Barchettaman

The return spring (?) for the derailleur seems to have seized, or broken. It will happily sit in the position from photo 3 and not spring back to how it should be, in photo 1.

The unit won’t tension the chain. The rivet on picture 3 is pretty gummed up. It’s not really old, either.

Is there anything I can do, or is it junk? I haven’t tried anything yet, I thought I would ask here first.

thanks in advance!

BTinNYC 

I think it's finished. If the spring is unhooked, I don't know how one would get it re-hooked. These RDs are still common and low cost so, yeah, play taps and thank it for many good shifts.

Barchettaman

I’ve cleaned that area up and worked some
light spray oil in and around the rivet. She’s trying to come back to life!
There’s definitely a bit of springing-back going on!

spclark 

Know anyone with an ultrasonic cleaner you can drop it into for a few cycles?

Unless that main spring's really busted, what looks like fine encrusted grit & grime just may be as much inside as out, keeping things from moving as they'd been designed to.

Andrew R Stewart 

Generally it's the mounting bolt's pivot that gets gummed up and/or corroded, less so the cage pivot. I see VERY few actually broken springs compared to pivots that have been neglected and allowed to freeze up. If this der's cage pivot does free up I suggest checking and servicing that upper/B pivot too.

The cage pivot shaft being riveted just means Shimano didn't intend this pivot to be able to be taken apart. The grime on the exterior isn't the real issue, what's inside the pivot is at play. Still I like a clean der so I suggest cleaning the rest of it than lubing all the moving parts, again if the cage doesn't start to work freely don't bother. Andy

Barchettaman

Successfully revived! The ultrasonic cleaner worked perfectly.

maddog34

you now have a very clean, DE-GREASED derailleur. Expect advanced Wear Rates.

in the future, avoid riding through so much sand.

79pmooney

Not needed by the OP but I have helped out ancient derailleurs that could not quite push the chain onto the small cog with bungy cord. Two tight wraps around the parallelogram. I secure it with a sailor's whip but knots could be used or sturdy wire ties. (On a Mk nothing SunTour Cyclone from my parts box. 40 something years old, perhaps 50. With the bungy, shifts like new.)

spclark 

OK now treat it to an overnight soaking in ATF at minimum, then see how it works once installed.

Those tension springs were intended to be fitted well-greased. If you can't break it down to clean & re-grease you need to lube it with something that'll both penetrate then stick when the excess is drained away. ATF is a decent choice, tends to leave enough of itself behind where access is close to impossible barring an effort you can't undo.

mpetry912 

soak in isoproyl alcohol, and then ATF, followed by Diesel fuel, and then depleted uranium

maybe time to buy a new one ? just sayin.

/markp

choddo

Did the ultrasonic cleaner take any of the black anodising off?

Barchettaman

No. It looks brand new.

I have oiled it as well as I can and will reinstall it on the bike next summer when it will get a new chain, cassette and chainring. It’s a Bosch powered e bike.

I think there’s plenty of life in it yet!

Barchettaman

It has had a reasonably hard life I suppose, the bike sits outside, but I haven’t ridden it through any sand. I wonder if these cheaper Shimano derailleurs leave the factory with insufficient lubrication on that pivot.

Anyway, when I replace the drivetrain I will repeat the rejuvenation process. I hate throwing stuff away that has life left in it.

choddo

With that in mind, I’d make sure it’s covered if left outside, to maximise its working life.

soyabean

Derailleurs on bikes stored outdoors are often like this.

I used to soak entire units in diesel overnite to loosen up hard springs, now I can do it in 30 mins with ultrasonic.

Crankycrank

+1. Storing bikes uncovered outside is equivalent to felony bike murder. Well, not quite that bad but this will reduce the life of your bike considerably. I live about 3/4 mile from the ocean and tell all my neighbors to keep their bikes indoors or at least covered as it only takes about 8 months to turn it into a pile of rust and corrosion.

Barchettaman

The bikes are under cover (they are locked up in a covered area by the shed) but the sides are exposed to the elements. There’s nothing I can really do, we don’t have a garage. Stuff rusts and gets worn out anyway, but I’m pretty good at keeping on top of maintenance. Checking the derailleur pivot springs will be another item on the check list, going forward.

Fortunately we’re not by the coast.

choddo

You must be able to get stuff like this?

https://www.decathlon.co.uk/p/protec...e/_/R-p-308715

deacon mark

It is not an expensive derailleur at all I would replace it in a heartbeat easier than cleaning.

choddo

Disposable society

SW84

Why not disassemble it and get the spring greased up? Just take pictures as you go.

deacon mark

[QUOTE=choddo;23033019]Disposable society [/QUOTE

They are wear items and have a useful life. At some point you just move to what is best to get performance.

smd4

You may have noticed you can’t disassemble that part of the derailleur.

SW84

I couldn't confirm that unless it was sitting in front of me.

choddo

Definitely riveted in that second photo.