Peterbilt 389 Dash Knobs

Frequently Asked Questions About Peterbilt 389 Dash Knobs

What are Peterbilt 389 dash knobs used for?

Dash knobs are the small control knobs mounted on the dashboard that operate functions such as headlight switches, dimmer controls, wiper controls, heater and defroster settings, and other dash-mounted switches. They are often replaced when the original knob cracks, fades, or breaks off from wear.

Will these knobs fit my Peterbilt 389 without modification?

Most dash knobs in this category are designed to match the factory fitment for Peterbilt 389 models, but knob shaft sizes and mounting styles can vary depending on the model year and which specific switch or control they are paired with. Check the listed shaft diameter, spline count, or attachment style against your existing knob before ordering to ensure a proper fit.

What materials and finishes are available?

Dash knobs are commonly available in chrome-plated plastic, billet aluminum, and chrome-plated metal options. Some are offered with textured or knurled grips for easier handling, while others include a smooth, polished finish for a factory-matched or upgraded appearance. Choose a finish that matches the rest of your interior trim for a consistent look.

How do I install a replacement dash knob?

Installation is typically straightforward. Most knobs either press onto a splined shaft, thread on, or are secured with a small set screw or retaining clip. Remove the old or damaged knob by gently pulling, unscrewing, or loosening the set screw, then align and press or screw the new knob into place. If your knob uses a set screw, a small hex or Allen wrench is usually all that is needed.

Will the printed labels or symbols wear off over time?

Knobs with printed or engraved labels can fade or wear with frequent use and sun exposure, especially on plastic knobs. Metal or billet aluminum knobs with engraved rather than printed markings tend to hold up better over time. If you want long-term legibility, look for knobs described as laser-engraved or debossed rather than surface-printed.