top of page





Everybody's speedometer reads a little differently.  If three cars are going down the road at the same speed, mine may say we are going 50 mph, while yours says 48 and the other guy's says 51.  The Odometer Check lets you see the difference between your speedometer and the rallymaster's.  This is important, because the speeds for the rally were set on their speedometer, and you've got to go their speeds.


Measure the distance for the Odometer Check on your odometer.  At the end of the Odometer Check, stop and compare your distance to the distance given in the route instructions.  If your distance is 5% less than the rallymaster's, then your indicated speeds also must be 5% less - if they say go 40 mph, you go 38 on your speedometer; it's just your speedometers that disagree.


To find your exact correction factor, divide your measured distance by the distance in the instructions.  The result is your factor, and it will usually be between .95 and 1.05.  If yours is .975, then you have to indicate speeds 2.5% lower than the rally speeds.  If it is 1.04, you have to indicate speeds 4% higher.  This may not sound very important, but if you choose to ignore a 2% factor on a two hour rally, at the end you'll have a 2 1/2 minute error because of not applying your factor, even if you do the rest of the rally perfectly.




Staying on time is a very difficult thing to do, if you want to win.  How do you know exactly what speed to drive?  How do you make up or even measure the time you lose at stop signs?  What do you if do if the rally says go 48 mph, but the truck in front of you is going 37?  What if you're given a speed change that takes you from 18 to 55?  The Odometer Check takes care of part of your problem; it sort of tells you what speeds to drive (I'll cover the 'sort of' in a minute).  Some SOP‑ers ignore the Odometer Check, figuring that a correction of only 1 or 2 percent is only important to the computer types.  These people are beaten before they start.  Often the winning time in SOP is less than 1% of the driving time for the rally.  After you've figured your odometer factor, what do you do with it?  Well, you adjust your speeds by that percentage.  Figuring this percentage in your head is not hard; to get 1% of any speed you just move the decimal place - 1% of 37 mph is .37 mph, etc.   So let's say your factor tells you to run 2% slower than the instructed speeds.  If the rally says go 40 mph, you decrease it by .80 and drive at 39.2, or 39, right?  Wrong.


Unfortunately, in most cars, there is another built-in error factor – the difference between your odometer and your speedometer.  They are both driven off the same cable, but usually the speedometer needle is moved by a magnet.  This means that when your front wheels are going 50, your speedometer may be saying 52.  To find out what this error is in your car, find a good empty road some morning and do this: drive at a constant speed (say 50) and wait for a tenth mark to come up on your odometer.  Start a watch and drive at that speed for exactly one mile, as indicated on your odometer - never mind that it isn't a real mile.  At 50 mph, a real mile takes 1.20 minutes - 1 minute 12 seconds.  If your odometer is off 5% and your speedometer is also off 5%, you'll do your indicated mile in exactly 1.20 minutes.  At 40 mph, you'll do it in 1.50 minutes, 2.00 at 30, 2.40 at 25, and so on.  Run your indicated mile at each of these speeds several times, so you can get a good average speed reading at each speed.  Now let’s say that at 40 mph your times were 1.53, 1.55, and 1.52.  Your average is around 1.53, and it should have been 1.50.  1% of 1.50 (move the decimal) is .015, and you're slow by 0.03, so you have a 2% error at 40.  Check the other speeds as well; the error probably will increase as the speed goes up.  So what does it mean?  Suppose you find there's a 3.5% error in your speedometer at 50.  You're on a rally, and your odometer factor says you have to run 2% faster than the rally speeds.  So when the rally says go 50 mph, you have to increase that by 2% (1 mph) for your odometer factor, and then increase it again by 3.5% (1.75 mph) because of your car's error, because when your speedometer says 50, you're only going a bit over 48 mph.


Trying to do two factors at once is mucho hard.  The way the errors have worked out in my Z, I just remember that I have to increase all my speeds by 1 mph at anything from 20 to about 33, 1.5 mph from there up to about 45, and 2 mph from there on up.  So I just correct each speed according to the odometer factor I have for that event, and then add the right amount to correct for the error in my speedometer.


If you do these two things right, the Odometer Check and the speedometer error, you will be couple minutes ahead of most SOP cars right off the bat.




Being late is horrifying to beginning SOP‑ers; they will do anything to avoid it, even to the point of such idiocies as running STOP signs.  This is a super-dumb idea; it gets you tickets, and it gets your car bent.  Worst of all, intersections are where most of the nasty, hard to see signs are hidden.  By avoiding a few seconds of late time, you are liable to end with a max for missing a sign.  Once you know how to get back on time, you will find that being a little late, is no problem.


How do you measure time lost at a STOP sign, with decelerating, acceleration, speed changes, and all that garbage going on?  Go find a straight empty road with no stops and pick 2 landmarks a few tenths apart, like a tree and a billboard.  Now, do it again, but pretend there is a STOP in the middle of your run.  Stop, look both ways, and crank it back to 30.  The new watch reading at the billboard tells you how much time you lost making a stop at 30.  Do this for a bunch of speeds.


That's all some people do.  They remember that they lose say 5 seconds at 30, 8 at 40, and so on.  That's fine, but what happens when you have to wait at the STOP because a truck is coming?  Rather than assume you're always going to lose the same amounts, it's better to have a watch running and get an exact figure each time.  So go back to your empty road.


You've found that you lose X seconds when you stop in a 30 mph run.  Drive at 30, and find an imaginary stop sign.  When you've slowed to half of the rally speed (in this case 15), start your watch.  Stop the car and accelerate back to 30, stopping the watch when you are back up to half the rally speed (again 15, in this case).  The watch should read almost exactly the same X seconds that you've determined you lose at 30.


If your car is a bunch faster or slower than mine, you will have to leave your watch running a little more or a little less time than half speed to half speed.  The point is, you can develop a method for measuring your dead time exactly, and the nice part is it works with speed changes and trucks too.  If you are going 20 mph and the rally says 'Right at STOP, change speed to 60 mph', you start your watch when you've slowed to 10, stop the watch when you get to 30, and you know cold how late you are.


The other main place where you lose time is when you go off course, realize it, and turn around to get back on.  Now, how late are you?  This one takes guts, because what you want to do when you turn around is stuff your foot in it.  Here's a better way, start a watch when you start to turn around.  Drive at the same speed back up the road as you were driving coming down.  When you get back on course, you are late exactly twice the amount shown on the watch.  If you are good, with numbers, you can save yourself some time.  Say you are going 30 and you find you are off course.   You start a watch, turn around, and head back at 45.  When you get back on course, you know you're late by two and a half times the watch value, because you came back at 50% over the assigned speed.


So now you know how late you are, but how do you get back on time?  The way most of us do it is by, percentages: if you go 10% over rally speed you gain 1 second every 10 seconds; 25% over, gain 1 second every 4 seconds; 50% over, gain 1 every 2 seconds.  If you are 10 seconds late, you can make it up by driving 10% over speed for 100 seconds, or 25% over for 40 seconds, 33 1/3% over for 30 seconds, etc.  If a speed change comes up in the middle of your make up time, you just change speed so that you stay the same percentage over the assigned speed.  Say you are 10 seconds late at 40 mph, and from the look of the road you think you can make it up by going 20% over for 5 times the lost time: 50 seconds.  You go 48 (20% over) for a while, and you hit a speed change to 20.  Fine!  Change speed to 24 (still 20% over) and wait for the rest of your 50 seconds to run out.


This also works the other way, if you drive 10% below rally speed you only lose 6 seconds per minute (1 second every 10 seconds).  So if you are in an area where the signs are hard to read, don't fight it; slow down, start a watch, find the sign, and then make up the time when you're not hassled.  This is also how, you handle, the truck in front of you that's going 11 mph slower than you're supposed to go.  Don't kill yourself passing him and don't panic; pick a percentage below rally speed that you can drive, figure the lost time, and make it up later.  This is exactly what the computer people do; they do it by measuring distance, you do it by measuring time and speed.


Once you can consistently make up the 10 or 15 seconds you lose at STOPs, you can go after the 2 or 3 you lose in corners.  We all have to slow for at least some of the corners, and this obviously costs time.  I make it up by the percentage game, but Dave Harris had a really unique way of handling it.  He'd treat a tight corner as a STOP, because knew he could make that up perfectly.  It was a little unnerving to be close behind him on a road like 142 (Carbon Canyon), watching him stop in the corners and smoke off on the straights.  An unorthodox technique, but it worked well for the Harrises.


The easiest way to make up time is to arrange things so you don't have to; run early!  I leave checkpoints and pauses about .25 early most of the time, so when I get to a STOP or an area jammed with signs, I can check things out for 15 seconds before I have to get nervous.  Then when the road straightens out and I'm not looking for three things at once I use my formulas to get .25 early again.  Doing this takes a lot of pressure off stop signs and such, but I run the risk of getting zapped at quick checkpoints.  So I leave checkpoints right on time if I can't see where the road goes or if it feels like a good time for a quick leg, and during each leg I drop back on time when I'm in an area that might have a checkpoint.


Usually this works out fine, but sometimes I guess wrong.  On a La Mirada rally last year, I smelled a checkpoint and paused out the .25 that I was early.  I promptly got .20 late at a STOP and found a checkpoint right around the corner.  I took a .14 on the leg, .33 total for the rally, and lost to the Keckhuts, who had .25 total.  Another time I was .25 early on a road that couldn't possibly have a checkpoint on it, but it did.  I stopped right at the In marker, and took a .03 on the leg, plus a 1 minute penalty (richly deserved) from John Classen for stopping in front of the checkpoint.  So you can still get in big trouble, no matter how many fancy formulas you use.




I may have given the impression that to be a good SOP competitor you need to keep both eyes glued to the speedometer at all times.  Unfortunately, if you do that your not only lose rallies, you'll probably customize your car against a tree.  The business of holding speeds and making up time is the icing on the cake; you need it to beat the other good SOP‑ers and you need it to occasionally knock off the people who run with instruments.  However, you need to be able to do it automatically, almost in your sleep, because your real concentration is needed to keep you on the road and on course.


Practice holding speeds without looking at the speedometer.  Set the car at 45 mph, watch the road for a while, and then look down and see how far off 45 you are.  During a rally, you can't stare at your speedometer; you'll have to stay on speed just glancing at it once in a while.  If you catch yourself a little below speed, don't just go back to the right speed; drive a little over speed for a bit to compensate.


One final piece of advice for beginning rally people:  Ignore this article for several months.  Run as many rallies as you can, ask a million questions, and concentrate on learning how to follow instructions, how to interpret various clubs general instructions, and how to stay on course.   Then worry about making up time for STOP signs.  Knowing how to make up time doesn't help when you're falling for all the traps.  If you want to get good fast, run the hardest rallies you can find, and then get the people explain thoroughly any trap you fall for.  You don't become an Olympic skier by staying on the bunny slopes.


HOW TO DO IT - a guide to SOP rally techniques was written by Elliott Woodward (Elliott Woodward, with navigator Rick Turner, won the 1975 SCCA National Rally Championship in class B using these techniques - an excellent testimonial to their effectiveness.)

bottom of page