Still going over my recent bike purchase. Realized my rear caliper isn't working correctly due to a sticky rear brake cable. It does not slide free at all.
It looks new so I question whether the previous owner used an incompatible inner and outer cable pairing.

The front seems to be older/dirtier but works fine however I was thinking I might as well replace that one if I am going through the trouble of doing the rear.

One question...do modern brake cables like shimano and others fit the campagnolo brake levers?

To answer your first question, it's barely worth the time it takes to decide. I often lubricate sticky cables, but sometimes, it takes so much effort that I realize I should have replaced one. Try either, and you'll know soon enough which is the better strategy. Cables are cheap, and oil is cheaper.

Brake cables and housings are pretty much the same as they've been. Housings for shifting have changed, though, so use housings that are designed for shift cables. New shift housings are straight, not wound.

When in doubt, throw it out. Modern, lined housing and pre-stretched, slick, stainless cables are great.

Campagnolo made a lot of different brake levers, but generally speaking, yes, Shimano SLR and Jagwire cables are perfectly compatible with old and new Campagnolo levers.

+1.They're cheap, I just replace them.

I never, ever re-use old cables or housings, it's just not worth the aggravation.

I avoid using used shifter wires because today's STI levers cause fatigue failure about a half-inch from the cable head, then a strand starts to unwind and shifting deteriorates.
Used shifter housing can be problematic in that it needs to be scrubbed out with a bent-up cable wire, solvent and compressed air, and then may also have an embrittled plastic cover, which serves a structural function.

With traditional brake levers, there's no sharp bends in the system. But the ends of used housings will need to be cut off if sharply bent.
The inner brake wire may break strands at the anchor bolt, especially with older brakes which crimp the cable severely.
Trimmimg the ends of housings fortunately makes the inner wire effectively longer, so the distressed part of the cable can be pulled past the anchor bolt allowing a new portion of the wire to be clamped.

I am less forgiving with cables which show heavy rust, I toss 'em.

Often a "sticky cable" turns out to be either a tight caliper pivot or a coil at the very end of the housing may have intruded into the bore of the housing, interfering with the cable's movement.

Certain lubes are incompatible with the plastic lining in housings, and can create a very creaky actuation. Metallic substances used as extreme-pressure lubricant additives can cause a lot of friction.

I have used current brake cable inner wires as shifting cables, inside of shift housings, for bikes or tandems with very long cable runs, and these worked well as long as I avoided any highly-viscous lube in the housings. The older Campagnolo and other brake wires were even thicker than current brake cable's 1.6mm however.

The OP's problem sounds interesting and I look foreward to hearing the diagnosis.

FWIW, I actually recycle a lot of cables/housings with seemingly excellent results. I prefer the older GripShift "Jonnisnot" lube which is plastic-friendly and effective with a minimal dose applied to the inner wire. I use a PTFE dry aerosol spray in the housings as a cleaner/prep, and as I said I run a bent cable through the housing to provide scrubbing action with this stuff:

thanks guys. so shimano brake cables or other aftermarket which are either wet or dry lubed and coated will fit my 80's campy athena brake levers? I haven't taken apart the levers but I wasn't sure if the cable stop was a different shape or not (the molded on metal piece that is held by the brake lever) between brands.

I figure 2m of outside housing and two inner brake cables should be enough for a front and back job on a 57cm bike?

Could be at the caliper too; front nuts on bolt too tight.

There are several different types of barrel stops all still easily brought just make sure you get the right one ounce you have the cable out it should be pretty clear which one you need.

Yes, there are different ferrules for different cable housings, but brake housings are all 5mm OD these days so doesn't matter one bit.

What matters is that newer Campag Ergo and aero brake levers require a 6mm OD ferrule, whereas Shimano aero and STI levers should never have a ferrule on the end of the brake housing, since the lever body is sized for the 5mm OD housing. I often have to extract ferrules from Shimano levers that were mistakenly fitted and prevent new housing from seating in the lever.

For shift housings, brand matters and Campag housings have used an odd 4.5mm housing that requires their own ferrules. The ferrule OD is the same for all shift housings tho, so a Campag or Shimano housing can be substituted if the corresponding ferrules are used, as per zukanh1.

Yes, 2m of housing will be more than enough for f&r brakes.

Thought it was the caliper at first prior to posting. I had it apart, cleaned it and reinstalled. While doing so I played with the brake lever and brake cable...there is much resistance/Stickiness in both directions (pulling or pushing the cable from either end).

I also think the routing of the cable is suspect as well as it doesn't seem to enter the caliper straight on rather as it enters it seems to rub slightly against the adjustment screw..

Some calipers tend to get tighter pivots upon installation, so always re-check the caliper movement before attaching the cable.

I sometimes see problems with older aero levers where the cable tries to saw through the ferrule in the lever. The housing must not make too much of an off-angle entry into the lever or massive friction can result.