Hello everyone.
Today's post is about needle roller bearings, which are often used in motorcycle swingarms and rear linkages.
The point is that when you replace a bearing, you can't just say "as long as the size matches, a slightly different design will do".
I hope it helps if you are thinking of replacing genuine bearings with aftermarket ones.
I was planning to replace the bearings originally fitted to the bike with ones from a bearing maker, instead of genuine parts.
The photo below shows a rear linkage bearing from my G650GS (650 cc).
The needles are packed in with no gaps between them.
When I removed the seal, I found it was marked HN1816.
And this is the bearing I was going to fit instead.
The needles are held in a cage, so they are not packed in tightly with no gaps.
Its part number was HK1816.
I wanted new bearings, so I thought "if the size matches, it will fit" and casually bought bearings of the same size instead of the expensive genuine parts.
But although the bought bearings were the same size, what was inside them was different. So I wondered, "Is it really OK to use these?" That is why I wrote this post.
When I looked into it, the HN1816 (the bearing originally on the bike) turned out to be a full complement drawn cup needle roller bearing.
The HK1816 (the one I bought as a replacement), on the other hand, is a caged drawn cup needle roller bearing.
For terms such as full complement needle roller bearing, I referred to NTN's website (below).
https://www.ntn.co.jp/japan/products/catalog/search.php?categoryId=140&searchWords=#page-1
Source: NTN website (in Japanese)
This table sums up the differences between the two bearings.
| Part number | Notes | Inner diameter (mm) | Outer diameter (mm) | Width (mm) | Basic dynamic load rating (Cr) | Basic static load rating (C0r) |
|---|---|---|---|---|---|---|
| HK1816 (bought as a replacement) | Caged needle roller bearing | 18 | 24 | 16 | 11.6kN | 16.8kN |
| HN1816 (fitted as genuine) | Full complement needle roller bearing | 18 | 24 | 16 | 17kN | 32.5kN |
The table shows that the sizes, such as the inner diameter, are the same, but the load ratings are different.
My guess is that the HN, with its needles packed in tightly, is stronger under load.
I took the data for each bearing from the pages below.
Source of the HN1816 data
Source of the HK1816 data (in Japanese)
The swingarm and rear linkage carry the load at the rear of the bike.
If a bearing ever failed, it could cause a crash.
With that in mind, I decided it was better not to casually swap the genuine bearings for ones I had picked myself.
In the end, I gave up on fitting new bearings, and greased and reused the genuine ones.
By the way, the bearings originally fitted in the swingarm were caged (HK type). So for the swingarm, I did replace them with the same type: NTN HK2216 (G650GS swingarm bearing replacement).
It was a good lesson about swapping genuine parts for generic ones.
Please be careful when you replace genuine parts with generic ones too.