Muscle Mustangs & Fast FordsHow To Chassis Suspension
Granatelli Tubular Front End Install - Dietary Supplement
Drop 67 Pounds Off The Front End Of Your Ford With A Granatelli Tubular Front End And A Set Of Skinnies.
The laws of physics cannot be broken or altered, and with that, we know a lighter car runs down the track quicker than a heavy one. That said, one of the easiest ways to get unwanted weight off your street/strip Mustang is to replace the heavy, stock K-member and A-arms with a tubular lightweight setup, like what is offered by Granatelli Motor Sports. The company offers front suspension components (amongst a selection of rear suspension parts) from '79 through '09. This article will focus on the installation of a kit for the '79-'93 variety. We shaved weight, improved handling, and thanks to the coilover springs, our front suspension is better suited for a fast-supercharged combination.
By now, most Fox-body Mustangs have had some hard mileage racked up, along with a need to update the underpinnings, as was the story with our featured vehicle. It was sitting on the side of the house nearly abandoned, but had some good parts and we wanted to bring it back to life. Despite its dormant status, the '89 LX coupe has a mere 64,000 miles on the odometer. The body is in excellent condition, save for a much-needed buff and wax job. The coupe belongs to my brother, Dominick, who unfortunately got too busy building a career to keep up with the car. So he parked it, but now it's time to shine up the hot rod and bring it back to its life as a fun street/strip Stang. The car is totally old school, but won't stay that way for long.
The front suspension was bone stock, save for four-cylinder springs and KYB struts. The short-block is original, but the upper half of the engine has been replaced. A set of TFS Street Heat heads, a Lunati cam, and a Ford Racing GT-40 intake help usher in the 15 psi of boost from a Vortech S-Trim blower. The car had run 10.93 once, in excellent air and was a consistent low 11-second player at the local tracks. We have some new plans for a powerplant that you will read about in a later issue, but for now we wanted to focus on getting weight off this 3,220-pound (without driver) notchback. Coupes are known for being lightweight, but this car still carries most of its street amenities-minus the air conditioning because it quit working.
Dom had removed the compressor, condenser, and hoses. A six-point rollbar adds weight to the total package, but helps for rigidity and safety. It killed us to make that modification, but the car was run at the track quite a bit and it is required by NHRA rules. Adding to the "heavy" parts list is a Dynamic Racing AOD transmission. The trans is far heavier than the paperweight T-5 transmission. The minimum weight is a shocker at first, but when you add in those bits of information, it's not a surprise the coupe was carrying that much mass down the 1,320. We remedied that situation in one day with a trip to DMC Racing in Halifax, Massachusetts.
Granatelli Motor Sports shipped us a tubular front end kit, which includes tubular K-member and A-arms, a coilover strut conversion, and caster/camber adjustment plates. The tubular products come powdercoated. We reused the stock spindles, but added five-lug brakes thanks to Late Model Restoration's complete five-lug conversion kit. The kit comes with front and rear brake conversions-this month we installed the front parts. Be sure to check the next tech installment to see how we installed the five-lug rear brakes.
Our final modification to the coupe was in the rolling stock department. Due to the five-lug brakes, we added a new pair of front wheels. One phone call to Summit Racing provided us with Weld Racing Drag-Lite rims (15x3.5) and Mickey Thompson Sportsman front-runners, which are D.O.T.-legal, too. There are dozens of styles of wheels for Mustangs, but we love the classic Drag-Lite look. After all, this car is old school and the traditional Fox-body Mustang look was fitting.
We arrived at DMC Racing bright and early, only to find the lift in the shop was being occupied by an extremely high-dollar musclecar. DMC is predominately a chassis shop, so it only has one lift. We said "forget it" and did the install on the ground, just like a typical enthusiast doing the job in his or her driveway. The car rested on a pair of jackstands, amidst all of the race cars sitting on build plates. The only special tool the DMC gang used was an engine hanger, used to secure the engine as the K-member was dropped out from underneath. Total installation time was around six hours, with taking time for photos and putting every part on the scales to record our weight savings.
The Granatelli tubular parts went on effortlessly, though perhaps the hardest part was getting the stock hardware off the factory A-arms. The Granatelli kit requires you to reuse your factory hardware, but considering the inactivity of our vehicle, it took some WD-40 and Justice Brothers rusty bolt spray to get things loosened up. Once off, the nuts and bolts cleaned up nicely and went right in. The Granatelli K-member also has a support bar that runs across the backside of the unit. It's there for extra support for the road-racing types. Unfortunately, it interfered with our long-tube headers. Those who have owned a Fox-body Stang with an AOD know what a complete hassle full-length headers can be. Luckily, the support is bolted on and easily removed. It also reduced weight by another two pounds. We feel confident in removing the crossbrace because the overall design and construction of the Granatelli K-member is great. The unit is boxed in several critical locations, and the tubing employed is heavy-duty.
Adding coilover struts to your Mustang has a variety of benefits. The first noticeable advantage was the ability to adjust ride height. The other is to get a better front spring to help transfer upon launch. Granatelli includes two spanner wrenches to crank the collar up and down. All too often, people want to crank the coilovers down so much that the front end is on the ground. Running it that low usually isn't the best method, as weight transfer suffers, as well as ride quality. We kept the ride height near stock for two reasons. One, was to let the springs settle for a day or two. The second was because we are going to be overhauling the backside and felt it would be better to adjust the front and rear ride height at the same time. Granatelli sent us 300-pound springs because of the car's status as a street machine. Spring rates are a touchy subject, depending on who you talk to. You don't want a spring that is too heavy, otherwise weight transfer suffers and ride quality will be harsh. However, a really light spring might not support the heavy front end of a street car. A light spring will also cause a rather soft ride that can result in too much oscillation on bumpy and curvy roads.
The trick in selecting springs is finding the proper balance; the 300 pound springs we employed should offer great ride quality, but definitely aren't for the hardcore drag racer. "The best method in determining the front spring rate would be to weigh the car on four-corner scales. But generally, in a Mustang with a supercharger (which is nose heavy) the 165-pound springs will work nicely for hardcore drag racing and limited street use. Naturally aspirated cars can run a 155- or 160-pound spring. If anything, this car will ride as nice as it did before with the four-cylinder springs," comments Dennis McPherson of DMC Racing. The springs are great for a daily driver; just don't expect a 300-pound spring to help a car like this leave the starting line like a NHRA Super Stocker. Granatelli offers a variety of spring rates, selecting what is best for your application is up to you.
We must also note, not every combination works well with coilover springs. Lower horsepower combinations, or ones with extremely heavy front ends, tend to work better with traditionally mounted springs. The reason is traditional springs are taller, and when compressed in the factory location offer more stored energy. This problem reared its ugly head with our Project Frightning, which had a Lightning supercharged engine in a lightweight coupe. The car was extremely nose heavy and we ran a set of heavy front coilover springs to keep the front from sagging. That, in turn, hurt its ability to get the front end hiked up when the car left the starting line. Another instance where coilover springs hurt is in a dedicated drag race vehicle that runs a street-legal drag racing class. If the Stang features a naturally aspirated, small cubic-inch engine, and the car must roll on tiny, drag radials, it's likely the front end will need to come up quickly in order to plant the drive tires. The ultimate deciding factor for converting to coilover struts is your combination. Given the popularity of superchargers and turbos, getting weight off the front end, and having the variety of spring rates available, means switching to coilovers can help your car hook when setup properly.
One nice addition to our vehicle was adjustable caster/camber plates-a must for any coilover conversion. We set our plates to Granatelli's recommendations. The trick to maximizing performance is to get a zero toe alignment with lots of positive caster. It reduces rolling resistance and helps stability at higher speeds. Also helping rolling resistance are the skinny Mickey Thompson Sportsman front-runners. The smaller wheel and tire package saved 26 pounds over the heavy billet Boyd Coddington wheels and Dunlop radial tires.
Overall, the Granatelli K-member, A-arms, coilover springs, Strange struts, and Latemodel Restoration five-lug front rotors saved 39 pounds on the front end. Then we removed the crossbrace on the K-member due to header clearance, and that brought our total savings to 41 pounds. The rotors were a little heavier than stock, so doing just the Granatelli K-member, A-arms, and coilover springs will drop your Stang down by about 43-45 pounds. The front skinnies offered us even more savings as we saw a total of 26 pounds (43 for big wheel/tire per side versus 30 for the Weld/Mickey Thompson combo per side), when compared to our regular rolling stock. That effectively brought our car's overall weight down to 3,153 pounds, without driver.