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Old 01-04-2010, 10:00 AM   #1
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Default Gearing Ratios for on-road

Hi guys,

Need help on gearing ratios for on-road.Especially the effects of you changing the pinions or spurs etc.Really appreciate any inputs.Many thanks in advance.
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Old 01-04-2010, 10:03 AM   #2
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what car
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Old 01-04-2010, 10:12 AM   #3
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im currently on Serpents 733 and 966
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Old 01-04-2010, 10:40 AM   #4
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go to serpents site and there should be a gear chart
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Old 01-04-2010, 10:52 AM   #5
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well i know abt the charts and numbers.but what does the numbers mean and how does the numbers apply to tracks and engines you are on?
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Old 01-04-2010, 11:24 AM   #6
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The type of gearing is depending engine and exhaust combo and also the track.

Lighter gearing (smaller pinion and/or larger spur) will give:
- a faster accelerating car
- better high speed cornering
- more top rpm on the engine (resulting the same topspeed)
- a more tricky car (more power on the wheels)
- less wear on the clutch
- less critical clutch

Heavier gearing (larger pinion and or smaller spur) will give:
- slow acceleration
- bad high speed cornering, the engine will stay on a lower rpm loosing power
- less top RPM but maybe more top speed (for what its worth)
- easy driveable car
- more wear on the clutch
- more critical to find the best working clutch

With my Mugen/Eagle-R09 I was always running 50/46 on 17/20 but When I swapped to 16/19 I was 0.3 sec a lap faster. Because most tracks have the layout you must accelerate from corner to corner for many times that the lower top speed on the straight is no issue.
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Old 01-04-2010, 11:33 AM   #7
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Quote:
Originally Posted by Roelof View Post
The type of gearing is depending engine and exhaust combo and also the track.

Lighter gearing (smaller pinion and/or larger spur) will give:
- a faster accelerating car
- better high speed cornering
- more top rpm on the engine (resulting the same topspeed)
- a more tricky car (more power on the wheels)
- less wear on the clutch
- less critical clutch

Heavier gearing (larger pinion and or smaller spur) will give:
- slow acceleration
- bad high speed cornering, the engine will stay on a lower rpm loosing power
- less top RPM but maybe more top speed (for what its worth)
- easy driveable car
- more wear on the clutch
- more critical to find the best working clutch

With my Mugen/Eagle-R09 I was always running 50/46 on 17/20 but When I swapped to 16/19 I was 0.3 sec a lap faster. Because most tracks have the layout you must accelerate from corner to corner for many times that the lower top speed on the straight is no issue.
Good info, as always, so help me out here, because I totally forget....

What do calculated gear ratio values mean in this 720 spreadsheet?

http://nitrokb.netne.net/720/front%2...rive%20720.xls
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Old 01-04-2010, 11:49 AM   #8
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Larger spurs and smaller pinions can result in more fuel effeciency. This can also be other way around but mostly in this situation.(depending on MY experiences.)
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Old 01-04-2010, 01:22 PM   #9
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Quote:
Originally Posted by rmdhawaii View Post
Good info, as always, so help me out here, because I totally forget....

What do calculated gear ratio values mean in this 720 spreadsheet?

http://nitrokb.netne.net/720/front%2...rive%20720.xls
That is one of my spreadsheets! Good to see that they are used!!!

The calculated gear ratio number means that you get a higher top speed for lower numbers. I use this to compare one pinion/spur set to another of a different ratio when gearing for a particular track. This number does not take into consideration the diameter of the tire which is a major contributor to OVERALL gear ratio.

Also, the top of the spreadsheet has the FRONT to REAR overdrive ratio info based on the diameter of the tires that you have on your car. This is useful because a lot of people run different pulleys on their car. This spreadsheet allows you to change the number of teeth on the pulleys to see what impact it has on the front to rear overdrive ratio.

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Old 01-04-2010, 01:38 PM   #10
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Originally Posted by Winner's Circle View Post
That is one of my spreadsheets! Good to see that they are used!!!

The calculated gear ratio number means that you get a higher top speed for lower numbers. I use this to compare one pinion/spur set to another of a different ratio when gearing for a particular track. This number does not take into consideration the diameter of the tire which is a major contributor to OVERALL gear ratio.

Also, the top of the spreadsheet has the FRONT to REAR overdrive ratio info based on the diameter of the tires that you have on your car. This is useful because a lot of people run different pulleys on their car. This spreadsheet allows you to change the number of teeth on the pulleys to see what impact it has on the front to rear overdrive ratio.

Lee Muse
Thanks Lee!!
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Old 01-04-2010, 06:13 PM   #11
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For serpents you want to use there drive calculator. Its nifty program on there web site. You can adjust all the paramitors. Like tire size, pulleys, gear ratio's.
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Old 01-04-2010, 09:27 PM   #12
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Quote:
Originally Posted by Roelof View Post
The type of gearing is depending engine and exhaust combo and also the track.

Lighter gearing (smaller pinion and/or larger spur) will give:
- a faster accelerating car
- better high speed cornering
- more top rpm on the engine (resulting the same topspeed)
- a more tricky car (more power on the wheels)
- less wear on the clutch
- less critical clutch

Heavier gearing (larger pinion and or smaller spur) will give:
- slow acceleration
- bad high speed cornering, the engine will stay on a lower rpm loosing power
- less top RPM but maybe more top speed (for what its worth)
- easy driveable car
- more wear on the clutch
- more critical to find the best working clutch

With my Mugen/Eagle-R09 I was always running 50/46 on 17/20 but When I swapped to 16/19 I was 0.3 sec a lap faster. Because most tracks have the layout you must accelerate from corner to corner for many times that the lower top speed on the straight is no issue.
Thanks Roelof,

Yeah,the local track i usually plays has alot of tight turns and hairpins with just a single short straight.I guess I just have to get a couple of pinions and spurs to try which is best.

Thanks to the other guys for all your inputs,given the gearing ratios issue almost settled.But how about the other factors such as tire size,engine and pipe and manifold combo affect the car on different tracks?
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Old 01-05-2010, 01:27 PM   #13
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Quote:
Originally Posted by tq23 View Post
Hi guys,

Need help on gearing ratios for on-road.Especially the effects of you changing the pinions or spurs etc.Really appreciate any inputs.Many thanks in advance.
Gear Ratio
The primary tuning option relating to your car’s transmission is the ability to change gear ratio by using different spur gears or pinions. Gear ratios are most often quoted in the form “2.4 to 1”. This can be represented in writing as 2.4:1. This means that the motor must rotate 2.4 times for the car’s driven wheels to complete one full revolution.
Most instruction manuals should tell you the internal ratio of your car.

The formula for calculating gear ratios looks like this:
(# Teeth on spur divided by # teeth on pinion) multiplied by Internal Ratio = Gear Ratio

We’ve already seen how gear ratios can be represented as numbers (e.g. 7.8:1). The tricky part is in describing ratio changes in general. If you put a bigger pinion on the car, the ratio will change to a small number (say 7.4:1). Whilst the numerical figure has become smaller, the actual gear ratio 7.4:1 is said to be a ‘higher’ ratio than ‘7.8:1’. Similarly, moving to a smaller pinion will produce a ‘lower’ ratio (say 8.2:1). Changing the spur gear has the opposite effect. A smaller spur gear will result in a ‘higher’ gear ratio, and a larger spur gear will give you a ‘lower’ gear ratio.

Confused? Stay with me.
Gear ratio changes do a couple of things. Let’s look at both the ‘lower’ and ‘higher’ gear ratios separately to see what we find.
A lower gear ratio will mostly give you more run time and more acceleration. It’s also generally easier on your motor.
A higher gear ratio will generally give you more top speed, and less run time. It’s also tougher on your motor.
Once you get to a certain ratio point (lets call it the ‘optimum ratio’) continuing tonchange to a higher ratio will do nothing but damage. It will result in your motor overheating and being damaged, and in extreme cases, your car may actually go slower.

Look at this simple chart, which might help make things clearer.

Pinion Spur Gear Ratio Gearing Top Speed Acceleration Run Time
Bigger smaller higher up more less less
Smaller bigger lower down less more more

For help on choosing your actual gear ratio for any given motor or track, consult your car's instruction manual or check with the local fast guys.

Hope that helps!

AFM
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Old 01-05-2010, 05:19 PM   #14
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what about mtx4r...with standard internal pulley with 17, 23 pinions and 59,53 spurs..???

how tu calculate the ratio?
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Old 01-05-2010, 06:20 PM   #15
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Quote:
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what about mtx4r...with standard internal pulley with 17, 23 pinions and 59,53 spurs..???

how tu calculate the ratio?
MTX 4 Internal Ratio is 2.16

So your first gear ratio is 59/17 = 3.47 x 2.16 = 7.496 final ratio
Your second gear ratio is 53/23 = 2.304 x 2.16 = 4.977 final ratio

Which at, lets say 35,000 engine rpm with 62mm cut foams would give you
55.06 kph speeed in first gear. and 82.96 kph in second speed

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