This suspension arm is designed to fit the rear upper arm position on the Revo behind the engine. (CAN be used on both sides) When used with the Traxxas big block installation kit. This arm allows extra space behind the engine so you can use an engine with a pull start, rotostart or Tiger Drive. It is a direct replacement for the stock arm. It has the same dimensions for the pivot pin and pivot ball. It is installed the same way as a stock arm where the pivot ball forms threads as you thread it in. As long as your printer is tuned properly. There shouldn't be any need to scale the model. All the holes and sizing should be correct for printing with Nylon. PETG and PLA+ will work but don't hold up quite as long. PETG or PLA+ will require an 1/8" (3.2mm) drill in the pivot pin holes. The pivot ball fits in all materials. In testing, standard Nylon (PA6 or PA12) is best material for this part.

I designed this in FreeCAD using an old New Era Models Aluminum arm and a stock arm as a model. I changed some of the specs to allow as much extra space as possible.

Nylon can be a little bit of a pain to print. So PETG or PLA+ can be used as well, but since they are quite a bit more rigid. It is important to make sure your suspension arm goes through the full range of motion without contacting your engine. Your filament of choice will determine printing temps and retraction settings. For Nylon, Buying quality filament and printing on Glass or Garolite with a brim width of at least 8mm inside and outside is a very good way of reducing printing issues. Personally I like smooth Glass with a coating of Elmers Glue Stick.