While a clutch is not necessarily a performance-enhancing item, an aluminum flywheel can be. The clutch just makes sure you can use everything you've got. Prior to the clutch installation, we had made runs with and without the Bassani exhaust system, and with the factory shorty headers and on street tires, the Mustang ran a best e.t. of 12.87 seconds at 112 mph. This was in 28 degree weather no less. We tried to test the car right after the Bassani installation, but that's when our clutch problems began. The temperature had risen to around 60 by then, and we managed a 12.98 seconds at 109 mph before the clutch started slipping in third and fourth gear.
With our new Clutch Master FX 300 and aluminum flywheel on board, we clicked off a 12.82 seconds at 110 mph in still warmer weather. This improvement was no doubt the result of a clutch that didn't slip, but also the performance of the Bassani exhaust and the aluminum flywheel.
Here you can see how our O2...
Here you can see how our O2 sensors have been rerouted to fit the long tube headers. You can also see how part of the bearing retainer from the transmission was lodged in the clutch assembly.
If we can say one thing about the flywheel, it's that drivability has increased quite a bit. The engine feels much more unrestrained, and the lugging and jerking that we experienced with the steel unit is gone-replaced with a smooth and eager engagement. At the track, the new clutch bit hard during every gear change, and the engagement allowed us to slip the clutch just enough to get the car out of the hole in a timely fashion-at least considering that we were dealing with a factory 2.73:1 ring-and-pinion ratio. Now that we had the holding power to harness the ProCharger's 389 lb-ft of torque, it was time to slash elapsed times with an improved ring-and-pinion ratio.
Pro 5.0, the name you know for its aftermarket shifters, also sells ring-and-pinion sets, so we called them up for a set of 3.55 gears ($199.00). We didn't want any problems with the law either, so we needed a speedometer correction gear for the speedometer cable. A simple call to Downs Ford in Toms River, New Jersey, was made and Joe Amato had the little white gear sitting on our desk in just a few days. Dan Garrity of Danny's Pro Performance handled the ring-and-pinion installation in about two hours. We filled the differential up with some Castrol 75W/90 synthetic gear oil, along with a tube of friction modifier for the Traction-Lok, and then it was time to hit the track once more.
We were able to put a few hundred miles on the gear set before we took to the track, and by the time we did, the spring rains that seemed to come every other day parted, to let the blazing sun cook us on the track. Since traction was an issue with the 2.73 gears, we knew we had to step it up if we wanted to see some low elapsed times as the new ratio would certainly cause more wheel spin. For this, we looked to BFGoodrich and its drag radial tires.
Our car was equipped with Ford Racing's Cobra four-wheel disk brake conversion, and the larger rotors require special offset rims if you want to use a 15-inch slick. While BFG offers drag radials in 15-inch sizes, they make them in 16- and 17-inch sizes as well. We had two '99-spec 17x8-inch Cobra rims taking up space in the office, so it seemed like a perfect match.
Fox-bodies are not known for their large fenderwell areas, and since we were dealing with an 8-inch-wide wheel, we could only go with the 275/40/17 drag radial. When Steeda gave us its Q400 to wring out, they happily included an identical set of these sticky tires. The BFG's handled 4,000-rpm launches like a charm, so we had to get a set for ourselves.
Something's amiss here. We...
Something's amiss here. We replaced the old bearing retainer with a new steel unit that Danny's Pro Performance had at the shop. If you are still running the original transmission, you may need to change this, as the stock aluminum ones become scored and often inhibit smooth bearing travel.
On the Cobra wheel, the 275s stick out but not obtrusively. Hitting potholes (a common occurrence in the Garden State) will certainly bring them in contact with the wheelwell lip, so if you want to leave them on, go with a 9-inch wheel with an extra inch of backspacing and you should be set. The drag radials, unlike street slicks, have an actual tread that works in inclement weather should you get stuck in the rain. They also have a very soft and sticky compound that gets the job done on the strip.
And speaking of the strip, with the drag radials heated, the 3.55 gears poised, and the Clutch Masters FX300 waiting, we made quite an impact on our elapsed times despite blistering 90-degree temperatures. The first run was a get-acquainted 12.73 seconds at 110 mph. Then, we slipped the clutch to a 1.90 short time and tripped the clocks in 12.58 seconds at 110. If it were not for the BFG's, we would not have been able to get down the track at all as the track surface went away as the day wore on. Two more runs, a 12.77 and a 12.68 were also logged, but by this time, we were fighting Mother Nature.
The Pro 5.0 gears made quite the impact on e.t., but it wouldn't have been possible without the grip of the Clutch Master's FX 300 system and the ability of the BFGoodrich drag radials to put it to the ground. Had we seen cooler ambient temperatures, there may have been an even greater improvement in elapsed time, but we'll take three-tenths, and the confidence that our clutch can handle whatever we throw at it.
When removing the pressure...
When removing the pressure plate, grab the clutch disk too as there is nothing supporting it other than the plate.
Our stock flywheel was in...
Our stock flywheel was in decent shape given the mileage, but we hope to add another 100 or so horsepower to the engine, so a high-performance piece like the one from Clutch Masters should be considered.
Another thing to do while...
Another thing to do while the clutch is out is to replace the rear main seal. As you can see, ours was leaking quite a bit (in addition to the rear intake gasket), but the flywheel, pressure plate, and clutch disk were rather clean. These leaks can cause clutch failure, but in our case, it's just too much horsepower.