What RPM Gains Can Be Expected from a Lighter Axle on a Go Kart?

  • Thread starter steven mosher
  • Start date
  • Tags
    Gain Rpm
In summary: Additionally, you may be able to find lighter flywheels without sacrificing durability. A lighter flywheel may allow for greater acceleration, but it is unlikely that you would be able to notice a difference in speed.
  • #1
steven mosher
8
0
I need to know whether to invest in a new lighter axel for a go kart

Before I take the plunge, I'd like to get "some" kind of idea of the kinds of gains one can expect from this kind of change.

The conditions as I know Them.

the 5Hp engine achieves max torque at 5200-5400 RPM.

the motor is geared at 6:1 and the gearing from the motor to the rear axel
is 34/27.. for a combined gear ratio of 4.76:1.

The current rear axel weighs on the order of 4 Lbs, without tires.
what kind of RPM gains could one expect from reducing real axel weight
to 2 lbs?

Note: the different between first and last is somewhere on the order of 1-2 % of rear axel RPM.
 
Science news on Phys.org
  • #2
The weight of the axel will affect your acceleration, but not your top speed. Since a torque is essentially a force, weight (mass) and torque are related by f=ma. Finding out how much is a little difficult because you have to add together the angular acceleration of the rotating parts and the linear acceleration of the car.
 
  • #3
In principle, a lighter axle helps acceleration. In practice, however, you won't find a measurable difference. (By axle, I'm assuming you mean the shaft between the final drive and the wheel.) The axle, being far smaller in diameter than the wheels, and considering that moment of inertia is proportional to the square of diameter, has an inertia effect which negligible compared with the inertia effects of the wheels, or even the crankshaft.
 
  • #4
Thanks a ton

You just saved me 675 dollars!
 
  • #5
krab is right that you won't notice a difference by changing the axle, but you could with other components. For example, the flywheel and clutch can be important (you still have those on go-karts, right?). You can define an effective mass due to the rotating parts, and you'll find that it is proportional to the square of the gear ratio from the wheels to the part you're talking about. So even if the object's moment of inertia is relatively small, its effect can be magnified a lot.
 
  • #6
Dear Steven,

As Stingray suggests, a lighter flywheel may be worth looking into.

Years ago, some short track motorcycles reduced the rotating mass of their flywheels for greater acceleration by removing the flywheel's electrical guts.

Instead of generating its own electricity from the spinning flywheel, the motor ran off a total-loss ignition system. A small battery powered the breaker points and spark plug and easily lasted for a short race.

In addition to the reduced rotating mass near the rim of the flywheel, the motor was relieved of the far smaller burden of generating the electricity.

The effect was small, but useful in racing.

Carl Fogel
 
  • #7
Thanks Guys

Flywheel modifications are not allowed in this stock clas; however, it is possible to work with lighter gears ( reducing rotating mass) on the engine.
My understanding is that this type of modification would go to acceleration only
 

1. How does a lighter axle affect the RPM of a vehicle?

A lighter axle can result in higher RPMs for a vehicle. This is because a lighter axle requires less effort to rotate, allowing the engine to rev up more quickly and reach higher RPMs.

2. Is there a specific weight that an axle should be to optimize RPM gain?

The weight of an axle will vary depending on the vehicle and its intended use. Generally, a lighter axle will result in higher RPM gain, but it is important to consider other factors such as durability and safety when choosing an axle weight.

3. Will a lighter axle improve the overall performance of a vehicle?

Yes, a lighter axle can improve the overall performance of a vehicle. In addition to increasing RPMs, a lighter axle can also improve acceleration and handling, as it reduces the weight and inertia of the vehicle's drivetrain.

4. Are there any downsides to using a lighter axle for increased RPMs?

There are a few potential downsides to using a lighter axle for increased RPMs. Firstly, a lighter axle may not be as durable as a heavier one, which could lead to increased wear and potential failure. Additionally, a lighter axle may not be suitable for heavy-duty or off-road use.

5. Can a lighter axle be used as a replacement for other performance upgrades?

A lighter axle can contribute to improved performance, but it should not be viewed as a replacement for other performance upgrades such as engine modifications or suspension upgrades. These upgrades work together to optimize a vehicle's overall performance.

Similar threads

Replies
19
Views
1K
  • Mechanical Engineering
Replies
7
Views
2K
  • Mechanical Engineering
2
Replies
48
Views
21K
Replies
2
Views
6K
Back
Top