The 5.0 Mustang is one of the most popular cars found at the track today. There’s a good reason for that too. The Mustangs excellent power to weight ratio in stock form. Along with the very large availability of parts from both the factory and the aftermarket. Make it a great starting point from which to build a competitive race car.
Still the Fox-body Mustang is not without its shortcomings. The nose heavy weight bias, non parallel four link rear suspension, and other items need attention. Luckily most of them are easily remedied.
The first thing that needs addressed is the tires, on the 5.0 Mustang tires are a vital link between the car and the racing surface. Making them the single most important part for making your Mustang launch correctly. The factory supplied rubber, Goodyear Eagles for most years models. Are a great tire for a road going machine, but not exactly what you want for drag racing. The tires short sidewall height, combined with the hard rubber street tire compound. Mean lots and lots of wheelspin and long black skid marks everywhere.
So changing to a true drag racing tire is in order. For street/strip driven cars drag radials are a hard tire to beat, for a track only ride racing slicks or cheater slicks (AKA M/T ET Streets) are what you want. Mustangs can run with either a 26″ or 28″ tall tire (factory rubber generally runs about 25.5″ tall) with only slight massaging of the inner fenderwells. Using a 15×8″ wheel with a 5.5″ backspacing and you should be able to fit a 275/60×15 drag radial or a 28×12.5-15LT ET Street or a 28×10.5-15 slick. The difference in numbering is in the way the tires are measured, slicks are listed by tread width, the others are given by section width (overall sidewall to sidewall width).
A 28″ tall tire, like the above sizes works best for a high horsepower,stroker motor, supercharged,turbocharged and/or nitrous car. If your ride is more conservative in the horsepower department, a 28″ tire would definitely be overkill. One thing to consider is the weight of your tire, taller tires = heavier tires. After your car launches that same tire now becomes a liability, because of rotational inertia (takes more power to turn em).
In other words if your car hooks just fine with a 26″ tire without excessive spin . It will actually be quicker and faster with the smaller and lighter tire. If your budget limits you to only one set of tires the shorter tires are definitely the way you want to go. A 28″ tire will also require a rearend gear change (to keep your engine in its powerband) as well. Which is an extra expense that I’ll discuss in a later post.
While I’m on the lighter is better topic, most factory wheels are extremely heavy. Changing your rims to a lightweight aluminum rim like a Centerline or Weld Draglights, or if you’re really in the money a set of Bogart Dragonflys. Will definitely shave some precious time off your 60′ ET , as much as .10 second or more on most cars.
Aluminum wheels will require longer wheel studs to properly fasten them to your Mustang.Factory studs are just not long enough to do the job.You can use a long shank lug nut that fits inside the wheel to secure them. Or better yet, use the 11/16″ drive studs with a flat spacer and lug nut (much, much stronger).They also can be torqued to 100 ft. lbs. instead of 80 ft. lbs. like with the stock 1/2″ studs. Safety rules require the stud to extend at least the diameter of the stud (1/2″) into the hex portion of the lugnut (3″ studs will do the job).
Radials are generally run tubeless, slicks and ET street type tires can be run tubeless, but are generally run with tubes inside. Running tubes in your tires requires you to run screws through the bead. To prevent tire from creeping on the wheel and ripping out your valvestems. 10-12 self tapping S.S. screws equally spaced around the bead on BOTH sides of the wheel should do the trick. Every other screw goes through the rim at a 90 deg. angle (straight in), the alternate screws should penetrate the bead at a 45 deg. angle. Make sure the screws you use are long enough to go through the wheel flange but not so long as to puncture the tube/tire. Something like a #12 hex head x 1/2″-3/4″ length should do the trick, (make sure you check though).
Screws are not recommended on drag radials, so use a bead-lock type wheel with these tires. Make sure you have your new wheels and tires professionally balanced before hitting the race track. Peel and stick wheel weights work better than the hammer on kind that most tire stores use. Do yourself a favor and pick some up and bring them along with you when you go to have them mounted.
Now that your Mustang has some new rubber, its time to air them up. Buy a high quality tire pressure gauge (liquid filled is best), made specifically for low pressure. The old pencil/stick type gauge your grand dad used, is just not going to cut it anymore! My recommendation is to start out on the high side of the pressure range, (DO NOT EVER exceed maximum pressure rating on sidewall) and gradually lower the pressure 1-2 psi at a time. Keep checking your 60′ times, look for the pressure that gives you the quickest 60′ time. After that you can fine tune pressures by 1/2 pound at a time, to find the perfect number. Be aware of the fact that a drag slick with low air pressure is a bit of a hairy ride (Bias Ply Squirm) that takes a little getting used to, be careful! By now you should have lowered your ET by several tenth’s of a second (at least). Keep reading along with me and soon I’ll bring you more racing tips and techniques to make you quicker and faster.