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How to Measure a Trailer Spindle  

Updated 09/23/2025 | Published 05/22/2014

Question:

I need to find out how to measure a trailer spindle.

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Expert Reply:

I have included a picture that shows the measurements needed for a spindle, bearings, seals, faces, and hubs. The spindle measurements are labeled A through F.

A is the spindle shaft diameter
B is where the grease seal sits
C is where the inner bearing sits
D is where the outer bearing sits
E is the thread diameter at the end of the spindle for the nut
F is the spindle shaft length

I have also included a link to our spindle main page for you. The measurements need to be as accurate as possible so you will need to use dial or digital calipers.

expert reply by:
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Michael H
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Michael M. profile picture

Michael M.

9/7/2024

I bought a digital caliper from Harbor Frt. so i can you spindle measurements requested as follows A = 1.739 inches B = 138.2 inches C = 1.356 inches D = 1.074 inches E = 0.746 inches F = 1.085 inches I still think that inner bearing hub measurement is about a half inch shorter than my old drum bearing height that i provided in an earlier email. Please call 440 221-9610 if you have questions. Thanks. Joe Veri

Anthony profile picture

Anthony

9/23/2025

F but overall length is 106mm C is 34.7 A is 43.6 No B dimension D is 1 inch E 7/8 15/16 The last two don’t have a digital caliper - tape measure The length in 4areas are starting at mount flange 1” 1 7/8 1” 1 of threaded

Jon G. profile picture

Jon G.

9/23/2025

@Anthony Thanks for all of the numbers! Let me reformat this info real quick: A = 1.717" B = N/A C = 1.366" D = 1" E = 7/8" or 15/16" F = 4.173" Ideally we'd have caliper dimensions for all sections, but from the info you gave me, it sounds like you have a #84 spindle so a replacement bearing kit would be # BK2-100. Were you just looking for a bearing kit?
Anthony B. profile picture

Anthony B.

9/23/2025

@JonG looking for everything - hub and bearing and seals Also considering changing to a electric brake kit to upgrade the trailer My current wheels are 5 ok 5.5 and the center hole of wheel is roughly 3 1/2 inches if that matters
Jon G. profile picture

Jon G.

9/23/2025

@AnthonyB In that case you'll need the Easy Grease Trailer Hub and Drum Assembly # AKHD-555-35-EZ-K (2 per axle) and the etrailer Electric Trailer Brakes # AKEBRK-35-SA (1 per axle). You're also going to need a Trailer Breakaway Kit # 3802308, 10 Gauge Wire # 10-1-1, and Butt Connectors # DW05745-10 in order to power up and use the electric brakes properly. Do you already have a 7-Way plug on your trailer?

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