Help me un-weld

[Pavel]

I've put this off for over two months but I have a gear train problem that I've never seen the like of before.  I went out on a two day trip with a Warmshowers visitor I had, to see him off and to have some fun miles.  Mission accomplished, I can home and put up the bike.  The trip involved cool but nice weather and no rain whatsoever.

a few weeks later we had a nice day in mid december and I went to go for a short ride. My gears would not change.
Looking into what disaster befell my infallible - I checked the Rohloff and was relieved that it was not the Rohloff itself but rather the quick release.  More specifically it seems that where the Rohloff cable enters the aluminum quick release adjustment screws (on the bottom side) that the cable is welded to the aluminum.  How on earth can that happen?  It is as if someone welded the two together in an April fools joke.  So does anyone know of any magical anti April Fools compound?  Is there any lube that should "unseize" a stuck steel cable to aluminum bond?  I'm at a loss to begin to fantom how such a thing could happen but though it is minor I now may have to go spend the money to order a new adjustment mechanism and new set of cables and wait for who knows how long, so any tips would be greatly appreciated.

Thanks.

[Danneaux]

Hi Pavel!

So sorry you've got a problem, and such a galling <sorry> one at that.

Either PB BLaster or Kroil are my liquids of choice for breaking galvanic bonds. See: http://www.thorncycles.co.uk/forums/index.php?topic=4685.msg23181#msg23181

To better understand the problem, I need a bit more clarification.  You've got a Nomad, so the problem must be in the EX (external) shiftbox that attaches to the left side of the hub (under-chainstay cable entry).

I doesn't sound as if the adjustment screws/cable seats are welded to the shift-box entry, but the cables to the adjusters.  Hmm.

Could it be the shift-box itself? One overlooked maintenance item is the regular replacement of grease int he shift-box. Have you taken off the box and looked inside?

If it is the cables that have welded to the adjusters, an overnight with PB Baster or Kroil should help greatly at releasing the bond.

A difficult problem, for sure! Please keep us informed as things develop, Pavel.

All the best,

Dan. (...seizing <groan> the opportunity to offer help)

[Pavel]

Yes it seems like the cable to the aluminum adjustment screws that the cable passes through right before going into the external shift box - or perhaps somewhere inside the cable further up.  I disassembled the shifter box and all inside is well, nicely greased and all.  What is suprprising is the incredible strength of the bond. I will try the PB blaster or Kroil (thanks!) whichever I find first and report back. 

[Danneaux]

Hi Pavel!

If the liquids don't work...then I suspect you might have a frayed cable, perhaps just ahead of the adjuster.

Does the grip-shifter wiggle freely, or is it packed-up as well? I suppose the shift unit could have seized for some reason.

All the best,

Dan. (...who is a'frayed it may be more than what spray can fix)

[il padrone]

Most cables these days are all stainless steel, or at least zinc-plated or similar, so corrosion bonding is unlikely. "Welding" is not what it is. Most likely problem is a frayed cable due to broken strand(s). Whatever the case, I'd be simply pulling the cables out (yes, both of them) and replacing them. Relatively low cost and simple fix.

[Pavel]

Well I'm trying out the PB Blaster - so far it has been soaking for about two hours ... and no go yet.  It definitely is welded together rather. Inside the bore of the adjustment screw the cable is so tight that when I take a vice-grip to the round steel cylinder that acts as the stop and pull with all my might ... the cable will not move.  I've never seen anything like this, and now my interest is saving myself the cost and the headache of ordering the adjustment mechanism.  Kinda depressing!

[geocycle]

Sounds like superglue sabotage to me!  Any chance of a picture, i can't imagine what is going on here???

[Danneaux]

Hi Pavel!

Is it both cables that appear "welded", or just the one?

Have you tried turning one or the other of the adjusting screws in to see if some slack can be created? Do the adjusting barrels turn at all?

Can you wiggle the shift barrel any?

The reasoning behind the above is, if there is a bit of slack, the free cable might be used to gently leverage the one that is stuck for whatever reason. With the present problem, it seems there's no slack in the system, which is worrisome in itself.

The PB Blaster should have had some effect by now, having soaked a couple hours, though it could take overnight. I have in some cases waited a week, reapplying it daily. That stuff really does work great on galvanic corrosion.

I'm still leaning toward the known (frayed cable), in part 'cos like you, I can't imagine the mechanism by which it could have galvanically welded.

Best,

Dan. (...who openly admits to bafflement in this case)