Triumph / BSA Crankshaft Roller Bearing 70-2879 / 68-0625 - MRJA 1 1/8 - Choose Brand / Clearance Rating

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If you are performing a complete engine rebuild and your drive side roller bearing is in need of replacement I highly suggest installing a BSA and Triumph roller bearing manufactured by a reputable company such as the bearings we have to offer you today.

Roller bearings fitted to Triumph 650 and 750 unit twins as well as BSA 500 and 650 unit twins came equipped with a MRJA 1 1/8 roller bearing. Original bearings where made by RHP, R&M and Hoffmann. Finding those original roller bearings are almost impossible to find today. Luckily the MRJA 1 1/8 roller bearings we offering today are just as good, affordable and available. 

We are aware that there are many sources online and the popular forums that are talking about the roller bearing clearance rating on each bearing that they should have. I will address this below so you can select the proper roller bearing for your application and also have confidence while doing so.


Choosing the correct clearance

Triumph used the same part number 70-2879 / E2879 for both bearings with the "CN" and "C2" clearance. I will decode this below...

If you own a Triumph 650 unit twin we suggest install a 70-2879 / E2879 roller bearing with a normal clearance rating or a "CN" rating. This type of bearing is correct for all

Triumph 650 unit twins (Bonneville, T120R, TR6, etc) from 1966-19722 on the drive side.

For BSA A50 and A65 unit twins from 1966-1972 they use the same bearing as the Triumph 650 unit twins... Clearance normal "CN" rating under part 70-2879 / E2879 or 68-0625. Again, BSA unit twins (Lightning, Thunderbolt, Royal Star, etc) on the drive side from 1966-1972.

Triumph 750 unit twins from 1972-1983 use the 70-2879 / E2879 roller bearing is a "C2" clearance rating. The "C2" clearance rating is the correct roller bearing for all 750 models including the TR7,  T140, Bonneville Speical, etc

If you are uncertain of which bearing you need, select a "C3" roller bearing..

Use the drop down menu to select which bearing you desire - choose from brand, application and clearance rating for your engine

  • Made in England by RHP
  • OEM part number is 70-2879, E2879 and 68-0625
  • Free shipping in the USA