Di2 9070 RD "living dead"

Discuss light weight issues concerning road bikes & parts.
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mrlobber
Posts: 889
Joined: Sat Oct 23, 2010 9:36 am
Location: Where the permanent autumn is

by mrlobber

A Di2 9070 RD. One of many which have passed through my hands, but finally it seems I have a problem.
Crashed last year, didn't rebuild another bike with it until recently.
Worked fine for a couple of rides.
Today, some kms from home, it suddenly shifts into the smallest cog and stays there.
If I want it to downshift, I hear the motor in the RD working continuously until I press the upshift button (the the motor stops working), but the derailleur body doesn't move.

If I dowshift and simultaneously move the body by hand, it moves to the cog I push it to, and stays there. Now pressing the upshift button, it shifts straight to the smallest cog again.

The same happens if switching to RD micro adjustment mode - trying to adjust it inwards, I can hear the motor roaring, but nothing happens.
The behaviour of the RD kinda resembles crash mode, but only "one sided" - as if the motor is somehow disconnected from moving to one side (inboard), but not the other (outboard). In any case, trying to "exit crash mode" (if the RD happened to enter it) doesn't do anything.
SME-PC1 check says "the RD may be faulty" (but upgraded its firmware just fine)

Any ideas? Is it toast?
Retired bikes: Cervelo S5 2015 / Felt AR FRD 2014 / Cannondale SS HM 2014 / Scott Addict SL 2014 / Scott Plasma Premium 2014 / Orbea Orca 2008 / Look 596 /

alcatraz
Posts: 1942
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

A friend had exactly the same problem, but it was slightly more annoying because the derailleur decided to stop working 2 months after a crash.

Shimano has generous di2 support but in our case the bike was bought 2nd hand so no go. We ended up sending it to this repair guy and he swapped the motor out. Worked perfectly ever since. (3 months now) Special care needs to be taken to seal the motor compartment.

We paid 80usd to fix it. (China)

by Weenie


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ms6073
Posts: 2717
Joined: Fri Jul 23, 2004 8:24 pm
Location: Houston, Texas

by ms6073

Not much to offer as you proabably already know that the rear derailleur will also exhibit that behaviior if the battery is below 7% charge or the system 'senses' a battery fault.
Michael - The Anaerobic Threshold is neither...

XCProMD
Posts: 719
Joined: Sat Jan 26, 2008 10:25 am
Location: Cantabria

by XCProMD

Typical fried potentiometer. Either complete servo swap as mention above or new RD.

It’s enough to bend the parallelogram links or the complex link mechanism between servo and parallelogram to fry the pot.


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mrlobber
Posts: 889
Joined: Sat Oct 23, 2010 9:36 am
Location: Where the permanent autumn is

by mrlobber

Thanks, clear. :thumbup:

Anyone knows if the servo are identical between 9070/6870 series?
Retired bikes: Cervelo S5 2015 / Felt AR FRD 2014 / Cannondale SS HM 2014 / Scott Addict SL 2014 / Scott Plasma Premium 2014 / Orbea Orca 2008 / Look 596 /

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