SLX rear derailleur issue

[leeubok]

I finally upgraded my old 3x gearing last year to SLX 1x12 and a Sunrace casette. A couple of friends have gone this route and are extremely happy with it. I'm however not impressed. Gear changes aren't smooth and very clunky, and recently it developed another issue, which I haven't seen on the hub yet.

 

When gearing down the bottom jockey wheel (if that's what you call it) doesn't move back to keep the chain tight, so the chain starts to hang. If I push it forward and let go it snaps back to hold the chain tight, but I have to do this every time I've gone up a few gears and then down again.

 

 

 

I took it back to my LBS, at very short notice and not a lot of time for them to work on it. So kudos to them for still helping me out. He said they cleaned it out and correctly torqued something. Upon collection I went for a short ride, gearing felt a little better and derailleur seemed fine.

 

Very next day I take my bike out and chain is sagging again, even worse than before. I'm a 3 hour drive away from my LBS so can't quickly take it back and leave it there to have them sort it out. Has anyone experienced this before and have some advice on what I can do to solve this?

[Captain Fastbastard Mayhem]

The gap between the top jockey & the cassette, which is controlled by the B Screw at the back of the derailleur, seems to be much too large, in that pic. But if it's not keeping the same gap all the way down, then it's an issue for sure. May be an issue / fault with the clutch itself, or it's binding on something?

[JacBrand]

Looks like there is an issue with the clutch. Check if it is in the unlock position (see if that fixes the tension)

As above, the B screw limit seem wrong

[Mojoman]

So it looks like the actual cage section is not springing back to a taught position?
Hss the spring become detached somehow?
No expert on RDs but its just a cage and a pivot point and a spring to bring the tension up?
As miles mentioned maybe have a look at the clutch assembly on the RD.
Maybe even detach that RD and give it a good clean and lube up and make sure all moves freely? 
 

Edited July 3, 2020 by Mojoman

[leeubok]

I've tried the clutch lock and unlock and neither position helps. In fact it doesn't feel if the lock mechanism works at all

[Hairy]

Take a look and see what the clearance is like between your frame and the smallest cog when the chain is on this

 

EDIT: Please ignore

Edited July 3, 2020 by Hairy

[Captain Fastbastard Mayhem]

I've tried the clutch lock and unlock and neither position helps. In fact it doesn't feel if the lock mechanism works at all

IMO then it must be binding somewhere. Either in the clutch, or there's a burr somewhere preventing movement, or something's out of alignment somewhere. 

 

That, or the B Screw being too far in. What makes me think it's not the B screw is that you say it snaps back to position when you move it forward and release it. If it was the B screw, it shouldn't do that. 

[Captain Fastbastard Mayhem]

I've tried the clutch lock and unlock and neither position helps. In fact it doesn't feel if the lock mechanism works at all

the clutch on / off just changes the force required to move the cage. Not to lock it in place. 

[Mojoman]

If you jiggle and jaggle that cage back and forth does it feel like there is sufficient and uniform tension all the time?
No tiny stone that has managed to get itself wedged in somewhere? 
 

[leeubok]

If you jiggle and jaggle that cage back and forth does it feel like there is sufficient and uniform tension all the time?

No tiny stone that has managed to get itself wedged in somewhere? 

 

No it feels like it is catching somewhere. Before the shop opened and cleaned it I could push it forward just once and it would snap back in place. Now if I push it forwards and back it doesn't even snap back the first time

[MarcW]

I had the same/similar issue with a BRAND new XTR 12 Spd derailleur. Turns out the clutch was sticky and needed a service (Very quick job, basically needs a bit of Shimano grease on the clutch mechanism).  After that everything is working just fine. 

[Dusty]

So this only happens in the small cogs and not when the chain is higher up?

[leeubok]

So this only happens in the small cogs and not when the chain is higher up?

 

correct

 

I had the same/similar issue with a BRAND new XTR 12 Spd derailleur. Turns out the clutch was sticky and needed a service (Very quick job, basically needs a bit of Shimano grease on the clutch mechanism).  After that everything is working just fine. 

 

Supposedly this is exactly what my LBS did. Didn't work though..

[CdT85]

 

Even though the b-tension looks to be off, it wont affect your rd cage getting stuck like that. Did you not maybe overextend the rd causing damage? This could happen if you bottom out in you granny gear and your chain is too short.

It could either be that there is an issue with the spring / cage. The spring that puts tension on the cage might be slipping out of its detent and getting stuck, or the spring might be broken.

 

Alternatively, your clutch can be binding up.

 

Long story short, its new, you LBS where you bought it should replace it for you.

 

(exploded view of rd just for reference, I know its a 10 speed rd)

 

edit:

 

it could be that the bolt, securing the cage to the RD body might be too tight also. See bolt in blue circle

Edited July 3, 2020 by CharldT

[eddy]

 

 I'm a 3 hour drive away from my LBS  DBS (Distant Bike Shop)

 

Fixed.

 

PS.

 

If you bought it new, let the shop replace it.

[Eddie Stafford]

It is the clutch and is a very common problem with the 1 x 12 Shimano derailleurs. My XT derailleur is less that three months old and did exactly the same. I went through whole process of getting the derailleur hanger checked, trying spacers and a longer b-screw, but to no avail. Opened the clutch and it is dry, rusted and sticky. It is a hassle to take the derailleur apart to clean the clutch.

 

Exactly the same happened with the clutch of my previous 11 speed XT derailleur, whereas the 6 year old 10 speed XT derailleur's clutch on my other bike is faultless.

 

It really pis.... me off when you pay R2,500 for a derailleur and it stops working properly after less than three months! Surely Shimano must know about the problem.

 

We are not alone: https://crankjoy.com/review-update-shimano-xt-8100-arising-issue/