Been working on one of the cars this week. Managed to put ball bearings in the rear and crawler shocks to reduce the bounce.
Step 1. Line everything up with 6mm drill and clamp in position.
Step 2. Drill/melt with 12mm Dremmel stone (luck fit) and slice excess off with Stanley knife. Do in stages or tyhe plastic will mely & distort.
Step 3. Drill out for clearance of axle with 8mm drill bit.
12mmx6mmx4mm bearings are a perfiect fit.
Same method for main rear. clamp two halves together in the drill vice.
New shocks.
From another angle.
Body trimmed. 1/10 Carson all terrian wheels and tyres. Tip - to use standard bearings, sleeve first with aluminuim from a drinks can - gives a nice tight fit.