Mardave Diff Question?

[f888fhw]

I have balanced the Mardave diff by adding weight to the opposite side via the Zdrive. BUT I'm not sure if doing this will have a negative effect on the car with an increased moment of inertia on the diff drive shaft (basically i'm putting a form of a fly wheel on the shaft, increasing the amount of work the motor will need to do).

I can reduce the affect of the moment of inertia by making the weight diameter smaller and longer.

Has anyone got any thought regarding this? See the picture bellow.

[JimboJames1972]

I know there will be differences of opinion here, but I do balance my rear pod. At least, as best as I can...

First off I use the steel z-drive rather then the alloy one. This is a bit heavier and will definitely add to the fly-wheel affect when you accelerate your rear axel but, since its diameter is relatively small the increase is minimal (certainly less than I can notice on the track!). To help off-set this I either use a plastic diff cup or the alloy one I lightened.

Next I space the motor away from the pod. I usually run a Thunder Power motor and the position of its sensor cable plug allows me to space it further away from the pod than other motors. I use 4mm spacers. Much more than this and I also run out of motor axel to clamp the pinion to...

Lastly I add some ballast to the non-diff side of the pod. For me, 40g just about does it. This is in the form of thin lead strips that I attach to the outside of the bottom of the pod (keep the weight as low as possible).

My pod balances pretty much perfectly when taken off the chassis. My chassis also balances perfectly without the pod. Put the two together and the car balances just right :-)

I know that small chassis imbalance can be gotten over through different rear spring tensions (ie, run one tighter than the other) but in my mind this does not seem logical. I prefer to get the balance right through balancing my chassis.

Hope this helps,

James

[f888fhw]

Thanks for the reply. I think the best thing to do is try it then make my decision from there. If it feels better great, if not take it off and I have lost nothing.

It might be a better option on more flowing tracks as the axle will want to keep spinning on when off the throttle?

[dale]

You do want to balance the pod, but not by adding weight to the axle. Space the motor to the left as far as you can, then add lead to the left-hand side of the pod until its balanced.

You always want the rotating mass to be as small/light as possible.