Quote:
Originally Posted by Boxtaboy
I haven't changed out the IMS, and won't. I already got my money's worth in the years I've had with my car, and if it goes, the whole car goes, and it's ok. It's served me really well so far, so no complaints. That's not to say this whole thing hasn't intrigued me...it's interesting reading all the theories which is why I posted the link to that guy's comments. What really interests me is how fellow Boxster owner MarcW from PedrosBoard can get over 300K miles now (and still going) on his 02 base 986 with his IMS and clutch still original. If there is an inherent problem with the IMS design, how can some not fail at all?...ever? Why don't they ALL fail if they are flawed? Why only 1% or 8% or whatever the number is? What about the other 92%?....those are unflawed?....
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The longer that the failures go on, the more is learned. Early on, no one had any idea what was going on, but much has be learned since then. Several things can potentially either be involved of at least contribute to the issue; suspects include everything from grease wash out to engine cases with off centerline flange bores, and even IMS shafts that wobble because they do not rotate around their true center lines. Contributing to the confusion are competing claims by firms with replacement components; one says it is the bearing itself, another says the bearing is fine, it is lubrication that is the main issue. Yet both can't possibly be right. If you were to step back and think about it, if lubrication was the issue, why don't dual row bearings fail more often than single rows? After all, dual rows have twice the bearing surface area of single rows, so poor lubrication should affect them more often than single rows. Yet published stats from the class action case say that single rows fail 8 to 10 times more often than dual rows. So what is really happening, and whom should you be listening to?
One of the largest contributors to the confusion is that too many accept a single cause on little more than blind faith, rather than stepping back and trying to assess all of the information that is available. The reality of the situation is that there are multiple contributing factors, and while some cars have none of them, while others are not so lucky. Having pulled a lot of IMS bearings, you learn that some come out looking like they are brand new, others with fewer miles on them come out so loose that they acutally rattle when you shake them. Shops that do large numbers of retrofits note some engines that seem to be able to kill just about any type of ball bearing replacements while other seem not to care what type is used. Jake has noted cases of a single engine with multiple failures, so their may be situations where no ball or roller bearing is going to survive because of either multiple causes, or situations such as engine cases with off center flange bores are difficult to spot and even harder to fix. Imagine having to tell an owner that the car he or she drove into your shop that was happily running has failed pre qualification, and that the reason is terminal, requiring an engine replacement.
To say that this is a complicated problem is in itself an over simplification.