I just completed upgrading my '79 4 cyl turbo front brakes. I switched from the tiny 9" Pinto carryover setup to the modestly upsized 10.2" disks found on most early V8 Fox cars and all '87-'93 Fox 4 cyl only. Clearly Ford engineers realized that the marginal 10" brakes were needed on a 4 cyl car.
This conversion from 9" to 10" required new bearings, new spindles, new calipers, new hoses, new brake pads & revisions to the steel formed lines on the chassis. Basically this is a
BBK upgrade...and not much simpler. This upgrade would be quite cost prohibitive, unless you have used parts laying around like I do. I still think I blew $300 on this mod, including fresh
Brembo rotors.
An unexpected complication involved retrofitting
brake hoses. The hoses for the larger brakes have a different size fitting thread on the end that goes to the steel formed lines in the engine compartment. I think the original lines for 9" brakes had 3/8" thread and the lines for 10" brakes need to be 7/16" thread. Anyway, I had to fabricate a new steel line for the driver's side to the proportioning valve and form a short piece of line with copler and double flare for the passenger side. That set me back $75 for tubing benders and double flare tool. What a friggin' hassle to gain 1" of rotor size...Ford's brilliant idea to bastardize every setup & thwart mechanics.
The improvement in braking is significant. The 10" setup provides more torque bias to the front & that was welcome. They don't overheat as quickly either.
I decided against installing the larger '87-'93 10.9" V8 setup because they do not allow the use of 14" rims. I have fresh 14" tires mounted on nice T-Bird wheels for winter snow season and my car is driven all year....so not throwing those away to gain 0.7" more rotor diameter.
I might win the record for installing the smallest BBK ever (lol). They still look tiny through my SN-95 Cobra R repro wheels, but the rear drums look even stupider.