Rally Odometer/Clock



The installation and operation of your 800 will be explained in the following paragraphs. When the 800 is set up to run in seconds, those parts of the manual referring to hundredths of a minute also apply to seconds. Both the 800TSD and 800PRO share all but a few of the same features. The TSD model has a mileage alarm system which will sound a buzzer when the Odometer reaches a selected mileage. The PRO model can run an average speed for use in transit zones between stages. Although the speed function of the 800PRO will make these transit zones very easy, it is totally inadequate for normal time, speed, distance events. Even so, an 800PRO would put a tsd'er into an "equipped" class in almost every event.

Be especially sure to read all of the sections concerning sending unit installation and power connecting. Not following the relatively simple directions may result in needless problems during an event. Once you have the 800 in your car, practice before your first competition. An old rally, rerun without the pressure of staying on time, can check your mastery of the instrument. By thoroughly understanding how your 800 operates, you can adapt these instructions to fit any local rally practice.


The 800 utilizes an integrated circuit technology that is susceptible to damage from static electricity, the kind that shocks you after walking across a rug on a dry day. Therefore, several precautionary measures should be taken when you handle the unit. There is no danger of harming the 800 when the unit is in its case. If you must remove it, hold it by the front panel and avoid touching the printed circuit boards and their components. Even if you do accidentally contact a part, don't worry. It's very unlikely that any harm was done.

Mounting studs are located on the top and back of the case. If you intend to use the 800 on performance rallies, the case must be supported along the bottom so that the mounting screws do not take all of the shocks and jolts (the case may crack). The 800 will slide out of its case after the screws in corners of the front panel are removed.

The heatsink protruding from the back of the case is connected to the +12 volts side of the car's electrical system at all times. Be positive that it cannot touch the car's chassis or other metal parts connected to the chassis. This won't hurt the 800, but it will blow the fuse and shut you down! The heatsink as you might imagine, gets hot. Not hot enough to harm your car, but it will surprise you if you reach behind the unit and touch it.

The 800 is built with components which operate at temperatures between 0 and 70 degrees Celsius. Operation outside this range may cause incorrect calculations. Always allow for adequate airflow around the heatsink and case ventilation holes. On hot days when the car is closed and in direct sunlight, temperatures on the dash may exceed the upper limit. Watch out for this at breaks and rest stops. Turning off the displays will help keep the unit from overheating if you must leave the car in a poor location. If you run winter rallies and might leave the 800 unattended during an evening break, leave the displays on. They'll keep the circuits warm even the temperature is below freezing.

Sending Units

The 800 will operate from either of two sender types. The cable driven unit is designed for permanent mounting between the speedometer and the drive cable. The magnetic unit uses magnets which pass by the sender as the car's wheel rotates. Unless you run performance rallies or TSD rallies with a large percentage of unpaved roads, there is no real advantage to using the magnetic unit. Since the magnetic sender requires a certain amount of mounting time and mechanical ability, the cable type would be preferred. When wheel slippage is significant, the magnetic type will allow you to overcome this without using vulnerable outside cables and wheel gears.

Cable Sending Unit

Disconnect the cable from behind the speedometer, mount the sending unit to the back of the speedometer, the reconnect the cable. The short square pin included with the unit goes between the speedometer and the sending unit. When the car is moving, the cable should turn evenly without binding or making strange noises. A small amount of speedometer needle bounce at low speeds is normal; large fluctuations indicate a binding cable. Check for any sharp bends you may have caused in the cable. It might also be helpful to change the position of the cable or to rotate the sending unit on the back of the speedometer.

On a small number of cars it is difficult, if not impossible, to mount the sending unit directly behind the speedometer. In some cases, a short extension cable can be placed between the speedometer and the sending unit to allow easy access for making the connection. If your car is one of these, we'll let you know when shipping your 800. We can supply the cable at a small additional cost.

The sending unit can also be run from an un-driven wheel cable or from an auxiliary cable connected thru a 1:1 tee gear to the odometer cable. In either of these two cases, static electricity may develop in the cable and cause false inputs to the 800. GROUND THE SENDING UNIT BY RUNNING A WIRE BETWEEN THE CAR'S CHASSIS AND THE UNIT. Doing this is very important! Nearly every report of trouble made to Zeronics has been caused by failing to perform this one simple step.

When driving the sending unit from a separate cable, do not over grease the cable. The inner cable core needs only a light coating for proper operation. If the cable is packed with grease, the excess may work its way into the sending unit and block the sensor. The same holds true for a new odometer cable should you replace the one in your car. Don't grease it! The factory sends it ready for use.

The sending unit is not weather proof and may be damaged if left exposed. Always mount it in the car's passenger compartment or trunk. When the sending unit is not mounted underneath the dash, protect it from direct sunlight. High intensity light may leak in through the mating surfaces and cause the unit to operate incorrectly.

Your sending unit comes equipped with the proper cable fittings for your car. If you change cars, they can be replaced with a different type. With replacement, it may be necessary to adjust the washers located on the sending unit's rotor. The bent washers apply a slight drag to the rotor and prevent false outputs from extraneous vibrations. Increase or decrease the drag by bending the washer(s) until the rotor offers a small resistance when turned. Check the drag every 20,000 miles. A diagram of the sending unit's parts and assembly is found at the end of this manual.

Most cars use odometer cables which terminate with a 0.106" square pin. Some British and French cars use a 0.118" pin. Your sending unit comes equipped with the proper rotor to accept the pin size of your car. Should you switch cars, the other size rotor can be ordered from the price list at the front of the manual.

Magnetic Sending Unit

Because of the variety of cars and individual preferences, the installation of this sender can only be covered in general terms. Common sense dictates that all work done under your car be accomplished with the car on jack stands. Once the magnets are epoxied to the wheel, use every precaution if the wheels are spin balanced. A poorly attached magnet could fly off.

Refer to the drawings at the end of the manual for outline dimensions of the sender parts and a general mounting layout. Two small brackets are included to help in mounting and alignment. The body of the sender is completely threaded to also help in alignment. The final decision on how to mount the sender to the car is up to you. In general, all brackets should be short and sturdy. This will eliminate false output pulses caused by vibrations. Mounting to the rear and top of the wheel well will help shield the sender and brackets. For obvious reasons, the bracket should move with the wheel assembly when used on a front wheel. Single piston disc brake calipers should not be your bracket attachment base. The caliper shifts as the pads wear down.

Loop the sender cable so that it is protected from rocks and has plenty of room to flex. Strapping the cable to the back of the brake fluid line is a good way of leading it into the car. To help in routing the cable, small nylon strips (called cable ties) are included with the sender. Pass the strip around the cable and securing point, insert the small end of the tie through the other end, then pull up snug.

Once you have the sender mounted to the car, adjust it so that the magnets pass about 1/8" from its end (center point). Don't epoxy the magnets until the bracket and sender are set. During this alignment period, the magnets will hold themselves to steel wheels. Use tape to hold them on mags.

The sender requires two magnets mounted to the inside of the wheel (equally spaced for balance). These ceramic magnets have been specifically designed for this application. Other magnets will not work correctly. If you need additional ones, order them from the price list at the front of the manual. The magnets are very strong and might snap out of your hand when held next to ferrous metal or close to each other. Letting this happen may cause the magnet to split. The superior magnetic characteristics of these parts allows for non-critical alignment between them and the sender.

Five magnets and a two part epoxy are included with the sender. Two magnets are for the wheel on the car, two for the spare tire and one extra. THE MAGNET FACE MARKED WITH THE RED DOT IS THE SIDE WHICH MUST PASS THE SENSOR. Mount the magnet so that this entire face passes the end of the sensor. Mix the epoxy according to the directions on the tube and allow it to set for at least 24 hours once the magnets are in place. Be sure that the wheel is free of dirt, oil, etc. First, completely coat all surfaces of the magnet with the epoxy. This forms an epoxy box around the magnet and will keep it from working loose. Next, position the magnet on the wheel and build up the epoxy on all sides except the sensing surface. Spread the epoxy out so that it has a large bonding area on the wheel. Since the magnet is flat and mounted to a curved wheel, fill in the empty space with epoxy.

The sender will operate at temperatures from -40C to +150C. It Is also waterproof and will continue to operate even if submerged while fording a stream. If you run rallies where ice and slush are common, you might use a little caution when parking your car during rest breaks. Because of the relatively close spacing of the sender and magnets, an ice bridge could form between them if they are in alignment when you stop. Though it's not likely that you would pull the sender off center when you leave, being overcautious won't hurt. By marking the locations of the magnets on the outside of the wheel, you can leave the car sitting with the parts away from each other.

Electrical Connections

A prewired power cord is included with your 800. Connect the red wire to +12 volts (uninterrupted by the ignition switch) and the black wire to ground. Attach the leads as securely as you can make them. Only a momentary power loss, either +12 volts or ground, will erase the data in the 800's displays. Do not select a power lead from under the dash. It may contain numerous slip-on connections as it is routed from point to point. Your best tap point is at the fuse holder where the main power lead enters. If there are no screw-on terminals in the holder, strip back the power lead's insulation and attach the red lead at that point. Solder and then wrap with electrical tape for a secure joint. Attach the ground lead under a screw found in a metal part of the car's chassis. Scrape away any paint which might cause a poor electrical path. Using a cigarette lighter plug for your power connections is inviting disaster during a rally.

You will have noted that the power connector has four pins instead of only two. The pins are wired in pairs, two for +12 volts and two for ground. If your installation requires additional connectors, follow this system of doubling up on the pins. This is another precaution against a momentary power loss.

A 3 or 4 amp. fuse is located in the +12 volt lead of the power cord. Never run your 800 without this fuse in place. It is your protection against shorting the heatsink. A spare fuse is taped to the back of the case. In the unlikely event more fuses are needed, they can be found at most service stations, electronic supply stores and TV repair shops. In desperate circumstances, a fuse from your car's electrical system may work. Take one from the fuse holder that runs an unneeded circuit (radio, fan, etc.).

After you have completed your power connections, plug in the 800 and see if it will turn on. If the leads have been reversed, the fuse will have blown. THIS TEST SHOULD NEVER BE PERFORMED WITH THE SENDING UNIT CONNECTED. Plugging the sending unit in when the leads are reversed will put a direct short between +12 volts and ground which bypasses the fuse.

Keep the sending unit and power connector pins free of dirt and grime. Never wrap masking tape around the pins. A light brushing with steel wool once a year will keep the contact in good condition. You may use tape to hold the connectors together if you feel they might separate because of their location in the car.

Your 800 will operate on voltages from 7 to 20. Fall below 7 volts and data will start dropping out of the displays. Your car's output voltage normally varies between 10 when starting and 14 when charging. A good battery is your best protection against having the voltage go below 7 volts.

While the car's nominal output voltage is 12-14 volts, electrical noise and large voltage spikes can occur at the same time. The 800 has adequate safeguards to isolate it from this type of noise (from fans, lights, etc.). THE ONE EXCEPTION IS SOLID METAL IGNITION WIRES. While few cars come equipped with these wires as standard equipment (Alfa Romeos are one), if your car has them, they need replacement with standard carbon resistance wire. Don't forget the wire between the coil and the distributor.

Porsches have solid wires but are also equipped with supressors to eliminate the generated noise. No new wires are required. If you feel that solid wires are absolutely necessary, use a shielded type. This wire is available at some automotive parts outlets. It's relatively expensive, but it keeps the noise down.

Don't be tempted to "see what happens" before being convinced to change the wires. In some cases the effect is obvious and immediate... the counters start rapid and sporadic counting as soon as the car is started. In other cases, hours of close observation may indicate that all is well. Don't be misled by this apparent lack of trouble. This noise can be extremely elusive. Why risk getting bad checkpoint scores. Change the wires!


Your 800 is run by a small computer known as a microprocessor. Switching the 800 on allows the microprocessor to begin executing its program from a known point. When first turned on, the 800's displays come on as zero, blank, zero, blank. This will indicate to you that the unit has just come up from a power off condition. If it occurs during your shakedown drives, a faulty power connection must be found and eliminated. Occasionally, a defective power connection will be indicated by a random pattern of digits and blanks. Always switch the 800 off and start it up in normal fashion. Then find the bad connection. If you use a little care in making your power connections, you will never have a problem of this sort.

Once the 800 is switched on, it will not operate until you acknowledge the power up condition by turning the Odometer Control Switch to OFF. At that time, the zero/blank pattern will be replaced with 00.00 in the displays. At the same moment, the correction factor will be set to 4500, the mileage alarm to 99.00 miles (TSD) and the speed to 45 mph (PRO).


The Odometer records official rally mileage from 00.00 to 99.99 in increments of 0.01 mile (km). Once you have corrected the 800 at the end of the odometer calibration leg, the mileage in this counter will match the rally's official distance.

The middle display is an Auxiliary mileage register which records distance in a manner similar to the Odometer. It can be used for speed change to speed change mileages on TSD rallies, or instruction interval mileages on stage events. This display will also be used for the speed calculations on the PRO model.

Real-time-of-day is shown in the Clock display. It counts to 59.99 minutes (59.59 seconds) then returns to 00.00 to start the next hour. This display is also used to view other functions on your 800. Even when this is occurring, the Clock continues to operate and will display correct time when you return to it.

The displays' intensity is controlled by the switch at the lower left of the front panel. Use BRT (bright) for daytime and DIM for nighttime. The top position turns the displays off.

Correction Factor

The 4 digit correction factor adjusts the 800 so it will run at official rally mileage. The factor can be viewed in the Clock display by switching the Odometer Control Switch to either +CF or -CF. Actual adjustment of the factor will be discussed later. The following paragraphs will acquaint you with the basic correction factor information.

The formula for adjusting your factor at the end of the odometer leg is:

                                       OFFICIAL MILES
                         NEW FACTOR =  -------------- X OLD FACTOR
                                       ODOMETER MILES
Example: Your factor at the start of the odometer leg is 4200. The odometer leg is 14.92 miles long and the Odometer reads 15.07.
                                       ----- X 4200 = 4158
4158 is your factor for the remainder of the event. Of course, you can change it should conditions later require you to.

Before running your first rally, you may want to establish a "base correction factor" (BCF). This is the factor which will run the 800 at statute miles (km) in your car. Once obtained, make a habit of starting each rally with this factor. It will normally keep you within a few percent of the rally's mileage and thus make the odometer leg easier to run.

To find your BCF, it will be necessary to run your car against a known statute distance. Many highways have mileage markers, or you could use an old rally measured in statue miles. When a suitable course is not available, lay one out using the car's odometer. A more precise BCF can be developed when the opportunity arises.

The course selected can have any length although it's a good idea to make it at least 5 miles. Set in a factor of 4000 and run the course. Use the formula to calculate your BCF. A rerun of the course with the new factor will find your Odometer mileage equal to the course's "official" length.

Your exact statute mile factor does not need to be your BCF. Your calculation will be easier if you round off the last two digits. 5529 would go to 5500, 3579 to 3600, and 4841 would round to 4800.

There may be times (it may start raining) when you will want to adjust your factor during the rally. Small changes can be mentally calculated quite easily. For each 0.01 mile you wish to adjust your mileage in 10 miles, change the factor by the value of its first digit. Increase the factor to increase your mileage. For less mileage, decrease the factor. Suppose your factor was 6012 and you wanted to increase your mileage 0.01 mile for every 10 you travel. Change the factor to 6018 (6012 + 6). As another example, your factor is 4850 and you need a decrease of 0.02 mile per 10 miles. Change the factor to 4840 (4850 -4.8 -4.8).

If you know the number of revolutions per mile at the input of the sending unit (either the cable or wheel), you can calculate your BCF from the formula below. A little math will tell you that you need a minimum of 400 revolutions per mile to run the 800. Most cars have between 800 and 1600. None are lower. Undriven wheels vary between 800 and 1000, depending on wheel size.

                    CORRECTION FACTOR = --------------------
                                        REVOLUTIONS PER MILE

Most American cars and many foreign models have odometer cables which turn at 1000 revolutions per mile. The BCF in these cases would all be around 4000. The 800 will also run in kilometers. The correction factor has been designed so that it will not normally go above 5000. This gives you sufficient range to increase the factor to let the Odometer read 1.00 at the end of 0.62 mile (1 kilometer = 0.62 mile... old factor X 1.61). The 800 doesn't know or care what the unit of measurement is. That's for you to decide. Of course, speeds for the 800PRO are now entered in KPH, not MPH.

Checkpoint Switch

This control locks the data displayed in the Odometer, Auxiliary and Clock whenever it is thrown to "checkpoint". The counters continue to accumulate information, but this new data is not displayed until the switch is turned off. This feature allows the navigator to hold information he wishes to record. At the same time, the 800 will keep on with its normal operation.

This switch should also be used as you cross a Checkpoint's timing line. The mileage to the line (Odometer) and your actual arrival time (Clock) will then be locked in the displays. If you are mistimed, the Clock will verify the time-in you want. After you are satisfied with your time, turn the switch off. The displays will immediately update to the counters' present data.

As was mentioned before, the Clock display can show several types of data. However, when the Checkpoint switch is activated, time-of-day is locked into the display no matter what was there before. You won't be caught looking at the correction factor if you suddenly encounter a checkpoint.

A jack is mounted on the back of the case to allow for external operation of the Checkpoint function. Simply wire the plug provided with your 800 so that the circuit is completed when you activate your switch. See the diagram at the end of the manual.

Odometer Control Switch

This switch is located just to the right of the Odometer display. When it is turned to PWR (power off), the power to the 800 and the sending unit is off. In all other positions, the unit is powered.

FWD/OFF/REV (Forward/Off/Reverse)

These three positions control the count direction of the Odometer and Auxiliary. Whenever you are switched to any position but OFF or REV, the 800 continues to receive and register mileage as if it were in the FWD position. The blank positions between REV and PWR, and -CF and TEST are also FWD as far as the 800 is concerned. These unmarked positions will prevent you from accidentally switching the 800 off or into test.

The OFF position prevents the recording of mileage in either the Odometer or Auxiliary. You can switch to OFF to leave the rally course during a break or when you don't want mileage registered. Whenever the 800 is taken out of OFF, the next distance pulse does not occur until you have traveled exactly 0.01 mile (km). At the beginning of the odometer calibration leg, you can insure an accurate measurement by pulling up to the start line in OFF, or by momentarily switching to it just prior to leaving. Since the 800 continuously calculates distance, you may get a mileage count right after the Odometer has been zeroed. This feature of OFF would then be useful at the end of the Odometer calibration leg, at transit zone ends and whenever the rally's mileage is zeroed.

At a checkpoint out-marker, the Odometer could have pulsed 50 feet prior to it. The next count would now occur shortly past it. Any time calculation that you were doing would now be based on nearly 0.01 mile too much. A quick switch to OFF will make the first count occur 0.01 mile after the leg begins.

A second jack is mounted on the rear of the case to allow external operation of the OFF function. A common practice on performance rallies is to have your mileage read slightly high. If you use this technique, use the jack to hold your mileage until you reach the turn or clue. Wire the switch as mentioned above in the Checkpoint section.

Z (Zero)

To zero the Odometer, turn to Z and push the .01 button on the right of the front panel. As mentioned above, the Odometer continues to register mileage when in the Z position. It's only when you press the pushbutton that the counter zeroes. Since zeroing requires that you perform both actions, it's unlikely that you would unintentionally clear the Odometer during an event.


These positions allow you to adjust the mileage in the Odometer. In +D, the pushbuttons add mileage in increments of 1.00 mile, 0.10 mile and 0.01 mile. -D allows the subtraction of mileage in the same amounts. It makes no difference whether the car is moving or stopped when using these modes. Remember that the Odometer continues to register "on the road" mileage as if it were in the FWD position.

You will use these two positions to set your Odometer to official rally miles at the end of the odometer calibration leg, to adjust for wheel slippage, and to correct the Odometer at checkpoints where your mileage is in error. When returning from an off-course excursion, you will be in REV and unable to use +D or -D. If your mileage should need adjustment, it's not likely to be more than a hundredth or two. Simply wait until you regain the rally course and then make the correction.

+CF/-CF (Correction Factor)

To view or adjust your correction factor, switch to +CF or -CF. In either position, the correction factor is displayed in the Clock counter. The 3 pushbuttons will allow you to increase (+CF) or decrease (-CF) your factor. Remember that 4500 is loaded into the factor when you first turn on the 800. Your BCF will normally be close to this value and you can adjust to it simply by bumping the factor up or down. Ignore the decimal points on the display and pushbuttons when you're working with the factor. As with the other positions, the Odometer continues to run forward while in CF. You can check your factor or change it at any time except when you are in reverse and returning from off course. Then you'll probably have more pressing concerns than peeking at the factor.


This position activates an internal pulse generator which causes the 800 to run as if it were in a moving car. You can test or demonstrate the unit in this mode. The 800 behaves like the car is going 60 mph (kph), 1 mile per minute, when the correction factor is 1707.

Auxiliary Control Switch

This control selects the operation mode of the Auxiliary (Aux.), sets the Clock, sets the alarm mileage (TSD) and runs the speed calculation function in the 800PRO. The count direction is dictated by the Odometer Control Switch. Likewise, the Auxiliary will not register if the Odometer control Switch is OFF. Tying the counters together this way allows for easy operation in most rally situations. To turn the Auxiliary off independently of the Odometer, turn its switch to OFF. Ml (Mode 1) lets the Auxiliary count as determined by the Odometer. +D, -D, Z, CLOCK, +/-Alarm (TSD), LOAD (PRO), and the blank positions are all M1 positions and let the Auxiliary continue to count when switched to one of them. The +D, -D and Z positions perform the same way as those on the Odometer.

M2 (Mode 2)

This position, when used with the Checkpoint switch, lets the Auxiliary serve as a point-to-point mileage register. When the Checkpoint switch is thrown, the Auxiliary's information is held as previously explained. Once the information is locked in the displays, the counter zeroes and begins accumulating distance from the point where the switch was thrown. When the switch is turned off, the Auxiliary shows this new mileage and continues to count normally.

Most unequipped calculation methods use speed-change-to-speed-change mileages. Mode 2 lets the navigator write this mileage down while the Auxiliary begins measuring the distance traveled at the new speed. On stage events with instruction interval mileages, a quick switch into and out of Checkpoint will zero the Auxiliary for the next mileage.

The external Checkpoint jack can be used for zeroing the Auxiliary when it is in Mode 2. If you run stage events, you may find it more convenient to have this separately mounted zeroing switch.

Setting the Clock

To zero the Clock, switch to CLOCK and press the .01 pushbutton. As long as the button is pushed, the Clock will hold at zero. The .10 and 1.00 buttons are used to advance the Clock.

The quickest method for setting the Clock to time-of-day is as follows. Just prior to an even minute on your time reference, zero the Clock. Keep pressing the .01 button to hold the Clock at 00.00. When the even minute arrives, release the button. The first time count will occur exactly 0.01 minute later. This has set the hundredths part of the Clock. Next, use the 1.00 button to run the minutes up to the correct time. That's all there is to it.


The 800TSD model can be set to sound a buzzer when a preset mileage is attained in the Odometer. This mileage appears in the Clock display when you switch to one of the Alarm locations. Use the pushbuttons to set in the mileage you want. When that mileage occurs, the buzzer will sound for 3 seconds and then turn off. The operation of the Alarm system is automatic. You can effectively turn it off by setting in 99 miles because most rally mileage reverts to zero before reaching that high a value. Remember that 99.00 miles is set into the Alarm when the 800 is first turned on.


This feature of the PRO model will help you keep the car on time during average speed transit zones between stages. As with all types of rally time calculations, it is necessary to compute an amount of time based on the speed you are assigned and the distance you have traveled. Once you have this time, it can be compared to the actual time (time of day) to see whether you are early or late. On the 800PRO, the computed time is fed into the Auxiliary where it can be visually compared with the clock. To make your comparisons easier, the rightmost digits (hundredths) of the Auxiliary and Clock will be blanked out. There is no need for the final digits because performance rally transit zones don't require exact on-time rallying.

When the computed time displayed in the Auxiliary is ahead of the Clock, the car is early based on the speed set in the 800. Slow down to get back on time. Conversely, when computed time is less than the Clock, you may speed up until the times are close to being equal.

                     34.7            23.3            23.3
                     AUX             AUX             AUX

                     34.5            23.8             .45 <-(SPEED)
                     CLOCK           CLOCK           CLOCK

                     (EARLY)         (LATE)

The 800PRO computes time when the control switch is turned to either RUN or SET. When on SET, the average speed that the 800 is using for its calculations will be shown in the Clock. The first two digits will blank to avoid confusion. To change the speed, use the .01 and .10 pushbuttons (ignore the decimal points). You can adjust the speed only in an upward direction. To enter a speed that is lower than the one now showing, advance up through 00 then on to the new one. Most transit zones are run at a single speed so you won't need to change the speed very often. Any speed from 1 to 100 mph (kph) can be entered. When 00 is set, the speed is 100 mph.

At the start of the transit zone, you must always set the Auxiliary to your assigned time out from the end of the stage. This is done so that you can make a direct comparison between it and the Clock. For example, suppose time outs are being obtained by dropping the hundredths from your time-in and that you have just crossed a timing line at 39.67 (minutes). To set the Auxiliary to 39.00, you could switch to +D or -D and punch in that value. Then you would switch over to RUN. As a better alternative, turn to LOAD and push the .01 button. The Auxiliary will automatically set to 39.50 (minutes). Now switch to RUN and you're ready to leave.

There are two reasons why the Auxiliary was set to 39.50 and not 39.00. First, by the time you get your car stopped at the end of the stage you'll be a short distance past the timing line from where your time out will be based. To be entirely accurate in setting the Auxiliary, you would have to account for the computed time from the timing line to where the car is stopped. In most cases this would amount to about 0.1 to 0.2 minute. This would still leave the Auxiliary with about 0.35 too much time in it. Let this extra time act as a safety cushion. When the Clock and Auxiliary are running together during the transit zone, you'll still have a 15 to 20 second buffer before you actually are early.

How is the time put in the Auxiliary determined when you use LOAD? The time loaded is simply the minutes displayed by the Clock plus .50. If you used LOAD when the Clock read 42.16, the Auxiliary would go to 42.50. As you can probably imagine, by the time you got around to loading the Auxiliary in the above rally example you would be at least into the next minute and 40.50 would be incorrectly loaded instead of 39.50. Should this actually happen, switch to -D and back out the extra minute. When the 800 is "split" with the Checkpoint switch, you can still use LOAD. The time will be loaded into the Auxiliary even though you won't be able to see it until you switch out of Checkpoint. More importantly, the time loaded will be based on the time split in the Clock, not actual time. This will allow you to setup the 800 while you're waiting to be given your time in and time out. In the previous rally example, your clock would be split at 39.67 while you waited to verify your time in. You would turn to LOAD, push the .01 button, then turn to RUN. The 800 is ready for the transit zone even though the information is not shown. When you are satisfied with the official arrival time given you by the workers, switch out of Checkpoint. The Auxiliary will display 39.50 and you can be on your way.

Always remember that the Auxiliary must be set to the out time you desire. If you need to adjust it after you've used LOAD, the +D and -D positions can do it for you. Some cases where this might be required are: (1) time outs are based on rounding up to the next minute, or (2) you cross the timing line very close to an even minute and the workers time you in a different minute than the one you have split.

The lengthy description of LOAD/RUN/SET was provided to give you the basic elements involved in keeping the car on time during a transit zone. In practice, the procedure is quick and simple. Assuming that your speed was already correct (many rallies assign the same speed for all transit zones), and that time outs are obtained by dropping the hundredths, this is what you would do:

  1. Throw the Checkpoint switch as you cross the timing line.
  2. Turn to LOAD and push the .01 button while you're waiting to get your time in.
  3. Switch to RUN.
  4. Switch out of Checkpoint after checking that you have been given the correct time.
  5. Check the time out you entered into the Auxiliary with your assigned time out.
  6. Begin the transit zone (you'll probably be late when you start).


The normal control switch positions are FWD and Ml (M2). Make a habit of always returning to them after using another position. After a rally or two, you will have seen how simple the operation of the 800 is during actual competition.

The accuracy of your 800 is much greater than you will need on a rally. When your correction factor falls in the normal 3000 to 6000 range, you can correct your mileage to about plus or minus 0.01 mile in 60 miles. If you and the rallymaster can agree to within 0.01 mile after 10 miles or so, that would be about normal with all things considered.

The Clock will stay within 0.01 minute over the period of an all day event. Extreme temperature fluctuations may slightly affect its accuracy. This may happen should you leave the 800 turned on overnight in cold weather. Even in these cases, the Clock will not vary by more than 0.02 minute per day.

The 800 has been constructed to withstand all the normal jolts and bounces it might receive during a rally. When using your 800 on stage events, don't mount the unit rigidly to the car's frame. This will only transfer every shock taken by the car directly to the 800. Application of a little care in your mounting arrangement will insure many years of trouble-free rallying.

Although your 800 is built only with quality components, there is always the possibility it may stop functioning correctly. As a first step in correcting the problem, notify Zeronics and describe the malfunction. It may not be necessary to return the unit. Most major parts are mounted in sockets for easy removal and replacement. This feature is found on all Zeron models. It's your assurance of quick and inexpensive repair of any problem you might have.

*******************LIMITED WARRANTY*******************

Zeronics warrants this product to be free from defects in workmanship and material for a period of one year from original purchase. Our obligation under this warranty is limited solely to repairing or replacing, at our option, any part when the product is returned to us within the warranty period providing: (1) the defective unit is returned to us transportation prepaid by purchaser, (2) no modification or change has been made to the unit's circuitry or wiring, (3) the unit has not been damaged by misuse, neglect, improper operation, accident, or alteration as determined by Zeronics. No other obligation is implied or expressed.

(Subject to Change Without Notice)

The following items are available should you change rally cars or set up a second car.
We pay the shipping charges.

For a fee of $8.00 you may return your cable sending unit and have the fittings exchanged for a different car. This offer is good only when the fittings to be removed from the unit are still in use on a currently produced car. Your old fittings will be kept by Zeronics and the replacements will be mounted on your sending unit. The sender will be inspected and the rotor drag adjusted.

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