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Making Your Mustang Hook, Part 1
Tires and Drag Racing
Now-a-days, it's not uncommon to see a street-driven 5.0 Mustang that has 400 and even 500 hp. With the wide availability of quality cylinder heads and 10 psi from an S-Trim Vortech, power is relatively easy to come by.
Once a person has spent the money to build an engine capable of these power numbers, one of the first things they do is take it to the drag strip for a quantifiable result, an ET slip. Unfortunately, many people are disappointed their first time out and come home with a 1/4 mile ET that is one full second slower than they thought it should be.
One of the most over-looked and taken for granted aspects of a good ET is traction. Consideration has to be given to tire choice, traction bars and other suspension tuning. This Water Box is part 1 in a 3 part series and will discuss tire choice. Traction Bars and Suspension mods will follow in the next few weeks.
Tires and Drag Racing
The most important modification you can make to give your Mustang optimum traction is investing in a pair of drag slicks. There is nothing like the feeling of letting out the clutch at 5000 rpm and feeling the car shudder and seeing the sky for a brief second. Too many people take tires for granted, or even worse, think they can get by with a street tire. For a person that will only visit the drag strip once a year, fine. But for someone who is looking for an optimized ET, slicks are a must.
Just about every brand of slick will work well. Plenty of serious racers all use a different brand of slick and do just as well as one another. We've tried all of the available slicks that fit the Mustang, Good Year, Firestone, Mickey Thompson, M & H and Hoosier. From our experience, no tire lasts as long, and hooks as consistently in different conditions as Mickey Thompson's ET Drag. But you can't go wrong with any of the other slicks we've listed.
Perhaps the most common MT size is a 26" x 10", which when mounted on a 15" x 8" wheel with a 5.5" backspace fits a GT or LX very well and requires only minor hammering of the inner wheel well. At 26" tall, the tire is nearly stock gatorback height. The 26" x 10" is a good tire and provides plenty of traction. But for optimum traction a better choice is the MT 28" x 10.5" slick. The tire is only slightly wider than the 10" version, but the additional 2" of height provide more leverage and a larger contact patch when the tire flattens during the initial launch. This alone provides more traction and better consistency. Unfortunately, this tire requires more hammering and minor trimming of the GT's ground effects for a proper fit. Don't be afraid of a little hammering, once the car has a tire on you'll never know.
Slick Preparation
It has been traditional practice when mounting a drag slick to use racing inner-tubes and wheel screws. Wheels screws are drilled through the outer lip of the wheel and extend only a fraction of an inch into the tire, the purpose is to keep the slick from spinning on the rim during a hard launch.
While this is widely accepted, it's not the best way to mount a slick on cars running slower than 8's. For years, we too had used inner-tubes and wheel screws until a famous Super Stock chassis builder told us not to. So we tried a pair of slicks that were mounted tubeless and screwless. Low and behold, the car's 60 ft times decreased and the car was more stable on the big end.
There are several reasons for the improvement. Inner-tubes actually prevent the tire from distributing air pressure evenly and properly. When using an inner-tube, the bulk of the air pressure is placed on the center of the tire instead of evenly across the tread. Many racers use as little air pressure as possible in an effort to make the slick hook harder. When in fact, the average slick will hook its best without an inner-tube when air pressure is around 11 - 14 psi hot.
Too little air places most of its pressure on the outside edges of the slick, not fully utilizing the center. And too much air does the reverse. It's much the same with radial tires, if they're under-inflated the edges wear prematurely and over-inflation wears out the center of the tread. So once you've gotten rid of your inner-tubes, start increasing air pressure a pound at a time until the car looses traction and then back up a pound. Another way to check for proper tire inflation is to drive through a small amount of water and then onto dry pavement. Look at the water marks the slicks left. You'll easily be able to see if the contact patch is even or if it is favoring the edges or center.
A slick with too little air pressure causes the car to sway and feel unstable at the end of the track. Running additional air pressure stabilizes the car on the big end of the drag strip and makes the ride feel much safer and stable.
And don't worry about the slick spinning on the rim. If they're properly mounted, it's not a problem. We've paid close attention to slick travel, and on a high 9 second, 3450 lb Mustang, they only move about one inch every 20 passes, hardly anything to be concerned about.
D.O.T. Slicks, Sticky Street Tires and Drag Radials
There are a significant number of occasional racers that can't bring themselves to buy a set of slicks but want something more than their Good Year radials provide. A number of companies have stepped up to the plate with offerings to meet this market. While a D.O.T. tire that works well at the drag strip sounds very appealing, they do not work as well as a true slick, regardless of what the advertising may claim. The only exception is Mickey Thompson's ET Street series, which are nothing more than an ET Drag with some very small and narrow tread lines which all but disappear after a burnout or two. It's amazing that they received D.O.T. approval, nevertheless, they work extremely well. M & H also offers a slick-like tire that has D.O.T. approval, they work fairly well but they're not as good as the Street ET.
There are also a number of soft compound street tire offerings from Hoosier, MT, McCreary and BFGoodrich. All of these tires will provide better traction than a highway radial, but they still can't match the performance of a good drag slick. There are some racers who have made impressive passes with these tires, but they're the exception, not the rule. We even have a customer who runs 12.20's on slicks and with exceptional driving, 12.60's on his Michelin radials. But it's important to remember that people with results like these are few and far between, so don't be disappointed if you can't duplicate them.
A common mistake we see at every drag strip we go to are racers doing burnouts in the water box with their treaded D.O.T. tires. Excessively heating a street radial can actual diminish its ability to provide traction. Many of the treaded "sticky" tires like the Hoosier Quick Time and MT Sportsman Pro will do a little better when hot. But the problem is that a treaded tire will carry water with it up to the starting line in between the treads no matter how furious the burnout. Even a small amount of water on the starting line will send the stickiest tires up in smoke. So if you're racing with a set of treaded tires, try and avoid the water box. You'll most likely hook better, and racers behind you will be much happier.
Slicks are a Wonderful Thing
Still, after knowing all the facts there are many people who are hesitant to buy a pair of slicks. The costs are relatively low, especially when compared to many of the other modifications people make. A used pair of 10-Hole LX wheels can be had for around $50, and 15x8 Weld Draglites are very affordable. A quality set of slicks will run you in the neighborhood of $300. So considering the cost, it's a relatively inexpensive way to pick up 4 tenths, or as much as a second.
Time and time again we've seen cars with 300 hp run quicker times than cars with 400 hp, all because of traction. So if you're planning to go drag racing, and want an optimum ET, be sure to go prepared and make sure you have a set of slicks. The bottom line is that you'll never realize the full potential of your car with a radial or street oriented tire at the drag strip. Slicks are not that expensive and can often make a more substantial difference in ET than additional power.
Tires and Drag Racing
Now-a-days, it's not uncommon to see a street-driven 5.0 Mustang that has 400 and even 500 hp. With the wide availability of quality cylinder heads and 10 psi from an S-Trim Vortech, power is relatively easy to come by.
Once a person has spent the money to build an engine capable of these power numbers, one of the first things they do is take it to the drag strip for a quantifiable result, an ET slip. Unfortunately, many people are disappointed their first time out and come home with a 1/4 mile ET that is one full second slower than they thought it should be.
One of the most over-looked and taken for granted aspects of a good ET is traction. Consideration has to be given to tire choice, traction bars and other suspension tuning. This Water Box is part 1 in a 3 part series and will discuss tire choice. Traction Bars and Suspension mods will follow in the next few weeks.
Tires and Drag Racing
The most important modification you can make to give your Mustang optimum traction is investing in a pair of drag slicks. There is nothing like the feeling of letting out the clutch at 5000 rpm and feeling the car shudder and seeing the sky for a brief second. Too many people take tires for granted, or even worse, think they can get by with a street tire. For a person that will only visit the drag strip once a year, fine. But for someone who is looking for an optimized ET, slicks are a must.
Just about every brand of slick will work well. Plenty of serious racers all use a different brand of slick and do just as well as one another. We've tried all of the available slicks that fit the Mustang, Good Year, Firestone, Mickey Thompson, M & H and Hoosier. From our experience, no tire lasts as long, and hooks as consistently in different conditions as Mickey Thompson's ET Drag. But you can't go wrong with any of the other slicks we've listed.
Perhaps the most common MT size is a 26" x 10", which when mounted on a 15" x 8" wheel with a 5.5" backspace fits a GT or LX very well and requires only minor hammering of the inner wheel well. At 26" tall, the tire is nearly stock gatorback height. The 26" x 10" is a good tire and provides plenty of traction. But for optimum traction a better choice is the MT 28" x 10.5" slick. The tire is only slightly wider than the 10" version, but the additional 2" of height provide more leverage and a larger contact patch when the tire flattens during the initial launch. This alone provides more traction and better consistency. Unfortunately, this tire requires more hammering and minor trimming of the GT's ground effects for a proper fit. Don't be afraid of a little hammering, once the car has a tire on you'll never know.
Slick Preparation
It has been traditional practice when mounting a drag slick to use racing inner-tubes and wheel screws. Wheels screws are drilled through the outer lip of the wheel and extend only a fraction of an inch into the tire, the purpose is to keep the slick from spinning on the rim during a hard launch.
While this is widely accepted, it's not the best way to mount a slick on cars running slower than 8's. For years, we too had used inner-tubes and wheel screws until a famous Super Stock chassis builder told us not to. So we tried a pair of slicks that were mounted tubeless and screwless. Low and behold, the car's 60 ft times decreased and the car was more stable on the big end.
There are several reasons for the improvement. Inner-tubes actually prevent the tire from distributing air pressure evenly and properly. When using an inner-tube, the bulk of the air pressure is placed on the center of the tire instead of evenly across the tread. Many racers use as little air pressure as possible in an effort to make the slick hook harder. When in fact, the average slick will hook its best without an inner-tube when air pressure is around 11 - 14 psi hot.
Too little air places most of its pressure on the outside edges of the slick, not fully utilizing the center. And too much air does the reverse. It's much the same with radial tires, if they're under-inflated the edges wear prematurely and over-inflation wears out the center of the tread. So once you've gotten rid of your inner-tubes, start increasing air pressure a pound at a time until the car looses traction and then back up a pound. Another way to check for proper tire inflation is to drive through a small amount of water and then onto dry pavement. Look at the water marks the slicks left. You'll easily be able to see if the contact patch is even or if it is favoring the edges or center.
A slick with too little air pressure causes the car to sway and feel unstable at the end of the track. Running additional air pressure stabilizes the car on the big end of the drag strip and makes the ride feel much safer and stable.
And don't worry about the slick spinning on the rim. If they're properly mounted, it's not a problem. We've paid close attention to slick travel, and on a high 9 second, 3450 lb Mustang, they only move about one inch every 20 passes, hardly anything to be concerned about.
D.O.T. Slicks, Sticky Street Tires and Drag Radials
There are a significant number of occasional racers that can't bring themselves to buy a set of slicks but want something more than their Good Year radials provide. A number of companies have stepped up to the plate with offerings to meet this market. While a D.O.T. tire that works well at the drag strip sounds very appealing, they do not work as well as a true slick, regardless of what the advertising may claim. The only exception is Mickey Thompson's ET Street series, which are nothing more than an ET Drag with some very small and narrow tread lines which all but disappear after a burnout or two. It's amazing that they received D.O.T. approval, nevertheless, they work extremely well. M & H also offers a slick-like tire that has D.O.T. approval, they work fairly well but they're not as good as the Street ET.
There are also a number of soft compound street tire offerings from Hoosier, MT, McCreary and BFGoodrich. All of these tires will provide better traction than a highway radial, but they still can't match the performance of a good drag slick. There are some racers who have made impressive passes with these tires, but they're the exception, not the rule. We even have a customer who runs 12.20's on slicks and with exceptional driving, 12.60's on his Michelin radials. But it's important to remember that people with results like these are few and far between, so don't be disappointed if you can't duplicate them.
A common mistake we see at every drag strip we go to are racers doing burnouts in the water box with their treaded D.O.T. tires. Excessively heating a street radial can actual diminish its ability to provide traction. Many of the treaded "sticky" tires like the Hoosier Quick Time and MT Sportsman Pro will do a little better when hot. But the problem is that a treaded tire will carry water with it up to the starting line in between the treads no matter how furious the burnout. Even a small amount of water on the starting line will send the stickiest tires up in smoke. So if you're racing with a set of treaded tires, try and avoid the water box. You'll most likely hook better, and racers behind you will be much happier.
Slicks are a Wonderful Thing
Still, after knowing all the facts there are many people who are hesitant to buy a pair of slicks. The costs are relatively low, especially when compared to many of the other modifications people make. A used pair of 10-Hole LX wheels can be had for around $50, and 15x8 Weld Draglites are very affordable. A quality set of slicks will run you in the neighborhood of $300. So considering the cost, it's a relatively inexpensive way to pick up 4 tenths, or as much as a second.
Time and time again we've seen cars with 300 hp run quicker times than cars with 400 hp, all because of traction. So if you're planning to go drag racing, and want an optimum ET, be sure to go prepared and make sure you have a set of slicks. The bottom line is that you'll never realize the full potential of your car with a radial or street oriented tire at the drag strip. Slicks are not that expensive and can often make a more substantial difference in ET than additional power.
