99firehawk

excactly why there is so much chicken little syndrome. The internet is a breeding ground for misinforamtion

dstrimbu

Not from the Internet, guys... I know better than to believe the **** I read here... <g>

No less than Bruce Anderson in the new (June) Excellence mag commented on this; page 20 in the Tech Notes section. Bruce mentions that the first design of the Porsche tool 9699/1 - the crank position / concentricity check tool - didn't have a relief hole, and could get hung up when checking crankshaft / case concentricity because the tool was so tight... so they drilled an 1/8" hole in the tool to vent air behind it...

Bruce then goes on to say that "...one wonders if the frequency of engine replacements before the tool was refined didn't help condemn the M96 engine in the eyes of many Porschephiles."

So - the number of 996 engine replacements could have been exaggerated. Bruce then goes on to say that "...it should be noted that even some 987s and 997s have experienced RMS failures."

In my humble opinion, "some" failures in the M97 motor beats the Hell out of his earlier quote: "My best guess is says RMS problems affect between 50 and 100 percent of the (M96 motors), but it all depends on who you ask."

Guys, I love you all dearly, but I cannot believe that Porsche GmbH would allow such an expensive issue to continue to occur across a type change. You shouldn't believe it, either...

Just MHO. I'm not an automotive engineer, but I did stay at a Holiday Inn Express last night...

-don

MMD

Why don't you correct my "misinformation?" Because _you_ don't know what you're talking about.

I subscribe to and read "Excellence," and "Panorama."

That's where I get my info on RMS.

The engine _should_ be machined (like I explained) for concentricity, until it is it will continue to experience the RMS failure.

Do the research and learn about the RMS.

There. Feel better?

John Velasco

here here!!!

JasonAndreas

Where was it written that the M96 engine is not machined after casting? If the gear carrier is moving (and that is what) ends up allowing oil to seep past the RMS I don't think you can blame QC nor can you introduce an additional boring/machining step to workaround the issue.

Go back and read Brad's message. I don't think he meant for you to take the chicken little comment personally? He is one of the few posters that wrenches on the 996 and 997 for a living so he might know something about them. If he was changing a RMS (literally) everyday of the week but has only seen two from an M97 then maybe redesigning the seal was a better idea than redesigning the bottom-end?

OCBen

Those of us who know MMD know better than to believe anything he ever says. So don't waste your time getting frustrated trying to explain anything to him. He's one of those who likes to pretend he knows when he clearly doesn't. He says things just for the sake of making it seem like he knows what he's talking about, and often misleads others with his misinformation in the process.

And whenever anyone calls him on it he backpeddles and refuses to admit he was wrong. After all, he knows more than engineers and Porsche technicians because he subscribes to magazines.

Of course all cast components on an engine get machined in order to establish the interface between mating components. But don't waste your time trying to make him understand that. It's like the old saying about trying to teach a pig to sing - you waste your time and it annoys the pig.

99firehawk

I Just subscribed, maybe now i can finaly figure out what that rms thingy really is

MMD

Why don't you STFU and go attack someone else; maybe find some gang members on a street corner to harrass?

MMD

Everything you wanted to know and need to know about the RMS:

http://www.renntech.org/forums/index...ic=6731&hl=RMS

It's a definitive essay on the RMS problem from Renntech.

Your "Leader" will of course claim the essay is full of sh*t because I refer you to it. Right, Ben? Whadda guy!

MMD

LOL. BSed like a true amateur. Read about the RMS so you don't misinform everybody here.

MMD

I'm too busy to find the reference to the fact that Porsche racing engines do not have RMS failures because, unlike production engines, they are machined for concentricity of the crank around the RMS.

Read my freekin' post and don't misquote me. Every fool knows there's considerable machining of any crankcase casting for proper clearance of journals, bearings etc..

OCBen

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_____________________


Oh, make sure you don't let your magazine subscriptions expire either.

OCBen

Marcel, Marcel. Why can't you be more like Marceau? Miming would really become you, you know. You should give it a try.

Judging by your profanity laced reaction I'd say the truth hurts.

Remember what I told you. There are quite a few knowledgeable individuals here on Rennlist who will call you on it and take you to task whenever you post the misinformation you're so fond of doing. This is not like that other board you like to frequent so often where you seem to "know" what you're talking about just because nobody there seems to know any better than anyone else. In a situation similar to the blind-leading-the-blind, the fool who yaps the most among other fools is deemed the smartest. Keep that in mind if you wish to appear smart and intelligent.

Oh, if I were you I'd be a little cautious in my replies. The last time you were banned for mouthing off with profanity like you're doing right now it was for a whole month. The next time may likely be longer and possibly permanent. Maybe that's what you're working on based on your rant posts here.

MMD

Holy Sheet! Grow up.

Here's me coming down to your level:

You got banned how many times for attacking and insulting people? At least twice that I know of. Not a very good example for a Rennlist Member, Self-Proclaimed Rennlist 997 Forum leader and rocket scientist.

I'm done. Wow. Unbelivable!

JasonAndreas

I don't know the history between the two of you but even when I don't get along with someone I find it beneficial to try and explain something rather than call someone an idiot incapable of understanding. And if I can't explain the subject then maybe I don't know it as well as I think I do?

What I don't understand is how you can machine the crankcase afer the bearing cage has been installed and the engine assembled? (If I'm missing something obvious please don't hesitate to point it out). Besides the fact that you can't machine the crankcase opening if the crankshaft is installed; I've placed an already assembled gearbox inside a 5-axis machine and an extremely large boring machine and it was total nightmare for the person doing the setup work. I can't imagine doing that to an engine especially with the tolerances required. How would you fixture it? Even if you could do it several hundred times a day that still wouldn't stop the bearing cage from moving X number of miles later. When your Porsche mechanic is measuring the crankcase for concentricity what they are looking at is how much the crankshaft has moved. The crankshaft is off center an ever so tiny amount as a result of the bearing cage moving inside the crankcase? If (as you say) Porsche was not centering the boring tool during the initial machining then the RMS would leak from the beginning and never pass QC.


Yes for the most part the 964/GT3/TT style crankcases don't suffer the same style of RMS failue but because the equivalent of the bearing cage is actually cast as part of the crankcase. (I don't have an M97 to tear apart so a diagram from PET will have to do)

964/GT3/TT


M97 (#14 is the equivalent that is bolted inside the engine)



The crankcase halves are still fixtured the same way and machined (I will try to find some photos showing this.) And there is still the possibility of movement between the two halves of the crankcase so people would (in earlier incarnations of the 964/GT3/TT crankcase) shuffle pin them (insert dowels) to prevent it. And of course they can still suffer from an actual seal failure (here's a photo from one of mine).




I familiar with the magazine article and it is a decent overview but I'm not so sure of some/most of the theories and information put forth. Two piece crankshaft? Mobil 1? (Porsche started using that in MY92 long before the M96), etc. Hopefully when Adrian publishes whatever RMS info he has uncovered for his 996 book we will know more?