Bruce In Philly

Fred R. C4S

You are a sage.

Peace
Bruce in Phily

porka

worry about the rms.. I just had mine done.. only $1400 at the dealer though!

bpossel

Hi All!

I am new to the 911 world. After reading all of the posts on the IMS issue, I hope to be in the "less than 5%" group. I have an early '05 997.1. Manufacture date is 2/05 with a warranty start date of 3/05. Currently has 40k miles and no issues! The underside of the engine is dry as a bone! No leaks, no seepage.

I was instructed by my local Memphis shop to wait until I do a clutch overall to replace the bearing. So I will drive her. as this is my daily driver. I average about 12k yearly with a combination of city, highway miles. At first I was shifting in the 3k rpm zone. After reading the forums, I am now shifting in the 4k range and even driving on the highway in the 4k zone.

More to come….

Bob

PhilD

That certainly makes fiscal sense. Early 2005 builds are most probably higher risk, but that doesn't necessarily mean high risk.


Once warmed up I shift between 5-6k, unless I'm driving hard. On the highway I sit in 6th, which is usually around 3-4k.

Congrats on the p-car!

Joe90mmm

From here this is my options now... ?

Direct oil feed (DOF) 1900$ Pelican
LN bearing 650$
Pelican bearing update 165$
Do nothing, 8% risk of failure 0$
Other option ?

Can you guys summerize and comment all of our options here so far, from best to worst ? Also considering that I can change the bearing periodicaly as a maintenance.

Thanks for the IMS Review guys.

Bruce In Philly

Pedro had a DOF solution for around $800

http://pedrosgarage.com/Site_2/TechnoFix_DOF.html

Peace
Bruce in Philly

Fahrer

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

BogdanR

The exit will be there once the bearing breaks :-)

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. Given that you have a narrow bearing that is press-fit into a hollow shaft, and then turns on a spindle secured by a torqued nut, that fitment of the component parts might play as critical a role as the parts themselves.

BogdanR

There's a good reason for that IMS shaft to exist. Porsche engineers are not exactly morons, I would not think...
Think of it this way the new direct injection engine does not have one. Why? Just to be rid of an engineering blunder? Probably not. Direct injection engines control the burn inside the cylinder better so there's less resulting torsional load on the CS. That means less dynamic dampening is needed therefore there's no need for an intermediate shaft to act like one in the first place...

I've struggled with the reason why this IMS was needed to begin with for a while now… With the IMS the layout is actually more complex, with more parts to potentially fail and most likely more expensive (not cheaper how it was suggested above). Think about it: even the assembly procedure is more complex with more precision parts to be fitted, therefore more expensive and more position error prone. So why bother with something like that in the first place ?

Well they needed dynamic damping in the timing system to counteract the CS induced vibrations and to a lesser degree to insulate the feedback vibration due to the camshaft operation. Without a properly damped chain tensioner (and hydraulic ones are traditionally not good at this) it's impossible to do it otherwise but having an intermediate shaft whose mass is supposed to absorb all the vibration induced loading. How all the calcs were done, no one but Porsche knows, that kind of stuff is proprietary and a close guarded industrial secret.

So, there you have it. When you sit down and really think about it logically there's no other way to interpret it... Of course I might be 100% wrong... I'm just an engineer :-)

Bruce In Philly

As I understand the history, Porsche has always used an IMS in their air cooled engines since 1965. While it is good sport to try and understand why, it may lead to incorrect conclusions as to why this thing fails. A different logic path may be better when considering an approach to mitigate failure risk. This problem never occurred until the engine was redesigned. What is different then? Again, very dangerous ground here, but did you notice that the bearing on the other side of the IM doesn't fail? 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)?

Now this does not explain why, but to quote an old joke "Doctor, it hurts when I do this...."

Peace
Bruce in Philly

Bruce In Philly

Interesting information here.....

http://theimssolution.com/ims-101/

Keep in mind, as we all have learned, that this vendor has their own theory.... Pedro has his....

IMHO, should I have one of these engines, would be to fit a DOF solution and not just a stronger bearing. But no one really knows for sure other than a small group of engineers and accountants in Germany.

Peace
Bruce in Philly

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.

I'm with BenZ, there's something else here we don't understand. Tolerance stack up, bad lot of bearings? I don't know. Bearings generally like to be preloaded so the ***** will rotate instead of slide. Not sure how this is addressed in the IMS bearing.

Bruce In Philly

I have time and am bored today.... so I will write some more drivel....

There are other reasons for complex and expensive parts than to mitigate a vibration issue.... The whole point of a flat engine is to get the weight down low in the chasis... other concerns such as engine length become factors.... Unlike the Porsche of today, they really seemed to desire performance goals more than many, like American car companies who desired low assembly and parts costs. Before you start making assumptions about what you see, you may want to think about the broader why first. I am not sure we know this.

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

Peace
Bruce in Philly

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