Attribute Freightliner Kenworth Practical impact Seat geometry Larger seat diameters; specific wedge profiles Varied seat diameters; different slot/key patterns Fit must be confirmed before reuse Wedge vs flat usage Common use of factory wedge/caster shims Mix of wedge and flat shims across models Choose correct profile to correct caster/camber Typical materials Hardened steel or plated alloys Stainless and plated steels common Material affects corrosion and creep resistance Common failure modes Shim crushing at point loads; wrong wedge angle Shims shifting with reused hardware; stacking errors Use spreaders and fresh locking hardware Inter changeability Limited without checking fit and spec Limited; some aftermarket cross fits exist Always verify diameter, slot, and locating features
Why shims matter for fleets
Shims control tiny geometry changes that create big effects on tire wear, steering, and driveline load sharing. Choosing the correct shim for Freightliner or Kenworth models prevents uneven wear, reduces comebacks, and protects expensive components.
Key compatibility essentials
- Verify fit: Confirm outer diameter, locating hole position, slot width, and keying before reusing or substituting shims.
- Match profile: Freightliner often requires specific wedge angles; Kenworth models may accept different tapers or flat shims—use the correct profile for the seat.
- Material choice: Use corrosion‑resistant alloys for exposed locations and hardened steel where compressive loads are high.
- Avoid blind swaps: Do not assume interchangeability between manufacturers; small differences in seat geometry change outcome.
Performance differences and what to watch for
- Freightliner: Factory wedge shims can precisely correct caster and pinion angle when used correctly; failure usually comes from crushed thin plates or incorrect wedge orientation.
- Kenworth: Many models rely on careful stacking and correct slot orientation; failures often stem from reused hardware allowing shim migration or incorrect stack sequencing.
- Both: Incorrect material or lack of load spreaders leads to creep, crushing, and progressive alignment drift.
Installation tips for reliable results
- One‑change rule: Change only one shim stack between measurements; re‑measure and document before proceeding.
- Use load spreaders: Install properly sized plates or washers under thin shims at concentrated load areas to prevent crushing.
- Replace locking hardware: Always replace stretched U‑bolts, nuts, or locking washers; torque to OEM sequence and re‑check after run‑in.
- Document precisely: Photograph shim stacks with a ruler inset, record before/after alignment numbers, and log shim thicknesses in the vehicle file.
Shop best practices
- Stock labeled kits: Keep model‑specific shim kits by truck family and post a simple conversion chart at each alignment station.
- Training: Teach techs to read wedge orientation, recognize seat geometry differences, and follow the one‑variable‑change workflow.
- QA protocol: Require ruler‑inset photos, torque verification after initial run‑in, and a 500–1,000 mile follow‑up inspection for major shim changes.
- Standardize documentation: Store shim stack composition, measured results, and photos in the service record for future reference and warranty defense.
Final recommendation
Treat Freightliner and Kenworth shims as precision components: confirm fit and profile, use proper materials and spreaders, change one variable at a time, and document every step. These disciplined practices reduce tire and component wear, lower comebacks, and protect fleet uptime.
