Project 1993 Ford Mustang Cobra Gearset Install - Part 2 Increasing Toxicity

The 4.30 gear and differential swap were pretty straightforward, and he knocked it out in a few hours. We had also noticed that Stolen Goods' clutch pedal had tightened up recently and asked Stolzenburg to check its adjustment while the car was up in the air. We were using FRPP's adjustable cable, aluminum quadrant, and firewall adjuster at the time.

When the car was returned to us, we took it for a drive and were surprised to see that the 4.30s were remarkably easygoing on the street. With the Astro Performance 0.62 overdrive ratio in the transmission, that steep of a gear is completely livable on a daily basis, cruising at about 2,200 rpm at 55 mph. Once you begin to go faster than that, you'll see how fast the 4.30s accelerate the tach needle. If you live in a state where the normal highway speed limit is 55-60 mph, you should have no problem with the 4.30s. Here in Florida, we're used to 70-mph interstates and toll roads, so you may want to consider something a bit tamer if you plan on hitting the long drive.

We opted to trailer Stolen Goods to the track this time for the aforementioned cruise-rpm issue, and the fact that we were fully prepared to hammer it at the track. Since we didn't have to drive it, it was much easier to keep the car cool, and we iced down the intake and power pipe before each run.

Launching at 4,000 rpm and shifting at 6,400, we experienced wheelspin at the top of First gear, and our 60-foot time was a dismal 2.05 seconds. We crossed the finish line in 12.50 seconds at 114.03 mph. On our next hit, Stolen Goods hooked a bit better, knocking down the short time to a best-ever 1.74 seconds. We did tickle the rev limiter at the top of Third, but e.t. improved to a 12.17 at 113.23 mph.

Pass number three began with wheelspin at the top of First again, and a 1.78-second 60-foot time. This was followed by a 12.23 elapsed time at 113.76 mph. We also detected what we thought might be a bit of clutch slip during the 2-3 gear change. This was later confirmed on the return road when we rolled down the window and the smell of toasted clutch waffed in.

Attempt number four produced our best short time of the day at 1.70 seconds. The quarter-mile elapsed time checked in at 12.28 seconds at 112.65 mph. The lower speed was no doubt the result of us going through the traps on the rev limiter in Fourth gear. It seemed the 4.30s were a bit steep for the 26-inch tall Mickey Thompson tires we were using. To combat this on the next attempt, we opted to short-shift First at 5,800 rpm and shift each subsequent gear at 6,000 rpm.

Wheelspin at the top of First gear during attempt number five slowed the 60-foot time to 1.88 seconds, but the short-shifting worked down track as we improved slightly to a 12.26 at 114.86 mph. The mph was our fastest ever, so we knew things were headed in the right direction.

Until now, we hadn't been powershiting Stolen Goods, but we had to do something to get this Pony where it needed to be. For run number six, we launched the car at 4,000 rpm, and experienced wheelspin at the top of First once more, netting a 1.84 60-foot time. It seemed that as the car's weight transferred back forward after launch, it unloaded the tires too much, causing the wheelspin. Powershifting the Pony did help, though, as we clocked a 12.19 at 114.64 mph. Our last run of the day started with a 1.89 short time. This time, however, it wasn't wheelspin but clutch slip that we experienced at the top of First gear. The clutch did hold on each shift, but we could smell the dreaded brown dust after the run, and the engine compartment wreaked of it as well once we got back to the pits. Stolen Goods clocked a 12.36 at 114.14 mph.