Another IMS bearing thread

[Jamesp]

Originally Posted by woodsman

Double check timing??

Valve timing???

[Jamesp]

oh, man!, I'm hijacking the thread again!

[Jamesp]

IMS Bearing!, IMS Bearing! Phew! There, we're back on track.

[thom4782]

Walter…IMHO: any new design must also fix the single row OEM bearing’s Achilles heel, namely its relatively poor load carrying capacity compared to dual row ones.
This inherent weakness, not lubrication, explains why single row OEM bearings failed 8 times more frequently than their dual row counterparts.

So if you or someone else could develop a more affordable design for single row shafts that matches the dual row’s load carrying performance, then owners could drive their cars around worry free for the life of their engines.

[Jamesp]

From what I've seen, and this is simply gut feeling with - NO DATA - so I normally wouldn't say it,... the OEM single row bearings are adequate for the loads provided they have uncompromised grease lubrication. The dual rows are overkill and because of the additional load carrying capacity, can tolerate poor lubrication over a much longer time. Bearings tend to fail in an exponential manner. That means small changes in RPM, load, or other variables can lead to quick failures. I studied a case of police car alternator bearing failures. Turns out the additional electrical loads on a police car at idle was killing the batteries because the alternator could not keep up at idle. The solution?, a smaller alternator pulley so the alternator turned faster at idle. Going down the freeway those alternators were turning plenty fast. The result was repeatable bearing failures in the alternators.

[Jake Raby]

Originally Posted by Jamesp

From what I've seen, and this is simply gut feeling with - NO DATA - so I normally wouldn't say it,... the OEM single row bearings are adequate for the loads provided they have uncompromised grease lubrication. The dual rows are overkill and because of the additional load carrying capacity, can tolerate poor lubrication over a much longer time. Bearings tend to fail in an exponential manner. That means small changes in RPM, load, or other variables can lead to quick failures. I studied a case of police car alternator bearing failures. Turns out the additional electrical loads on a police car at idle was killing the batteries because the alternator could not keep up at idle. The solution?, a smaller alternator pulley so the alternator turned faster at idle. Going down the freeway those alternators were turning plenty fast. The result was repeatable bearing failures in the alternators.

Guess what.. The 6204 is a GM Alternator bearing!

[thom4782]

James: if your 'gut' hypothesis were true, then failure rates of single and dual row bearings would be similar. They are not. Data submitted in the Eisen lawsuit showed single row bearings failed more than 8 times the rate of dual row bearings.