Advice on Di2 9070 rear derailleur non-op

[alcatraz]

We tried to warranty our derailleur which was newer than 3 years which is within shimanos warranty policy for di2, but we couldn't show a proof of purchase so ultimately it was sent back to us unrepaired by shimano. The bike had been bought 2nd hand. We felt bad for troubling the store so we asked to cover their costs, so we paid them for their trouble. Few shipping fees only.

After this we tried 3rd party repair.

If you do decide to give 3rd party repair a try make sure they have some spare parts like motor/curcuit boards and that they seal the electric compartment well, otherwise it breaks after a few wet rides. I asked the guy to seal it well and it still broke. After sending it in a 2nd time he couldn't swap the broken board because he had no spares. Shimano doesn't exactly sell boards, you need to harvest them and even then he said it's not always possinble to swap. Something with the board needs to match something else. So it's not just a straight swap 9070 to 9070.

What really confused the hell out of us was that the same derailleur could work differently on different bikes. On some it was almost dead, on some it worked seemingly fine.

Once when we thought it was over after testing on the stand happily we closed the case, only to have it die the following day. We give it to a technician and he says that after 2-3 weeks of testing on 2-3 bikes it works flawless. Yet on our two di2 bikes it doesn't (9070 + r8050 group).

This wasn't a derailleur that looked like it had been around the world. Aside from a few scratches it looked like new.

Anyway, a nightmare. Maybe in the future they will have found a way to do it.

[wheelbuilder]

unfortunatley I cannot warranty, I am not the original owner.

Will reprogram shifters tonight on etube to see if left shifter can move the RD and meeting a local rider tomorrow to test my RD function from his bike shifter wire and vice versa.

we'll see. thanks for the feedback all.

You can still give it a shot. Part of being a (brand) dealer is dealing with all sorts of warranty claims, and it's only a few minutes of work for the shop.

I recommend trying to have a dealer warranty it as well. We used to have all kinds of people come in with Shimano warranty stuff, and never had a problem with the customer being second or third owner. It is simply a phone call from an authorized dealer to the warranty/tech desk. It helps if the shop is familiar with the procedure and can be friendly with whoever is on the other end of the phone. In fact, I don't think I've ever had a rep say no. If they are suspicious in some way, the worst that can happen is they want the broken part first before they send new one, but usually they will send new part, and trust the shop to send in old one. Sometimes they don't even care about that part of it either. I think a lot of it depends on rapport the dealer has with Shimano.

[Rudi]

I washed the bike with a wet cloth and dried, no spray or pressure at all. Hard to believe that fried the RD!
This is my first foray into Di2, are they that sensitive to water infiltration? How can one have any confidence riding in the rain?

I'll echo some of the other answers beyond this post. Di2 is generally brilliant/fatastic/foolproof, until it isn't. At that point I've generally found it a lot harder to figure out what has exactly gone wrong - it isn't as obvious as a snapped cable for example.

I've had one bike new from 2013 with zero Di2 issues, and my wife's bike from the exact same manufacturer at the exact same point of purchase that needed a few things replaced along the way. The biggest pain is if the failed part is inside the bike, B junction.

[ylwgto]

It is a dead RD, tested from another bike.
At least the shifter is ok...

Thanks for the feedback!
I'll give the warranty route a shot through my LBS

[ylwgto]

i sourced a used Ultegra derailleur and am up and running flawlessly again. thanks

[wheelbuilder]

i sourced a used Ultegra derailleur and am up and running flawlessly again. thanks

Nice, good for you! However don't dismiss the warranty claim. Doesn't require much effort. Call around and find a shop that is familiar with the process. I can almost guarantee they will hook you up and get a new one on the way. Then you will have 2.