I have duel rate springs on mine and some metal wheels!! When I put my diffs together I put loads of grease between bearings on main shafts an then thin smear on diff cover!! I hoped grease would make a semi water tight seal when assembled!! Love mine keeps up with scx10s and trx4s I want a quicker motor though!! Want a little bit of roost when I gun accelerator Sent from my ONEPLUS A6003 using Tapatalk