3.5" Oil Bath Cap Trailer Axle Dexter 9K 10K Kit with Plug and O-Ring – For 10K GD Axles
Complete oil cap service kit for 21-88 oil bath hub applications. Includes one 3.5" oil bath cap, one sealing O-ring, and one center oil plug for compatible 10K general duty axle setups.
Key Measurements & Specs
| Specification | Detail |
|---|---|
| Part Number / SKU | 21-88-KIT |
| Product Type | Oil bath cap service kit |
| Cap Reference | 21-88 / 021-088-00 style oil bath cap |
| Cap Size | 3.5" threaded oil bath cap application |
| Seal / Plug References | 010-163-00 O-ring and 046-032-00 center plug references |
| Quantity Included | One kit: 1 cap, 1 O-ring, 1 plug |
Fitment / Application
| Category | Details |
|---|---|
| System | Oil bath trailer hub / drum systems using 21-88 style caps |
| Primary Fit | Commonly used on 10K general duty axle applications after July 2009 where 21-88 cap fitment is required |
| Fitment Method | Verify the cap number, threaded cap size, hub application, and matching O-ring before ordering |
| Important Note | Not all 10K oil bath hubs use the same cap. Compare the existing cap and seal references before installation |
Top Features
| Feature | Buyer Benefit |
|---|---|
| Complete Service Kit | Includes the cap, O-ring, and center plug needed for a matched oil cap service replacement |
| 21-88 Style Cap | Built for compatible hubs that use the 21-88 / 021-088-00 style oil bath cap |
| Oil Bath Sealing Support | Helps maintain oil retention when the cap, plug, and O-ring are properly installed |
| Shop-Friendly Kit | Keeps the common wear and sealing pieces together for quicker hub service work |
Overview
This 21-88-KIT oil bath cap service kit is assembled for compatible trailer hub applications using a 21-88 style oil bath cap. The kit includes one oil bath cap, one O-ring, and one center plug, making it a practical replacement option when servicing a leaking, damaged, or worn oil bath cap assembly.
R&P Service Insight
Oil bath hubs depend on a clean sealing surface, a properly seated O-ring, and a tight center plug to retain lubricant around the bearings.
- Check the cap number: Match the replacement to the existing 21-88 style cap before ordering.
- Inspect the O-ring groove: Clean old oil, grit, and damaged seal material before installing the new O-ring.
- Confirm oil level: After service, fill and inspect the hub according to the trailer or axle manufacturer’s service procedure.
R&P Knowledge Hub
Compatibility: Designed for compatible 21-88 oil bath cap systems. Verify before ordering if your axle, hub, or cap style differs.
Vehicle / System Fit: Commonly associated with 10K general duty trailer axle oil bath hub applications after July 2009 where 21-88 cap fitment is used.
Installation Notes: Replace the cap, O-ring, and center plug together when the cap assembly is leaking or when the plug and seal are worn.
Performance Insight: A properly sealed oil bath cap helps retain lubricant, protect bearing components, and reduce the chance of oil loss during trailer operation.
Brand & Fitment Note
Selling Brand: R&P Carriages curated service kit
Application Reference: 21-88, 021-088-00, 010-163-00, and 046-032-00 are used as application and component reference numbers for fitment matching.
What This Means: This listing is for one R&P Carriages oil bath cap service kit, not a guaranteed OEM-branded item unless specifically stated on packaging or product labeling.
Before Ordering: Verify cap size, thread style, hub application, O-ring reference, plug reference, and axle/hub compatibility before installation.
R&P Repair Insight
Oil bath cap leaks are often caused by an aged O-ring, damaged plug, cracked cap, dirty sealing surface, or incorrect cap selection. Match the replacement kit carefully before disassembly.
- Cap Fit: Confirm the existing cap uses the 21-88 style replacement before ordering.
- Seal Condition: Replace the O-ring any time the cap is removed for service if the seal is flattened, cut, or brittle.
- Leak Check: After installation, inspect for seepage around the cap body and center plug before returning the trailer to service.
Features
Complete 3-Piece Kit
Includes one oil bath cap, one sealing O-ring, and one center oil plug for a complete cap assembly service.
21-88 Style Application
Designed for compatible hubs that use the 21-88 / 021-088-00 style oil bath cap reference.
Oil Bath Hub Service
Supports proper lubricant retention when installed on the correct hub with a clean sealing surface.
Fitment-Safe Replacement
Best matched by comparing the existing cap number, cap size, O-ring reference, and hub application before ordering.
Included Components
| Quantity | Item |
|---|---|
| 1 | 21-88 style oil bath cap, 3.5" application |
| 1 | 010-163-00 style O-ring for 21-88 cap applications |
| 1 | 046-032-00 style center oil plug |
