Rear derailleur mounting

Pavel Spirine

I've come across a problem which has never manifested before.. so am I overseeing something blindingly obvious???

I just swapped a rear Sram X7 derailleur from a Marlin Malt 2 frame to a Specialized Hardrock Pro (2009). Now when I screw the hollow mounting bolt into the rear hanger, all the way till it's tight, the derailleur is still loose by about .5-1mm (wobbles about) and the little tab/washer isn't clamped. The bolt will not go in any further because from what I can tell it has a hardly noticeable shoulder that protrudes past the tab/washer... Does this make any sense to anybody?

Given the cost of a Deore derailleur (and shifter as I assume I can't use the X7 shifter with a deore derailleur) I will probably just replace it is as it looks quite old, if the above problem has a tricky solution! Would be nice to keep it though to save some money and since it always worked so well...

Cheers

nicklouse

make sure that you have the tab correctly aligned.

and sram mechs are not sprung like shimano.

Pavel Spirine

I aligned the tab correctly, and tightened the bolt. But even after tightening it, the tab was free to rotate (it doesn't clamp in any position). The shank of the bolt seems to be a TINY bit longer than the thickness of the tab...

I've never come across this problem before and the only thing I can think of is that the merlin had a slightly recessed tapped hole?

nicklouse

yes the b-adjust washer tab should be free to rotate untill the screw comes to rest on the drop out.

can you get pics?

dave_hill

It is possible that the MErlin had a slightly counter-bored mounting hole.

The thing is, if the bolt is bottoming out (i.e. you've tightened it as far as it will go) then that's it - short of having a counter-bore machined into the hanger.

Bear in mind that if the mech is old, it will have worn and you'll be getting play even with the bolt fully tightened - it does happen eventually. Even new mechs have bit of play in them, they don't tighten hard against the frame.

And yes, unfortunately a Deore mech will not work with Sram shifters because the leverage ratio of the Deore is 2:1 where the shifters are 1:1.

Pavel Spirine

dave hill, you've got it absolutely right, the shank bottoms out on the bracket (which is why I assumed the merlin had a counterbored hole). I don't really fancy counterboring the hole so will probably just get a new rear derailleur. This build is ending up costing a fortune

As for the play you talk about, it definitely wasn't this loose on the merlin and my nearly new Giant XTC 3.5 with an XT rear mech has absolutely no play in it.

Nicklouse, I'm aware that it should be free to rotate, but it's more wobbling than rotating at the moment! Can't really show it very well with a pic but will try knock something up in paint.

Pavel Spirine

ta-da![/img]

dave_hill

Another option would be to place a washer between the derailleur and the hanger.

nicklouse

looks normal to me.

most mechs have a gap there.

pic of your mech in the threaded area?