Clutch driver and Gearing

umaxk99

Member
What determines clutch driver selection Trial and error, engine torque, RPM drop? Running crate 375 class on a fairly long track have to burp throttle in one corner and breath little more in the other. on a 18 driver now but was recommended to try a 15. I will drop 700-1000 rpms at times
 
Track size and shape and the amount of momentum you can make because of good grip, What is your target RPMs ? what RPMs are you getting now with the 18 driver ? with which rear gear ? Do you know close track size ? What are your lap times ?
 

umaxk99

Member
Track size and shape and the amount of momentum you can make because of good grip, What is your target RPMs ? what RPMs are you getting now with the 18 driver ? with which rear gear ? Do you know close track size ? What are your lap times ?
Track size is around 1/5th mile. was on 18/62 (3.44) mostly turning 5400-5700 which im finding was not nearly enough rpm. tried 16/60 turned it a little harder. My target is around 63-6400. in the 18sec lap now
 

umaxk99

Member
Track size and shape and the amount of momentum you can make because of good grip, What is your target RPMs ? what RPMs are you getting now with the 18 driver ? with which rear gear ? Do you know close track size ? What are your lap times ?
Ive got a 15/56 on it now was gonna try saturday but we canceled for the hurricane ofcourse lol
 
Track size is around 1/5th mile. was on 18/62 (3.44) mostly turning 5400-5700 which im finding was not nearly enough rpm. tried 16/60 turned it a little harder. My target is around 63-6400. in the 18sec lap now
18 sec lap time it's gotta be bigger than a 1/5 mile, how are you running compared to others in your class ?
 

alvin l nunley

Premium User
Ive got a 15/56 on it now was gonna try saturday but we canceled for the hurricane ofcourse lol
I'll be real interested in seeing the results of that 15/56.
I heard the other day that someone is making sprockets to hold a gear as low as 40 teeth. I wonder what a 13/?? would do? We used to run 13 tooth clutches on the enduro tracks all the time. That's with a 2 cycle, at 12,000 to 14,000 RPM. Never had any problem with wearing them out.

Be the first on your block to try them out. Ha ha
 

Bumpy

Member
Where you are running in the pack is the question,
not how many RPMs you are turning. 18 to 15 driver
is a monumental move in my mind. I tried once to be smarter
and went from 17 to 18, bar-b-qued my clutch and slowed
down.
What are the other guys running ?
 

umaxk99

Member
18 sec lap time it's gotta be bigger than a 1/5 mile, how are you running compared to others in your class ?
to be honest i question my 4 or the beacon seems quicker than that. Its always me and another guy 1-2 out of 5or 6 karts. i won heat and feature last race but he seemed quicker at times then i would pull. That is when i tried the 16/60. Im just wondering if im leaving some speed on the table and how most folks decide when and why they swap a driver. I had heard flat footed and momentum use larger driver and on and off the gas use a smaller driver?? guess im looking for a magic formula lol. And i just double checked its a 1/4 mile
 

umaxk99

Member
Where you are running in the pack is the question,
not how many RPMs you are turning. 18 to 15 driver
is a monumental move in my mind. I tried once to be smarter
and went from 17 to 18, bar-b-qued my clutch and slowed
down.
What are the other guys running ?
Nah I been up front or 2nd mostly but to me this other guy is faster more often. I had been on 18/61 or 62 by recommendation mostly and had some success but tried the 16/60 because im hardly ever flatfooted in the corners unless track comes in good for feature. it seemed to be better. wondering if i should try the 15/56
 

umaxk99

Member
Where you are running in the pack is the question,
not how many RPMs you are turning. 18 to 15 driver
is a monumental move in my mind. I tried once to be smarter
and went from 17 to 18, bar-b-qued my clutch and slowed
down.
What are the other guys running ?
huge ratio change i know but i was only turning 5400-5700 with the 18/62 and looking more around 6300-6400
 
Your RPMs are still little low with the 16/60 SO 16/62 would get them closer 6400, If you were to try the 15 use a 58 rear, Your still lacking speed that's either set up OR Tires OR both.
 
Your RPMs are still little low with the 16/60 SO 16/62 would get them closer 6400, If you were to try the 15 use a 58 rear, Your still lacking speed that's either set up OR Tires OR both.
And as you find that speed you will increase momentum which will require slight gearing adjustments, roughly 1 tooth at a time off the rear for every
3 to 4 th gained on stop watch.
 

Bumpy

Member
huge ratio change i know but i was only turning 5400-5700 with the 18/62 and looking more around 6300-6400
We turned 57-5800 and finished 2nd in the heat race, about 3kart lengths back.
A friend said we were not turning enough RPMs and to go up a
couple of teeth. I wanted to go down a couple of teeth. He had won
more races than we had so I listened. We finished 2nd - half a straightaway
back. But we turned more RPMs which I guess was the point. :unsure:
The point is to go faster. It's not an RPM contest. If I could run 1-2 at a lower
RPM than others I wouldn't care and would work on tires and making sure
there was nothing robbing power.
 

umaxk99

Member
Let me ask like this saying that a 3.50 final drive is gonna get my RPMs where they need to be at some track...what would be the faster gear 18/63 or 16/56.
 

alvin l nunley

Premium User
Let me ask like this saying that a 3.50 final drive is gonna get my RPMs where they need to be at some track...what would be the faster gear 18/63 or 16/56.
How about 12/42 or 14/49? A lot less chain and slower chain speed too! I know, let Mickey try it first, he'll try anything. lol
If it was me, I'd be making much smaller gear changes! One tooth on the axle makes a difference.
 

Skidude

Member
I’d run the 18/63. If you ran the 16/56 you could only drop 3 teeth on the axle before you would have to change clutch gear to keep going in that direction. The 18/63 gives you plenty in either direction to make changes at the track without pulling the clutch off.
 
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