Recommended Dexter Fortress Threaded Aluminum Oil Cap to Replace a Dexter 021-036-00 Cap

Question

Question:

I’m wanting to upgrade my clear plastic oil caps dexter part number 021–036–00 to these aluminum caps. Will these fit? It’s going on a 2003 model big Tex trailer with Dexter 10,000 pound axles.

asked by: Clint S

0

Expert Reply:

Yes, they will! The Dexter Fortress Threaded Aluminum Oil Cap item # DX39CR is a replacement for Dexter's 021-036-00 cap. It fits 4" threaded hubs and is easy to access to fill or drain your axle's oil.

expert reply by: Jerred H

0

Jerred H.

11/3/2025

Hey, how did the switch to the aluminum oil caps go on your Big Tex trailer? Your update could make it easier for the next person upgrading from the clear plastic caps.

Answer 1

My contact at Dexter Axle confirmed that Oil Cap Kit #RG04-270 is a correct replacement for the older part reference 21-36 which is now discontinued. Both oil caps have the same 4-inch diameter and are fully interchangeable. The only difference is…

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Answer 2

Dexter recommends a SAE 90, SAE 80W-90 or SAE 75W-90 oil to be used. I recommend the Kodiak Synthetic Bearing Oil for Oil Bath Hubs #XLPROLUBE as it is a synthetic 90 weight oil that helps reduce friction and to keep bearings cool. Since your cap was…

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Answer 3

Hey Eric, so we do have what you need with the replacement cap part #VA55JR but the one you mentioned is smaller so it would not work for you. The cap you need is 4 inch diameter and the one you referenced is 3.75 inch.

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Answer 4

Nowadays you would be able to find the axle capacity stamped on your axles, but that was not always the case. If you are unable to find that information on your axles, you still have other options. The first thing I would do is try to determine the…

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Answer 5

It looks like you're likely trying to replace your hubs/drums on your Dexter axle and I do believe that the "0100" you found on the spec plate actually reads "D100" since that was one of the models that Dexter had for this…

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Answer 6

Hey Steven, I was able to find out that the center cap part number you mentioned is for a 3.75 inch diameter wheel pilot hole so for a suitable replacement we carry the #KE95JV which would work great. Did yours break or did they fall off?

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Answer 7

Hey William, thanks for reaching out! Yes, the Dexter Fortress Threaded Aluminum Oil Cap #DX27CR will work with 15K oil bath axles. If you have a specific axle in mind, let me know what it is and I'd be happy to reach out to Dexter if you're…

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Answer 8

Hey Frank, thanks for reaching out! What Dexter Axle means by this is that you want the grease zerk fitting from the wet bolts in the Dexter E-Z Flex Suspension Kit #K71-653-00 to face the outside of the trailer, rather than under the trailer. I see…

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Answer 9

I would not be able to tell you what replacement you need based on the information you gave but there is a way for you to find out what replacement hub will work for you. In order to find the correct replacement hubs for your trailer, you need to…

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Answer 10

As long as the seal in the bearing kit part #BK1-150 is flush with the hub it is okay to have a small gap between the seal and inner bearing. When installing the seal you only insert it enough so that it is flush with the hub. The seal's job is…

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Answer 11

Roadmaster makes a base plate kit that is designed specifically for the Rugged Ridge bumper like you have which is part #1437-3 which you could attach a Roadmaster tow bar like the Falcon 2 #RM-520 directly to.

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Recommended Dexter Fortress Threaded Aluminum Oil Cap to Replace a Dexter 021-036-00 Cap

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