HD6 Dozer Repaint Story

[MikePhua]

History of the HD6 Dozer
The HD6 was produced by Allis-Chalmers from about 1955 through 1974. During that period they built over 25,000 units of various HD6 variants.  It was made as a crawler-tractor / small dozer for agricultural and light industrial work.  Its engine is a 5.6-liter 4-cylinder diesel, delivering roughly 57 horsepower (net) and capable of around 45 drawbar horsepower in tests.  The weight is in the range of 12,400 to 13,400 pounds (≈ 5,600 to 6,100 kg) depending on version.
Because of its robust design, many HD6s are now collectors’ items. Owners often restore old units, sometimes with the goal of having them show-quality. Repainting is a significant part of such restorations.

Repainting the HD6 Dozer
When repainting an HD6, several technical and aesthetic aspects need attention to get a result that both honors the original and holds up over time.
Paint Color and Authentic Appearance

• The classic color for Allis-Chalmers HD6 is the signature “AC orange.” Over decades, paints fade, change in hue, or are reformulated. In some areas, the exact old formula was discontinued for regulatory reasons.
  
• One restorer noted that the newer AC orange from standard supply cans ended up being lighter than the original, especially in sunny climates where UV exposure accelerates fading.
  

Surface Preparation (Term: “Prep Work”)

• Sand-blasting or media blasting the old paint off to bare metal ensures no residual layers that might peel later.
  
• Rust treatment: any rusted metal must be cleaned and treated (e.g. with rust converter or primer) to avoid under-surface corrosion after repaint.
  
• Weld and body repairs: any dents or damaged metal should be straightened, filled, and ground smooth.
  

Primer, Paint Type, and Finish

• Use of proper primers is important—for adhesion, corrosion protection, and long life. Zinc-rich primers or epoxy primers are often used.
  
• Top coats: either enamel, urethane, or polyurethane finishes. Each type offers different UV and weather resistance. Urethane/polyurethanes are often more expensive but hold up better outdoors.
  
• Protective clear coats may be applied to avoid oxidation or chalking.
  

Components and Detail Work

• Attention to detail: bolts, fasteners, decals, nameplates, the grill, vent screens, the operator’s station—these must frequently be masked or removed to paint properly.
  
• Undercarriage parts: tracks, rollers, idlers often are painted or at least cleaned and rust-proofed.
  

Costs, Time, and Labor

• A repaint to show quality (strip down, restoration, high-quality finish) can take hundreds of man-hours.
  
• Material costs include paint, primer, masking, body filler, equipment rental or purchase, and possibly sand-blasting.
  
• For example, material cost for a full dozer repaint might run several thousand dollars depending on region and paint type; labor even more.
  

Small Story
An owner in Northern California completed a restoration of a serial #1117 HD6, likely among the earliest built. It was freshly repainted and exhibited at a regional logging display. The paint was still drying during the show, yet the transformation from rusted, dull metal to bright, glossy AC orange drew wide admiration. Another restorer, a few years earlier, had used a synthetic enamel with hardener and noted that after just a few summers, sun and heat shifted the hood and tank color slightly toward oxidized yellow-orange. That experience led him to choose a more fade-resistant urethane finish for his next HD6 project.

Suggestions and Best Practices

• Test small paint samples in sun and shade to see if color shifts under UV before full paint job.
  
• Keep the HD6 stored under cover when not in use or display outdoors avoided midday brightness to preserve color.
  
• Use quality masking to protect non-painted parts. Remove decals and nameplates and replace if worn.
  
• If original AC orange formula is unavailable, select a modern equivalent and note that a slight difference may exist but that weathering tends to bring them closer over time.
  
• Repaint schedule: every 10-15 years for show machines; for working machines, maintain touch-ups and rust repair as needed to avoid large repaint jobs.
  

Summary
Repainting an Allis-Chalmers HD6 is more than just applying new paint. It’s about historical authenticity, material quality, and painstaking preparation. From thousands of HD6s produced, many will endure only if owners invest in proper restorations. Done well, a repaint transforms a rusted relic into a gleaming piece of history, sustaining both structural integrity and heritage aesthetics.