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All kinds of things are running through my mind........
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Suggestion · Original poster
Please excuse the noob question but with all the buzz about the IMSB failures, I began to wonder why Porsche uses an IMS.
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Suggestion
Nothing wrong with an IMS, everything wrong with using a sealed ball bearing to support it.
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Please excuse the noob question but with all the buzz about the IMSB failures, I began to wonder why Porsche uses an IMS. Why not drive the cams directly from the crank?
you heathen...you dare to question how the gods build cars. us mortals are not permitted to know the workings of the evil elves from the enchanted black forest
Heathen eh? I can live with that. So the sole purpose of the IMS is to reduce the chain speed and in turn increase chain life? I'm sure sharper minds than mine have long ago figured out that this is the best solution...but I just can't help think that more robust chains and/or more robust oil cooling of the chains would be a simpler, lighter, and possibly even less expensive means of extending chain life.
Thanks for the link...that is a very interesting write-up on the subject.
The 547/1 4 Cam Carrera engine was the first with an "IMS", known as a layshaft in the mid 1950s. Porsche retained the layshaft (IMS) through all aircooled engines and through the 2013 GT3 and Turbo. In all the aforementioned applications that shaft was supported by a plain, journal bearing that was pressure oil fed. These never failed, in fact I've never, not once ever seen one fail.
The reason for the IMS was to drive the camshafts with a lower drive chain surface speed, and also to drive the oil pump.
The 9a1 DFI engines drive the cams from the crankshaft as the IMS was omitted. Porsche utilized the IMS for almost 60 years for a very, very good reason. Not until they utilized a ball bearing to support the IMS did problems begin to occur.
Yes, my IMS Solution (
www.theimssolution.com
) backdates the engine and retrofits the M96/M97 with a pressure oil lubricated and supported plain journal bearing. This supports both radial and longitudinal loads.
I think the pertinent question isn't why they designed the engine with an IMS, but rather why they chose to have one end of that shaft ride on a sealed ball bearing, not significantly more robust than what you find in a swimming pool pump...
All you noobs need to ask or discuss this in the appropriate thread in the sticky above(The IMS DISCUSSION Thread). There was a reason why it was created and stickied in the first place. Thank you and welcome.
Would have been Nice to see Friday out with a few 'heres my new 911", "why I love my 911", threads not this crap again.
dont know why we all dont go out and beat the crap out of our 911 bodywork with a ball pean hammer, be quicker that the depreciation by a 1,000 IMS threads
Thank you for the admonishment and I understand the frustration that comes from "noobs asking questions that have been beat to death" problem that happens on these forums. I've read the sticky. I've read many many threads related to the IMS bearing issues. I have no desire to rehash the failures, the rubbish bearings, or any of that. What I'd never been able to find is a discussion for the reason a layshaft/IMS is employed in these engines. That is all I wanted to learn about or discuss; NOT IMS bearing failures of the M96/M97 engines. I'd like very much to one day post "here's my new 911" but in the meantime, I enjoy learning as much about them as I possibly can.
While we are on the subject...what's the best oil to use to avoid IMS failures? Please be specific about brand and weight and don't be afraid to be subjective.
Absolutely. Nothing wrong with an IMS, everything wrong with using a sealed ball bearing to support it.
If having an IMS was a bad thing, Porsche wouldn't have even made it into 1960.
Yep, you got me. But since I've all but ruled out a 996, can you give me some dirt on the 993 so I can drive the prices down on those? (see, I can be sarcastic too!)
I didn't realize engine architecture would be a contentious topic on a forum for high-performance cars. Other than boobies (nice pic, btw), what else is considered non-contentious? Brake caliper color?
Anything about the IMS is tough due to the damage it has done to the value of the cars. The internet discussions have cost more in lost value than actual IMS repairs
Oil. Oil always makes for a good thread around here
Understood. For the record, I was in no way trying to kick a hornet nest or contribute in any way to devaluing anyone's car. I certainly get why the bearing topic is touchy. Maybe "layshaft" would have brought less heat??
No worries from my end, I'm being entirely sarcastic. I know that she'll never sell that car so while irritating the depreciation issue isn't that big of a deal to us. I also don't lose sleep over our 13 year old factory IMSB either
IMS is used by Porsche so people can fear monger about the IMS on internet forums thus causing the used 996 prices to drop allowing me to buy the one drive one for last 4 years for the price of a new Toyota.
Define "lay shaft". All kinds of things are running through my mind........
Explanation: I am home with two days of chills and fever...feel miserable. I thought a couple of beers would help.
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