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Old 02-27-2003, 10:29 PM
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Default Belt vs shaft

i'm looking to go to elec racing and i was wondering whats the difference from belt and shaft. Most of the new elec cars i've seen are shaft driven.
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Old 02-27-2003, 10:44 PM
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A shaft car are more direct (responsive) to trigger movement.

A shaft car got some more acceleration, while belt cars got more top-end. A belt car are a little less responsive, and therefor often easier to drive.

Personally I believe that the movement to shaft cars are a marketing phenomonen. The industry need to develop something new, to continue sales.

If one system really was that much better, that system would have dominated for years. Both shaft and belt cars have existed for quite a long time by now.

So choose what attracts you most. In the end, it's 80% driver and 20% car.
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Old 02-27-2003, 10:56 PM
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Originally posted by Cole Trickle
A shaft car got some more acceleration, while belt cars got more top-end. A belt car are a little less responsive, and therefor often easier to drive.
Why is that? Why do belt driven cars have more top end than shafts? I beleive they're both the same it's just that some belt driven cars can slip their belt on power and when braking where shafts cannot.
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Old 02-27-2003, 11:56 PM
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The difference in performance between belt and shaft drive is slim. Like others have said it seems that shaft drive has a slight advantage in acceleration compared to belt drive. I'm not sure about top end, even with gear ratio being the same it depends on how heavy (or light) the actual drive train components are.

Efficiency aside, most electric shaft driven cars i've seen has the shaft running through the middle with electronics, motor and battery position beside it. Personally i do not like this because i love symmetrical chassis. Thus my favorite layout to this day is dual belt with saddle pack (a la Pro 2, 414, TA04 etc). But shaft drive does have the benefit of not using belts & pulleys that can be fouled up in less than ideal conditions.

Tamiya released the TB Evo 3. It may be a car you'd like to look into.
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Old 02-28-2003, 01:04 AM
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The reason for differences in acceleration and top-end are this: The loss in a shaft system, is constant. But a belt car got a little more resistance at low speeds. But when speeds increaser, then the belt want to move away from the pulley (centrifugal forces, I believe) and this way the resistance between belt and pulley are reduced.

Personally, I've never had problems with "fouled up" belts and pulleys.

Belts requires a little more attention, because they stretch a little over time, thus tension have to be adjusted. A car like XXX-s, requires less cleaning and theres no problems with stones in the belts. However, personally, I find that the belt maintenance is so little, that it's not worth talking about.

I haven't tried a shaft car. But from time to time, I hear people complain about torque steer under heavy acceleration. As far as I know, some models have more problems with this than others.
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Old 02-28-2003, 05:22 AM
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I've been running a TC3 (shaft) for about 4 years now. I have tried a Losi XXXS (belt) before and am getting ready to try one again.

On the TC3, I never noticed the torque steer problem that people keep mentioning. I've run stock and mod with it and neither has had this problem. This car definitely applies the motor power directly. Acceleration is a little better than with the Losi. There is more noise due to the bevel gears, but the drive train is VERY free.

On the Losi, my experience was that it is a VERY smooth car. The power application is a little less aggressive. I found that the drive train is not as free as the TC3, at least on my cars. Based on track performance of these cars, that is not significant, but may require a different driving style to keep the car rolling through the corners.

I think a shaft car is the better car for a driver who squares off corners or slows down a lot for corners. It's aggressive pull out of the corner can make up for some of the speed lost where a belt car would not recover as quickly.

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Old 02-28-2003, 05:43 AM
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Jeff,

I think this the most object description I've seen so far.

It's also the explanation, that makes most sense to me.
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Old 02-28-2003, 07:26 AM
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Thank you Cole.

This topic always seems to generate some fun debate. My opinion is that neither of these designs is bad, just different. There are people that are a bit more opinionated than me though!

The one thing that always strikes me as funny is when the people who drive the belt cars ask me how bad my torque steer is! My comment is always that I've never noticed any torque steer. What I HAVE noticed (mostly in mod) is the brutal transfer of power to the wheels which can sometimes break traction. I think some people are mistaking this for torque steer.

The definition of torque steer that I have is: The effect of the motor on the turning wheels to change their direction.

This definition is based on when the first references to torque steer came out for real cars with front wheel drive. Basically this was when you were trying to steer the car and apply throttle, the motor would fight your efforts on the steering wheel and attempt to change the direction of the front wheels.

With this definition, both belt and shaft cars may be experiencing torque steer.

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Old 02-28-2003, 07:41 AM
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I have tried both a shaft drive(Academy STR-4pro) and a single belt(Kyosho KX-1), and other than the initial(from dead stop or from near stop in a really tight corner)acceleration advantage of the shaft, I really don't see much of a difference. In fact, once the cars get up to speed, my belt drive car seems to carry more speed down the straight, but it does have a one-way installed while my shaft car doesn't, so that could account for that.

To tell the truth, I just don't see what the difference is. I've done well with both and put in nearly identical times with both. Its just a matter of which cars look best to you, but the performance differences really are minor.

Just my 2 1/2 cents!
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Old 02-28-2003, 11:03 AM
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Talking Shaft

I would have to say shaft...
but then again... I'm biased'

-Dave
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Old 02-28-2003, 11:42 AM
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As far as I know, it aint possible to use a one-way pulley on a shaft car (nor single belt).

I think that it should be taken into account, when choosing a car. Especially since it seems that a one-way pulley are easier to drive, than a one-way diff, yet one could gain a good advantage. Also, when using a one-way pulley, you're able to use that nice light front ball-diff.

This is not really a concern for first buyers, and of course not for people who dont like one-ways.
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Old 02-28-2003, 12:47 PM
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Originally posted by gotpez
Thank you Cole.

This topic always seems to generate some fun debate. My opinion is that neither of these designs is bad, just different. There are people that are a bit more opinionated than me though!

The one thing that always strikes me as funny is when the people who drive the belt cars ask me how bad my torque steer is! My comment is always that I've never noticed any torque steer. What I HAVE noticed (mostly in mod) is the brutal transfer of power to the wheels which can sometimes break traction. I think some people are mistaking this for torque steer.

The definition of torque steer that I have is: The effect of the motor on the turning wheels to change their direction.

This definition is based on when the first references to torque steer came out for real cars with front wheel drive. Basically this was when you were trying to steer the car and apply throttle, the motor would fight your efforts on the steering wheel and attempt to change the direction of the front wheels.

With this definition, both belt and shaft cars may be experiencing torque steer.

Jeff Gilligan
That is an interesting observation. However, you can't compare the forces on a real car to an RC car in regards to torque steer. In shaft driven electric RC cars, the placement of the motor is key. The TC3 and EVO3 have a motor mounts perpendicular to the centerline of the car. This mount moves in the vertical direction when power is applied and released to and from the motor. Just like applying power to a electric buggy when in the air will adjust pitch of the car, applying power to a shaft drive touring car adjust the pitch. Keep in mind the position of the touring car motor is parallel to the centerline of the car, not perpendicular as in the buggy. The forces as the power is applied pitches that side of the car causing it to lift. This lifting causes weight to be transfered to the opposite side of the car which, in turn, creates more applied power on the front wheel causing the car to pull to one side (torque steering). The new HPI shaft drive electric car has it's motor mount on the centerline of the car. This design, as explained to me by Thad Garner (HPI driver), was developed by Atsushi Hara significantly reduces the torque steering. Hope I didn't confuse anybody.
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Old 02-28-2003, 01:02 PM
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Not confusing Neil, good explanation.

The chassis will get light on one side in a TC3 when the motor spins. This effect should be minimal compared to off road vehicles though. When an off-road vehicle adjusts it's attitude in mid-air, it isn't just the motor spinning that does the adjusting, it is also the entire drive train, including the driven wheels. That is a great deal of weight acting together to re-orient the car.

In my experience with the TC3, the effect of this is not noticible, especially with a stock motor.

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Old 02-28-2003, 01:05 PM
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Originally posted by Cole Trickle
As far as I know, it aint possible to use a one-way pulley on a shaft car
?? Thats funny.? On my barracuda I have dual oneway set up.... one in the front diff housing and one on the center shaft

-Dave
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Old 02-28-2003, 01:13 PM
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Originally posted by JDM_DOHC_SiR
?? Thats funny.? On my barracuda I have dual oneway set up.... one in the front diff housing and one on the center shaft

-Dave
I think he said "pulley" which is not used in shaft car in anyway. He also said one-way diff, which is what you have.
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