Box Stock

Gearing one more time

B

bullerman

Member
Ran box stock class on 5500rpm rule. 350lb class approximately 625 ft track.
Hot laps on 16/60 and averaged 3943 rpm. The track was wet and slow.
I went to a 16/64 for the heat race. Average rpm was 4282 with a best lap of 12.58. A friend of mine looked at the tach and we decided to run a 15/64. I did and the my best lap was a 12.52 with average 4443 rpm.
I am still looking for the 4700 to 4900 rpm range range. To me it almost shows I need to go to a 14 driver. I know the guy I passed for the lead is running a 12 something. Still not sure what to do but with this track I don't think it is going to be a 16 for sure. I run a Hillard Flame clutch with 2800 engagment. O the start qhen we came out of 4 and got on the gas about half way down the straightway it felt like it kicked in overdrive. I don't think the clutch was slipping. Could it be it just hit its power range. I still don't know how to use this Mychron five but I think it will tell me. Just wondering about the gears. Just wasn't much difference between the 16/64 and 15/64. Seems like it should have been more.
One thing though in the feature.
 
bullerman said:
Ran box stock class on 5500rpm rule. 350lb class approximately 625 ft track.
Hot laps on 16/60 and averaged 3943 rpm. The track was wet and slow.
I went to a 16/64 for the heat race. Average rpm was 4282 with a best lap of 12.58. A friend of mine looked at the tach and we decided to run a 15/64. I did and the my best lap was a 12.52 with average 4443 rpm.
I am still looking for the 4700 to 4900 rpm range range. To me it almost shows I need to go to a 14 driver. I know the guy I passed for the lead is running a 12 something. Still not sure what to do but with this track I don't think it is going to be a 16 for sure. I run a Hillard Flame clutch with 2800 engagment. O the start qhen we came out of 4 and got on the gas about half way down the straightway it felt like it kicked in overdrive. I don't think the clutch was slipping. Could it be it just hit its power range. I still don't know how to use this Mychron five but I think it will tell me. Just wondering about the gears. Just wasn't much difference between the 16/64 and 15/64. Seems like it should have been more.
One thing though in the feature.
Click to expand...
This tells me your chasing gearing when your issue is tires, set up, and driver not maximizing momentum. The fact that you were able to still win the race, tells me your competition is off even more than you are.
 
16/60 at 3900 rpm = 41.86 mph
16/64 at 4200 rpm = 36 mph
15/64 at 3500 rpm = 35.43 mph
On a 34" circumference tire .
 
I will say this track is not a momentum track in my opinion.We have to run groove tires, no prep. The track is usually rough.. i wouldn't say the kart is loose or tight.
The track is egg shaped. You have a 120' straightway on one side and a 145' on the other. I am trying to race at what I am reading rpm wise on the site. I don't see anyway I can race at 4800 with a 16 / 60 on this track. I have tried a 16 60 and I was at 4100 rpm. I will say my fastest lap time was on hot laps with a 16 60. Will keep trying though.
 
flattop1 said:
16/60 at 3900 rpm = 41.86 mph
16/64 at 4200 rpm = 36 mph
15/64 at 3500 rpm = 35.43 mph
On a 34" circumference tire .
Click to expand...
On treads the speed is going to be more due the larger circumference. The relationship should stay similar.
If your on an off the throttle , trying to root your way under others ?
 
one tooth on the rear equals 100 rpm. a tooth on the front 300 rpm. if its a stock predator 4600-4800 rpm is target. Forget what everyone else is doing. don't chase their set up work on yours. there won't be much difference when both gearing options are wrong.
 
J'-remy said:
one tooth on the rear equals 100 rpm. a tooth on the front 300 rpm. if its a stock predator 4600-4800 rpm is target. Forget what everyone else is doing. don't chase their set up work on yours. there won't be much difference when both gearing options are wrong.
Click to expand...
And you nailed it, both are wrong.
 
What we know from first post:

16/60=3.750 gear ratio, ...tach=3943 "The track was wet and slow."
16/64=4.000 gear ratio, ...tach=4282 which was an improvement in rpm
15/64=4.267 gear ratio, ...tach=4443 and best lap time of 12.58 which was an improvement in rpm and your lap time came down

IMHO the answer is pretty simple put more gear on till you quit improving your lap times and/or rpm does not improve.

When your lap times quit improving or you can't make it spin faster no matter what the gearing, then fix other stuff to go faster.
After you fix other stuff to go faster, you'll then be able to start taking gear off and go faster still till your lap times again stay the same.
At that point there's probably still more you can do with driving and setup to include tires, to go faster.

The above is the way everyone has to do it to learn to go fast with what they have and so will you which your learning to do.
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"I still don't know how to use this Mychron five but I think it will tell me. "
It already told you what you need to know.

" Just wondering about the gears."
I hope what I explained takes some wonder out of it?

"Just wasn't much difference between the 16/64 and 15/64."
The fact is there was a difference.

"Seems like it should have been more."
Going fast is not about there should have been more it's about the fact there was more.
 
bullerman said:
I run a Hillard Flame clutch with 2800 engagment. O the start qhen we came out of 4 and got on the gas about half way down the straightway it felt like it kicked in overdrive.>>>>> I don't think the clutch was slipping. Could it be it just hit its power range.<<<<<?????
Click to expand...
You ain't got nuff HP to get a fell like the clutch just kicked in because of the engine,
It's Box Stock and per the other info you gave us your not even close to getting all you can out of your engine.
Up until the point where you felt like the clutch kicked in, your clutch was slipping.

Fix your clutch problem and it will help you get faster.
To fix your clutch problem on here we need more information about the clutch and I suggest you start another thread to get the help.
It's better to attack separate problems separately, especially this one to keep one from blurring the other.
Information= Brand, type, how you set the engagement of the clutch and how you think you know what RPM it's engaging at.

---------------------------------------------

See the last sentence in post #2

We get our fun on here hearing you report back last race out you lapped 2nd place. ... :)
 
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paulkish said:
You ain't got nuff HP to get a fell like the clutch just kicked in because of the engine,
It's Box Stock and per the other info you gave us your not even close to getting all you can out of your engine.
Up until the point where you felt like the clutch kicked in, your clutch was slipping.

Fix your clutch problem and it will help you get faster.
To fix your clutch problem on here we need more information about the clutch and I suggest you start another thread to get the help.
It's better to attack separate problems separately, especially this one to keep one from blurring the other.
Information= Brand, type, how you set the engagement of the clutch and how you think you know what RPM it's engaging at.

---------------------------------------------

See the last sentence in post #2

We get our fun on here hearing you report back last race out you lapped 2nd place. ... :)
Click to expand...
2800 on a box stock is near perfect that is right where the torque peak is.
 
Thank You

I went back and saw as you commented on he said his engagement was 2800 and that's great.
Him feeling a kick in the pants after the start made me think and still does make me think his clutch slipped out on the track and likely did not engage down at 2800 rpm.

Does the "kicked in" also make you think his clutch might be slipping on the starts?
I don't mind being wrong just offering thoughts on his problem to get him faster.

thanks again

paul
 
LOL, another question just came to me about his postings

Box Stock what?
We don't know what engine he's using and calling Box Stock?
I figure most are thinking predator but it might be briggs, boxstock clone, even a honda or something else.
 
When you get old you need all the help you can get. I am running a box stock predator out of the box governed to the 5500 rpm rule.
Hillard Flame clutch with white springs. Was on a 15/64 driver. It looks like it starts pulling off at about 2800 by my tach to me but if feels like a slow engagment.
Here come the being old part. I was cleaning the clutch and discovered I had one shoe different than the other three. I doubt if that helped. I run the clutch inboard. I now have all the shoes with what I call the leading edge forward. I am calling the leading edge the rounded off end with the holes.
in it.
I know there isn't much power there but maybe that is what I was feeling. Maybe it slipping and just getting locked. I agree that I not getting all out of the motor. Maybe why I been having gearing issues.
 
the leading edge is the edge facing the front or leading the rotation.
flip the shoes so the L faces forward then thats leading .
My belief is it needs flipped .
 
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Got the shoes turned with the L facing forward. Shoes and drum clean. Hope this does it. I was looking at the BMI gear chart. For the gear I was running 15/64 with a right rear tire diameter of 11.5 inches, the left is a little smaller turning 4500 rpm speed comes out to 36.8. I was at a little over 35 mph.
Racing promoter suggested a 16/60. I tried it but just didn't think i was turning enough rpm but I had the fastest lap I have run with that gear. Mph wise all I would have to turn is 4100 in theory to be two miles an hour faster. I just don't think the track is large enough or I have guts enough to get 4800 or 4900 rpm out of the motor. I probably am going back to the 16/60 . Thanks for all the suggestions.
 
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