Gearing question

b13

New member
The people we race with talk about putting a smaller driver gear on to help, but they change the the rear gear to and have the same ratio.
So my question is this, Is a 15/59= 3.93 better then a 16/63=3.93 and if so how/why?
 

Flathead8

New member
With the 15/59, you'll have a slower start, but more speed at the top end
and the 16/63, you'll have a quicker start than the 15/59, but will lose the top end. Flathead8
 

DBR9601

New member
Bigger tracks require bigger driver gears and vice versa. Me personally I like the 16/63 if it is going to mostly be green flag. If you are running short sprints with lots of cautions you will need the 15. Also a way you can tell is looking around at the guys up front. If they are small on the back they are on a 15. If your motor is running hot but turning the right RPM's you need to usually go down a bell. It is working the motor too hard...
 

paulkish

Premium User
It can't be said one is better or one will make a difference in all situations. Though the ratio's may be the same, the physical parts are different. Because there is a physical difference, there is a physical difference when they are operated.

If one will be better for you in your particular situation, will only be known after you try each and decide for yourself if one works better. Or one will be better if one gives better times on the stop watch. Only you can decide.

It's often asked in racing, "What is a tenth worth?". Sometimes winning or loosing is determined by much less then a tenth.

How and why there can be a difference would require describing the physical difference and how physics will work differently on each. It would also require describing how the difference will effect how your kart interacts with the tracked based on available hp, available grip, the track configuration and how each would effect your need to maintain momentum at every place around the track. It would also require how the physical differences will effect acceleration and braking at every place around the track. You would have to then take all the data from all the possible variables, combine them and pick out what is the biggest change and if the biggest change is enough to over come combined small changes. Or, you can just put a stop watch on the results and maybe just go by which seems better and might give you a small racing advantage if each give the same times.

or... If the tracks often real rough maybe there suggesting the smaller axle gear because they know a 63 will sometimes dig into or rub on the track.
 

sCREamnClones

New member
I'm in the process of 'testing' that theory right now. I have NO reason too dis-agree with it, but...I am curious how much effect it 'actually' has before 'I' wud go out and re-invest in up-grading my inventory. At this point, I am comparing combinations focussed on a '13T' and '15T' drivers. I think I can 'safely' say that YOU will NOT notice any difference between your 15-16 combo, because the +/- is still going to be rather suttle. Note that the true delta in your comination(s) does favor the '16' in that it's actually '3.9375' versa's '3.9333'!
There are several issues that add into this 'theory', but 'I' think a key element is...'Inertia'! ('lighter-is-better", so 2speak!)
 
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b13

New member
My thinking is look more at the ratio and use whatever driver is the best to get you there.
 
With the 15/59, you'll have a slower start, but more speed at the top end
and the 16/63, you'll have a quicker start than the 15/59, but will lose the top end. Flathead8
How does that work? They are both the same ratio, (within .01) 3.93 – 3.94
To go faster you need to turn more RPM if the ratios are the same.
For instance.
@6000 RPM with this ratio;
15/59 gets you 49.16MPH
16/63 gets you 49.03MPH
If anything, the bigger gears get you less speed, although I doubt you would see or feel .13 MPH difference.
Don’t take this wrong, it’s a common misunderstanding with a lot of people.
 
I wonder sometimes about how much people stress over gear ratios, (same ratio, different drivers) and pay no attention to the air density or the EGT.
I can “prove”, beyond a shadow of a doubt, that these two items have a “real” effect on HP, and along with more HP comes better lap times.
And how many have a compression gauge? You might laugh, but compression is the “Holy Grail”.
 

Flathead8

New member
Yes exactly, and Alvin you're right, it is a difference, but not noticeable, just like everyone has been saying, choose the driver that fits the track and your driving preference.
 

rebsfan4

New member
With the 15/59, you'll have a slower start, but more speed at the top end
and the 16/63, you'll have a quicker start than the 15/59, but will lose the top end. Flathead8
You have this backwards. With virtually the same ratio, the smaller driver will ALWAYS pull harder and have faster acceleration than the larger driver.
 

OBADMAX

New member
with the 15/59, you'll have a slower start, but more speed at the top end
and the 16/63, you'll have a quicker start than the 15/59, but will lose the top end. Flathead8
this sounds backwards to me or i have allways looked at it wrong for all these years but i think you do have this backwards
 

b13

New member
You have this backwards. With virtually the same ratio, the smaller driver will ALWAYS pull harder and have faster acceleration than the larger driver.
Thats what we're after is harder pulling, but in my mind the ratio is whats important not the size of the driver. It would think a 16/64 =4.00 would pull harder then a 14/55=3.93. :confused:
 

daybrace

Member
i always say if i have to use a gear bigger then a 65 in the rear,, i go down on driver, so i can stay a 65 or less rear gear. i have run a 14 driver, 50,s rear gear on tracks that people were on a 17 driver and won. puller all the way up the straight, same as at most of our tracks now,, people try to run 17 drivers and the people winning our on a 15 driver turning thier motors hard,, i have never seen a difference when you a hooked up and have the right ratio it will pull and not be gear bound,
 

rebsfan4

New member
I don't care what ratio my gearing combo is.....so long as the combo at the time produces the overall fastest lap time. Too mant folks get hung up on the ratio IMO.
 
How does that work? They are both the same ratio, (within .01) 3.93 – 3.94
To go faster you need to turn more RPM if the ratios are the same.
For instance.
@6000 RPM with this ratio;
15/59 gets you 49.16MPH
16/63 gets you 49.03MPH
If anything, the bigger gears get you less speed, although I doubt you would see or feel .13 MPH difference.
Don’t take this wrong, it’s a common misunderstanding with a lot of people
.
We have tried to explain this to you for years now, and the bigger gear, on a bigger track, will produce more speed.
Please get some experience on the subject before actually telling wrong info.
 
Many years ago, and I think I’ve told this story before; I was at an Enduro race and talking to this guy about gearing. I told him I was running a 14/62. He told me what I needed was a 13 tooth driver. I asked why that would make a difference. “I don’t know”, he said, “but that is what all the really fast people started running last year” Curious I thought. I just couldn’t imagine what difference that would make. Before the day was over, I happened to run into one of the “fast guys” that I was told had changed to the 13 tooth gear. “Why the change” I asked. “This other guy is telling me you found the 13 tooth was faster than the 14 tooth.” He smiled. Then he told me the reason for the change. It seems that Horstman had a run of 14 tooth hubs with a bad heat treat and the teeth were going away really fast, so the 13’s were the only thing available that were good. A lot of people started running the 13s because of this. It became common knowledge that the 13 tooth sprocket was faster than the 14. After all, didn’t all the fast guys use it!!
 

Bob Evans

Grumpy Old Admin
Staff member
How does that work? They are both the same ratio, (within .01) 3.93 – 3.94
To go faster you need to turn more RPM if the ratios are the same.
For instance.
@6000 RPM with this ratio;
15/59 gets you 49.16MPH
16/63 gets you 49.03MPH
If anything, the bigger gears get you less speed, although I doubt you would see or feel .13 MPH difference.
Don’t take this wrong, it’s a common misunderstanding with a lot of people.
.13 mph is something like 2.5 inches per second. That would be noticeable if you were right behind someone.
 

Bob Evans

Grumpy Old Admin
Staff member
The people we race with talk about putting a smaller driver gear on to help, but they change the the rear gear to and have the same ratio.
So my question is this, Is a 15/59= 3.93 better then a 16/63=3.93 and if so how/why?
If you are racing a sprint track with slow corners, they are correct.
If you are racing an oval where you're wide open all the time, it's the other way around.
 
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