Why ball diffs?
 

Hey guys

Recently replaced my old Baja Champ with a Baldre. And Im wondering... why ball diffs? Whats the great advantage of these compared to the old style cogwheel based diff?

The old car had run at least a year... and the last couple of months with a eZrun 9t... the diffs were fine. Id even say they were smoother than the ball diffs in my new car.

If someone with insight could elaborate a bit Id appreciate it :)

/Morten

the ball diff works as a semi limited slip diff,

To expand on what bigred says, the geared diff is an "open" design and as soon as one wheel looses traction, all the power will go to that wheel because that's how open diffs work. So, when you go into a corner and the inside wheel unloads, the car will loose some traction and hence it will be slower. Ball diffs are constantly under tension and whilst they will allow some rotational difference to take place between wheels, they will not slip (hence the term limited-slip diff) enough to allow the power to bleed away on cornering, which means the car is faster round a lap. The downside is they can be more maintenance intensive as they need setting up properly and occasionally need nipping up as the balls wear. Geared diffs are more a fit-and-forget item.

I'll be glad to see the back of ball diffs in electric cars...

They came out to answer a problem in the early 80s - how to create a simple, lightweight diff, with a limited slip action.

But that was in the days of 1200 cells and sealed 35-turn motors.

Now, we have so much power that the diffs struggle to stay in good condition, and the adjustability is pretty limited, at best you have a tight and a loose setting between the diff slipping or locking up. On top of that they completely bewilder beginners.

Sealed gear diffs are so much more consistent in their adjustment and virtually bulletproof. Modified electric cars now have so much power that the extra weight is not a hindrance. Great to see the new Durango will have them - if I had £1,000 spare I'd get a Durango simply for that reason! It's a shame that so few other manufacturers have gone down that route. Serpent did it for their touring car but I think there were a few other issues with the brand at the time which stopped them being widely used.

And it took Tamiya about a decade to build a decent ball diff... the first ones in the Astute and Madcap were just plain weird. Notchy and with effectively no adjustment.

I dunno, my ball diff's are mostly 'fit and forget' (unless I let Millzy have a go).

The only issue with oil filled geared diffs, that usualy, to change the action requires a lot of work, where a ball diff just means, nipping up the diff screw a little.

Cheers guys!

Now it makes sense :)