate (screw and retaining plate removed to take this photo). The small lever return spring and pawl release also looks and functions as it should. Obviously I will need to disassemble the small lever and related parts once again to get the barrel assembly back in the large lever/housing assembly when that time comes. No success trying to get the barrel/shifter assembly to function while separated from the rest. .I'd like to feel confident that there is no reason to take the barrel assembly apart, but I still think something inside there is causing the problem.

jdave5917

If it works, then it's beautiful.

jethin

I salute your tenacity. I once made it to about step 1.5 before I gave up and started drinking.

RobbieTunes

Those were SO notorious for cable insertion errors. Your symptom sounds like that, and 90% of the ones I've worked on were simply that, or a subsequent loose evil piece of cable due to that.

Only one, ever, didn't respond to simple disassembly and reassembly. Out of maybe 10-12, from SLX to DA. I punted on that one. I have limits.