Big Boy Gearing

Macdaddy

New member
I know I know gearing always becomes a touchy subject but I need some help. I race at space coast speedway in cocoa and running a box stock sealed motor and weight in at 407lb with no lead. They don't offer a sealed heavy class so that's out of the question. I need some input for any of you bigger guys that may have some insight on what gears to try. Any help is appreciated.
 
As far as just weighing more that depending on the rear gear the others are on is usually just 2 more rear teeth, or if there rear gear is on the bigger side already you would run a front driver size smaller. Do you know good gearing for most and your asking only because of the added weight ? OR your starting in the dark ? If so we'll need to know close track size, how much momentum you can carry, and do you know your target RPM ?
 
The kid that runs in front is running a 12 49 but he's right at the min weight 375. I ran last night a 13 53 turning 6186 rpm. I can pretty much keep it pegged to the floor and drive around. I a new driver and I have only raced 3 times so far and I wanna keep competitive.
 

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The kid that runs in front is running a 12 49 but he's right at the min weight 375. I ran last night a 13 53 turning 6186 rpm. I can pretty much keep it pegged to the floor and drive around. I a new driver and I have only raced 3 times so far and I wanna keep competitive.
Do you know what your Ideal target RPM should be ? Do you know what RPM the kid running in front is turning ?
 
It appears that, right now, you're both running pretty much the same gear ratio. Try adding 2 teeth to the axle. You'll need to pick up about 200 RPM to be going the same speed on the top.

What have you done to the engine? Timing, compression ratio, fuel, spark plug, blue printing??

All these questions need to be answered!!
 
What Al said, you want your peak RPM at the end of the straight, should be around 6500 to 6700 maybe 6800 for a box stock unrestricted clone. Add a tooth to the rear gear for each hundred RPM (approximately). If your not gaining RPM you went too far and you need to back up. Gearing past the limit of your motors top RPM can damage your valve springs.
 
He said he's running 6300 rpm.
I assume you tried starting with the 13 driver to avoid the Mini gears, which should be fine you don't need the mini gears to make your max speed, Box Stock should't be over 6400 maybe 6500 max. Add 2 teeth to the rear first 32 lb more weight will hinder you some but isn't to crazy, remember gearing is not everything bottom line I guess I'm saying he's not winning ONLY because he's on a 12/49, with only running 3 races your probably not maxing out momentum yet, is your kart handling OK, how do you feel your tires stack up ?
 
Ya my kart feels good. It pushes the front the first 2 laps a little it was cold when I raced sat so that could be causing it. Ill add 2 teeth to the rear and see what that does. I can keep it floored all the way around the track so I feel my momentum i can keep it up.
 
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Ya my kart feels good. It pushes the front the first 2 laps a little it was cold when I raced sat so that could be causing it. Ill add 2 teeth to the rear and see what that does. I can keep it floored all the way around the track so I feel my momentum i can keep it up.
Figure out what max RPM's it likes, then Tires, Tires, Tires, Tires !!

Good Luck !!
 
RULE #1:
Do your turning and decelerating while going uphill. (uphill is up the bank of the track)
Do your accelerating if possible mainly downhill, then when going straight or while reducing the amount your turning.

Downhill is your friend lean on and rely on your friend.
Uphill is your enemy USE and control your enemy to defeat it and to store your spoils battling it for accelerating.

RULE #1:
In order of importance your "potential" end maximum speed down the straight is determined by:

1. How long you make the straight.
2. Your speed at the start of acceleration.
3. How much turning you have left to do after the start of acceleration.

The above 3 items are what determines your "potential" speed at the end of the straight.
While driving you can alter the above 3.

RULE #1:
Gearing needs set so you can use up your engine per racing needs either at the end of the straight or earlier.

1. You NEVER change gear to be just as good as who your racing against.
2. You add gear to gain a racing advantage some place before the end of the straight.
3. You take off gear to gain a racing advantage towards the end of the straight.

Everything else are variables which can be adjusted off the track to allow you to improve on track to reduce your time between the end of the straight and the start of acceleration onto the next straight.

RULE #1:
How good you are on the straight is determined by how well you got thru the last turn.
You can only get faster on a straight by improving on:
1. How fast you got thru the last turn,
2. Your trajectory or how your setting and positioned when you start your acceleration.
3. The length you set for the next straight.

IMHO you must relate any and all off track adjustments offered to you to how it will improve what's determined by RULE #1. ... :)

... gota go find a coffee ... :)
and yeah .... all the above is proly just incorrect wrong bull which should be ignored because it's all just IMHO and ain't necessarily right anyway. ... :)
 
In the above I made no mention of momentum.
Here a quick about momentum.

"Momentum depends upon the variables mass and velocity. In terms of an equation, the momentum of an object is equal to the mass of the object times the velocity of the object. where m is the mass and v is the velocity."

The simple of it is you can only gain on what's lighter thru the turn or anywhere else, if you constantly increase your entry speed and/or maintain more speed between turn in and the start of acceleration. ... period

You can only do it if you are able to use the additional grip potential you have because of having more weight.

The last lap screw up by the first place car allowing Bell to gain position into the next turns was the first place driver not taking advantage of stored potential accelerating down hill. If he had run the same line as Bell it would not have been blocking it would have been to use the bank of the track to accelerate. The racing toss up of it was "when" Bell stopped using the first place car to punch a hole in the wind and gain on it switching instead to using stored energy downhill to pass.
Bell an experienced open wheel racer setup driving for when he was going to switch from good air to using stored momentum.
Too soon or too late and the race would have ended differently.
The first place driver lost because he extended turning while accelerating and Bell.

The second thing which allowed Bell to overtake the first place driver was not about lack of brakes by the first place driver, it was about how well the first place driver blocked Bell and positioned Bell at turn entry.

... maybe??????? ... :)
 
Ya my kart feels good. It pushes the front the first 2 laps a little it was cold when I raced sat so that could be causing it. Ill add 2 teeth to the rear and see what that does. I can keep it floored all the way around the track so I feel my momentum i can keep it up.
I'm trying to figure out how your holding it wide open with those tight turns. We've ran asphalt for many years on a similar looking track and while you can hold it wide open at times, your faster times come with knowing where and when to let off or trail brake. 35# heavy aint' alot either so don't sweat that.
What tires you on and how much air ?
Your motor shouldn't turn over 6500, I'd shoot for 6300-6400.
 
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