I own a 99 F150 SC 2WD 4wdisc 4wABS and I too am confounded by this front disc issue. It started with the front passenger side caliper problem at arround 110K. I wasn't really that concerned with investigating the root cause. I just felt it was time for servicing. New rotors (drilled and slotted), bearings, seals, and pads. Three weeks later, the driver side caliper started to fail. Again since they weren't changed out, I didn't investigate. I changed the calipers out along with the lower ball joints at the dealer's reccommendation (the ball joints changeout were found to be unnessessary). I'm now spun off into a level of pissed I've not seen in a long time. Dealer provided calipers (rebuilt only not OEM), replacement ball joints (without any means of relubricating).and three weeks later the driver side caliper locks up and destroys the rotor. Again new rotors, rebuilt calipers, pads, bearings, seals. This time during the bleeding process, the passenger side vents like a race horse, the driver side seems to have a prostate problem. When all parts are new and flow appears impaired, root cause analysis is a must(should have done it first)! Bleed all lines starting with the furthest first taking note of velocity and volume. If all bleed the same with good flow look at component level failures. If all are of poor flow look at the master cylinder or the ABS(good luck trying to find the lines for the MC to the ABS). Line condition (rusted) may force a complete line set change even if they are not the source of a restriction(turn one line nut and roll the tube). If only one caliper seems to be affected, the master cylinder is OK but the ABS or the associated line is suspect, as could be the caliper. Please note that if this is a intermittent problem it is not a line restriction or MC failure but a component problem(caliper or ABS). Good luck troubleshooting. Have lots of DOT4. Try speed bleeders. Invest in stainless steel lines. Look for the best, not the most expensive. The F150 rates the best.
Last edited by tomkane; 10-27-2007 at 12:06 PM.