Understanding driver changes vs rear sprocket

N

Nocoolname

Member
I’ve just got back into kart racing for the first time since I was a kid, nearly 20 years later might I ad. I understand basics of gearing but I feel like I’m missing something pertinent when it comes to changing drivers vs rear sprocket. I thought that the driver size and the rear sprocket sizes were irrelevant as long as you were obtaining the same final ratio. For instance a 16/66 is a 4.13 and 15/62 is a 4.13, would there be any difference to running one driver over the other? Or does the final ratio determine things regardless of which driver is being used? I’m running a box stock class on a small local 1/8th mile paper clip track with little banking and usually dry clay surface. I’m currently running a 14/61 and I’m not having much success, my last race I was turning 5290 and we have a (5500 rpm max) I just can’t get speed down the straight away like the lead karts. I’m weighing in at 432lb on the scales in a 410 class so I’m having to give up a little weight also. I’ve heard different people saying there running everything for a 12 driver to a 19 driver and honestly I don’t know who to believe. Some guidance or explanation of what I should be trying to achieve is appreciated and thanks in advance.
 
Your turning it to much at 5300, pull 5 teeth off the rear 14/57 4850 rpm is good, just because the max rule is 5500 has nothing to do with your target rpm's, plus that 5500 is on the stand, not on track. If tires are right and say the 14/57 ends up good, you can run 13/53, 15/61 and be just as good, smaller driver or bigger than those would probably not be quite as good.
NOTE you could be somewhat gear bound and need to pull more than 5 rear teeth, pull until you hit 4850 rpm then if you need more speed look to your tires, and set up an if you improve there then you'll need to pull even more teeth.
 
Racing is a speed contest, not a contest to see who can turn
the most or correct RPMs. Nothing you do to your kart matters unless
it produces more speed/lower lap times.
Forget about the RPMs, look at your lap times. Follow
Racing Promotor's advice.
 
Thanks guys, I appreciate the input. Anyone else with any information I’m all ears and willing to listen and take it all in. I’m not too prideful to ask for help it’s just a matter of getting people to be truthful lol. I know a lot of guys have put in the time though and are not willing to share their knowledge and I respect that. This is my first time messing with a predator and I’m clueless, when I last ran we was running stock appearing Briggs and that’s been a while lol.
 
What are your rpm drop's in the corner's ? Are you off the gas any ? A lot of it could be because of corner speed is not very good , which is a set up issue and not so much a gearing issue . I am a bigger guy , so I tend to be 1 tooth down on the drivers than some of my lighter racers , which seems to pull me thru the corners better .
 
He's gotta correct his gearing issue before he works on set up, he's way over turning it now, once he gets gearing correct then if he still needs speed then look to tires and set up, then if he get's it rolling better he'll need to pull even more rear gear every 3 ths gained is a tooth off.
 
GClary said:
What are your rpm drop's in the corner's ? Are you off the gas any ? A lot of it could be because of corner speed is not very good , which is a set up issue and not so much a gearing issue . I am a bigger guy , so I tend to be 1 tooth down on the drivers than some of my lighter racers , which seems to pull me thru the corners better .
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Off the gas just a quick blip on entry then right back into it. Had the kart to tight first time out and I could hold it wide open but I took some cross out and loosened the kart up a bit and now just kind of blipping the throttle on entry. Idk what the rpm drop is but I’ll try to watch my tach this week and see.
 
my advice is to run around 4600. A bigger front driver is an advantage as it has a bigger mechanical advantage, you will have less chain tension and less chain friction.
 
So I swapped up the driver and the rear sprocket and brought my ratio down pretty good. Went out in hot laps and we only turned about 4200 so we added a few teeth out back and ended up turning right at 4800 with a 16-65 in the feature and was good enough to bring home the win. Thanks for all the help and guidance guys!
 
Nocoolname said:
So I swapped up the driver and the rear sprocket and brought my ratio down pretty good. Went out in hot laps and we only turned about 4200 so we added a few teeth out back and ended up turning right at 4800 with a 16-65 in the feature and was good enough to bring home the win. Thanks for all the help and guidance guys!
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SWEET !! Good Job now just because it got ya the win, don't get hung up on that 16 driver only, play with it a little the 15/61 or 14/57 could end up slightly better OR you'll prove you like the 16 driver best.

Good Luck !!
 
Also don't just stay focused on gearing, start paying real close attention on what your kart is doing and could it be tweaked to picked up more speed, whether that tweak is set up or tires.
 
Nocoolname said:
So I swapped up the driver and the rear sprocket and brought my ratio down pretty good. Went out in hot laps and we only turned about 4200 so we added a few teeth out back and ended up turning right at 4800 with a 16-65 in the feature and was good enough to bring home the win. Thanks for all the help and guidance guys!
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When you say so added a few teeth to back, how many was a few ? I'm asking so you know how many rpms the track picked up on it's own going from 4200 to 4800 wasn't all from only adding a few .
 
"...ended up turning right at 4800 with a 16-65 in the feature and was good enough to bring home the win."
Proving once again that lap times not RPMs win races.
Congratulations.
Feels good don't it ?
 
racing promotor said:
When you say so added a few teeth to back, how many was a few ? I'm asking so you know how many rpms the track picked up on it's own going from 4200 to 4800 wasn't all from only adding a few .
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If I recall correctly I think we added 3 teeth, the kart was tight in practice but we made some adjustments to loosen it up as well. It kinda just worked out that our adjustments and the gear change fell into a perfect storm.
 
Just wanted to do another little update. Haven’t made any gear changes since my previous post. Kart has been doing very well ran 2nd in the feature this past race. The guy who out ran me got out a couple kart lengths every restart and then we pretty much stayed in that same position not gaining or losing any ground. I have a little extra weight over them I know. I’m currently running a maxtorque clutch and it starts engaging around 2200. Thinking about changing clutches so I can get maybe 500rpm more stall out of the hole to help me on restarts. Thanks for the help and info so far guys. It has been greatly appreciated
 
Nocoolname said:
Just wanted to do another little update. Haven’t made any gear changes since my previous post. Kart has been doing very well ran 2nd in the feature this past race. The guy who out ran me got out a couple kart lengths every restart and then we pretty much stayed in that same position not gaining or losing any ground. I have a little extra weight over them I know. I’m currently running a maxtorque clutch and it starts engaging around 2200. Thinking about changing clutches so I can get maybe 500rpm more stall out of the hole to help me on restarts. Thanks for the help and info so far guys. It has been greatly appreciated
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Following. What clutch and did it work
 
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