How to Measure a Trailer Hub or Dust Cap to Find the Right Replacement Dust Cap

Updated 04/21/2020 | Published 09/12/2015

Products Featured in This Question

Grease Cap, 1.988" OD Drive In - Qty 2

(1994)

$7.06

4" Carbon Fiber Digital Caliper

(24)

$12.72

Question:

I have a golf cart trailer that I turned into a utility trailer. I just finished the trailer up and I have notice that my new dust cap fell off. Is there any way of measuring the old dust cap that I have that I replaced with the new. I really dont want to take the wheel off again.

asked by: Kevin

Expert Reply:

You can measure either the outer diameter of the part of the dust cap that fits into the hub OR the inner diameter of the hub where the dust cap goes using calipers such as # PTW80157. Calipers are needed because the measurement has to be as accurate as possible.

I also might be able to figure it out based on the outer bearing number which you should be able to see without taking the hub off.

expert reply by: Michael H

David N.

2/11/2020

MY hub measured 1.9996. Do I use a 2.0 cap or what size is correct?

Jason S.

2/12/2020

You will want the Grease Cap, 1.99" OD EZ Lube Drive in with Plug - Qty 2 # RG04-040. The caps don't get rated to the ten thousandths place.

Brandon C.

4/19/2020

Hello I measured my dust cover at 1.775 with digital calipers. I need two for my boat trailer and was hoping to find some bearing buddies.

Chris R.

4/21/2020

We don't have a Bearing Buddy set that quite matches up to the diameter you listed. Would you be able to measure the actual hub bore diameter (instead of the cap itself) with that caliper?