Shimano electronic shifting experts

[Brads]

Okey doke

Shimano Di2 rear derailleur RD-6770

I need to replace the B axle spring and the plate axle spring.

Part numbers Y5XW98010 and Y5X298030 Neither are available, anywhere.


The RD-6770A parts are Y5YC98010 and Y5YD98020

Now you can see the similarities in the part numbers but are they compatible ? I can't believe such a recent component has been rendered obsolete so quickly.

The parts look for all the world the same bloody things so hopefully I can make at least the spring fit.

Hope some parts geek reads this.

 

[Milkfloat]

@JhnBssll is probably your man for Di2 jiggers pokery

 

[Brads]

PM 'd him thanks.

 

[SpokeyDokey]

@Brads

Found one part for you.

https://www.sjscycles.co.uk/search/?term=Y5X298030

 

[si_c]

Try SJS cycles they definitely have the second part.

Edit: Beaten by @SpokeyDokey

 

[JhnBssll]

The B-Axle and plate axle springs are the main two springs in the mech, as I'm sure you know. I would first check if there's any play in the pivots and the general condition of the mech; for these two parts to need replacing it's likely the rest of the mech is also needing attention.

If the mech is in otherwise good fettle I would go with the info above and order the Y5X298030 plate axle kit from SJS which appears to be a direct replacement along with the Y5YC98010 B-axle kit for the 6770-A in the hope that the likelihood is very little has changed, and if the new axle were not to fit theres a good chance you could make the new spring fit with the old axle parts.

Unfortunately 6770 parts are becoming hard to source; I recently fitted 6870 to my wife's bike as it was the cheapest available option, even using second hand parts and having to replace the rear hub to move to 11 speed

 

[Brads]

Yeh that's what I thought.

Shocking that support for that group-set has vanished so soon.

Well spotted on the other part mind, I was on SJS website for an hour earlier and missed it .

Will go with that plan and hope for the best. The rest of the mech is fine, it's just not putting any tension in the chain. It's done a few KM's but should still be serviceable.

 

[JhnBssll]

Will go with that plan and hope for the best. The rest of the mech is fine, it's just not putting any tension in the chain. It's done a few KM's but should still be serviceable.

Have you whipped it apart and cleaned it all up? It's possible that the springs are fine but the axles are bound up with corrosion or debris - worth checking anyway

 

[Globalti]

Have you whipped it apart and cleaned it all up? It's possible that the springs are fine but the axles are bound up with corrosion or debris - worth checking anyway

Definitely this. You are wasting your time and money because generally the springs don't lose tension but what I have always found with Shimano derailleurs is that the pivoting parts get rusted up or crudded up with muck and become stiff. Take it all apart, clean and even polish the moving parts, grease and reassemble.

 

[Brads]

Ey up.

It's all free and moving easy, just weak as piss.

Did some digging and a chat with Maddison at my LBS and found that Levers, Battery, Junction box etc are all compatible with the latest Rear and front changers, so those and a cassette and chain will see me in 11 speed land.

They also confirmed that 6770 has bugger all support.

 

[JhnBssll]

Yup - its the mechs that define the number of gears in a Di2 system. The shifters are 'dumb' in that respect, they just send up and down signals, it's only the mech's that really know where they are and how far they can move

When 11 speed Di2 arrived you only needed to replace the rear mech to get a functional (if slightly less refined) 11-speed set up. This was later stopped by means of a firmware upgrade requiring front and rear mech to both be the same 'speed' for the system to work at all, apparently due to chain width differences hindering the front shifting and trimming slightly when using a 6770 front mech in an 11-speed setup.

 

[Brads]

Yup 2014 update killed the front mech compatibility.

Was oit today and the bugger will not hold the 2nd and 3rd lowest gears now as well.

Roll on my return to Glentress and I can put spending loads off until later.

 

[Fab Foodie]

Reading this I’m glad as a luddite I’ve stuck with my 2004 Dura ace old- fashioned cable operated derailiers....16 years perfect service :-)