Removing the spring from a Campagnolo limit screw

[bryce]

Is there anything wrong with removing the spring from a Campagnolo Athena 11 speed rear derailleur's inside limit screw (the one that stops the mech going into the spokes)? I'm running with a Shimano 10 speed cassette and the limit screw isn't quite long enough. It stops the derailleur shifting into the spokes well enough but still lets the chain occassionally go off the big cog into the spokes. Without the spring the screw should go in far enough to prevent this.

It's possible that careful cable adjustment is enough but even if this works cables only last about 6 months so adjustment needs to be reasonably safe. A very slightly longer screw would also work. Annoyingly it's only a fraction of a millimeter too short. I'm not sure where to find such a screw that'll fit inside the derailleur.

Getting a cassette with the missing cog would also resolve this problem but gets expensive especially with disc brake hubs.

[NATURAL ANKLING]

Hi,

NO, but you need to lock the screw at the desired position
You could try shortening the spring
Or even packing the space occupied by the spring with washers.
Even space the deralliuer mount screw with washers to pull the derraliuer out further (between deralliuer and frame)

Dont rely on the cable.

[fastpedaller]

Can you identify the thread of the screw (maybe m3) and then replace it with a longer one? The spring is most probably there to prevent the screw rattling loose (ie it's a locking device for the screw), so if you could shorten it it would still do it's job if the screw compresses it - that's the 2nd option.

[jb]

The spring prevents it from turning with road vibration. you could take it off and put some thread lock on the screw, providing you are going to leave it in one position.

[NATURAL ANKLING]

Hi,
Or take out spring and use a nut to lock off the adjustment at position.

[bryce]

It appears as if there isn't a similar spring on a Tiagra mech, so it's not obvious that it's essentual even if it does help.

I think the screw is a M4-14. The problem with finding a replacement is the head goes into a hole in the mech, so the head needs to be small enough to fit.

[Brucey]

if it is a question of a mm or so then you could fit a washer between the mech and the dropout, or in the RH locknut stack on the hub. This would push the mech and the cogs further apart , thus obviating the need for a revised limit screw.

cheers

[Valbrona]

A Campag B screw is nowadays located at the cage. In the case of earlier Campag stuff the B screw used to be located in the 'traditional place', and traditional style B screws came in a variety of lengths - triple Campag RD B screws were particularly long.

Why am I mentioning Campag B screws and not Campag limit screws? Well, me thinks they are the same and can be had on eBay/other sources in a variety (possibly three) of lengths.

[Mick F]

Longer screw.
Simple.

[CREPELLO]

Replace the spring with a few windings of PTFE tape.

[fastpedaller]

It appears as if there isn't a similar spring on a Tiagra mech, so it's not obvious that it's essentual even if it does help.

I think the screw is a M4-14. The problem with finding a replacement is the head goes into a hole in the mech, so the head needs to be small enough to fit.

If you can get a stainless steel screw with a slot head, then just file the diameter of the head down until it fits.

[Mick F]

I was thinking ages ago about fitting Allen-headed screws in both the front and rear mechs.
This would standardise the tool system for the complete bike.

Why they are slot-head I don't know, as nothing else is with Campag.

[NATURAL ANKLING]

Hi,
Grub screw / set screw (headless with hex soc recess for hex key) .
PTFE is a lubricant and if using thread lock you would have to degrease well and would not be reliable to reajust later.

If no spring then it might have a plastic insert which the screw passes through with just a hole which applies friction to the thread.

Most reliable method preferred method is to space deraillieur away from frame with a washer / space , you wont need much.

[Mick F]

I don't know if anyone has tried this:
Screw in either limit screw and see if you can adjust one far enough to ignore a outer or inner sprocket.

I've tried it, and although the chain won't go to the outer/inner sprocket, the system complains with a chain rattle. Basically, the mech is designed to do the full width of the cassette plus or minus about half a cog or less.

If you move the mech's hanging position, you could possibly upset the other end of the cassette.

OTOH, if you remove the limit screws completely, the mech will go WAY out beyond the cassette in either direction as the parallelogram itself has stacks of range. Hence my comment about fitting different screw lengths.

[NATURAL ANKLING]

Hi,

I was thinking ages ago about fitting Allen-headed screws in both the front and rear mechs.
This would standardise the tool system for the complete bike.

Why they are slot-head I don't know, as nothing else is with Campag.

Without looking it up the Hex key would have to be 2mm accross or sub 2mm.

As M4 thread is 3.3 mm tapping so using a 2 mm hex key would give 0.5 mm between the thread core (min dia) and the point of the key socket.
Using a 2.5 hex key would give 0.21 typical between thread and point of hex socket.

So its 2mm allen key or less, you know how tough adjusting the stops can be against the spring / cable etc, so the 2mm hex key socket would not last long and the socket fills with crud and then the socket if not deep rounds off, an so if forced shears off across the thread etc, etc etc,