Another IMS bearing thread

[evomind]

Originally Posted by JFP in PA

We have a couple OEM dual row customer's that would disagree with you as they had to replace their engines when the "not prone to fail" IMS bearings killed their otherwise fine M96's.................

So based on a couple of bad ones EVERYONE should have it done ASAP???
And how much do you charge for that?

[JFP in PA]

Originally Posted by evomind

So based on a couple of bad ones EVERYONE should have it done ASAP???
And how much do you charge for that?

I am simply stating an observed fact: All ball bearing IMS units have some level of failure potential, and that the dual rows do fail and take the engines with them. We have had personal experience with failed single row, dual row, and even the oversized post 2005 units. The risk is real, and how people respond to those facts is entirely up to them and their personal level of risk aversion. Not everyone can afford to jump for a new bullet if their current engine suddenly dies, and some people intend to keep these cars for a long time, so they adjust their priorities accordingly. No one is holding a gun to their heads. And if you choose not to do anything about yours, well, that is your business.............

[Jamesp]

Walter White, Jake is spot on with the comment that spinning an unloaded bearing does not reflect what is happening in the engine. Ivory tower bearing life (all other things being equal) is related to load and RPM. The implication is that operating temperature lubrication, vibration, contamination are all nominal for the bearing. Take a look at bearing manufacturers design handbooks for more information. The reason I did not perform an L-10 calc for the IMSB was because the load would have to be an estimate making the result worthless. By the way, RPM is at 1/3 crank speed. As far as changing the IMSB, Porsche should have manned up early and declared it a maintenance item, particularly the single row . As has been pointed out below, every part of a car eventually fails, the trick is to understand required maintenance to head off collateral damage from failed parts. To reduce the chance of IMSB failure in my engine, the intermediate shaft was modified and the bearing replaced with a high temperature C3 single row bearing. The bearing will be changed out as if it were a timing belt. That means scheduled bearing replacement, something Porsche dealers should have been doing years ago.