Dex210 Gear Diff
 

I have a Dex210 RTR and the back wheels were binding, when I let off the throttle the wheels would stop instantly and when driving it was like the drag brake was set to 100%.

After swapping bits around with my kit version of the dex210 I discovered that it was the diff at fault, it felt stiff and notchy compared to the geared diff that I built and put in my kit version.

I stripped the diff down and discovered that only 2 of the 4 small gears were in there which is how it must have came from the factory. I ordered the missing gears, shims and axel from JE, fitted them and filled it with the same oil as in my other car but it's still binding.

Any ideas ??

Take the rear wheels off and the pinion off and spin the driveshafts with your fingers.
You should feel any binding and be able to trace its source this way.

It's the diff that's binding but I just can't work out why, I thought it was the two missing gears that would be the problem but replacing them didn't make a difference.

Take the idlers out and spin the diff. Check the shimming is correct. Put the idlers back in one at time and check everything is free. There should be one spacer on each side of the idler gears. Put a few drops of shock oil on the gears to keep it lubed (25 - 30wt). Also check the screws that hold the gearbox casing together aren't over tightened.

Ok thanks, I'll give that a go tomorrow.

The diff in the RTR comes with 2 satellite gears only, that is normal.

Apparently the two gear diff is just as good as the 4 great, but it's lighter.
I thought it felt notchy too, so I got the extra bits.

The most likely culprits are the gearbox bolts being over tightened or the slipper spacer being crushed/worn.
But if you've narrowed it down to the actual diff, check the bolts.