RALZAOTO Trailer Oil Bath Dust Caps for Dexter 6K-8K Axles, 2-7/8" Threaded Polycarbonate Pack of 4 — Corrosion-Resistant

These RALZAOTO oil bath dust caps are 2-7/8" threaded replacement covers designed to fit Dexter 6K–8K (and some 9K) oil bath drums—sold as a 4-piece set that replaces part K71-038-00 and Dexter 21-35 / 23-29 caps.

If you maintain trailers with Dexter oil-bath axles, keeping the hub opening sealed against grime and moisture is critical. These caps are molded from durable polycarbonate to resist corrosion, discoloration and cracking, and they thread onto 2.75" (2-7/8" OD) hubs with 12 threads to restore a proper dust seal. They are intended for common Dexter drum numbers cast into the drum face such as 8-218, 8-219, 8-232, 8-285 and 8-286, and work on many 6,000–8,000 lb axles and some older 9,000 lb drums dating to around Oct 1, 1989 and earlier.

How do I know these caps will fit my Dexter drum?

Check the drum casting and thread size before ordering. The easiest verification is a visual match to the drum number and confirming a 2-7/8" threaded outside diameter with a 12-thread pattern.

• Look for cast numbers: 8-218, 8-219, 8-232, 8-285, 8-286
• Replaces Dexter part numbers 21-35 and 23-29 and K71-038-00
• Designed for 2-7/8" OD threads, 12 threads per inch
• Common on 6000–8000 lb axles; fits some 9000 lb drums made before Oct 1989

What materials and durability can I expect from these replacement caps?

RALZAOTO caps are produced in high-strength polycarbonate for long service life in harsh trailer environments. The material offers resistance to rust, oxidation and UV-related discoloration compared with metal caps, while remaining dimensionally stable under heat and vibration.

• Premium polycarbonate construction resists cracking and corrosion
• Color-stable under sun exposure; won’t flake like painted metal
• Lightweight yet strong—minimizes wear on threads and fittings
• Pack of 4 makes it easy to service multiple hubs at once

How straightforward is installation and maintenance?

Installation is simple and tool-free in most cases: remove the old cap and hand-thread the new one until snug. Periodic inspection for tightness and checking for contamination inside the hub keeps bearings and oil bath systems performing properly.

• Hand-screw on by aligning threads and turning until seated
• No special tools required; swap takes only minutes per hub
• Inspect annually or after heavy off-road use for seals and oil level
• Keep spare caps on hand to replace damaged or lost units quickly

What exact parts and quantities are included in this listing?

The package contains four RALZAOTO oil bath dust caps engineered to replace Dexter part K71-038-00 and compatible Dexter 21-35 / 23-29 style caps. Each cap is sized for 2-7/8" thread OD and fits drums with the listed casting numbers.

• Quantity: 4 dust caps per pack
• Thread size: 2-7/8" OD, 12 threads
• Replaces part numbers K71-038-00, Dexter 21-35, 23-29
• Compatible with drums 8-218, 8-219, 8-232, 8-285, 8-286

Who is this for: These RALZAOTO oil bath dust caps are for trailer owners, fleet managers and DIY mechanics who service Dexter oil-bath axles on utility, boat, car hauler and larger recreational trailers. If your drums show the listed casting numbers or you need a direct replacement for Dexter 21-35 / 23-29 style caps, this 4-piece set provides a durable, easy-to-install option to protect bearings and oil systems from contamination.