dj23

Greetings from Australia.

I’m seeking advice on the final step in reassembling a Shimano ST-EF28 right hand 7 speed combined gear/brake shifter. It links to a Shimano Altus 7-speed rear derailleur. I found the Shimano exploded diagram for the ST-EF28, but it is not detailed enough for the lower level internals. I gather some informed bikies think it is madness to try to repair/reassemble Shimano shifters, and I have heard that the only person who knows how to do it is a robot in a Japanese Shimano factory. However since I am so close to nailing this, I’m trying all options. Hence here I am. I’ve searched over this site but not found what I need. Plus this is quite a nice, lightweight MTB, and I like the crisp, clean shift of the left shifter, so I’d like to fully fix the bike

The story behind this is that I bought a cheap used Mongoose Maneuver DX 3.1 mountain bike, with the intent of practicing bike repair and maintenance before I buy something more up market and expensive. The main faults with the bike were: flat tyres; erratic brakes; only 2 out of 3 gears worked on the left shifter; most of the right shifter parts were supplied in a plastic bag – looks like someone tried to fix it and failed.

I’ve fixed the tyres and adjusted the V brakes. The left shifter now works ok, after I tried the WD40 treatment I read about here. WD40 also ungummed part of the right shifter mechanism.

Now the problem: By comparing the right with the working left shifter, I’ve concluded that all the right shifter parts are probably in the bag. I’ve also partly assembled the right shifter. However I can’t work out the final step, where a tricky spring is involved. In that area, the right shifter parts unfortunately are somewhat different from the left.

The attached pics make the situation clearer (I hope):

2353 is the left shifter with cover.
2354 is the right shifter with cover.
2356 is the left shifter (working, fully assembled)
2360 is the right shifter as I have partly assembled it, showing the plastic cable winder which locks into the clicker marked R.
2358 is the right shifter, slightly more assembled.
2366 and 2367 show how the parts A-F and H should roughly fit together. I do not know where the washer G fits. It is clear from the left shifter how they should be attached to the shifter body.

So where I would appreciate help:
1. Where does the washer G go?
2. It seems from the left shifter case that spring H connects C and D under tension. How do I place it so everything fits together properly?

I know I could (and might have to) buy a complete replacement right shifter assembly. But I am a bit compulsive with problems I think can be solved with enough thought, information and experiment. Any advice appreciated.

flash84

I have the exact same gear shifters. I am currently trying to rebuild the left hand one but I'll try help you with the right hand one.

1. Washer G would go in between the two moving arms.
2. I reckon you have to place both bits in the top of the gear shifter and then tension the spring afterwards by pulling it across with a flat head screw driver.

I am stuck with assembling the left hand gear shifter. I have put it all back together except I can't work out how the spring on the underside goes back in. It just seems impossible to put that spring back in. Anyone know how to fit the underneath spring?

flash84

I just realised I was trying to put the internals from a ST-EF20 shifter into the ST-EF28 and so that's why the last spring didn't fit. Different shifters... Doh!