What’s inside a di2 rear derailleur? Broken di2 won’t shift, how it works.

I took apart a Shimano Ultegra R8050 di2 rear derailleur motor pod/case to see what failed

[@Di2_GP]

Here is a detailed video of disassembly and repair of Ultegra R8050 - kzbin.info/www/bejne/nqqQl6CMeK6ioZo

[@kiwiman9754]

Thanks for showing the internals. Every other "how it works" videos are very basic

[@davidwebster2616]

Thanks for taking the time to show us this.

[@HARRIS2065]

Very interesting video. Hard to follow with so much movement but the end view of the inside and gears was the best. Thank you.

[@doindumbstuff4119]

Mechanic here, very interesting video. I will say though the amount of road grime on them both new and old is a bit of an indicator you don’t maintain your bike properly. Definitely needs a bit more tlc. These things are fairly robust despite them looking surprisingly basic inside. But saying that it shouldn’t die to road grime alone, or die in such a manner at all. Sorry you had to go through that in the firstplace but thanks for sharing. Very interesting to see why we’re being charged hundreds for some basic circuitry.

[@milarabeltran8248]

Been using conventional cable shifter for decades and never had any problems... poor shifting? i just replace the cable housing and cables with new one and that's it works like new again.

[@darrenhitchcox6345]

A friend asked me to look at his Di2 8050 and this would not shift up and without the chain on, the shifting was very weak. I suspect after seeing this that one side had loosened giving poor engagement to the worm gear. Thanks for showing the insides.

[@rswhalen1]

That would be an inherent design failure. Not wearout, not random, not no defect, not infant mortality. I wonder how many more of these modes are out there.

[@fikretuzgan5303]

It is certainly a design or workmanship issue. Those screws should not come loose. Another issue is that they did not consider repairability at all. If broken no way to fix it with this structure.

[@tarajones-legros3661]

Somebody send this video to their Shimano rep. Might get a free or heavily discounted replacement for your trouble.

[@gerbryf]

I have a dura ace 11sp mech that's just the same, you can feel that the teeth almost engage but they don't. Tapping it on a desk tightens it up, tapping the other way releases it. I've removed the di2 drive unit, but haven't gotten around to opening it up. Could it be possible to drill two holes in the plastic case to allow screwdriver access and tighten the screws, then plug the holes with small grommets and glue? Where would the holes need to be? Would the screws need removing to add threadlock (and could this be done?)? Thanks for the great video..

[@kramnnim]

After I made this video, someone linked me to @di2_gp on Instagram, he has videos much better than mine! I was thinking that drilling two holes would be much easier than his method though. I think you’d want to loctite the screws to keep it from happening over and over.

[@kramnnim]

Thinking more about it- on mine the screws were completely loose and rattling around, it would be difficult to get them out through the drilled holes. But if the screws were just a bit loose, the worm gear would have trouble engaging, I think, so it still might be worth trying. If you cut slots in the three mounting screws like I did, the Instagram guy suggested using new torx screws to replace them, m2.5x10

[@kramnnim]

Also, I should be able to determine the correct place to drill the holes if you plan to try it on yours. Assuming yours is r9150 and not 9070

[@gerbryf]

It seems my replies are disappearing!

[@kramnnim]

That’s weird, I got an email with your earlier comment but the comment itself is gone. Maybe KZbin doesn’t like comments with mentions of IG or something? Anyway, the guy from IG said he plastic welds the cases back together, which sounds daunting to me. I think silicone caulk would plugs the holes nicely. And the silver part that’s pressed onto the rotating shaft wouldn’t need to be pulled off…

[@MrSzwarz]

That's why I will not swich from mechanical to electronic groupset ; ) If your battery goes flat, ora electronics, you're can stuck in the middle of nowhere

[@OnzeManInKazakhstan]

Did you notice the part where he explained his mechanical derraileur died as well?

[@OnzeManInKazakhstan]

Maybe you should move the parts more around, that would make it even more difficult to watch. Just.place.the.parts.on.the.table.

[@TheFrontosa1]

don't open it, then you kan se you been scammed by simple eletronic

[@8paolo96]

Yeah, it looks so basic when opened, there are probably children toys with the same tech for 20$

[@shimona500]

cfrp frames cost like 500 to make. similar to those, it's not the materials of the end result you are paying for, it's r&d.

[@bikeman123]

I think Shimano have been selling di2 long enough now to make back their r&d.

[@shimona500]

@@bikeman123 ye, that's why they did 105 di2 (which you can get for around 1000 now). it's basically 11sp di2 dura ace with 1 more gear. for ultegra, dura ace they have hyperglide+ for example, and much faster fd. that's more R&D.