ZLeader

Gearing: You need the yeah racing motor mount if you don’t have it. The maximum gear combo I have been able to fit in TT02 is 78T / 53T 3.83 fdr. This was with a brushless 21.5. You will need to trim the gear box cover or even cut a hole out to clear the large pinion.

Now with a sport tune however, an FDR of 3.8 will heat the brushes and launch them inside the motor lol.. I’ve experience it first hand. So you’re probably need to gear it to 4.5 fdr tops.

Springs: Try a different brand spring.. yeah racing springs rates are an unknown for racing, so hard to say what you need.