Purpose of Grease Caps and How to Measure to Get Correct Size

Updated 04/26/2010 | Published 04/20/2010

Products Featured in This Question

Grease Cap - 1.988" Outer Diameter - Drive In

(2159)

$3.11

Grease Cap, 1.988" OD Drive In - Qty 2

(2159)

$6.81

Grease Cap, 2.44" OD Drive In - Qty 2

(2159)

$8.72

Question:

The grease caps have fallen off of my 2005 Fleetwood Niagra Pop up camper trailer, after a recent repair at the shop. They insisted that they were just for looks and did not need replacing. What is their purpose and do I need to replace the caps? If so, then what size do I need to order.

asked by: Karen R

Expert Reply:

The purpose of the grease cap is to protect the bearing and the axle from any dirt getting into the bearing, which would then damage the bearing, hub and axle. So it is a good idea to have caps on your axle.

To get the correct size cap you would need to measure the inside diameter of the cap mounting surface on your hub. Then that measurement would match up to the cap size outside diameter. The sizes of caps only vary by a small amount so the measurement has to very accurate. Some of the most common sizes are 1.98 inch, 2.44 inch and 2.72.

expert reply by: Jeff D