What kind of differential to use?

[Junpei]

I already own a 24-16 tooth differential and a 28 tooth bevel one, but I do not own the oldest version with 28 spur teeth. I was just wondering about the performance of the old one, the newest one and the 24-16 one, but I am afraid that the 28 tooth spur differential might be bad because it is usually driven by a 14 tooth gear, which is an extremely weak gear.

[Blakbird]

I think it depends on what you intend to use it for. 8868, for instance, has two of those old differential gears and they work great. I'm not sure I would use them in a trial truck though.

[allanp]

They work fine in non motorised models, when all they have to do it turn the engine/gearbox (tho modern gearboxes are harder to turn than the older ones). They will also work for small motorised models such as the car from 8082. Used in these applications it works great, the 1:2 gear reduction you get by using a 14t bevel is nicer than the very low reduction you get from the modern diff. However it cannot move much weight. As weak as those 14t bevel gears are the teeth will slip past each other before they break.

[OleBM]

Why do you need to only use the 14 teeth gear?

I ALWAYS use the old style 28 teeth diff with either a 12 or 20 tooth double bevel... It's the strongest diff lego has ever made.

[allanp]

The 12t doesn't seem to improve things much in terms of slippage, it least for me anyway I haven't tried it much, the 20t doesn't give enough reduction for my taste. Tho I have used it with an 8t alot, works great with that and quite strong as well as having a 3.5:1 reduction.

[OleBM]

The 12t doesn't seem to improve things much in terms of slippage, it least for me anyway I haven't tried it much, the 20t doesn't give enough reduction for my taste. Tho I have used it with an 8t alot, works great with that and quite strong as well as having a 3.5:1 reduction.

That's just a matter of how you build it

The 8T gear is just hopeless when it comes to heavy duty drivetrain. I guarantee you that this is the first part to break in drivetrain applications. With the old style diff 28T, the 12T gear is the way to go. You just have to know how to build it properly so the gears won't slip.

[Junpei]

Ok thank you OleBM and allanp! I didn't know that it would work with 12 tooth gears. I think it could also be driven from the side (horizontal to the 28 tooth ring).

[OleBM]

The 24-16 diff is also very good. If you're into modifying, you can cut and reduce the axlehole depth on one of the old 24T crown gears, to make it compatible with the 24t gear on the 24-16 diff, eliminating the needs for gears in between. The result is a very compact diff solution

Edited May 10, 2013 by OleBM

[Junpei]

The 24-16 diff is also very good. If you're into modifying, you can cut and reduce the axlehole depth on one of the old 24T crown gears, to make it compatible with the 24t gear on the 24-16 diff, eliminating the needs for gears in between. The result is a very compact diff solution

That seems like a feasible solution, but I only mod pieces if I have to, sometimes even rebuild a whole model. I'm kind of paranoid about having crown gears in a drivetrain though, they are the second weakest gear.

[1nxtmonster]

The ones provided with the 9398 coupled with a washer to keep the teeth from slipping does amazing. Like what boxerlego did.