Shimano Tiagra ST-4700 LH lever intermittent problem

[LinusR]

My left Tiagra ST-4700 lever has been failing to shift from inner ring to outer ring intermittently. This model: http://bike.shimano.com/content/sac-bike/en/home/components11/road/Tiagra4700/st-4700.html

It's on my Cannondale CAADX 2016 bike and to a certain extent the problem has occurred before, perhaps since I first had the bike. I try to shift from inner to outer and the lever is just slack - it doesn't pull the cable at all. It just moves freely. Then I would press the downshift paddle lever and it would click, then the upshift lever would work normally. It did this on occasion but not every ride. I thought nothing of it as my Campagnolo Veloce levers would sometimes fail to shift (rarely) and then something would click and it would be fine.

But this past week (the bike is now 18 months old) on two rides it has happened and the lever will refuse to engage the cable despite pressing the down shift lever and trying again. After several attempts over maybe 20 or 30 seconds and maybe with a hefty slap with my hand against the side of the lever it would again engage normally. It has only happened once on each three hour ride. Most of the time it works fine. I haven't changed the cable from new but the bike is one of four I use so it hasn't had heavy use. The lever when it works properly still shifts correctly and gives me the two trim positions from the small lever.

Having read elsewhere and on a previous thread https://forum.cyclinguk.org/viewtopic.php?f=5&t=106024&p=1011865&hilit=4700+pawl#p1011865 I suspect one of the internal "pawls" is sticking and I need to lube it possibly with some "spray grease"; maybe one of these: https://www.eurocarparts.com/search/spray%20grease

So where do I squirt the spray grease in or should I do something else?

[Gattonero]

Shimano shifters can be clogged up by the coating of those new gear wires, or by splinters of a frayed wire.
Remove the wire and inspect it, I won't be surprised if it's damaged. And before using "grease" I'd go for something that would free up the parts, then some light lubrication.

[LinusR]

OK, thanks. I'll give that a go and report back.

[Brucey]

the kind of spray grease you need for shifters is semi-fluid spray grease. If it doesn't say 'semi-fluid' it is probably the wrong stuff.

Apply that after you have freed off the mechanism with something else.

cheers

[LinusR]

Thanks Brucey.

[LinusR]

I think I've identified the problem. I can now repeat the malfunction. I'll post some photos later and maybe a video to show what is happening. I've directed some GT85 into the part that's sticking and gave it couple of drops of oil with the bike upside down. Full report later.

[LinusR]

I've identified what I think is the problem. When the small lever is operated to shift from big ring to small ring or when used to "trim" the front mech two other small levers are pulled by this lever. One of them, I believe, is not returning fully and/or engaging in the ratchet (a pawl in the mechanism is sticking and not engaging properly).

I can repeat the malfunction, thus: with the front mech in the inner ring position, press the downshift paddle, then hold the outer small metal lever and slowly allow both the pieces to return to their normal position (sorry this is difficult to explain). Now the large upshift lever will be free and won't engage and I'm able to move it with my little finger.

In the first photo I am pointing to the small lever that is sticking.



Second photo showing the lever in its normal position.



So I squirted some GT85 into area where this small lever rotates, worked the lever back and fore, and finally turned the bike upside down and dripped some gear oil into the mechanism that moves.

The third photo I'm indicating with my finger where I sprayed GT85 and dripped gear oil.



Whilst I can still repeat the malfunction (as above) just one flick of the large upshift (brake lever) is enough to free it and it will then engage properly.

I should credit terrycojones who identified a similar problem with Ultegra levers and posted about it here with explanatory photos. Although he identified the problem as the rubber hood interfering with the lever: http://road.cc/content/forum/201074-strange-shimano-ultegra-gear-shifter-intermittent-failure

[LinusR]

I can confirm that the fix I used above has worked. No problems since. Levers working better than when new.

[peetee]

Rubber hood problem was highlighted in my post '105 and ultega 10 speed shifter issue'.

[clipol]

Hi guys,
Last Saturday I got my Merida Ride disc 3000 equipped with Tiagra.
I was more than overwhelmed with it only for two days when the LHS lever refused to switch gears at all.
I then contacted bike shop about the issue and was advised to send the part to them for an inspection. As a last resort I tried to do the trick with degreaser and compressed air. After lubing I was excited because it started clicking. Unfortunately as soon as I refixed it to dropbar, it stopped working
It seems like it is going to be a long week or two since they have to send it over to shimano for a test.
So now I'm stuck and don't know what to do...

[Brucey]

FWIW I have since encountered a ST-4700 LH shifter with the same exact problem as linus describes, except that it didn't respond to the usual treatment; no matter how much lube was applied in exactly the right spot, the pawl that allows the shift mechanism to latch and therefore the shifter wouldn't play ball.

Eventually I fixed the problem by very slightly bending one of the sheet metal tabs that supports the pawl pivot pin; as it was, it was rubbing very slightly against the pawl and the return spring wasn't always able to overcome that amount of friction. The tweak was so small that I couldn't actually tell if I'd moved it or not, but the effect was the shifter went from 'intermittent' to 'perfect'.

The relevant pawl is easily accessed by removing the lever hood and removing the access panel (#11 below) in the base of the shifter.

https://si.shimano.com/pdfs/ev/EV-ST-4700-3864.pdf

cheers

[Magri66]

Hello, I'm resurrecting this thread because I'm trying to fix a similar problem with a Tiagra ST-4700 LH shifter. Mine abruptly stopped working completely last week after having been intermittent over last few months. The inner lever works to change down to the small ring on the FD but the larger outer lever moves freely but does not engage or pull the gear cable when trying to shift to the outer ring. I have detached the cable from the FD and can see there is no movement in it when moving the outer lever - the problem is definitely in the lever mechanism.

What I would like a view on is whether this is fixable. I have tried all the youtube video advice about fixing shifter problems by removing old grease and then re-lubricating, but not having any joy with that.

The problem seems to be the "pawl" shown arrowed in blue in the photos attached. It does not engage with the ratchet wheel, unless manually pushed in. It, the pawl, is just rotating freely. If I push it in manually, it engages and shifts the gear, but as soon as we shift the other way it un-latches and then remains free. I can move it freely . In one of the posts above there is reference to it being sprung. It feels like it needs to be sprung as there is no other mechanism I can see to force it to latch. MIne is just moving freely . Should this pawl be sprung? Os it possible the spring is broken or lost?

What do you think ? Time for a new shifter or is this fixable?

Thanks
Liam

[LinusR]

I believe it is better to manipulate the mechanism while it has tension on the cable (Brucey will confirm if I am right or wrong). I think the lever relies on tension to engage. So if you don't have it tensioned you won't get very far in figuring it out. I found turning the bike upside down and working the mechanism and those two pieces of metal either side of the small lever - spray with GT85 - and then dribbling gear oil into where they moved fixed it. No problem with mine two years on.

[Brucey]

in addition to the above I have had to hook a spring back on a pawl in a LH ST-4700 shifter before now. Could it be a similar problem?

cheers

[Magri66]

Thanks for replies.
Re the tension, yes good point, so last night I re-assembled the gear and FD and tensioned the cable, but no luck, problem still there. I did not try more lubricant though, maybe that's worth a try.

Looking at the part more closely (the pawl that is not returning to position) I cannot see what mechanically it is interlinked with it to move it back. It seems to have full freedom of movement through about 180 deg. So it doesn't look like a lubrication problem.

But I did make a discovery this morning. I was thinking there must be something to move it back, so I had a much closer look under a bright light and made a discovery.

Just off to the right of the pawl, on the same spindle, is a tiny coiled spring, which is pinned at one end to the long lever, but at the other end is LOOSE !! So to your comment , Brucey, that could be the spring that i need to get working again. I've attached a pic, the arrow top right shows where it is attached (you can't actually see the connection but it is there, on the right, to the bottom of the large lever) and bottom left is the free end. Now why would there be a loose spring there? It could be there to return the pawl to position ready for the next move to the large ring.

But there appear to be two issues with that hypothesis. One there does not seem to be an obvious place to connect the loose end of that spring to, and secondly if it was to connect to the pawl direct , the way it is positioned the spring tension would be working the pawl away from were it needs to be, rather than pushing it into position.

So I'm thinking now that maybe there was another part ( that has gone missing, hence the sudden fail) , to which this spring attached, and in combination they moved the pawl. Anyone got any pics of the inside working of an ST-4700. LH that they could share? There is nothing like that level of detail on the Shimano documents I've seen.

Meanwhile I'm looking out on ebay for anyone selling a old ST-4700 for parts - if i had a working lever system I could see if mine was any different. In the meantime happy to hear any other suggestions, especially if anyone knows what that spring in the photo is suppose to do. I'm not ready to admit defeat yet - these levers are almost brand new and mostly been used on an indoor turbo trainer.

Thanks