shimano st 6703 problem...

team47b

I have a problem with the left (front) shifter (shimano 6703 10 speed triple, 1 year and 3 months old) on Mrs T's bike.

She was changing from the 50 to the 39 lever moved but front mech didn't. I released the cable and checked the mech was working normally, it was.

Today I took the cover plate off the shifter to see what was occurring, I checked that the cable is free to operate, it is, but the part the cable is attached to doesn't rotate, like it's stuck. There are no obvious bits hanging out/broken, the springs are all attached.

As you can tell I know very little about these shifters, but is this a common problem, what can I do to fix it (other than spend £150 on a new one :shock: ) what is preventing it from turning, has it turned too far, can I take this apart?

EDIT UPDATE: moving the two levers to try to try to understand it when out drops a bit and falls to the floor! It is a threaded alu piece, it has a largish head which is curved at the ends but with flat sides, this bit is not broken, anyone know what this bit is, would a photo help?

Thanks for any help/ideas/knowledge

mister p

Contact the dealer you bought the bike / shifters from. There is 2 year warranty on Ultegra so that is the first thing I would do.

team47b

thanks for that mister p, I have just emailed Chain Reaction Cycles as you suggested, awaiting there reaction now

Bordersroadie

I had the same problem on a 6703 left shifter, just stopped working, and a stray aluminium part detached and fell out, in my case a small threaded square shaped nut.

The shifter was part of a Cube bike I got from CRC. I sent the shifter/lever back to CRC along with a warranty claim form (I attached photos) and after about 4-5 weeks I got a free replacement from them. Great service back-up, CRC, in my experience.

team47b

Sounds like an identical problem, and also on a Cube from CRC.

I have emailed CRC a second time, still waiting for a reply.

Where did you get the warranty claim form from?

Thanks Bordersroadie for your help, I'm sure that CRC will sort it out when they get round to replying, I have always found them more than helpful in the past.

Mrs T also says thanks, now she doesn't feel that she broke her bike!

Bordersroadie

team47b wrote:

Where did you get the warranty claim form from?

I'm happy to be of help! I think I recall that I downloaded it from the CRC website. I just re-read your posting and it does indeed sound like an identical piece that fell out of yours.

team47b

I sent the shifter back to CRC as they requested, one week later (posted from Portugal) they have just emailed me to say...

Your faulty Ulterga shifter has been replaced. Your item is being packed and will be dispatched within the next 24 hours.

The warranty period on your item is from the original date of receipt. All replacements are quality checked, please refer to the manufacturers guide for maintenance details.

If you have any other queries please don't hesitate to contact us.

Really fast service from Chain Reaction Cycles

Bordersroadie

I do love a story with a happy ending [wipes tear from eye] - but seriously, I'm pleased for you and your missus and it's the same great service from CRC that I got myself.

Happy shifting!

ANOpax

Apologies for resurrecting an older thread but I came across this thread when googling 6703 shifter problems as I, too, have experienced the 6703 shifter lock with subsequent appearance of small threaded aluminium part.

However, the suggested solution of warranty replacement isn't available to me so rather than shell out £150 for a replacement, I thought I would have a go at fixing it. In the course of doing so, I have unearthed a design/manufacturing flaw which affects the 6703 LH shifter and, I believe, the 6700 LH shifter too.

My reason for posting is not to have a moan at Shimano but to help other 6700/6703 users out there avoid this problem in the first place and fix it if the problem occurs without returning the shifter to Shimano or buying a new one.

So, let's start with the basic design. There is a conventionally threaded hex head machine screw which enters the shifter body from the rear. You can see the head of this screw when you look at the back of the shifter. This machine screw goes through the long axis of the indexing mechanism and locates through another hole in the shifter body just behind the levers. The machine screw then enters the threaded aluminium piece which I and several other posters have found drops out when the shifter 'breaks'. The threaded aluminium piece is effectively the 'nut' which holds the whole assembly in the right place in the shifter body. When the aluminium 'nut' works loose and falls out, there is enough play in the locating hole in the shifter body for the machine screw to shift its alignment which throws the alignment of the indexing mechanism out and causes it to jam or stop downshifting.

I managed to fix my shifter by taping the levers in the open position to give me access to the space behind the levers. I then taped the aluminium 'nut' to the end of an allen key, dropped it down onto the exposed end of the machine screw, tightened up the machine screw from the back of the shifter and voila, the shifter is working again.

The reason why I believe that this is a design or manufacturing flaw is that the LH indexing mech is always shifted inwards in an anti-clockwise direction when seen from the rear. What this does is cause the machine screw to rotate anti-clockwise as well if theres any friction between indexing mech and the machine screw around which the mech rotates. Eventually, this anti-clockwise movement of the machine screw causes it to unscrew itself from the aluminium 'nut' with the consequence that the shifter stops working and the nut drops out.

A simple solution would be to thread lock the aluminium 'nut' to the machine screw but I wasn't able to do that. What I will probably do is bond the hex head of the machine screw (which is exposed at the back of the shifter) to the shifter body with a small dab of adhesive - enough to stop the screw rotating.

I hope that the explanation has been clear.

derek48

Hi

I'm struggling with EXACTLY this problem at the moment, and can see from your very helpful explanation where the aluminium 'nut' should go. However I can't see a way of locating the nut on the end of the machine screw, desite trying your taping to allen key technique. You must be a lot more dextrous than me. Should the 'nut' be installed in any particular orientation? I can't see why it is this particular shape. Any advice would be very gratefully received.

Thanks

Bordersroadie

That's a very interesting story and an excellent helpful posting for future users (maybe for me too, even with my warranty replacement shifter, one day. . .but hopefully not).

The thing that amazes me a bit is that we have all managed to retrieve this minute threaded component rather than it having fallen out and got lost during a ride, since it seems to drop out after the event, so to speak, when fiddling with the lever, once stationary, to try to make it work.

Bordersroadie

ANOpax wrote:

A simple solution would be to thread lock the aluminium 'nut' to the machine screw but I wasn't able to do that. What I will probably do is bond the hex head of the machine screw (which is exposed at the back of the shifter) to the shifter body with a small dab of adhesive - enough to stop the screw rotating.

Are you saying that this would be a potential fix even in the event that the "nut" has become unscrewed and lost? Or does it require the nut to still be in place?

derek48

Having spent two hours today unsuccesfully trying to refix this 'nut, I have gained an intimitate knowledge of the workings of the 'innards'. The shape of the aluminium 'nut' has a 'stepped' section which appears to centre the machine screw in the body of the shifter. I can get the mechanism to work by manipulating the position of the screw with an allen key, but the position is absolutely critical, and therefore, for a permanent fix re-installation of the 'nut' would appear to be essential. If I do ever manage to refix it, a dab of superglue might be a way of preventing it from unscrewing itself again. I still don't understand why it is this shape however.

team47b

Interesting idea about movement unscrewing on the left hand shifter, left and right hand threads would solve this apparent design fault.

Now that we all know what the problem is, perhaps we should let Shimano know. I realise that they probably are well aware of the problem and that warranty is probably cheaper for them than redesign.

But I think that 'they' should be made aware that we know

ANOpax

Hello again and apologies for the late reply.

In answer to the questions about the aluminium 'nut' orientation;

Yes. It is critical to get it the right way round. When viewed face on, looking through the hole in the 'nut', the outer side is convex and the inner side is flat but with a raised ring around the threaded hole. It is this raised ring which seats into the oversized hole that the machine screw protrudes through, thus centring the machine screw and bringing the whole indexing mechanism back into alignment. The moulding of the plastic of the shifter body will also 'lock' the 'nut' into a portrait orientation when it is properly seated.

I have a confession to make on how I attached the alu 'nut' to the allen key. I got lucky and the nut threads actually jammed nicely on the hex shape of the end of the allen key I was using at the time. So, in my case no tape was involved but I figured I'd suggest doing it that way as it is more generic and relies less on being jammy like me and having the right sized allen key to hand. I did tape the shifter/brake levers open though after unsuccessfully trying to remove them (I followed the Shimano service instructions which are available online but couldn't drift the hinge pin out). If you still can't get the nut onto the end of the machine screw using the allen key technique then I'd suggest that your next avenue of repair is to remove the shifter/brake levers.

I would point out that it is necessary to get the exposed end of the machine screw centred in the oversized hole before you try to place the 'nut' on it. If the machine screw isn't centred, the raised ring on the 'nut' stops the 'nut' from seating properly and the thread of the 'nut' won't catch that of the machine screw.

As a postscript, my chosen method of preventing the machine screw from rotating again was to drop some superglue between the rim of the machine screw head and the shifter body. Hopefully, this will be enough to lock the screw against undesired rotation but not glue it so tight that it can't be removed in future if need be. The shifter has done 88 miles since repair and been absolutely fine.

ANOpax

Bordersroadie wrote:

ANOpax wrote:

A simple solution would be to thread lock the aluminium 'nut' to the machine screw but I wasn't able to do that. What I will probably do is bond the hex head of the machine screw (which is exposed at the back of the shifter) to the shifter body with a small dab of adhesive - enough to stop the screw rotating.

Are you saying that this would be a potential fix even in the event that the "nut" has become unscrewed and lost? Or does it require the nut to still be in place?

Just to confirm what Derek48 said after a couple of hours working on his shifter; In order to fix a shifter, the 'nut' needs to be put back in place as the alu 'nut' is crucial to the alignment and proper functioning of the indexing mechanism. What I was referring to when I mentioned glue was that there needs to be a way to prevent the screw from unscrewing itself from the nut again in the future. As you'll see from my post above, I ran some superglue into the gap around the head of the machine screw in order to bond it to the shifter body and hopefully prevent it rotating in future.

derek48

Search down this forum for 'Shimano 105 5700 shifter disassemble' and all will be revealed. I've ordered the two special tools to remove and replace the lever, so should be relatively easy. The link to the Shimano tech doc is also very useful. Thanks to the OP.

ANOpax

Thanks for the link to the 105 thread. Removing and refitting the 'e' ring was not the stumbling block in trying to get the lever off (I used a pair of flat bladed watchmakers screwdrivers)- it was trying to drift the hinge pin out which caused the most grief and led me to give up on that route. I hope you have better luck than I did with that !

Bordersroadie

ANOpax wrote:

Bordersroadie wrote:

ANOpax wrote:

A simple solution would be to thread lock the aluminium 'nut' to the machine screw but I wasn't able to do that. What I will probably do is bond the hex head of the machine screw (which is exposed at the back of the shifter) to the shifter body with a small dab of adhesive - enough to stop the screw rotating.

Are you saying that this would be a potential fix even in the event that the "nut" has become unscrewed and lost? Or does it require the nut to still be in place?

Just to confirm what Derek48 said after a couple of hours working on his shifter; In order to fix a shifter, the 'nut' needs to be put back in place as the alu 'nut' is crucial to the alignment and proper functioning of the indexing mechanism. What I was referring to when I mentioned glue was that there needs to be a way to prevent the screw from unscrewing itself from the nut again in the future. As you'll see from my post above, I ran some superglue into the gap around the head of the machine screw in order to bond it to the shifter body and hopefully prevent it rotating in future.

Thanks again for taking the time to respond.

winstonc

ANOpax, thanks for your detailed explanation of how it works. I fixed my 6703 levers, but the nut keeps coming undone - after only 5-10 shifts, it stops working and I have to tighten the bolt again. Is the superglue holding up for you?

ANOpax

Hi winstonc,

Apologies for the delayed reply but to answer your question; Yes, the superglue is holding up. Is your bolt still rotating after you've tried the superglue?

Bordersroadie

ANOpax, since your superbly detailed posting back in May I've been meaning to do the same procedure to my left hand lever but life has got in the way as it does and I never got round to it. . . I've since put a couple of thousand miles on this particular bike, without further incident, touch wood (I wonder if my replacement lever had a revision to it. . .?).

Anyway, whatever, I still plan to make the fix you recommend and having read through your description of "how to", I have one question. Can the whole process be done with the lever in situ, on the bars, or does it have to be removed? And do either of the cables need to be removed? Sorry if I've just missed the obvious and thanks again for your input to this problem.

ANOpax

Hi Bordersroadie,

I'm glad to hear that your replacement shifter has been working without fault. If you wish to superglue the hex headed machine screw to the shifter body then you will need to remove the shifter. This can be done without removing your bar tape as the shifter can be completely unbolted from the retaining ring which secures it to the handlebars. Simply peel the front part of the rubber shifter hood back far enough to give you access to the bolt head which secures the shifter body to the bar retaining ring and undo the bolt completely.

However, in order to pull the shifter body far away enough from the handlebars, I suspect that you might need to slacken off the brake and front derailleur cables but I can't be sure. You certainly won't need to remove them completely as the hex machine screw head that you want to superglue is recessed at the back of the shifter body whereas the brake and derailleur cables exit the shifter body from the top surface of the shifter.

I hope that makes sense.

Bordersroadie

ANOpax, excellent, thanks again. I can follow the rest of your instructions. Cheers.

dee4life2005

Apologies for resurrecting an old thread, but I've just had what seems to be the same problem with my 6703 10sp triple shifter (right hand one). It would upshift (to larger cogs) but the downshift lever had no effect. It appears something is preventing the return spring from returning the internal lever back to it's starting position as if I do it manually with my finger then downshifts work fine until I upshift again.

When I had the shifter off the bike to examine it a small 5mm x 5mm x 1mm (roughly) piece of plastic / aluminium fell out - it has a circular hole in the middle. It looks like it's broken off something rather than being a nut in my case though.

Does this sound like the issue you had, or something more terminal ?

Bordersroadie

This sounds exactly like what fell out of my left hand shifter, a sort of rounded off rectangular aluminium piece the same size as you describe, with a very small threaded hole in its centre.

If you still have this piece then, although it's a fiddly job, you can reattach it if you follow the instructions detailed in the earlier posts. If you've lost it then you're Donald Ducked I'm afraid.

By the way for the record I did apply superglue to the rear of the shifter where the small threaded bolt comes through (which passes through the nut we're describing) and screws into an integral nut set into the plastic body (which is a separate nut as I recall, although in my case I didn't reassemble, I got a warranty replacement full STI assembly). And, so far it has not given me any further problems, one and a half years later.

Good luck with yours, you save a heap of cash if you can fix it.

dee4life2005

I've already purchased a replacement, in case I can't sort it.
I still have the small part that broke off (woohoo), thankfully it remained in the shifter for the 30+ miles after the shifter broke!! I'll take a closer look to see if it's threaded - it didn't look it, but then it would be a very small/fine thread i guess. Then I just need to follow the above posts to work out exactly where it needs to go and then I guess the fun begins (and much swearing probably) trying to put it back.

It's just a shame that these shifters aren't serviceable items, as it's annoying for an otherwise working shifter to fail in such a way because of something so small.

dee4life2005

Oh nuts. After re-reading your post, and the thread, now that I have the shifter in front of my I think I can see the "aluminium threaded bolt" you're talking about. Sadly mine is still firmly seated. I've also compared the new shifter I got with this one and where I thought the plastic bit is missing from it isn't. On looking really really closely and after flushing again with loads of WD40 to get the remains of the grime out I noticed that the upper spring is broken. DAMN!

New shifter time then. I have now dismantled it so that I at least have a right shift lever and paddle for the spare box.

At least I now know to keep an eye on that bolt in future, so thanks for that.

RobinB2

Resurrecting an old thread - I have just had a similar issue on a 2013 Cube Agree - not bought from CRC but from my LBS. Unfortunately, despite the much appreciated advice from ANOpax, it looks like the nut fell out of my shifters when they packed in about 5 miles from home

Seems like a bit too much for this to be coincidence in that I appear to be the third Cube owner complaining of this - possibly a dodgy batch of shifters? Since mine are now about 2.5 years old, looks like I'll have to scour ebay for a replacement

Unlike ANOpax I am going to have a bit of a moan at Shimano - these shifters are an absoloute night mare to maintain - replacing cables for example is far more difficult than it should be. With this latest issue I'm now beginning to think that this Ultegra series is not of the quality I would expect

RobinB2

Correction to the above - having now checked Ultegra versions, suspect it is the 6700 shifters that I have, so comments re dodgy batch may not apply. However general poor quality of Ultegra 67 series shifters still stand

DrLex

Annoyingly, I think I've broken mine in a similar way. Thought I needed to remove a cable panel to refit the front mech. cable, but must have dislodged something, as it now won't upshift, and the panel has deformed when I pushed harder. Cable fed in from the bottom. LBS on Monday - I suspect a new shifter will be the prognosis.