Bearing dimensions-What do they mean?

[djsb 491]

What do the various bearing dimensions refer to? I particularly refer to the bearings on the swingarm.

There are 30x37x20 (23 and 24 (Is 23 the same size as 24? ) below), ((21 below)17x24x30 needle bearings and one 20x37x9 (22 below) ball bearing. I'm guessing that the middle dimension is the OUTER diameter as the dust seal and needle bearing that are seated next to each other have the same 37mm diameter. If this is the case am I correct in assuming that the first number is the INNER diameter (is that the ACTUAL diameter of the needles or is it the diameter of the collar it is meant to accomodate?). And is the smallest dimension the width of the bearing? I hope someone can clear up my confusion. Thanks.

https://www.bike-parts-honda.com/honda-motorcycle/750-MOTO/NC/2014/NC750XDE/Frame/SWINGARM-CHAIN-CASE/71541/F_26/2/19298

[arengle 449]

Inner(bore) X Outer X Width.  this is how they publish the numbers for bearings.

[embee 7,288]

Most bearing stockists list bearings by reference number but you can select them by dimensions, for example select needle roller bearings at https://www.bearingsrus.co.uk/bearings

 then select drawn cup needle bearings and 30 bore, 37 outside dia, and 20 length to get this

https://www.bearingsrus.co.uk/bearings/needle-roller/drawn-cup-needle-roller-bearings/hk3020-skf

The bore of the needle bearing is the diameter of the shaft/sleeve it runs on. The bore of a deep groove ball bearing for example is the size of the shaft/spindle it fits over.

Note there are often versions with seals included, as used in the linkage system.

I've used that supplier many times with excellent service.

Edited July 9, 2018 by embee

[djsb 491]

Also I wonder why there is only one ball bearing and why is it on the right? Seems a bit unbalanced.

[embee 7,288]

The principal loads in the swingarm pivot are carried by the needle rollers, the single ball bearing is there to locate it and stop sideways movement.