How to Determine Correct Replacement Hub & Drum

Updated 09/06/2023 | Published 09/04/2023

Question:

I am converting an old equipment trailer from Hydraulic to electric brakes. It appears to be in excess of 5-6k axles, for the time period. I have a new set L and R of 12inch x 2inch brake pad assembly, 5 bolt hole, installed. But the hub/drum I got with it, second hand purchase, does not align correctly with my bearing location nor axle diameter..... dumb mistake on my part. I would like price and availability for 6 bolt Hub /Drum to mount up to the 12inch x 2inch brake assembly I have. I would also like the price and availability of a Hub/Drum set including Brake assembly set to determine if I should just order the entire set R and L to be sure it will work this time. I do have the Hub/Drum I am replacing. So if Bearing part number is needed I can take a look at those also to provide that information. Below are the measurements based on the axle diagram noted that you use in post replies I have seen: A = 1 7/8 inch B = 1 1/2 inch C = straight from B to D D = 1 1/4 inch F = 3/4 inch length off base plate The seat point of the inner bearing at B ridge to the seat point of the outer bearing at D ridge is 3 1/4 inches length. D outer bearing set point path is 1 inch wide, to step down at E set point ridge of washer retainer and nut threads at E. Please inform me at your earliest convenience if these specs will suffice, or not, to identify the Hub/Drum needed for this restoration project. Also the price and availability of parts to accomplish the transition to electric brakes. Thank you

asked by: Lee H

Expert Reply:

The measurements you gave aren't quite enough because you have to measure the spindle down to the thousandths of an inch. So you need to use a digital caliper and measure your spindle at the places in the diagram you say (which I also posted for you below).

For example, if your grease seal (B on the diagram) was 1.719" inner diameter, your inner bearing (C on the diagram) had a 1.378" inner diameter, and your outer bearing (D on the diagram) had a 1.063" inner diameter you would use Trailer Hub and Drum Assembly # AKHD-545-35-EZ-K.

The measurement does have to be very precise, which is why the digital caliper measurement is needed. I have added a link below to our entire selection of hub and drums for you once you know this info.

expert reply by: Kyle S