[Matthew Acton-Varian]

I’ve recently upgraded my R7000 105 rear mech to an Ultegra R8000 (bought used off ebay for £15) but there is a small amount of play in the cage that wasn’t in my R7000 mech.

If it is just the mounting interface on the outer plate of the cage that is worn, I can easily get a replacement. But if the internal body of the derailleur is also worn, then the mech is a lemon. Is there a way to check before I splash out another £15 on spares for a dud?
I can’t justify the cost of a brand new mech (hence second hand) so I would rather call it quits and know whether I’ve thrown money away before I double my losses – and just put the 105 back on before I sell it.

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[hawkinspeter]

Matthew Acton-Varian wrote:

Matthew Acton-Varian wrote:

The bolt holding the outer plate is as tight as I can get it but there is still a small amount of play.

I want to be certain that a new outer plate assembly will fix the issue as I don’t want to waste money on it if the derailleur body overall is also knackered.
 

Sorry, I can’t provide any certainty. I’d be tempted to try adding a washer to see if that removes the play. With mine, if I tighten up the pivot arm too much, it stops the cage from moving at all, so I have to loosen it very slightly until the cage pivots correctly.

[Matthew Acton-Varian]

The bolt holding the outer

The bolt holding the outer plate is as tight as I can get it but there is still a small amount of play.

I want to be certain that a new outer plate assembly will fix the issue as I don’t want to waste money on it if the derailleur body overall is also knackered.
 

[hawkinspeter]

Matthew Acton-Varian wrote:

It is not the pivot bolt, that is in order. It is just the cage that has a small amount of play from the body, with about, with enough movement to make shifting slow or skip.

The pivot arm comes as part of the outer plate assembly with the derailleur. There is also a T10 bolt that holds it in place.

If it is just the pivot arm and/or T10 bolt that is excessively worn, I can get a replacement, but I don’t want to burn more money on the mech if the internals of the derailleur body are also worn out.

Yeah, I meant the pivot arm that connects the outer plate to the derailleur body. Every few months, my one comes loose (different version derailleur though – mine’s Di2) and when I notice shifting issues, I have to remember to tighten that bolt up. (I don’t think it’s wear related, but more likely due to me mucking around with changing the cage to a fancy after-market one with oversized pulley and then changing it back when it didn’t work very well.)

[Matthew Acton-Varian]

It is not the pivot bolt,

It is not the pivot bolt, that is in order. It is just the cage that has a small amount of play from the body, with about, with enough movement to make shifting slow or skip.

The pivot arm comes as part of the outer plate assembly with the derailleur. There is also a T10 bolt that holds it in place.

If it is just the pivot arm and/or T10 bolt that is excessively worn, I can get a replacement, but I don’t want to burn more money on the mech if the internals of the derailleur body are also worn out.

[hawkinspeter]

Could be the pivot bolt that

Could be the pivot bolt that attaches the derailleur to the frame. You’ll need to undo the cage to get to it, but the pivot bolt is just a hex key fitting (careful you don’t displace the spring inside as it can be fiddly putting it in the right place).

Edit: I’ve just had a look at the exploded view (https://dassets.shimano.com/content/dam/global/cg1SHICCycling/final/ev/ev/EV-RD-R8000-GS-4285A.pdf) and I’m thinking of the pivot bolt that attaches the cage to the derailleur body, not the derailleur to the frame.

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