Tamiya Mini 4WD bearings guide: axle, counter gear and 520 roller bearings explained

Out of the box, almost every Tamiya Mini 4WD kit spins its steel wheel axles and counter gear on plastic eyelets or brass bushings. Replacing those bushings with ball bearings is the single biggest free-rolling upgrade you can make on a B-MAX car.

The catch is that Tamiya sells three main bearing groups under similar names (6 mm axle and counter gear bearings, 520 roller bearings and 9 mm guide roller bearings), and each one fits a different spot on the car.

1. Wheel axle bearings (6 mm outer diameter, 4 per car)

Every standard chassis — whether single-shaft like Super-II on Victory Magnum (19434) or mid-motor MS on Avante Mk.II (18614) — takes four 6 mm axle bearings in the chassis eyelets:

Avante Mk.II6 versionsCar page › Victory Magnum8 versionsCar page ›

• HG Round Hole Ball Bearings (4 pcs), 15519: the current race standard (¥1,540 / RM49). Machined to tighter tolerances than the older sets, with a smooth round 2 mm inner bore that lets the hex axle spin with the least drag. This is the axle bearing specified in the Super-II Setup Book.
• Round Hole Ball Bearing (4 pcs), 15111: the budget round-hole set (¥880 / RM29), sold in Malaysia as "PRO MS Compatible" but the same 6 × 2 × 2 mm size. A solid step down from 15519.
• Hex Hole Ball Bearing Set (4 pcs), 15287: older hex-bore axle bearings (¥880 / RM31) where the inner race locks onto the 2 mm hex shaft instead of presenting a smooth round bore.
• Low-Friction Plastic Bearing Set, 15523: POM plastic eyelets (¥220 / RM9). Lighter and cheaper than steel ball bearings, used when keeping weight or cost down matters more than free spin.

2. Counter gear bearings (inside the gearbox)

Inside the gearbox, the counter gear spins on a short shaft and needs one small bearing pressed inside its hub so the gear teeth stay meshed under load:

• Single-shaft chassis (Super-II, FM-A, AR, VS, VZ): a single 6 × 2 × 2 mm bearing from 15519 or 15111 (Tamiya says 15519 fits drive shafts and counter gears on every car), or a Fluorine Coated Steel Bearing (4 pcs), 15393 (¥616 / RM28), fits inside the counter gear hub, paired with the Fluorine Coated Gear Shaft (Straight), 15390 (¥176 / RM9).
• MS chassis: Tamiya sells a dedicated Gear Bearing Set (MS Chassis), 15347 (RM20) that combines the bearing and the matching counter gear shaft in one pack.

3. Roller bearings: 520 and 9 mm (520 inside aluminium rollers)

Bearings for the guide rollers on your front and rear bumpers are smaller than axle bearings:

• 520 Ball Bearings (4 pcs), 94752: 5 mm outer × 2 mm inner (RM30). These press into the centre of 13 mm and 19 mm aluminium rollers (and come pre-installed in sets like 15398 double aluminium rollers) or fit inside plastic gear hubs.
• 9 mm Ball Bearings (2 pcs), 15344: 9 mm outer diameter (¥616), bolted directly onto a 2 mm screw as a compact guide roller.

Cleaning and oiling

New Tamiya bearings come packed with thick storage grease so they do not rust on the shop shelf. Before racing, flush that factory grease out with parts cleaner and add a single drop of Bearing Lubricant Oil, 15531 (¥528) so the balls spin freely without running dry.

15531Bearing Lubricant OilPart page ›

In this post

15519HG Round Hole Ball Bearings (4 Pcs.)Part page ›15111Round Hole Ball Bearing - PRO MS CompatiblePart page ›15287GP287 Hex Hole Ball Bearing SetPart page ›15393Steel Bearing 4pcs - Fluorine CoatedPart page ›15523Low-Friction Plastic Bearing SetPart page ›94752520 Ball Bearings - 4pcsPart page ›15344DR 9mm Ball Bearings (2 pcs.)Part page ›15347Gear Bearing Set (MS Chassis)Part page ›15390Fluorine-coated counter shaft, straightPart page ›