[Rivermaxx]

Here my experience with aluminum against steel. In a t-maxx there is a steel idler for reverse the rides against plastic gears.when you install a bigger .21 size engine the first gears to break are the reverse gear and then the primary or foward gear. I got all 7075 gears inside for a bullet proof tranny. After about a 1/2 gallon of fuel I pulled it apart to grease the gears and check things out. I noticed the aluminum gear and the idler wearing the teeth out on each other. The guys who make the aftermarket ultramaxxed gears for electric and otb 1st and 2nd gears for nitro use a special brass alloy idler and input gear just because of ths reason ever wonder why there are 3 versions of the Ultramaxx gears . I know it will last a while but eventually it will show definate wear keep it grease and it will last even longer. I bet delrin would be alot stonger than then the stock plastic gear.Ue used it for the first foc conversion and it seemed to work good. Probably cheaper to produce and make.