Weighted Ergo Knob for Thrustmaster TH8S – 3 Sizes, Ballast Chamber & Indexable Pattern Cap

A shifter knob that fits your hand – and has some real weight to it.

Most sim-racing knobs are light and one-size-fits-all. This teardrop knob for the Thrustmaster TH8S comes in three sizes. It has a hidden ballast chamber for a heavier, more car-like shift, and a shift-pattern cap you can line up properly no matter where the thread stops.

Features

• 3 sizes: S (Ø43 × 69 mm), M (Ø46 × 77 mm), L (Ø49 × 82 mm)

• Ø28 mm ballast chamber – about 40 / 60 / 75 g of 4–6 mm steel balls (S / M / L)

• Snap-in pattern cap on 36 splines – re-align in 10° steps

• Caps included: 7+R (TH8S layout) and 6+R; caps fit all sizes

• Soft diamond knurl on the palm bulge

• Uses the official TH8S DESIGN PIECE unchanged – screws onto the official adapter

• No supports

Why an indexable cap?
A screw-on knob stops at a random angle, so a printed shift pattern usually ends up crooked. Here the pattern sits on a separate cap: pull it out, turn it, press it back in.

Printing

• Knob body: upright (as in the 3MF), 0.2 mm, 5 perimeters, 15 % gyroid, elephant-foot compensation 0.2 mm

• Cap: face down (as in the 3MF), 0.2 mm, 3 perimeters, 20 %

• Official adapter: 100 % infill (per Thrustmaster)

• Tip: add a color change at 0.4 mm on the cap and the engraved pattern comes out in a contrast color

• Body + cap ≈ 37 / 43 / 47 g

Assembly

1. Mount the official adapter on the TH8S following Thrustmaster’s instructions.

2. Screw the knob onto the adapter until it seats on the shoulder.

3. Fill the chamber with ballast; fix it with a drop of hot glue or a bit of foam so it doesn’t rattle.

4. Press the cap in with the pattern facing you until it clicks. To re-align, pull it out by the notch, turn, press back.

Fit & tips

• Cap too tight or loose: XY Size Compensation −0.05 / +0.05 mm on the cap.

• Start with less ballast – the H-pattern springs are tuned for a light knob.

Credits & license
Remix of THRUSTMASTER: Official TH8S Gear knob files – the DESIGN PIECE is used unchanged, everything else is new. Designed with AI assistance (Claude by Anthropic). CC BY-NC-SA 4.0.