Hey peeps,
I regularly clean up the clutch roller bearing on my Shimano mechs. I decided over the weekend to go a bit further and do a full clean up and re lube all the pivots and springs. However, I found the spring and pivot that sits behind the clutch was just a rusty mess.
It got me thinking, how the heck do I stop this happening? I don't want to have to strip the mech back on a frequent basis unless I have to. I'm thinking about getting a replacement spring and pivot bolt plus accessories from my LBS to "save" the mech (no way I can clean the spring up well enough).
Any hints from anyone on how to prevent the spring ending up a puddle of rust over time?
Cheers.
I’ve just done similar maintenance and also found a rusty spring (though it still works fine so I cleaned it, greased it and put it back). The best I’ve found from searching around the internet is that water gets in via the hole in the outer plate where the spring latches on, and a potential solution is to use some silicone sealant to block that hole.
Is it just me or is the Shimano 12s worse than the 11s for this too? I don't think the seal is as good or the hole is bigger as living in a humid climate i'm having to strip 12s derailleurs far more often than I did with the 12s.
... and i've just realised that I could potentially use an 11-speed derailleur with a 12s shifter as long as the cage is correct length. Might give that a go.
I stripped an M7100 mech this afternoon after taking it off a bike last week. It's got over 6000km on it, is on its second set of jockeys, but otherwise hasn't been maintained as such.
Clean enough, bit of dry crud. Wiped clean, greased and reassembled.
My take on preventing a rusty spring? Don't wash your bike. That's what kills these components.
Blog post associated with pics.
I live in Scotland, so not washing will quickly lead to no cycling for other muddy reasons. It is good to hear I'm not the only one. It looks like SJS cycles sell all the really rusted bits (spring, pivot bolt, bumper) but you have to buy a full inner plate to get some of the stuff. About 35 all in. Better than 95 for a new mech though. On the 12.speed Vs current 11 speed, I honestly don't think there is much difference. The clutch mechanism has been a pain from the get go. The only maintenance I used to do on rear mechs was change the jockey wheels when they ended up like shiruken and changed cables out when they got grouchy (before the days of full length outers and internal routing). Hardly ever have to change jockey wheels now but the clutch needs babying. Grr.
How big is the hole that the spring end pokes out of? Big enough for a grease gun and a very generous skoosh of grease to fill the void?
Or a regular squirt of some light oil - GT-85 or similar to help flush any water out.
In all my years of biking, I've never stripped a mech down into individual parts to service...I do tend to squirt the pivots on the parallelogram as well as the exposed sprint with some GT-85, but I never disassemble to clean. Having never had a clutch mech go saggy on me, I've never seen the need.
Is there a genuine need here or is it just to hopefully (and helpfully) prolong the life of the mech? Is the rust just a light surface rust or is the spring properly corroding?
The spring is definitely "properly corroding" as is the pivot bolt and the bumper washer at the inner plate end. I reckon that the spring will be ok for a few months more if I just refit it but we are talking significant potting. The bumper washer is worse. I like the idea of smoothing some light oil (maybe more like chain lube than GT85) into the hole if there's room to do so. Not sure there is but I'm going to look for sure. There is a gmbn service video where they recommend coating the spring with hub axle grease to prevent corrosion.
This was how my spring looked after removal but before cleaning - signs of rust and didn't clean up anywhere near as well as that of @montgomery in the picture above:
Worse though was the P-axle - the one that goes all the way through and forms part of the clutch mechanism on one side (where the hex key is inserted in montgomery's top picture) and the nut for the cage mechanism on the other. That was not moving freely beyond a range of approximately 30°, to the point where the chain was sagging in all of the high gears because the cage wasn't rotating to take up the slack. I removed the axle (with a lot of GT85, persistence, and expletives), cleaned everything with IPA, smoothed off the axle and its housing with some fine emery paper, greased and reinstalled, and now it's working fine. To be fair, until the last month the derailleur has worked flawlessly over 7000 miles since I bought it (second hand off ebay, so no idea how much use in total), so I'm not complaining.
New springs, seal cups, axle bolts and 1 end plate arrived today. Joining my list of essential spares (along with blinking clutch bearings). Also going to try some rust removing chemicals to see what the old spring ends up looking like.
