Limitless Purpose of 1:1 gearing for speed runs?

[Procrastinator]

I am far from an expert even though I’ve gotten some of my cars to hit over the 150 mark. I’ve usually started with what I know is a good setup and adjusted things from there. Today’s motors and lipos are so good, I usually set the car up to go about 130 and then step it up incrementally from there. I’m in the mid 140’s with the limitless and I feel like at this point every little bit matters. I’ve seen people a few times mention 1:1 gearing and wondering what is the idea or purpose of that? I’ve always used my logs to gauge motor rpm (shooting for max rpm), and then gear accordingly to how my logs look. That May be wrong, but it’s got some fairly respectable numbers so far. Any info on 1:1 gearing or why it’s important would be much appreciated!

 

[Overpowerrc]

It’s about the ratio
If you run 34t spur and 29t pinion you have a 1.17 ratio
Calculate ratio:
spur/pinion
if you run 34t spur 34t pinion that’s 1:1 which means that 34/34=1 so
34/27=1.25
34/28=1.21
So on etc
This ratio equation is basically how many times the pinion rotates to make 1 full rotation of the spur

 

[Procrastinator]

Is there any mechanical advantage to having a 1:1 gear ratio though? I’ve seen a few people mention it a few times, seemingly like it was, but I wasn’t sure. I’ve always just worked my through different pinion/spur setups until my Mph/logs looked good (hitting max rpm, good amperage readings, and decent temps). Obviously KV plays a huge role in it, but I feel like if I’m hitting max rpm (60-65kish for a TP4070) and have decent MPH (120+) then I have a solid baseline to work off, actual ratio not mattering as much. I could be way off base, but figured would be better to ask.

 

[drjim]

It's one of those "it depends" questions.

IF you have enough space, and

IF your motor can pull max RPM with that gearing

THEN you should go faster.

Another way to look at it is if your motor can turn 45,000RPM, then 1:1 gearing (pinion/spur) will result in the drive shaft turning at 45,000RPM.

 

[Streetsports]

Is there any mechanical advantage to having a 1:1 gear ratio though? I’ve seen a few people mention it a few times, seemingly like it was, but I wasn’t sure. I’ve always just worked my through different pinion/spur setups until my Mph/logs looked good (hitting max rpm, good amperage readings, and decent temps). Obviously KV plays a huge role in it, but I feel like if I’m hitting max rpm (60-65kish for a TP4070) and have decent MPH (120+) then I have a solid baseline to work off, actual ratio not mattering as much. I could be way off base, but figured would be better to ask.

How do you adjust speed? Hopefully with gearing and not by buying new motors until you find the sweet spot for mph. If you are using gearing then eventually you will get to 1:1 gearing or even over drive gearing. You're probably noticing it alot because it seems to be a great ratio for multiple cars when running a low kv motor. right now 800kv -1200kv is popular and therefore 1:1 is also a popular thing.

 

[Procrastinator]

How do you adjust speed? Hopefully with gearing and not by buying new motors until you find the sweet spot for mph. If you are using gearing then eventually you will get to 1:1 gearing or even over drive gearing. You're probably noticing it alot because it seems to be a great ratio for multiple cars when running a low kv motor. right now 800kv -1200kv is popular and therefore 1:1 is also a popular thing.

Haha definitely by adjusting pinion/spur gears, mostly just pinion Changes after I have a good baseline. I have seen people comment a few times “they are shooting for 1:1 gearing” and didn’t understand why when it’s never really been something I was concerned about. I thought maybe it was about keeping a motor in A certain rpm range was better than just shooting for max rpm like I do? I honestly have no clue. Fortunately I have a pretty solid, fast and reliable setup as of now, and was going to start messing with aero to see what kind of changes it would make, but wanted to be sure I wasn’t leaving a few easy mph out there. Thanks!