Diff Size and drive train loss

[Hen]

RA23, did you read the paragraph after the one you quoted?

Hen

[BrianRA23]

Almost everyone (except Kingmick) seems to be focusing on the acceleration issue. I think there are two questions.

What affect will it have on my 1/4mile times? - already answered
Will I be able to overtake going up a hill just as easy? (ie total rwkw change)

With an the loss when cornering will depend on the oil viscosity used, also affecting when the diff will lock up.

As I understand it straight cut gears in a gearbox will allow more power to the wheels. For a diff to be stronger it must have more gear surface contact and this is what will take the extra power.

[RA23]

RA23, did you read the paragraph after the one you quoted?

Hen

Yes, you are right. But that only addresses the rotational inertia issue, not the difference in rpm because of the gearing ratio, which even makes things worse (or better, depending on where you're coming from).

[oldcorollas]

it'S not directly simple...

there are a few things to consider....

larger diff has larger moment arm, on both pinion and crown, so any torque will have a lower force at the point of contact. smaller diff, same torque, = higher forces at contact points.

larger diff has larger surface area of contact (although that depends on the amount of surface actually in contact at any one time...) and smaller force..

smaller diff has larger force and smaller area...

this could lead to smaller diff having MORE friction from the gears themselves.

larger dif has larger bearings...... which will move further and consequently faster (the actual balls/rollers) so there may be more loss there...

however.. since smaller dif has larger forces, the reactionary forces thru the bearings will be greater... also because the distance between bearings is smaller, so there again is more leverage....

so.... larger diff has LESS transmitted power loss? maybe?

[ra23celica]

Joel and Hen have it right above, I weighed my RA23 rear axle complete and got 68kg. Then I weighed a complete RN27 axle (not for sale-don't ask!) with a G series LSD from a Surf in it, and converted with RA23 suspension mounting points (still not for sale!) and got 95kg, so roughly a 30kg or 50% increase, roughly.