Technical information and some opinions for building an ice racer

In order to build a safe and competitive ice racer it is helpful to have some information based on experience and known facts. This page has some of both and is designed for the first time car builder. I don't expect the winning drivers to give away all their secrets but I will try to get some useful and helpful information here. Statements in blue are opinions. Differing opinions are invited and encouraged. If you have anything you would like to see added to this page, email to birchlakeiceracers@yahoo.com .

Transmission ratios for common automatic trannys

Tire Circumference Calculator

Use the TAB key to step from field to field through the calculators.

Typical top speeds in 2001 were about 65 MPH

Transmission and Engine

Opinions vary greatly in this department. Some racers put a lot of money and effort into high horsepower engines, manual valve bodies, torque converters, and other performance mods. Others run what came in the car from the factory. Driveline modifications can get expensive quickly so it is my opinion that factory combinations can be competitive if effort and money is put into tires and handling first, then work on the engine. All the horsepower in the world won't help if you can't stick it to the ice or go around the corners. The rules don't have any restrictions on engines or transmissions so do whatever you want.

The rear end

The best way to determine the rear end ratio is to count the number of teeth on the ring gear then divide that number by the number of teeth on the pinion gear. Example: 40 divided by 13 = 3.0769 (3.08)
To find out the rear end ratio without opening the differential you can count the number of turns of the driveshaft yoke occur when you turn the axles exactly 10 turns, then divide by ten. It is not as accurate but it works. This requires either a "Posi" rear end or one that has been welded so that both axles spin together. If the differential is still "free" block one wheel, spin the other wheel exactly 20 turns, count the turns on the yoke and divide by 10. Most cars that get turned into ice racers start with "free" differentials and will need to be welded before racing so you might as well wait and count the teeth when it is opened.

Welding to render the differential inoperative is the cheapest way to lock the axles together. Lockers, spools, or posi carriers are also an option but it is generally agreed that a "one wheel wonder" will not create enough traction on ice to race competitively. There are various ways to weld the differential, I prefer to disassemble the spider gears and fill in three spaces between teeth on each side of the two differential gears then reassemble them into the carrier. The carrier doesn't need to be removed, and all welding slag can be cleaned from the welds without contaminating the rear end housing. It is important that the parts be allowed to air cool slowly during the welding process, if water is used to cool the parts they will become brittle.

Tires

Rear Tires
Opinions vary greatly on what the best tires are. The most common tires seen on race day are Blizzaks. Some racers have a selection of tires they use for different conditions, others stick with one type. This will depend mostly on your budget. Tire sizes can be used to fine tune the gearing of your car. Rear tire stagger is generally not used because more traction in the straights is lost than is gained in the corners

Front Tires
There are 3 basic setups for front tires:

• Factory studded ice racing tires, high reliability, light to moderate front bite, expensive.
• Snowmobile studded tires, moderate reliability, strong front bite, moderate expense.
• Bolted tires, low to moderate reliability, variable front bite, cheapest way to go.

Front Suspension

A variety of front suspension setups are in use, most people don't change much. Sway bars, spring rates, shocks, and wheel alignment is about all anyone changes in the front end. Here is a quick summary of what happens with some of these changes:

• The front sway bar reduces body roll by unloading the inside tire during cornering, almost always disconnected or removed in dirt cars to prevent pushing. Most ice racers leave it connected sometimes with unequal spacers on the left and right side.
• A stiffer right front spring resists body roll without unloading the left side tire. It also increases cross weight on the left rear.
• New shocks are usually a good idea since most ice racers start out as high mileage junkers. Racing shocks are expensive but offer a variety of compression and rebound rates.
• If you leave everything else alone in the alignment department, measure and record toe in(out). After even a minor collision the toe setting will change and alter the handling of the car. If the toe setting is known it can be reset between races and make the car more predictable next time on the track.
• Power steering is a must, ice racing requires a lot of counter steering in corners and you must be able to steer quickly to avoid obstacles and catch the car when it starts to spin. Manual gearboxes require more turns of the wheel (in most cases) for the same change in steering angle as power gearboxes, not to mention the effort required.

Rear Suspension

Adding a lot of weight to the car to increase traction (and rear percentage) makes the rear suspension an important part of setting up an ice racer. A variety of rear suspension setups can be found on race day.

• Air shocks increase load capacity and can be plumbed individually to make roll center adjustments. Increasing air pressure in one side has a similar effect to putting in a stiffer spring on that side which moves the roll center towards the stiffer spring. Air shocks are a good way to experiment with spring rates and roll center adjustments but they have reliability problems and are inferior as shock absorbers.
• Leaf spring suspensions are less adjustable but offer some advantages. Leaf spring rates are progressive, they get stiffer as they are compressed so it is easier to maintain ride height with heavier loads. Leaf springs also have built in anti-squat, axle housing rotation due to engine torque tries to lift the front of the spring which tries to lift the body of the car. This creates additional downforce on the rear tires without added weight. Roll center adjustments can be made with axle to spring spacers or shackles.
• Coil spring suspensions can be adjusted with spacers, unequal rate springs, or weight jackers. It is easier, and cheaper, to make spring changes with coil springs than leaf springs. The factory springs often need to be changed to higher rate springs due to the amount of weight added for traction on the ice. Station wagon or truck springs are readily available at a reasonable price. Anti squat is difficult to achieve with coil springs because of the mechanical linkage arrangement supporting the rear end so it is necessary to run more ballast weight. Maintain enough ride height to prevent the rear bumper from hitting the ice and unloading the rear tires.
• Good shocks are important on the rear end to avoid unloading the rear wheels due to ruts and heaves in the ice. They also help absorb vibrations in the rear axle from out of balance tires and surface roughness of the ice.

Body, Pipes and Armor

It is helpful to start out with a car that has a fairly solid body without too much rust. The trunk floor and rear fenders should be strong to hold the ballast weight. All plastic body trim, lights and parts which can be broken off must be removed before racing. This helps prevent debris on the track which is a hazard to tires and requires cleanup during and after the season (this is a lake, remember?) Check the gas tank straps and battery mount carefully. If the battery is mounted to a plastic inner fender well either move it or build a metal mount for the battery. Cut the outside sheet metal where it extends into the fender well to prevent cutting of tires after a collision. Use hood pins and trunk lid pins. It is not necessary to put on an expensive paint job, a car can look good for about $25 in materials and some effort, your sponsors will appreciate it. Make sure the car numbers are easily seen in contrasting colors, scoring the races can be difficult so make sure that your car gets scored every time around by making it easy to see your numbers.

Pipes and armor have been a topic of debate for years. This year it is still allowed but that can change at any time. Here are some things to consider when deciding about armor:

• Pipes and armor add weight, not necessarily in places where weight is needed. This weight must be accelerated and decelerated twice per lap.
• Pipes and armor, when attatched to the frame of the car stiffen the chassis. This stiffening has a loosening effect on handling and defeats the "crush zones" designed into the car to protect occupants in a crash.
• When not attatched to the frame the pipes protect sheet metal and help save tires but make repairs after a collision more dificult.
• Pipes attatched to the bumpers to increase height help prevent damgage. Especially in the rear where the stock bumber is usually sitting low because of ballast weight.
• If your car looks like a "battle tank" you are more likely to draw a black flag for rough driving

Miscellaneous Hints

• Move the wiper and defrost controls to the middle of the dash where the co pilot can reach them.
• On column shift cars heat the shifter and bend it away from the steering wheel to prevent accidental shifting.
• Secure weight in the trunk so it stays where you put it.
• Fix the exhaust system before the season starts.
• Remove the fuse for dome lights, eventually you will have a door that doesn't close properly.
• Dig the seat belts out of the back seat so passengers can use them.
• Clean the windows and put on good wiper blades.
• Get drunk after the races.

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