Mini Gear setups Part 2!

1fasttiller

Member
This has really got me thinking and staying up all night running in my mind lately....

We are headed to the World 100 in Jasper this weekend where my son will make his attempt to run with the "big dogs" of Jr2. I have always been taught by many on this page that know WAY more than me that even though a ratio is a ratio, that the larger driver you use the faster you will be. Now this whole "mini gear" post has me really wondering if that isn't the way to go, especially with plate engines that lack power?

A smaller front driver equates to a smaller rear gear, both are lighter meaning less reciprocating weight and force required to turn them, right?

I mean there has to be a reason The rules for this race clearly state "no rear gear smaller than 53 tooth" To me that says something!

In our scenario- I'm told by the guy who has set the pole in Jr2 two years now that 18/62 is the gear. This is a 3.44 ratio. I can achieve that same ratio using a 16/55. Is it worth trying or am I going to get killed by the kids running the 18 drivers?

Advice? input? I'm all ears! We need every advantage we can get to make this race a success!
 

flattop1

Dawg 89
Earl posted it's biggest advantage was in qualifying . (My take anyway).
Opinions and armpits . You have ceramics already ? They help as well . The cost of the gear, hub vs the gain , that is in question . Quick acceleration lighter is better , carrying the momentum once going heavier is better .
Your talking about using let's say 15 less chain links and 2 oz of hub weight .
So 6 oz total weight .
If your counting ten thousands of a sec , it would be plausible that it would help ..
Now the second part , the diameter of the gear and attending friction ?
 
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OVALTECH1

Premium User
I think the "53" gear rule is just to keep people from spending money they don't have!


That gear rule causes all kinds of money to be spent to make the most power in that rev range due to the gear rule. Amongst other things .
 

1fasttiller

Member
Earl posted it's biggest advantage was in qualifying . (My take anyway).
Opinions and armpits . You have ceramics already ? They help as well . The cost of the gear, hub vs the gain , that is in question . Quick acceleration lighter is better , carrying the momentum once going heavier is better .
Your talking about using let's say 15 less chain links and 2 oz of hub weight .
So 6 oz total weight .
If your counting ten thousands of a sec , it would be plausible that it would help ..
Now the second part , the diameter of the gear and attending friction ?
The 55 on the rear is certainly a hell of a lot smaller and lighter than the 62-64 we normally run. The steel driver on the bully is quote a bit lighter going from 18 to 16 tooth as well. I'm not sure if it really helps or not but dammit I'm going to at least try it in Practice!

Oh, and yes, all new ceramics with super light axle are already on it. Taking advantage of that rotating weight all we can with this plate motor!
 
Ya all missed my point i made earlier, its not the same ratio as you go to the little gears. Theres a reason for this.
If pole has been an 18-62 the last 2 yrs, you can bet your ass id be on an 18-62 then.
No lower than a 53 for this race, thats been the rule for karting for so so long up until recently.
 
^ I was just thinking the same thing as Earl.
If you KNOW what it is fast there, why in the world are you trying to experiment with something you don't have experience with?
Keep your "experimenting" at the local Saturday night level...not when you've got everything on the line for your biggest race of the year!


-----
🏁Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
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31 years of service to the karting industry
Linden, IN
765-339-4407
bcarlson@CarlsonMotorsports.com
 

gcashwell

Member
I don’t follow. The math says it is literally the same ratio. 40/10 = 60/15
Ya all missed my point i made earlier, its not the same ratio as you go to the little gears. Theres a reason for this.
If pole has been an 18-62 the last 2 yrs, you can bet your ass id be on an 18-62 then.
No lower than a 53 for this race, thats been the rule for karting for so so long up until recently.
 

rupp76

Member
Here is some food for thought on gear ratios, not all ratios are the same except for a very few, your example of the two year pole setter his gear ratio of 18-62 figures out to 3.4444444, your gear ratio that you’re going to run is 16-55 figures out to 3.437500, what does this mean you ask, if you think of a gear ratio as how far will I travel forward in one revolution of the tire this is where the difference is found in gearing

For example

15-51 ratio is 3.40000 with a 34 inch circumference tire you would travel 10.0000 inches forward

17-58 ratio is 3.4117647 with a 34 inch circumference tire you would travel 9.96551 inches forward

12-41 ratio is 3.4166666 with a 34 inch circumference tire you would travel 9.95121 inches forward

19-65 ratio is 3.4210526 with a 34 inch circumference tire you would travel 9.93846 inches forward

14-48 ratio is 3.428571 with a 34 inch circumference tire you would travel 9.916666 inches forward

16-55 ratio is 3.4375000 with a 34 inch circumference tire you would travel 9.89090 inches forward

18-62 ratio is 3.444444 with a 34 inch circumference tire you would travel 9.87096 inches forward

13-45 ratio is 3.461538 with a 34 inch circumference tire you would travel 9.82222 inches forward

15-52 ratio is 3.466666 with a 34 inch circumference tire you would travel 9.80769 inches forward

17-59 ratio is 3.4705888 with a 34 inch circumference tire you would travel 9.79661 inches forward

In my opinion I don’t think the rotating weight has much to do with it. Its all about the math

Also how much does the tire change in size once up to speed, how much air pressure you run in your tires

This only holds true once you have determined the TARGET ENGINE R.P.M for the track your racing on

Steve Sands

Rocket Sprocket
 

ColeAchey

Premium User
What I found from playing around on the track, a lot of it has to do with particular race tracks, types of tracks, conditions, and also maybe a little black magic:ROFLMAO:

There is one track we race on here that was monkey see monkey do and after the 3rd race there this summer everyone was going as small as we could. I never got below a 54 on the back, others for sure did. We won 3 clone races in 3 different weekends on 3 different gear combos, and a customer of mine won a 4th on a different one yet in that same span. To me, the conditions of each day dictated why I needed to go smaller and/or why I needed to run my normal setup, not simply because others were doing it. Every other track we ran this summer we ran our normal gearing, and had normal results, some wins, some bad days, and a lot less stress than switching gears all day playing monkey see monkey do.

Some have definitely gone down the rabbit hole on this, some with good results, some with no difference than normal. If you're hoping to find speed simply by doing some math and changing the gears out I would be very hesitant to do so. If you're struggling to get a certain rpm drop, certain acceleration, or trying to "free" up the engine side then maybe there is something to be found. BUT, if you don't get it right, or get it very wrong you'll be in for a world of hurt.

Something most haven't mentioned at all, but is at the very center of this entire topic is above almost every normal kart racers head, which is I think to Earls point he keeps making. The ones making this work know what they're doing and why. If you don't know what you're doing or why, you're never going to get anywhere and will certainly make yourself worse off by listening to anyone on here, the ones making it work aren't on here giving you the advice in the first place:unsure:

My two cents- I think if you stay between a 58 and a 62 on a current clone/kart setup you're in the ball park one way or the other for most conditions. The old adage of going up and up and up when the track is super fast still makes sense, unless you can't make the bigger front roll due to the bite/grip of the tires/karts/track, which then the only option to keep up with a track and not end up gear bound is to continue going down, usually further than the math would tell you.

Cole
 
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