Tightening up a Deore Lx Rear Derailleur

[cmjc]

Ah I see, so did you have a spare "o" ring, or did you make one.

I'd probably have to make one, unless anybody knows a supplier of tiny bits like that.

It'd be nylon or synthetic rubber I suppose?

Thanks again for the images, my fist sight of what's inside a derailleur.
Is that the spring in the picture background?
Might need a new one of those too.

 

[rc300]

Yup that is the spring in the background You can get small o rings easy from some shops or t'internet. I have a huge box of em cost £10

 

[rc300]

Yup that is the spring in the background You can get small o rings easy from some shops or t'internet. I have a huge box of em cost £10

 

[cmjc]

Righto, I'll look for some small "o" rings, and have a go at it next time I have to remove the rear derailleur. It's my workhorse bike, need it daily, so I want to have the bits ready.

Feels better fixing up the original parts rather than getting a new derailleur.

Thanks again!

 

[Neil]

It worked!

I employed one of those flat plastic date stamp tabs supermarkets use to seal loaves of bread.

Can you still get them, and if so where from? I could do with some for a repair / mod (car related).

 

[cmjc]

The plastic tab I used was from the loaf of bread we are still eating, bought it at my local supermarket. Nothing special, just a flat square of 1.5mm thick hard plastic with a hole in it. The finished shim is shaped like a "C" and the ends of the "C" hold it in place nicely.

You could make one out of many things.

I used the plastic of a disposable coffee cup to make shims to align my middle chainring better. It is 17 years old, and I didn't want to bend the ring into shape in case it broke. Slipped the shim under mounting bolt hole, on the crank spider.

It's working well.

 

[cmjc]

Several trouble-free thousand miles since my last post, I finally dismantled my RD by following rc300's excellent photo-instructions.

I was surprised to find my Philips-headed stop-post was only finger tight. Good job it didn't fall out last week when I was on a 1000km Asian tour on the bike. (I painted nail varnish on the thread to "lock" it and I'll keep an eye on it in future. Ditto the little Philips screw that holds the arm to the body.)

The photos here are of the near identical Shimano XT, but I found the Lx +not+ to have any "O" ring; instead it has a 3mm wide, 1mm deep, channel in the pivot shaft. I presume this channel is filled with grease when new, but mine was bone dry.

I got, and tried to fit, a couple of small "O" rings side by side in the channel, they fit snug, but when I pushed the shaft into the body, they were merely forced down the shaft instead of sitting in the channel, so I abandoned that idea and just filled it with thick sticky farm grease.

I also made a new plastic shim from a telephone charge card to take up slack under the plastic collar at the base of the shaft.

I cleaned, lubricated, and reassembled it all, adjusted the gears, and it works fine.

The lateral play I originally mentioned is no more than 5mm side to side now, the same as my new Sora road-bike RD. And that play comes from the parallelogram body.

I should mention that it is not necessary to remove the RD from the frame to do this, just take the chain and wheel off.

So what looked daunting, turned out to be easy, and well worthwhile, thanks to rc300.

This wonderful old bike is now entering it's 18th year of service, and it is still strong and sweet as a nut.

 

[hamster]

Small O rings like that are available in the plumbing section of B&Q in variety packs.

 

[rc300]

Cheers mate!

 

[cmjc]

Small O rings like that are available in the plumbing section of B&Q in variety packs.

Indeed, but I think you'd be wiser to get "O" rings from an engineering shop to ensure the synthetic rubber is up to specification. Plumbing washers will be plain rubber.

I got mine from a motorcycle accessories shop in the same rack as the engine seals, I got 2 for the equivalent of 14pence. But as I explained above, the Lx RD doesn't use "O" rings on this shaft, so I didn't actually need mine.

Incidentally, I also tried instead of an "O" ring, a length of twine wrapped and tied around the shaft to fill the channel, with a tad proud to take up any play.

It took up the play, but it made the RD too tight, resulting in iffy functioning, so I took that off too. Thick sticky grease seems to be the best for the Lx model.

It was so easy to fix, I'm going to make this procedure a regular part of 6 monthly maintenance.

There's no need to disconnect the gear change cable either, so it doesn't roger your shift settings, unless there was a lot of play as in my case.

Merry Christmas rc300, glad you got my gratitude!