@ gaborart: For my FF motor applications, I've used a variety of pinions for 1.5mm shafts, metal (Dart Hobbies, Slot It, MR Slot Car) and plastic (Scalextric Sport, Fly F1). For inline crown gears, SCX Pro and Slot It have been my choices.
All work fine in a variety of combinations.
Good progress. Chassis's rolling. Parts list includes:
motor - stock Scalextric FF050 from a Ford Escort Mk 1
motor pod - Devised Designs super slimline
pinion - 9t Fly March 761 F1
crown - SCX Pro 27t
front rims/tires - Slot It 15 x 8 plastic/Slot It low profile
rear rims/tires - Slot It F1/Paul Gage
guide - Sloting Plus
braid - Slot It
motor wire - Slot It
Body's mounted too. Nose is right down to the pavement. Interior tray needed more grinding to clear the motor as the body profile is lower than the 908-3.
Runs pretty good and will get better with tire truing.
Just need to install NSR Porsche 917 wheel inserts and modify/install rear tailight/trans detail and we're done.
This build went fast as the body was pretty much already done.
Dan