How differentials work

A differential is an important component in any vehicle, it allows the outside wheel to rotate faster than the inside wheel when you are cornering.This is necessary because when you turn your car the inside wheel has a shorter distance to travel than the outside wheel. Without a differential it would be very difficult to steer, if you had a rear wheel drove vehicle you would probably see the front wheels skidding along the road. You would also be putting huge pressure on your axle which would probably snap if you had good traction from your tires.

I know now you are thinking “I’ve taken apart cheap RC cars and they didn’t have differentials, how it that?” Well there are a number of reasons,

  1. Its cheaper not to have a differential and cost is a big factor in toy manufacture
  2. I guarantee the car was light making it easier for the wheels to slip slightly
  3. The tires were probably a plastic kind of rubber quite hard and low grip
  4. Possibly one wheel free wheeled
  5. And finally drifting a toy car is much easier with a solid axle because you want both wheels to spin and if there was a diff then probably only one wheel would spin.

Here is a great video showing how a differential work but there is quite a long introduction.

So now you are all thinking lets run out and buy a diff for our 1:32 scale tractors but unfortunately I don’t think you can get one that small. If someone knows better please let me know, I’d be very interested in that. What can you do instead of a differential on a 1:32 model? You have to leave one wheel free to spin, this will make your model steer much better but there is of course a downside. If you only have one drive wheel then you can only pull when that wheel has grip. Its actually the same with a differential, from a mathematical point of view one wheel is fixed and the other is driving but thats way too dull and boring for this blog. All you need to know is that is why tractors have a diff lock, you lock the differential and you can pull with two wheels or four depending on the vehicle.

I chose to keep the solid axle on my RC Fendt 936 build because I prefer to have the power to pull in a straight line and the steering is only okay. Unlike a toy RC car the SIKU model is heavy and has great grip from its rubber tires.

If you are working on 1:16 or 1:10 models then you have the option of adding a differential like the one above or even adding a gearbox which allows you to change gear. Pretty cool stuff but the costs will start to add up. Tamiya does some cool differentials and gear boxes if you are looking for those.

Here is a video of a Tamiya gearbox as an example, I think its from one of their 1:10 scale trucks.

If you have any questions then start a topic on the RC Tractors Forum and we’ll do our best to answer. Don’t forget to like us on Facebook, follow the updates on Twitter and keep an eye on the RC Tractors Website for any changes.

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