Team Ottsix Racing AR44 SCX10 II HD Hypoid Ring, Pinion & Locker Set (33T/8T)

33/8T AR44 Underdrive gearing. These gears worked very well in my Capra axles. This newer version has more material machined from the back of the pinion gear so gear mesh is better. The included shims are helpful, but not enough to properly mesh helical gears. You should have some 7mm I.D.(spool) and 5mm I.D.(pinion) shims on hand to make it perfect. Time will tell how well these hold up. For the price and expected longevity, you can almost buy two of these compared to the fancy "Vanq" brand. 9.5% underdrive is helpful!

These underdrive units for my Axial builders kit with the one piece AR44 axles were a real trouble to get meshed properly even with the shims as supplied. Since these were to replace the Boom Racing underdrive which also had meshing issues I can only conclude the limit is the ring gear size which has to be able to fit the casing and also fit the offset pinion so this is an inherent problem with adding underdrive. I guess Axial has done their homework and have used the largest ring gear (highest gear ratio) possible without sacrificing reliability.

To get smooth gear meshing I had to shim both the ring gear and the pinon away from each other as any other position the gear meshing felt like it was slightly binding or too tight of a mesh. However keeping the pinion and ring apart can cause clicking or skipping of the gear teeth when reversing with a bit of torque. Maybe I'll try and shim it closer after it runs in a bit which might improve the meshing issues.