Let me start getting the tech out of the way. 1988 Turbo Coupe 351W carb with T5. Ride has been together and driving for quite some time. It loves clutch cables, broke plastic OE quadrant installed after market FMS I think. Broke that cable, next cable insanely hard to push after a week, a month I don't remember. Changed it, now new one hard to push. I have long tubes, I have wrapped the entire length of the under hood clutch cable with header wrap insulation on one of these installs no help. Put a small heat sheild at closest point from cable to headers, no help. Flywheel is from a 66-67 Mustang 289, with the clutch/pressure plate kit being a diaphragm replacement set for that application. Bellhousing and clutch fork were used items. I apologize because I know this is long and I have left something out but anyone have a suggestion?
Make sure your throw out bearing isn't binding on the input bearing retainer at all. I had a similar problem on my T-bird...went for a year after the 351w swap with a used adjustable clutch cable of unknown origin, once it snapped, I couldn't keep a cable in it. My replacement cables were BBK's...they've gone to an extremely cheap rubber bushing on the plastic part in the firewall...once it starts deteriorating, you get really weird clutch action and it'll get an intermittent hard pedal. I went through 2 or 3 before I dug up what was left of my old one and re-used the rubber off of it....problem solved. Any clutch more aggressive than a stocker will wear down clutch cables quick, I've heard of guys in the mustang world going though 3 or 4 a year.
Good luck,
Don
I like your setup. I use to have 351 with a T5 setup for a few years.
As for clutch cable i found that it would get a bit of a kink at the bell housing and that would also kill a cable in a few months.
But number one thing i found that saved a clutch cable is a adjustable clutch pedal stop.
Using the firewall as a stop is bad.