Ok, lets remember this statement leading into the future when discussing the the problem with the M96 IMSB is only limited to lubrication.

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...

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.

The choice should be very clear to those people that there's only one way to truly solve the problem. I won't try to convince them, because once the development is done, I am done.. I don't sell the parts.

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.
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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.

Interesting lobes on that cam...

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I love a good IMS discussion. Just think what would we be talking about if not for the IMS.

That's basically what I am doing - putting in a new bearing, removing the outside seal, and installing the DOF. This is on a 2003 Carrera 4S with single row bearing. I'm just not 100% sure yet if I'm going back in with a SKF steel bearing or a ceramic bearing. I have both in my hands, but my mind is not made up. Transmission came out of the car Sunday. The RMS and IMS are both leaking oil, the IMS is leaking worse. This next weekend I'll get the IMS bearing changed out and oil feed installed. I'll probably start a separate thread with photos about the install and my impressions of the DOF system. So far I really like what I see with it. I got a nice set of instructions with clear photos and details on the install. The quality of the parts seems really good too.

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

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

When talking about the oiling question, it's importanty to keep in mind there are two very different situations to look at.

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.

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

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