TRAILER HUB OIL BATH CAP PAIR
Two - 2-7/8" BILLET ALUMINUM Oil Cap Fit Dexter 21-35 Trailer Axle Bearing Hub 6K-8K
Pair of threaded oil bath hub cap kits machined from solid billet aluminum. Designed to replace standard screw-in oil bath caps using 2-7/8"-12 external threads on compatible oil-lubricated trailer hub and drum assemblies.
Part Number: 21-35 Billet-KITX2 2-7/8"-12 Thread Pair Kit / Billet Aluminum
Overview
This billet aluminum oil bath cap pair is built for compatible screw-in trailer hub applications using 2-7/8"-12 external threads. These caps are commonly used as a stronger replacement option for Dexter 21-35 / 021-035-00 style oil bath caps found on many 6K-8K oil-lubricated hub setups. The kit includes two complete cap assemblies, typically suitable for servicing two hub positions on one axle where the thread size and hub configuration match.
R&P Service Insight
Oil bath hubs depend on a sealed cap to retain lubricant, protect the bearings, and allow service inspection through the center plug area. The wrong cap can leak, fail to seat, or damage the hub threads.
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Thread Check: Verify the hub uses 2-7/8"-12 screw-in threads before ordering.
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Seal Check: Replace the O-ring during cap service to help prevent oil seepage around the cap body.
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Hub Check: Inspect the hub face and threads for damage before installing the new billet cap.
R&P Knowledge Hub
Compatibility: Built for 2-7/8"-12 threaded oil bath hub cap applications commonly associated with Dexter 21-35 / 021-035-00 style caps.
Vehicle / System Fit: Used on many 6K-8K trailer oil bath hub systems and select older Dexter 9K applications built prior to 10/89 where the cap style and thread specification match.
Installation Notes: Clean the hub threads, install the O-ring correctly, tighten evenly, and refill or verify hub oil level according to the hub and axle service requirements.
Performance Insight: Billet aluminum caps are a strong upgrade where standard plastic-style caps may be prone to cracking, heat exposure, impact damage, or thread-area wear.
Brand & Fitment Note
Selling Brand: R&P Carriages billet aluminum replacement cap pair.
Application Reference: Replaces Dexter 21-35 / 021-035-00 style 2-7/8"-12 threaded oil bath caps where dimensions, thread size, hub type, and oil bath configuration match.
What This Means: This listing is for an aftermarket billet aluminum cap pair supplied with O-rings and rubber plugs for compatible oil bath hubs.
Before Ordering: Do not order by axle rating alone. Confirm thread size, existing cap number, hub casting number, oil bath setup, and included components before installation.
R&P Repair Insight
Oil bath hubs are only as reliable as their seal path. If the cap is cracked, cloudy, cross-threaded, or leaking around the O-ring, replace it before the hub loses lubricant and overheats the bearing assembly.
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Oil Loss: A leaking cap can allow lubricant to escape during towing, especially after heat cycling or long-distance use.
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Thread Damage: If the old cap was cross-threaded, inspect the hub threads before installing the new cap.
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Bearing Protection: After replacement, verify oil level and check again after the first tow for any seepage around the cap or plug.
Features
Billet Aluminum Construction
Machined aluminum body provides a stronger replacement option than standard plastic-style oil bath caps.
Threaded Screw-In Design
Designed for compatible oil bath hubs using 2-7/8"-12 external screw-in cap threads.
Pair Kit for Two Hub Positions
Includes two complete oil bath cap kits, typically suitable for servicing both hubs on one axle.
Service Components Included
Supplied with O-ring seals and rubber fill plugs so the cap service can be completed cleanly.
Specifications
| Specification |
Detail |
| Part Number |
21-35 Billet-KITX2 |
| Brand |
R&P Carriages |
| Product Type |
Trailer hub oil bath cap pair |
| Application |
Oil-lubricated trailer hub and drum assemblies using compatible screw-in oil bath caps |
| Material / Finish |
Billet aluminum |
| Thread Type |
External, screw-in |
| Thread Size |
2-7/8"-12 |
| Lubrication System |
Oil bath hubs |
| Quantity |
2 complete oil bath cap kits |
| Replaces / Cross Reference |
Dexter 21-35 / 021-035-00 style oil cap |
Fitment / Application
| Category |
Details |
| Vehicle / System |
Oil bath trailer hub and drum assemblies |
| Primary Fit |
Dexter-style 6K-8K screw-in oil bath hub applications using 2-7/8"-12 threads |
| Secondary Fit |
Also referenced for select Dexter 9K applications built prior to 10/89 where the cap thread and hub configuration match |
| Common Hub / Drum References |
8-218, 8-219, 8-232, 8-285, and 8-286 style oil bath hub/drum applications; also used on some oil bath disc brake hub assemblies where specifications match |
| Notes |
Verify thread size, cap marking, hub/drum casting number, oil bath configuration, and existing cap style before installation. |
Detailed Measurements & References
| Reference |
Detail |
| Thread Specification |
2-7/8"-12 screw-in thread |
| Cap Cross Reference |
Dexter 21-35 / 021-035-00 style oil cap |
| O-Ring Reference |
010-045-00 style O-ring |
| Rubber Plug Reference |
046-032-00 style rubber plug |
Included Components
| Quantity |
Item |
| 2 |
Billet aluminum threaded oil bath hub caps, 21-35 style |
| 2 |
O-ring seals, 010-045-00 style reference |
| 2 |
Rubber oil fill / inspection plugs, 046-032-00 style reference |
Verify all measurements, specifications, thread size, hub casting number, cap marking, oil bath configuration, and included components before installation. Dexter references in this listing describe compatibility and application style only; this listing is for a DURACAPS USA aftermarket billet aluminum replacement cap pair.
21-35 Billet-KITX2, DURACAPS USA billet aluminum oil bath caps, pair of 2-7/8-12 oil bath hub caps, Dexter 21-35 style replacement cap, 021-035-00 style oil cap, 2-7/8 inch 12 thread oil bath cap, trailer hub oil bath cap pair, billet oil bath cap kit, oil bath hub cap with O-ring and rubber plug, 8-218 oil bath hub cap, 8-219 oil bath hub cap, 8-232 oil bath hub cap, 8-285 oil bath hub cap, 8-286 oil bath hub cap, 010-045-00 O-ring style, 046-032-00 rubber plug style
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