Article about gears
took some time to make an article about gear ratios and how they can affect your ride based on how things appear on paper and not off real world events. leave comments and let me know if you enjoyed it. may make a few more depending on how this turns out.
Grinding Gears and Crunching Ratios
by: Samuel Morris
Almost every enthusiast at some point has asked themselves “what gear ratios should use for my my car?” and “which transmission should i use?” Well then, this article is for you. We will grind through each gear and crunch the pros and cons of gear ratios and how they will make your car react in a perfect world world and is simply based on theoretical information. This article is simply how it appears on paper without no real tests.
From as far back in my childhood as i could remember i loved cars and had a huge collection of hotwheels and matchbox cars. Later came Gran turismo as the enthusiasm increased. At 17, FINALLY!!!! my first car. A 1993 Mustang 2.3 auto fox. Every time i took the car to the shop i watched like a dog after a bone. Later, the shop owner allowed me to help around the shop helping the techs work on cars. I watched everything and learned as much as i could. Later i got a 1990 corvette.This time i was gonna do the tooling. some things worked, some things didn’t. After a few months, the car ran like a champ. a few years later, i lost the corvette to a flood, the later i wrecked the fox. it wasn’t pretty. No way to get back and forth to work so it was time for a new car. Enter my 2002 black mustang GT. the ONLY thing this car has went to a shop for is alignment and tires. If i had the tools to balance my tires and align the suspension i would do that to. Present day. I have a full set of tool handed down from my dad. now i work on my own as well as my friends cars. It’s funny when you watch as they bang their heads trying to figure out what’s wrong with it and i say something like a vacume leak or something simple like that. It’s even funnier when i crank my car and show them what happens when I demonstrate the problem and get the same results. Enough about me, time for what you came for, Gears and Ratios.
Grind and Crunch
Everyone wants to shave time off their ETs aor shave time off their lap time and an easy way to do that is with a ring and pinion set. Everyone thinks the best way to go is with a higher ratio. This isn’t always the best rout. a higher ratio does increase acceleration but also decreases the top speed of the vehicle and also causes you to go through the gears faster. Something that is usually overlooked. lets bring things into perspective. Gears multiply the engines torque before it gets to the wheels. For example, your engine makes 300ft/lb of torque. After modifying the output through a 2 to 1 ratio, that torque is doubled to 600ft/lb. 3 to 1 would equal 900ft/lb. So this leads you to believe a higher ratio is better but this isn’t always the case. The higher the ratio, the faster the engine has to spin to maintain that same speed. Now picture 2 cars going down the road at 60mph. one has a 1 to 1 ratio and the other has a 2 to 1 ratio. The 1 to 1 will be using ½ the RPM of the 2 to 1 and if it had the power could go twice as fast. Now lets go deeper into ratios. We have a blue and a red mustang. both are identical in every way except their final gear (aka the ring and pinion set). The blue stang has a 3.08 to 1 and the red stang has a 3.27 to 1 final ratio. The cars will be racing on a course that is flat and about 5-6 miles long, plenty of room to demonstrate the difference. The countdown begins and both cars are off. Both have the same transmission, the gears are as followed. 1st: is a 3.37/1 2nd: 1.99/1 3rd: 1.33/1 4th: 1.00/1 and 5th: 0.67/1. The red mustang jumps ahead due to it’s 3306fl/lb after its ratios while the blue only has 3113ft/lb after its ratios. now it’s time to shift. The red mustang shifts and it’s torque output after it’s ratios drops to 1952ft/lb
the blue mustang still has about 350RPM left before it shifts to second gear so it keeps it’s multiplication factor for a longer period of time. the blue stang catches up then shifts into second reducing it to only 1839ft/lb. the red one takes the lead again then BAM 3rd gear. Torque drops to 1304ft/lb. The driver of the red stang looks behind him and sees the blue one catching back up then gets passed before his opponent shifts into 3rd. The blue’s torque drops to only 1229ft/lb. A 75ftlb difference. He takes the lead once again and gets some distance. BAM 4th gear. he notices the drop in power, the car seems almost sluggish compared to first gear. The difference in output between 1st and 4th gear is 2325ft/lb, putting 4th gear at only 981ft/lb. the pressure is on as the blue stang catches up. The driver looks down and begins to sweat. He is about to reach redline. The blue stang is less than a car length behind him. The nose of his opponents car drops and he gets a bit of relief then glances down and sees 5800RPM. He shifts to 5th gear, his opponent gets right next to him then shifts into 4th gear. The difference in output is 267ft/lb with him at the disadvantage. He watches as his opponents taillights pull away. He feels as he has no chance but keeps his foot down on the accelerator. His hopes of victory is now gone. Then the inevitable. The back of the blue stang raises a little then drops back down. Finally both are in 5th gear. the advantage goes back to the red stang. He begins to catch up to his opponent. THEN the worse thing that could happen hits him hard. He looks down as his engine bounces the rev limiter. It’s a clear loss.
In the real world, i’m sure the outcome would have been different. How exactly, i don’t really know. It could be a coin toss. each has their advantages and disadvantages. So now lets take another look at how these ratios could affect a race. our same 2 lucky drivers are lined up again on a road course with the same cars as before. The green flag drops. they tear off the start line. The red mustang jumps ahead as the blue one falls behind. Into the braking zone, the nose of both cars drop. They turn hard into the corner, then cross the apex and roll on the throttle. The driver of the blue mustang looks in fear as his opponent pulls away. Each corner the gap grows. a difference of 4 car lengths now as they approach the final corner. The leader enters the apex and starts rolling back on the throttle. The car shakes as the engine backfires. the driver smiles as the rolls on the throttle catching the lead car. back on the front straight. Side by Side they enter the corner. The red mustang on the inside. takes the lead. Through the course pulling away with every bend. entering the final corner, the driver looks ahead and counts two downshifts. He follows and drops down a gear. looks up from his tachometer and sees his opponents cars shakes again with another backfire. He know his opponent just hit the rev limiter and reduces the gap. Down the straight into the first corner, bumper to bumper, the driver feels confident and has a plan to overtake his opponent. down the course, with a gap of 3 car lengths into the last corner. Both downshift a gear. The red in 4th gear and the blue in 3rd. across the apex, on the throttle. The driver holds the inside and accelerates hard and passes his opponent on the inside before shifting up to 4th gear. He looks back and smiles knowing he just passed his opponent. the final stretch of this 3 lap race. He shifts into 5th gear. his opponent approaches then dives to to right. Across the line. A photo finish. The driver stand there waiting anxiously for the results. The photo is put up on display. As both drivers stare at the photo. Then the driver of the blue mustang looks down in disappointment. He lost the race by a nose.
It doesn't matter what type of race you are running or what type of course you are racing on. Gears can make a huge difference in the outcome. Don’t just jump the lowest you can find. Do some planning and find the right ratio for your application. to high or too low of a ratio can be very bad and hinder your car's performance. Go to high and running fast through the 8th mile only to be beaten in the 1/4 because you ran out of gear isn’t exactly a great win. Chasing a land speed record and shifting to that last gear and watching your car lose speed because the ratio was too low isn't a victory. Then running through the autocross and finding out you got second place because your opponent shifted less than you. All these are possible in the real world and happen all the time, just you never hear about it. A good car has to have the right balance and that includes gears. Too high or too low can make or break you in a race. Do your homework and find what best suits the application. I hope you enjoyed this article. Remember, before you grind the gears, crunch the ratios.
Written 7/20/2013 11:54pm central time zone. Do not redistribute without prior permission from the author
Shoulinfox, the fox with a box of rox