Yor83

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Hi all!

I'm very new to this (and the world of) forum, so if this is the wrong place or something, please tell me!

I've a couple of questions about the Lego differentials. I'm turning the new Porsche 911 into an RC-car, and I want to put a differential in the rear axle. Now, I only have a space of 3 studs: 1 stud at each side of the axle itself. The rear-motor is an L-motor and has to be set in the full width of the car, so that its gear is placed parallel to the gear of the rear axle. So, the differential has to be for parallel gears.
With that in mind I ended up with the versions 6573 or 65414 (the 2020 version). Will those fit in the space of a width of 3 studs?

And there's something about gear ratios. In my mind, it is better to have a bigger gear on the axle of the motor itself, and a smaller gear on the rear axle that's connected to the wheels. But, with those 2 diff versions they both have a big gear in itself, probably bigger than the gear will be that's placed on the 'motor'-axle (if there's enough space for one of those diffs). Will that be a problem?

Hope that somebody can help me out with this, cause I'm new in the world of drving shafts and things like that!

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Part 65414 with red gear should fit, but it works with 12 tooth double bevel gear, not  20 tooth

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If you want to try what bricks fit before you order them just use LDCad or Stud.io to build it digitally first :classic:

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8 hours ago, Yor83 said:

In my mind, it is better to have a bigger gear on the axle of the motor itself,

Yes, You will have higher speed, but You will loose torque on driven axle. There could be not enough torque to start that Porsche moving

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It is the same question that appears for real cars and trucks - the ratio of the "final/differential drive":

  • Less reduction (driven gear is not so small, differential gear is not so big) leads the following features:
    + better start due to bigger torque
    + bigger weigh capacity
    + better fuel economy at low speeds (less electric currency)
    - lower high speed
  • Bigger reduction (driven gear quite smaller than a differential  leads the opposite things:
    - slower start to worse torque (and bigger currency for electric motors)
    - less weigh capacity
    + better fuel economy at high speeds
    + higher high speed

     

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