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If the problem was limited to lubrication, then Kirk's observation and most recent statements would not be relevant, but they are. |
It would be nice if you said more Jake. There are folks with their engines not just split, but with every bolt removed, hanging on this conversation. Not that I'll say who though...
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I'm about to put in a dual row ceramic bearing. I don't know if I should just put it in with the front seal removed or with Pedro's dof. Any thoughts? My stock dual row didn't fail and still looks and feels great after I pulled it out.
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I am a little busy at the moment... Creating another DFI Beast. While other people have just started developing M96 components and entering the market we are on our fourth year of DFI engine development at the next level. Yeah. They are a few years behind. They know it. This one is spankin' new out of the crate, built in March of 2013. It's getting fed some Raby steroids. https://scontent-a-iad.xx.fbcdn.net/...84914160_n.jpg https://scontent-a-iad.xx.fbcdn.net/...08428414_n.jpg https://scontent-a-iad.xx.fbcdn.net/...27900627_n.jpg |
Can't wait to afford to buy a different make of sports car to put this entire discussion behind me.
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If lubrication really is the problem, bearing size wouldn't matter. But the failure figures of the dual row versus single row IMS bearing from the class action lawsuit tell a different story. |
Here's what I see...
There are no verified in service dual row LN Retrofit failures across the years they have been available. In another forum, one LN developer recently expressed his view that dual row Retrofits are “…pretty much bulletproof and will probably never need replacing.” In theory, DOF will extend the service lifetimes of IMSBs although its developers have never indicated to the best of my knowledge by how much. So it's up to you. If you believe a belt is sufficient to keep your pants up, the install the Retrofit. If you're a belt and suspenders type person, then you might add DOF into the mix. If you do, make sure you order a LN Retrofit compatible DOF flange. My car is single row. For me, I'm planning to install an IMS Solution as soon as I can find a competent local installer. Best of luck. PS: My personal view from all the data I've seen is that majority of single row OEM bearings failed because they weren't stong enough. Dual row and single row OEM bearing also failed when their seals leaked thereby compromising lubrication. |
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http://986forum.com/forums/uploads01...1383015629.jpg |
I love a good IMS discussion. Just think what would we be talking about if not for the IMS.
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Kirk |
Charles, I think those numbers confirm what what we already know from the lawsuit: all else being equal, the dual-row bearings are more durable/reliable than the single-row bearings. Based upon experience in other applications, we also have reason to believe that a ceramic bearing should be more durable than a steel ball bearing of the same design. However, virtually all invovled in this discussion (including the LN Engineering site as per excerpts already quoted) also suggest that lubrication of the bearing is PART of the problem.
Kirk, I look forward to your updates. With a failure rate of approximately 1%, I would think that if you had a dual-row bearing you would likely be fine with a new dual-row steel bearing and DOF. With the single-row bearing, however, I wonder if the additional cost of a good ceramic bearing might not provide added insurance. Brad |
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I am not worried about cost. I have both - steel and ceramic bearings in my hands. I can put either in my 2003 C4S. The ceramic would be the obvious choice, right? My only concern there is the nylon cage that holds the balls in position. I have been researching this material to see how well it will hold up in a hot environment exposed to synthetic oil constantly. I see manufacturer's temperature specs ranging from 210 to 250 F. But we know that the bearing seal is rated for 250 F and it does not hold up well. I thought I saw that LN Engineering uses a steel cage, but I have not confirmed that. I know that Casper Labs used a steel cage precisely because the temperature limit of the nylon cage is too close to the hot operating limit of a Porsche engine. So I'm not sure I feel comfortable putting a ceramic bearing with a nylon cage in my car... Still reading and researching before this weekend. :confused: One advantage of the DOF is that the better lubrication should allow the bearing to run cooler. Kirk |
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Situation #1: Lubrication is a problem with the 'sealed" OEM bearings. When seals leak and oil mixes with grease, then friction increases and the bearing eventually fails. This seems true for both dual and single row bearings. Situation #2: After someone replaces the IMSB with an "unsealed" bearing, hopefully a ceramic one, sump oil lubricates the open replacement bearing. As I've said many times, the experience to date shows virtually no failures with this oiling method. So context really matters when talking about lubrication as a problem no matter who is commenting. |
Nylon seems to be a poor material choice for the operating environment the bearing will see. Personally I would shy away from using it in this application as the risk associated with its failure seems greater than the benefit of the ceramic materials in the bearing.
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Thom, if you read post#48 you would see that I do, in fact, talk about both methods of lubrication. And Kirk, was the ceramic bearing that you have purchased in conjunction with the DOF? Frankly, I share your concerns about the durability of the nylon race, even with the improved cooling that should come with DOF.
Brad |
You presume, since the LN ceramic was chosen and designed and modified (they got at least one wrong the first time but that was long ago) by a retired bearing engineer and Porsche nut, that there was a reason why they used the parts and designs they did. You also have 10k of owner's experiences to tell you a little about how well they chose. So deviating from that would seem to require some theory, study, test, experience...wouldn't it?
Now if you want to run the experiment on your engine, why it is your engine. |
This is going on and on and on LOL
I can see a lot of member bragging about their engineering background but can't see anyone throwing any sort of stress-strain curve vs (x)modulus formulas designed for bearing type selection, materials and applications :/ Fascinating thread otherwise! As little as I know on anything related to cars.... fuel dilution, glycol, calcium sulfonate contamination are the main cause of engine's internal parts/premature failures. Bearings and seals being mostly at risks. OIL BALLS anyone?! Why would anyone give a bearing more of that would be my first question. Personally, I have better things to do than worrying about a dumb bearing, or a cheap engine (this is not a Ferrari or a Lambo!). I do however ensure to carry out the regular maintenance on my little 986 roadster, have the fuel injection system, MAF and O2 sensor system functioning spot-on at all time, use PORSCHE APPROVED OILS, and my engine (and bearings) simply works as the "professionals" engineered it. Make sense? Some of the best bearings (perhaps overkill) in underground motorsport designs are made with TI(Ti-6Al-4V) races, 316 stainless steel balls, packed with solid oil, and sealed to prevent "contaminations". Already public info in case anyone really care to come up with a warranty for 50 years bearing (simple) design.... by all means be the Porsche engineering team's savior! |
I had not heard of Ti-6Al-4V so I looked it up! "Ti-6Al-4V's poor shear strength makes it undesirable for bone screws or plates. It also has poor surface wear properties and tends to seize when in sliding contact with itself and other metals." Sounds like exactly the thing for a bearing. I'll take 2
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I'll take 4 (four) of those NSK steel-on-steel ball bearing then. Those have the same coefficients of friction in both static and kinetic values as of rubber on asphalt! I believe TI is used for its thermal, durability and non-toxic properties. Properly done, ssteel can be harden far beyond TI... those balls are the ones that carry the load capacity if my memory is good.
I just heard some young dudes talking about this in the R&D center I worked for 20+ years. I was just their janitor mopping floors all day long and know nothing about nothing ;) sorry for wasting your time! |
Brad:
Nobody, including the LN developers, is denying that compromised lubrication did not play a role in IMSB failures. It probably was the root cause of most dual row OEM failures and about 1% of the single row ones. Poor lubrication doesn't explain the other 7% of single row OEM breakdowns. Weaker load carrying capacity probably does because that's the one key difference between dual and single row designs. People need an answer to a critical threshold question before choosing between LN Retrofit or a DOF lubricated unsealed bearing, namely is lubrication still a problem for unsealed replacement IMSBs? The LN data makes a strong case that the answer to the question is that there is no lubrication problem for unsealed replacement IMSBs. Not surprisingly, one DOF developer regularly says that lubrication is still a problem but he doesn't offer any hard facts to support his view. Thom |
Something interesting as a comparison w.r.t. lubrication of deep groove ball bearings.
ROTAX 582, water cooled 2 stoke engine run 6207 and 6206 DGBB's on their crankshaft @6500 RPM, Lubrication? 50:1 pre mix, that not a lot of oil. |
thom, if you read my posts you would see that we are largely in agreement: for example, in post 84 I suggest that for owners of the double-row bearings, the LN retrofit is the most cost-effective answer; for those with the single-row bearing, I opine that is likely also the case, although WITH BETTER EVIDENCE, I suggest that the DOF may also prove to be an important augmentation to a bearing upgrade/replacement.
We know that the dual-row bearing is more durable than the single row. We also believe that a properly engineered ceramic bearing should be more durable than a steel one. Finally, we know that inadequate lubrication is a causal factor in IMS bearing failure, regardless of the type of bearing. What we do not know is whether, especially for the single-row bearing, splash lubrication will be sufficient to ensure trouble-free, long term use. It would seem that LN are also unsure, in that they recommend replacement of their upgraded bearing every 3 years, or 50,000 miles. I wonder how many of the original sealed single-row bearings would have failed if replaced on that schedule! Brad |
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The single row retrofit bearing is recommended as a 50K component due to it's size and load carrying capacity- nothing more. The single row bearing simply is not robust enough, even when superior ceramic balls and hardened races are utilized. Two rows are certainly better than one. |
JFP, to you it may be a dead horse, but to others it has been worthwhile discussing the various bearings and the lubrication of the same. Jake, we all now know that dual-row are better than single-row and Porsche's own numbers verify the same. Indeed, it seems that your own opinion on the same has also evolved over the years for, as I recall, a couple of years ago your opinions in that regard were much more circumspect.
Nevertheless, if lubrication is a contributing factor to IMS bearing failure (and I thought we were all in agreement on that as well), then does it not also stand to reason that a better lubricated bearing should outlast one with poorer lubrication? You believe that splash lubrication with seals removed is not only adequate, but better than DOF for various reasons (aeration of the oil, etc.) and you may be right. Only time and further testing will tell. Regardless, my understanding of the issues has been enhanced by this thread and I strongly suspect that the same is true for others. JFP, if it has been tiresome for you, so be it. Anyway, barring some new and unexpected news/information, I'm certainly out of here. Cheers! Brad |
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http://986forum.com/forums/uploads01...1383337437.jpg e,g with a nonuniform distribution f(θ) = Fo*Sin(q) = (Fo)*(y/a) = 1.333*Fo*y where: f(θ) is the intensity of the force a is the radius of the hole and Fo is a scale factor calculated such that the sum of all forces acting on the nodes in the vertical direction (ΣFo*Sin2(θ)) is set equal to the specified force value, F. Intensity of the force is assumed uniform in the z-direction. |
Wish I'd have this crazy shaft diameter, alloy types, and bearing dimensions. I could run your simulation real quick but I don't! I just have a Boxster :)
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If spraying unfiltered oil on the back of an OEM style steel bearing assembly truly is the future for the M96/97 design engines, in a year or two it may become more obvious, but right now it looks more like trying to develop a trend line from too few data points and a whole lot of arguing. Those of us that stake our business's reputation on how well an aftermarket part will perform will take a wait and see position until there is enough data to confirm its viability. And arguing and posturing is not going to change that. |
Just throwing this out there:
I work with very expensive rotating equipment everyday. A few years ago, we started converting most of our bearings from oil bath (either oil flung up by an oil ring or having a level of oil just slightly above the outer race at the bottom of the bearing) to an oil mist system. The oil mist provides the bearing with a very small mist of oil to be pulled through the bearing. Most people thought that there would be bearing failure because of lack of lubrication, but the data shows that this is not the case. This misting amount is so miniscule, hardly any oil at all. Bearings do not need much oil to work properly and of course, too much is not better. They do need "good" oil though. I am sure that Jake could test (maybe he already has) how much oil is splashed up to this bearing. It would show whether that was enough lubrication. The only scenario where there might not be enough oil momentarily would be immediately upon start-up and under hard cornering. My Boxster has a 3.4L from an 06 Cayman. So I have that huge, single row bearing. I talked to Charles when I bought the engine and since I didn't want to open an engine with 20K on it, he suggested that I remove the outer race. I did and have ran it that way for the last few summers. |
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Too many simulations were utilized when designing the M96 engine, IMHO. The sweet spot between simulations and real world practical application is where I try to operate. Plus, I REALLY enjoy breaking things. I am damn good at it, too. |
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Simulation software are excellent at pre-evaluating stresses vs material-types and sizes selections. Some even comes with unique features under Menu > Dumb > Very Dumb > where you can select: Driver has failed O2 sensors, bad MAF, clogged FIs, Wal-Mart cheap oil, and it simulate the rapid effects of contamination and oil balls has on engines, steels and seals ;) Priceless. Look up for ANSYS Co. (ANSYS - Simulation Driven Product Development) |
Everything has a place.. We use simulations when they make sense, for all other things we use practical application. I use simulation software primarily for designing my camshafts and engine combinations.
The ability to put a cylinder head on a flow bench, gather port flow data, then throw a camshaft in the profiler and gather those numbers, then throw all of that into the matching engine simulation software and start building a new combination without having to assemble it is a great thing. That said, there are few times that things in the real world go the same when building that magical combination, and of course the second generation of it is always better than the first. Its engine evolution. |
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I'm still at a loss as to why people question the benefit of properly lubricating a ball bearing... Yes, the DOF system is a new product and doesn't have thousands of installs, but the SCIENCE that it is based on is old and well proven. So why question it so much? Sorry for being so blunt, but I think it's time to call it like it is... I personally discount most of what LN Engineering and Jake Raby have said regarding lubrication not being the issue because Jake has made it very clear that he is out for blood in a fierce competition here. He's looking to crush alternative products. If there is real science that he wants to share to add to the discussion of lubrication, then add it. Instead we get vague responses about our AOS maybe failing... I think the whole story on the importance of proper lubrication has changed. The IMS Retrofit website has been updated to sternly warn against direct oil lubrication now. Their UK distributor website hasn't been updated/changed yet though and it is very, very clear throughout - poor lubrication is the key contributor to the IMS failures. PORSCHE Intermediate shaft upgrade kit for PORSCHE BOXSTER ENGINE 986 AND PORSCHE 911 996 ENGINE The failure differences between single row 6204, double row, and single row 6305 bearings seem obvious to me. Without the proper lubrication what kind of problem are you going to have? Accelerated wear. Now if you have more balls or a bigger bearing will you be able to tolerate more wear before failure? Absolutely. So you would expect higher failure rates with the smaller 6204 bearing, but not because the bearing is so weak that it is failing due to low tensile strength. No, when we see IMS bearing failures we don't see shattered, broken bearing balls. What we see are worn races, worn balls, worn cages. I don't need 12,000 installs and years of experience to tell me that proper lubrication is the best answer to wear. No, there are millions and millions of installs and decades and decades of experience that tell us that proper lubrication is the BEST way to minimize wear in a ball bearing. That's why I see the IMS Retrofit with a stronger bearing as just a band aid solution while the direct oil feed is a real fix, root cause solution. Kirk Bristol |
I question DOF for one simple reason. Nobody that I've seen has provided one single hard fact that shows
lubrication is a problem for unsealed replacement bearings. Just because someone says something doesn't mean it's so. |
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http://986forum.com/forums/uploads01...1383673144.jpg This shows that the sump level is clearly below the IMS bearing (the green line). Then we also have pictures that show the small slit that the oil has to "splash" through to lubricate the bearing. http://986forum.com/forums/uploads01...1383673324.jpg Then on top of that we have a dozen or more IMS Retrofit failures and a new video on the TuneRS website showing a badly worn Retrofit bearing after just 40K or so miles... So you are right, there is no direct evidence to support the LN Engineering claim that there is sufficient splash lubrication for an unsealed bearing, but the indirect evidence would make me very uneasy about trusting such an important bearing to marginal, at best, oil splash. I think the indirect evidence is enough for me to want a more reliable and consistent supply of oil to this bearing = DOF. Now I have asked LNE in another post for any testing that they've done to show the oil level during dynamic running conditions, but they have not produced anything. On the other hand I just installed a DOF system on my 2003 Carrera 4S this last weekend and I have the peace of mind now that I know exactly what the state of lubrication will be for that bearing under all running conditions like hard cornering, hard braking, and acceleration - it will be exactly the same!!! Kirk Bristol |
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Nothing personal against anyone, of course. Time will tell it all, just like it already has with our products over the past 5 years of application. One thing is for sure, the pros won't ever be bragged upon, but you can guarantee that each and every "con" and "issue" will find its way into the public. It always does. This holds true for the handful of issues that we have had and with enough units sold, it will hold true for every single other product out there. Charles will be here later this week and we have an M96 on the engine dyno :-) |
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As for your supposition that LN used to say lubrication was a problem and now has reversed that stance, that is not correct. LN has always stated that the breakdown of the OEM grease in the sealed bearing and its washing away when the seals begin to fail precipitate bearing failures. It is that lack of lubrication by the now displaced grease, and the break down of the oil that often gets trapped in its place that eats these bearings. But they have correctly expressed concern both about running unfiltered oil into ceramic bearings, and about the thickness of the oil feed flange significantly reducing the center bolt engagement and support. LN has stated for years that they were adamantly opposed to installing their bearings into engines that showed signs of significant metallic debris in the oil or filter because it can lead to premature bearing wear and failure, which is one of several reasons they developed the spin on oil filter system that uses filters without by-pass mechanisms. A recent article in the technical section of "Excellence" discussed the importance of oil filtration in these engines and why it is important to consider replacing the OEM system with a "full flow" (read no bypass) style filter, even if it is the only modification you make to the car. Unfortunately, your perspective does not align with mine, as having more than 10,000 ceramic bearings happily running around for several years without unfiltered oil being squirted into them tells me an entirely different story..................... |
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Kirk Bristol |
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The biggest mistake that can be made is treating this engine like any other machine. Thats the opening line in both my WTI Engine Mechanical Class as well as my M96 102 Engine Rebuild School. |
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The seal on your IMS bearing is made of edacrylonitrile butadiene in case one needs to use science to make sense of things. The other questions you may want to ask yourself is why it is sealed per design, and what eats the seal off the bearing, again, before you think about giving it more of what may destroyed it at first place. Again, change your oil frequently, have your MAF/O2 air and fuel distribution spot-on and your bearing will work perfectly as designed and will live forever like on thousands of other pcars. So simple |
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