This IMS Dark Horse...

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02-21-2014, 07:49 PM

#61

BogdanR

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Quote:

Originally Posted by gpjli2

Come on now. Enough of this. For me there has been enough reverse engineering done on this topic especially in this thread. The comment that there will be an outlet for oil when the bearing breaks is bordering on trolling imo. I find it hard to believe you actually own one of these cars with this attitude.

With all due respect there are many engineers, Porsche even has a few last time I checked. If you have not yet gotten your car I hope it comes soon. The answer to overthinking ths stuff lies in the beauty of the machine, it's performance on the road, and the emotional connection it can establish with the inner child/man of the true auto lover.

Upon taking ownership or as soon as possible thereafter I suggest you find a sweet piece of road with good views and begin to experience the world through the eyes of Porsche owner and a car enthusiast. Forget the bearing, concentrate on the emotional door that may open for you if you let it. This advise comes to not from an engineer but from a therapist and hopefully a fellow Porsche lover.

Good luck and have fun out there.

GC

Man your funny bone needs some vitamins. This advice comes not from a therapist but from an engineer and a fellow Porsche owner.
With all due respect, of course.

Cheers! (I really mean it !)

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02-21-2014, 07:55 PM

#62

BogdanR

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Quote:

Originally Posted by Bruce In Philly

I hope a real Porschephile weighs in here as there are tons of histories written about Porsche engine development.

Peace
Bruce in Philly

Me too Bruce.
In case you wonder timing drives are one of the specialities of the company I work for. Among other things.

I have nothing to add to this thread and even if I did, I've lost interest.

Cheers.

Last edited by BogdanR; 02-22-2014 at 11:09 AM.

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02-21-2014, 08:06 PM

#63

utkinpol

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If you will have to drop down gearbox you can remove ims cover and carefully remove outer seal from the bearing. I understand it will improve lubrication. Some install DOF feed there but it is IMHO overkill. In my opinion if bearing was installed properly at the factory and level of vibrations is within specs then it should live long enough.

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02-21-2014, 11:10 PM

#64

RollingArt

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Quote:

Originally Posted by Fahrer

This is interesting but it appears that the DOF is still pumping oil into the ( IMS) tube with no exit.

The other end of the IMS tube is open.

Quote:

Originally Posted by Ben Z

If insufficient lubrication and insufficient load carrying are the primary causes of IMS bearing failure with the smaller, single-race bearing, then why isn't the failure rate five or ten times higher? And why do failures occur at vastly varying mileage? It would seem to me that there must be another powerful variable involved. The one that comes to my mind is assembly tolerance. ...

Who ever said insuff lube and load carrying are the MAIN causes?

I believe driving habits, maintenance, and moisture build up in the engine are the primary causes of IMSB failure. Where driving habits and poor maintenance help contribute to the moisture problem. The moisture starts just a little bit of corrosion on a bearing the sits all winter in an engine with excessive H2O. The next time the engine is fired up it's the beginning of the end. Once there is any wear or pitting started, there is no stopping it. It will just keep wearing faster and faster.

Quote:

Originally Posted by Bruce In Philly

As I understand the history, Porsche has always used an IMS in their air cooled engines since 1965. ... Hmm...did you notice that all the IMS bearings since 1965 were fed with pressurized oil and that the one failing uses a sealed bearing (the one at the other end is force fed oil)?

Porsche has always had an IMS shaft and so has just about every other manufacturer. The big change from the norm with our weak link bearing is not that it's a SEALED ball bearing, but that it is a BALL bearing. Porsche and everyone else have always used PLAIN SHELL bearings for the IMS, just like they use on the crankshaft. Porsche threw a sealed ball bearing on one end of the IMS to save the cost involved with getting an oil galley to that location in the engine. Toss a sealed bearing in there, save a bunch of money on engine manufacturing, and hope for the best.

Side note - Porsche had terrible reliability problems with the ball bearing cranks that they used on the four cam engines in the fifties. You'd think they'd learn their lesson. That was a crankshaft though and not a ims.

Quote:

Originally Posted by mattyf

Not sure I trust Pedro's engineering judgement in his test videos with the seal removed. The outer race of the bearing isn't supposed to spin.

Didn't watch the video, but that is one interesting thing about our ims, installed in our ims as they are, the outer race spins with the IMS and the inner race is bolted down. Believe that is also not a good thing for ball bearing performance.

.
So, BogdenR, did your 997 arrive yet?

Cheers,

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02-21-2014, 11:49 PM

#65

BogdanR

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I've done the PPI today. Apart from the back rotors being slightly under spec, theres a completely clean bill of health. Delivery is tentatively next Tuesday.

I have barely any nails left... :-)

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