Gerryattrick

A friend has just bought a Dura Ace equipped bike second hand that she wants me to service. There's a problem with the QR on the rear brake in that the bit that grips the cable moves with the QR instead of always staying in the vertical position. The previous owner obviously ran it with the QR fully opened and the cable tightened to correctly position the brakes. The front is fine and looks to be exactly the same mechanism (as confirmed in the Shimano tech doc). It looks as if it should come apart easily with a bit of prising, but doesn't, and as it's someone else's bike I'm wary of putting too much force on it in case I mess something up.

Any ideas please

dsbrantjr

There may be grit or corrosion holding it in place. A few drops of penetrating oil, (Kroil, PB Blaster, etc.) won't do any harm and may loosen it up.

Gerryattrick

I've tried that with no luck, but I'll give it a bit more of a soaking and leave it overnight to see if that helps.

Gerryattrick

This, together with a bit of effort - not too much but repeated for 10 minutes - worked. I used a strong cable tie to stop the QR lever moving and a hex spanner in the cable holding bolt to provide the leverage.

It now works perfectly.

Incidentally I asked a representative on the Dura Ace stand at the UK Cycle Show last week and he didn't have a clue

Kimmo

I'd have said WD40 and a spoke clamped instead of the cable for leverage.

Isn't there a little allen head bolt for disassembly of the QR?

Gerryattrick

That was part of the problem. The little allen head bolt came out OK but the QR was stuck too solid to dismantle.
I see where you're coming from with the clamped spoke but I think it would have bent as the pressure needed was too much, but the same principle with a slightly stronger steel rod would have worked.