At a Glance
- SKU: 21-88-KIT-LOTOF4
PRODUCT INFORMATION
Product Details
Oil Bath Hub Service Kit
X4(FOUR) 3.5" Oil Bath Cap Trailer Axle Dexter 9K 10K 8-415 430 After 2009
Four complete oil bath cap service assemblies with matching O-rings and rubber center plugs for compatible 3.5" trailer oil bath hub applications.
SKU: 21-88-KIT-LOTOF4 X4 Complete Cap Sets 21-88 Style 3.5" Oil Bath Caps
Overview
This R&P Carriages service kit is a four-pack oil bath cap kit built around the 21-88 style cap assembly. Each service set includes one oil cap, one matching O-ring, and one rubber center plug. The kit is intended for servicing compatible 3.5" oil bath trailer hub systems where the existing cap, plug, or seal has become worn, cracked, contaminated, or started leaking.
R&P Service Insight
Oil bath hub caps should be treated as sealing components, not just covers. If the cap or rubber plug is leaking, the bearing cavity can lose oil and take in dirt or moisture.
- Replace as a Set: Cap, O-ring, and plug should be inspected together when oil leakage is present.
- Check the Hub: Verify that the hub threads and sealing surface are clean and undamaged before installation.
- Confirm Size: Match your original 21-88 cap style and 3.5" oil bath hub application before ordering.
R&P Knowledge Hub
Compatibility: Commonly used with 21-88 / 021-088-00 style oil bath cap applications for compatible 3.5" trailer hub systems.
Axle Reference: Often associated with many Dexter-style 9K, 10K general duty, and #13G axle applications manufactured after July 2009. Always verify your exact hub and axle setup.
Installation Notes: Clean the cap threads and hub sealing surface. Make sure the O-ring seats correctly and the rubber plug is fully seated after oil inspection or filling.
Performance Insight: A leaking oil bath cap can lead to oil loss, hub contamination, bearing wear, overheating, and premature service failure.
Brand & Fitment Note
Selling Brand: R&P Carriages service kit using 21-88 style replacement oil cap components.
Application Reference: 3.5" oil bath hubs using 21-88 style threaded oil caps with 010-163-00 O-rings and 046-032-00 rubber center plugs.
What This Means: This listing includes four oil caps, four O-rings, and four rubber plugs — enough to service four compatible oil bath cap assemblies.
Before Ordering: Compare your original cap number, outside diameter, thread style, hub opening, O-ring, and plug style. Trailer axle and hub configurations can vary.
R&P Repair Insight
If oil is collecting around the hub face, cap threads, or rubber center plug, the cap assembly should be inspected immediately. In many cases, the cap itself may be reusable only if the threads and sealing surfaces are clean and undamaged. When in doubt, replacing the cap, O-ring, and plug together is the cleaner service approach.
- Leak Check: Look for oil residue around the cap shoulder, plug opening, and hub face.
- Seal Check: Replace flattened, brittle, swollen, cut, or missing O-rings.
- Plug Check: Replace rubber plugs that are loose, cracked, hardened, or no longer sealing tightly.
Features
Four Complete Service Sets
Includes four caps, four O-rings, and four center plugs for servicing four compatible oil bath cap assemblies.
21-88 Style Oil Cap
Designed around the 21-88 / 021-088-00 oil bath cap style used on compatible trailer hubs.
Includes Sealing Components
Each cap includes the required O-ring and rubber plug components for a complete cap service assembly.
Oil Bath Hub Maintenance
Useful for replacing cracked, leaking, worn, missing, or contaminated oil cap components during trailer hub service.
Specifications
| Specification | Detail |
|---|---|
| Primary Cap Number | 21-88 / 021-088-00 style |
| Listing SKU | 21-88-KIT-LOTOF4 |
| Brand / Supplier | R&P Carriages service kit |
| Product Type | Oil bath cap kit |
| Quantity Included | X4 complete cap assemblies |
| Application | Compatible 3.5" oil bath hub systems |
| Cap Style | Threaded / screw-in oil bath cap |
| Included Seal | 010-163-00 / 10-163 style O-ring |
| Included Plug | 046-032-00 / 46-32 style rubber center plug |
Fitment / Application
| Category | Details |
|---|---|
| Vehicle / System | Trailer oil bath hub systems |
| Primary Fit | 3.5" oil bath hubs using 21-88 style caps |
| Common Uses | Many Dexter-style 9K, 10K GD, and #13G post-July 2009 axle applications |
| Notes | Verify cap number, hub size, thread style, plug, O-ring, and axle/hub compatibility before ordering. |
Included Components
| Quantity | Item |
|---|---|
| 4 | 21-88 / 021-088-00 style oil bath caps |
| 4 | 010-163-00 / 10-163 style O-rings |
| 4 | 046-032-00 / 46-32 style rubber center plugs |
| Not Included | Hub, drum, bearings, oil, tools, and additional hardware are not included unless shown or stated otherwise. |
Important Fitment Note: Trailer hub and axle configurations can vary. Before ordering, verify your existing oil cap number, 3.5" cap application, thread style, O-ring, rubber plug, axle model, and hub setup. This kit is intended for compatible 21-88 style oil bath cap applications.
21-88 oil cap kit, 021-088-00 oil bath cap, 3.5 inch oil bath hub cap, Dexter style 10K oil cap, 10-163 O-ring, 010-163-00 O-ring, 46-32 rubber plug, 046-032-00 rubber plug, trailer oil bath cap service kit, 9K 10K GD oil bath hub cap, #13G axle oil cap application, R&P Carriages oil bath hub service kit, 21-88-KIT-LOTOF4
Thank You For Choosing R&P Carriages As Your Online Shopping Source!
Related Parts & Kits
Check fitment, measurements, and kit contents before ordering. Related parts may not be required for your repair.
Looking up part numbers in our catalog…
Your repair list1 item selected
Selected products are added together. Review the cart and verify kit contents to prevent duplicates. Prices and discounts are determined at checkout.
BEHIND THIS LISTING
PHOTOGRAPHY & RESEARCH
Ariah Granados
DIGITAL PRESENTATION & DEVELOPMENT
Ken Martin
ONLINE SALES & QUALITY ASSURANCE
Rayn Fisher
WE’RE HERE TO HELP
Not sure it fits?
Have your SKU or manufacturer part number, photos of the original part and mounting, and any critical measurements ready. Capacity, voltage, or bolt pattern can help too.
815-357-3292 · 270 E Jackson St · Seneca, IL 61360
CUSTOMER REVIEWS
Leave a Google review
Good people. Real trailer work.
Customer feedback summarized from Google and Yellow Pages. Dates are shown where available.
TRAILER PARTSGOOGLE
Ordered trailer repair parts repeatedly; praised fast service, careful packing, and accurate orders.
RV KEYSGOOGLE
Found the correct RV keys at a good price with free shipping; the keys worked as expected.
AXLE & LEAF SPRINGSGOOGLE
Needed an unusual axle and leaf-spring size; the team listened and helped him sort out the fit.
PARTS & SHIPPINGGOOGLE
Praised the OEM and aftermarket selection, discounts, quick shipping, and friendly parts staff.
CUSTOM AXLEGOOGLE
Got the axle he needed right away, set up with a custom spring perch.
WELDINGGOOGLE
Praised the polite staff and quality welding on a project.
GAS STRUTGOOGLE
Replacement struts brought a long-used door back to working order.
CUSTOM TRAILERGOOGLE
Had a trailer built to his needs at a fair price, then found parts for two other trailers in stock.
CUSTOMER SERVICEGOOGLE
Praised the customer service after working with R&P over several years.
GAS SHOCKGOOGLE
Found the gas shock he wanted at a good price with shipping included.
CARGO TIE-DOWNGOOGLE
Received swivel D-rings with backing plates and praised the price, correct order, and service.
PARTS DELIVERYGOOGLE
The right parts arrived the first time, with fast delivery and helpful staff.
PROJECT HELPYELLOW PAGES
Said project advice and prompt shipping helped finish a trailer project.
SHIPPINGYELLOW PAGES
Reported helpful service and fast shipment to Germany.
SUSPENSION KITYELLOW PAGES
Praised a suspension kit, fair pricing, and good parts.
TRAILER CORDYELLOW PAGES
Was pleased with a replacement trailer cord.
SERVICE & PARTSYELLOW PAGES
Noted dependable service and products across repeat visits.
AXLE INSTALLATIONYELLOW PAGES
Said the axle installation fit perfectly and thanked Josh and the crew.
HITCH REPLACEMENTYELLOW PAGES
Praised the crew’s professionalism during a difficult hitch replacement.
PRICE & SERVICEYELLOW PAGES
Liked the product, price, communication, and shipping.
LISTING INFORMATIONYELLOW PAGES
Said the product description explained what would work for the trailer.
PRODUCT & SHIPPINGYELLOW PAGES
Received the item as described with very fast shipping and plans to return.
COMMUNICATION & SHIPPINGYELLOW PAGES
Praised accurate description, quick shipping, and clear communication.
PRICE & PRODUCTYELLOW PAGES
Was happy with the product and its price.
SELLER EXPERIENCEYELLOW PAGES
Called it a pleasure doing business with R&P.
INSTALLATIONYELLOW PAGES
Was pleased with product quality, quick delivery, and an easy installation.
PRODUCTSYELLOW PAGES
Was enthusiastic about the products.
DURABILITYYELLOW PAGES
Was ready to install the product on every trailer they own.
REPEAT CUSTOMERYELLOW PAGES
Expected to buy again after a good experience.
INSTALLED PARTYELLOW PAGES
Reported that the newly installed parts were working perfectly.
REPEAT CUSTOMERYELLOW PAGES
Said things went well, as they had on previous visits.
COMMUNICATION & VALUEYELLOW PAGES
Praised clear communication and fair value.
TRANSACTIONYELLOW PAGES
Said the transaction went as expected.
PRICE & PACKAGINGYELLOW PAGES
Noted good value, careful packing, and fast shipping.
PROFESSIONAL SERVICEYELLOW PAGES
Found the team professional and easy to work with.
COMMUNICATION & SHIPPINGYELLOW PAGES
Praised fast shipping and good communication.
TEAMYELLOW PAGES
Shared appreciation for the owners and their company.
SHIPPINGYELLOW PAGES
Reported prompt shipping and said they would buy again.
CUSTOMER SERVICEYELLOW PAGES
Found R&P easy to deal with.
SERVICEYELLOW PAGES
Praised the people and the service.
FIT & SHIPPINGYELLOW PAGES
Reported a good fit, fair price, accurate listing, and quick shipping.
DELIVERYYELLOW PAGES
Received the order a day early and recommended the seller.
CUSTOM TRAILERYELLOW PAGES
Described a no-hassle, professional custom-trailer purchase.
TRAILER PURCHASEYELLOW PAGES
Praised a new trailer, custom additions, helpful staff, and clear pricing.
HUB COVERSYELLOW PAGES
Found the right hub covers quickly and got helpful maintenance advice.
AXLE HELPYELLOW PAGES
Said R&P helped their company get back on the road after an axle problem.
DUMP TRAILERYELLOW PAGES
Was happy with a dump-trailer purchase after comparing options.
BRAKES, DRUMS & SEALSYELLOW PAGES
Received clear help choosing brake assemblies and bearing seals, followed by fast shipping.
DUMP TRAILERYELLOW PAGES
Found a good deal on a 16-foot dump trailer and planned to return.
FRIENDLY SERVICEYELLOW PAGES
Thanked the staff for their patience and recommended the shop.
Showing 3 of 50
Need help with this part? Send photos, part numbers, and measurements. We’ll help you narrow it down.