Muscle Mustangs & Fast Fords
Ford Mustang Fidanza's Twin Disc Clutch Set
MM&FF Explores The Latest In High-Performance Clutch Technology With Fidanza's Twin-Disc Clutch Kit.
The clutch assembly that converts engine power to a useful source of propulsion has been around about as long as the internal combustion engine itself. Over the years we have seen technological developments both in the design and the materials used that have made the clutch assembly better in every way.
In addition to advancements in clutch technology, great strides in engine performance have been made as well, but all too often harnessing great amounts of horsepower and torque have come at the cost of driveability in a number of areas, including the clutch and transmission. These days performance enthusiasts demand more and expect their dreams and visions to become reality. Thankfully when it comes to harnessing massive amounts of street power with the lightest touch, Fidanza has the solution.
Fidanza got its start when owner Lou Fidanza built and raced a Jaguar during the '79-'80 SCCA C-Production race seasons. The racing program proved to be a successful venture, and Team Fidanza used technical knowledge gathered from many winning race seasons to answer an increasing demand from other racers for access to Fidanza-like parts, and thus Fidanza was born. These lessons learned on track have become the basis for the design and creation of his company's high-quality parts and accessories. Fidanza now supplies the aftermarket with a wide selection of flywheels, clutches, cam gears, flexplates, short-throw shifters, and CV shafts. It also now produces a twin-disc clutch system for a variety of Mustangs.
Derived from racing applications where more clamping power was needed in a confined space, the multi-plate clutch system was born, and most systems have the added benefit of reduced rotating mass due to their somewhat smaller size, at least when compared to your typical single-plate clutch system.
"Older 7.25- and 5.5-inch twins that we used in our Jaguar racing program were like on/off switches, but you had to use them if you were making a lot of horsepower," says Fidanza Vice President Bob Scheid. "Either that or you had to use a monstrous pressure plate and single disc for clamping force." Obviously these characteristics don't lend themselves well to street-based applications, so the Fidanza crew went to work to produce a streetable twin-disc system that is easy to install, affordable, and has great driveability.
"Our twin-disc for the Mustang features an 8.75-inch pressure plate," notes Scheid. "We wanted to keep a stock-like pedal pressure, and actually ended up with less pressure than stock when compared with the '05-up GT pressure plate. We also strap the center floater plate (between the two discs), which causes the discs to engage incrementally. The pressure plate engages a split second before the disc on the flywheel side. It's really like driving a stock car, yet its designed to hold up to 625 lb-ft of torque at the wheels. The strapping on the floater plate also eliminates the annoying rattling that older twin-disc setups are known for. All this holding power does not mean that driveability is lost though. Pedal feel is virtually unchanged and engagement is as smooth as our 3.2 Kevlar single-disc unit."
Fidanza purposely engineered its twin-disc setup to be easy to install. "We made the stack height from the back of crank to the fingers of the pressure plate exactly the same as stock," says Scheid. "The only difference is an extra disc. This design also allows the use of the stock slave cylinder and/or clutch cable. We needed to offer a complete package as well, so customers get a pressure plate, flywheel, floater cage and discs, and everything is balanced, index marked, and ready to install."
Fidanza's twin-disc system starts with a 1045 high-carbon-steel friction surface mounted to an aluminum flywheel, and it's attached with nuts and bolts so the friction surface can be easily replaced. The pressure plate features a diaphragm design, and Fidanza offers the twin-disc system with several different types of discs to suit your vehicle's needs.
We recently installed Fidanza's twin-disc in a suitably high-horsepower Mustang that was in need of both a strong clutch to handle its 600-plus rwhp, as well as a more driveable clutch that would make the Mustang, once again, fun to drive. Said vehicle, belonging to Matt Guida of Land O' Lakes, Florida, is a '92 model that sports a healthy 383ci Windsor engine boosted by a Vortech T-trim supercharger. Guida recently picked up a T-56 six-speed transmission to replace a notchy five-speed box, and all that was required to fit the clutch to the transmission was a change in the spline count of the clutch discs.
For the installation, we turned to Hurricane Performance In Orange Park, Florida, which has a ton of experience with Mustangs of all generations. We also took advantage of the dyno tuning services of TunersInc, which resides in the same complex.
In addition to poor shifting and clutch engagement, Guida's car suffered from poor tuning, especially on cold starts. TunersInc's Tony Gonyon made quick work of the ECM calibration changes that were needed to improve the driveability and idle characteristics of the Mustang.
The T-56 swap added a level of difficulty to the overall installation, as it requires a longer speedometer cable and a different crossmember, but the twin-disc setup is barely different from installing a single-disc unit. It's just one more disc and a floater plate. Once the clutch was installed, we also opted to upgrade some associated components with parts from Maximum Motorsports.
Maximum provided us with its aluminum firewall adjuster, clutch quadrant, and a slick new clutch cable. All three pieces have been engineered to provide the best performing clutch-engagement mechanism on the market, and the setup did not disappoint. In fact, we credit these components with making the clutch engagement even smoother than the Fidanza 2.1 single-disc clutch that we have in project Recession Special.
Fidanza has done a great job with its pressure-plate selection and clutch-disc material, and the Maximum Motorsport pieces allow their potential to shine through. All too often we've installed aftermarket quadrants, adjusters, and especially aftermarket clutch cables, only to have the pedal pressure increase when it really shouldn't.
We also took the opportunity to put the Mustang on the dyno, base lining it with the five-speed transmission, and then returning with the six-speed and twin-disc installed. We would expect the five-speed to be fairly efficient, and the car produced 605 rwhp and 522 lb-ft of torque. With the twin's smaller profile, we wondered if the reduction in rotating mass would improve power.
A perfect A-B clutch test would have been ideal, but we ran the car with the T-56 and the twin-disc clutch due to time constraints just to see what would happen. With the new setup, the Mustang knocked down 634 rwhp and 581 lb-ft torque. We attribute the increase in peak power to the fact that the supercharger belt did not slip as it did on the baseline. Our baseline offered 15.2 psi of boost, while during our follow up, the Vortech was huffing some 17.8 psi. There was also a huge increase in horsepower and torque under the curve, and we believe much of this came from the better ECM tuning that Tony Gonyon at TunersInc supplied, along with the decrease in rotational mass that the smaller 8.75-inch Fidanza clutch system offers.
The results of the dyno test were certainly skewed, however the change in driveability was as accurate and apparent as can be. Our subject vehicle's owner, Matt Guida, hadn't been happy with the way his Mustang was running and driving, but after the numerous mods we made within this story, we were able to turn his Mustang into something that was once again a pleasure to drive and enjoy.
"With the old clutch, the pedal feel was dead on the top of the travel with a stiff pedal travel on the bottom half," noted Guida. "Engaging the clutch required a lot of revs before letting out the clutch, at which time it would instantly engage and you would either have to accelerate and drive away, most likely with some tire spin, or immediately depress the clutch and roll forward, at which point you would have to start the process all over again. This made parking-lot driving unbearable, and loading the car on a trailer was a very difficult task.
"The Fidanza twin-disc clutch is a completely different experience. The clutch pedal feel is linear with engagement taking up about a quarter of the way off the floor. Engagement is smooth, and you can slip the clutch if need be without it biting excessively. Parking-lot maneuvering, as well as leaving a traffic light, is the same as when the car was stock. There is no longer any bucking or on/off type of engagement. The clutch's grip is apparently very good as spinning the 285-series drag radials in Third gear is easily done by rolling into the throttle.
"The new MGW shifter has a very accurate, tight feel without being too notchy. One more inch of reach on the handle would be welcomed, but it's better than the unit I had prior, which had a lot of slop, even when in gear."
Dual-disc clutch systems are not inexpensive, though the Fidanza piece is competitively priced in the market at about $1,300. That said, if you're making enough horsepower to warrant the use of one, then you're no stranger to opening your wallet in the name of speed. There's no point in making a ton of horsepower if you just won't drive it as much as you could, just because it's a pain. Fidanza's twin-disc clutch will let you do that and bring back the pleasure of driving.