Sram eTap rear derailleur sporadically stops shifting - then performs all queued shifts at once?

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XCProMD
Posts: 1125
Joined: Sat Jan 26, 2008 10:25 am
Location: Cantabria

by XCProMD

senergy wrote:Sorry for resurrecting this old post, but the internet always points to it as being the most knowledgeable for the dreaded eTap rear derailleur stops shifting properly. So, I thought I would add my 2 cents on what I’ve found. (I joined WW specifically although I have lurked here many times)
I have had Red eTap on my bike for the last 3 years with over 15k km with zero issues. I’ve since moved it to a TT bike with a blip box and still no issues. Important to note that approx. 13k km’s were with a waxed chain, i.e. clean!

I came across a cheap rear derailleur that doesn’t shift properly and after reading this thread I thought I can fix it, so I took the risk.
The derailleur was a mess, mud and grim everywhere! So, I thought sure, those pivot points will be cause.
20210616_142446.jpg
While the pivots were disconnected I tested the derailleur and found that it still had issues. So my issues were going to be inside the body. After removing all the screws I couldn’t figure out how to take it apart. There was a small gap so I sprayed circuit board cleaner in and watched muddy liquid flow out… That didn’t sit well for a quick win.

I struggled some more and eventually using a chisel and hammer removed the arm which allowed the body to come apart. You can see in the pictures that the arm goes onto a splined shaft.

As you can see in the pictures the inside was full of rust, mud and other debris.
(Note, I couldn’t find pics of inside the rear derailleur anywhere)
1.jpg
2.jpg
3.jpg
4.jpg
And with all apart it still failed to shift properly



After multiple cleaning with a circuit board cleaner and then a little bit of electrical lubricant you can see it all looks clean
5.jpg
And now shifts properly!! (I really should have taken it further apart and check on the reduction gear pivot points, but it seemed a little risky)



I’ve since put it all back together and run through 100ish full gear changes and it works perfectly.
Thanks Jugi and XCProMD for the help.
This is one of the best post in this forum in the last years, thanks @senergy.

Pretty much almost every eTap RD can be repaired following your advice. Unfortunately the sealing is quite poor.

On the other hand the concept is very robust , as opposed to the Di2 problems with the position potentiometer which are next to impossible to repair.


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jurna
Posts: 3
Joined: Sat Jul 19, 2014 8:06 am

by jurna

Thank you for sharing your solution @senergy!

I'm trying to follow your steps ant now I'm struggling to remove the arm to take it apart. Can you share more details how you've managed to remove it?

by Weenie


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senergy
Posts: 5
Joined: Sat Jun 19, 2021 12:38 pm

by senergy

Unfortunately I didn't get a good set of pictures on how to take it apart.
Steps are pretty easy though.
Remove the parallelogram linkage (green lines) as shown earlier in this thread and thoroughly clean. Test the shifting without these linkages and it if it works well put it back together and go for a ride. If it still pauses.. then read on.

Remove all the screws (red lines) holding the cover on, even the small triangle cover. One the triangle cover is removed I took out the cage and gave it a good clean as well.
Screenshot 2021-06-27 131843.png
Now turn the Derailleur over and try and wiggle the moving arm in and out to create some space between the arm and derailleur.
IMPORTANT - make a locating mark on the shaft and arm so you know where it has to be put back. (I didn't, but luckily I had another eTap derailleur that I could use a reference)
You then need to get a wedge/chisel/screwdriver underneath it and gently hammer. Try and work your way around the shaft to evenly lift it up.
The picture below is where the screwdriver goes, but obviously you need to remove the circlip and parallelogram linkages first.
20210627_101558.jpg
Once it's thoroughly cleaned I feel it needs some sort of grease rather than lube. My repaired one is a little louder than my other one. I'll look into this if I get another one to repair. Although, now that the cat is out of the bag everyone will be fixing thier own :)

jurna
Posts: 3
Joined: Sat Jul 19, 2014 8:06 am

by jurna

So you can count another fixed eTap rear derailleur based on the posts in this topic!
I had all the same issues as mentioned above (stops shifting, shifts several gears at once).
First I've tryed to use @XCProMD sugestion to clean the pins ant the bushings. Unfortunately that didn't fix my problem.
Then I've dissasembled all the internals based on @senergy instructions.
The hardest part was to remove the arm. My method was to use flat screwdriver and a small hammer. You push the screwdriver under the arm, then twist it back and forth and slowly arm comes off.
The inside was all dirty as expected:
IMG_20210628_185435.jpg
I've cleaned everything, but still shifting was sluggish and somtimes it stopped shifting.
Then I've dissassembled all the gears and cleaned them individually
IMG_20210628_203224.jpg
It seemed that the resistance was comming from that big gear where you attach the arm. It has o-ring seals and tight fitting. Unfortunately you cannot remove it completely. I've spend considerable ammount of time cleaning that gear - without motor attached, you can spin it with your fingers.
After assembing all the gears I've done countless shifts up and down and at some point shifts went back to normal - fast, crisp and wihtout any stops. I'm not sure if the controller has some autoadjustment period, o lube finaly got in, but it took a lot of time and patience to get it working again.

Today I've done 60km ride without any shifting problems on the road! Working as new.

This was one of the most valuable topics in my life, saving 500Eur for me. Thanks @XCProMD @senergy four your suggestions.

senergy
Posts: 5
Joined: Sat Jun 19, 2021 12:38 pm

by senergy

juma, I notice yours had the white wax like substance as well before you cleaned it. Did you ad any lube or grease back in before putting it back together?

jurna
Posts: 3
Joined: Sat Jul 19, 2014 8:06 am

by jurna

I've added a little grease on the motor gear only (in place of that white wax). An a little lube on other gears

Epsom
Posts: 2
Joined: Sat Nov 18, 2017 8:44 pm

by Epsom

I have the same problem. It up shifts when I press the blip. And as if all the presses, add up and does one continuous shift But the other blips work fine. It’s a Tri bike.

senergy
Posts: 5
Joined: Sat Jun 19, 2021 12:38 pm

by senergy

That still sounds like a Derailleur issue. The Blip Box have their own issues such blips stop working. In the cases I've seen its a broken solder which is relatively easy to solve.

gcartelli
Posts: 20
Joined: Mon Aug 26, 2019 7:11 pm

by gcartelli

Sorry again to revive, anyone have the weight on the A2 Rear Derailleur?

packageme77
Posts: 3
Joined: Mon May 23, 2016 4:33 am

by packageme77

gcartelli wrote:
Tue Sep 14, 2021 10:23 pm
Sorry again to revive, anyone have the weight on the A2 Rear Derailleur?
There you go. Weight without battery.
Attachments
A2.jpg

gcartelli
Posts: 20
Joined: Mon Aug 26, 2019 7:11 pm

by gcartelli

thanks! lighter than i was expecting. Basically the same weight as the listed version of the RED AXS RD.

Monsterinyourhead
Posts: 3
Joined: Sun Dec 05, 2021 7:12 pm

by Monsterinyourhead

Thanks to this thread, I was able to get a WiFli RD in what appears to be working order. It will complete a full range of shifts but, I am to a point where I am uncertain if it will behave correctly when under load. Let me explain...

I followed the steps shown in this thread on how to get into the gearbox of the derailleur. Once I was able to open the two halves, I noticed the oring gasket that spans the perimeter wasn't seated properly. With that said, I observed a fair amount of grime and debris in this area of the housing. This is just a wild assumption but, I suspect maybe this resulted in moisture and or corrosion on the PCB of the derailleur. I acquired this derailleur for a fair price and I wasn't concerned about damaging it any further. I used 99% isopropyl alcohol and a toothbrush to lightly scrub both sides of the PCB. Since I gave the board a nice scrub, I thought I would also clean and regrease all of the gears. It wasn't until I removed all of the gears that I realized I may have a problem.

I marked the position of the arm that was affixed to the gear shaft but, by removing all of the gears I think I upset the timing of the system. I say this because, once I removed the gears, I noticed once of them was magnetic and the other one was spring loaded. See attached picture. The gear that is spring loaded, I left in the housing. With that said, the magnetic gear indicates the system uses a Hall Effect Sensor.....to which I know nothing about.

My main question/concern relates to that gear shown in my picture that is spring loaded. This gear and the magnetic gear must not carry any load because; only the lower axle on each gear is secured. I don't know if the Hall Effect sensor controls the shifting limits to tell the system not to over shift or if it's a safety feature....or both?

I'm really wondering what position the spring loaded gear should be in upon reassembly? Does it need to be preloaded? I reached out to Sram but, I am guessing they won't offer this kind of technical support :)
Attachments
PXL_20211205_180750986.jpg

Monsterinyourhead
Posts: 3
Joined: Sun Dec 05, 2021 7:12 pm

by Monsterinyourhead

I'd like to take another shot at fixing one of these eTap rear derailleurs. If anyone has one they are looking to get rid of, please let me know.

bobones
Posts: 1271
Joined: Mon Aug 12, 2013 11:19 am

by bobones

Where are you?

Monsterinyourhead
Posts: 3
Joined: Sun Dec 05, 2021 7:12 pm

by Monsterinyourhead

bobones wrote:
Fri Dec 10, 2021 7:02 am
Where are you?
I am located in Minnesota, USA.

by Weenie


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