Sourcing Your Own Porsche IMS Bearing

I've been dragging my feet about posting more info about the IMS bearing I used. I just don't have enough confidence in my specific bearing to recommend the product. I also hesitate to post details because I don't want to start a really technical and insulting debate about bearings. Every thread on sourcing bearings on every forum I've seen has inevitably denigrated into "experts" claiming everyone else is an idiot...

For the above reasons, I've decided to post my research and findings without providing a specific link. My goal here is to provide all the info someone might need to find an IMSB without advocating for a specific bearing. A Google search for hybrid ceramic bearings of the correct size will yield several manufacturers. I recommend calling around and doing your own due diligence. Ultimately, I chose to go with a small company that custom assembles hybrid ceramic bearings. Below is the info you need to source your own bearing:

Update:  2/17/17 A few thousand miles an no issues... I'm still investigating this whole IMS nonsense. I'm cautiously growing more confident. At some point, I will take the transmission back out and test the bearing (probably around 10k miles from now). If it looks like it will last, I'll provide a source. 

Dual Row IMS Bearings

For Porsche Boxsters and 911s from 1996 to 2000 or 2001... ish
  • Bearing size: 5204 2rs (wide)
    • Boar (inner diameter): 20mm
    • Outer Diameter: 47mm
    • Width: 23.8mm1
  • Manufacturer: NSK
Dual Row Porsche Specs from NOC

Forget about trying to find a wide bearing. They are extremely difficult to find and nearly impossible to find with the snap ring cut out in the right place. Instead, buy a regular 5204 2rs bearing.

Single Row IMS Bearing

For Porsche Boxsters and 911s from about 2001 to about 2005.2

  • Bearing size 6204 2rs
    • Boar (inner diameter): 20mm
    • Outer Diameter: 47mm
    • Width: 14mm
  • Manufacturer: NSK
There are many manufacturers of both 6204 and 5204 bearings. A quick Google search will turn up many.

Additional Requirements 

  • Find a high-quality manufacture you trust
  • Make sure it's lubricated with quality lube
  • Make sure it has a steel cage or no cage (full complement)--plastic cages are not suitable for the high engine temperatures. 
  • Make sure the bearing is high quality:
    • Precision: Bearings come with different precision ratings from ABEC 1 which is not very precise to ABEC 7 which is extremely precise. I would avoid the lower classes (ABEC 1 and 2).


  1. The Bearing used originally was a 5204 2rs wide bearing. Some have suggested that the extra width of the bearing is an indication that it was custom designed by Porsche. That is not the case. Wide versions of the bearings exist, they are just rare.
  2. The early bearings are dual row bearings and are more robust. Porsche switched over to the idiotic, single row bearing sometime in 2000 / 2001. I haven't found any reliable info about exactly when the changeover happened, so if you have a 2000 or 2001 I recommend you just take it out (if you have the time) then order it.