Pedros Techno DOF IMS fix?

[Nine8Six]

Originally Posted by Jake Raby

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.

You guys need to look into modern simulation software. They are capable of answering many (members') questions without anyone having to break anything



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.

[Jake Raby]

Originally Posted by Nine8Six

You guys need to look into modern simulation software. They are capable of answering many (members') questions without anyone having to break anything



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.

Breaking things and gaining first hand experience is required.

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.

[Nine8Six]

Originally Posted by Jake Raby

Breaking things and gaining first hand experience is required.

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.

Couldn't agree more with you that breaking things is the proper way to get things tested, but not necessarily designed - modern software have helped a lot since the last decade. We had a "vault" filled with blown up everything when I was a wage-slave in Milton Keynes back in the days. The most expansive rubbish-pile I saw in my life! I've mopped the floors around it many times

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)

[Nine8Six]

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

[ganseg]

"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"

Which bearing did you install?

[Kirk]

Originally Posted by ganseg

Which bearing did you install?

SKF 6204 RSH JEM single row bearing. 2RSH means it has two seals, but obviously I removed one seal. The "RSH"is SKF's new and improved seal. JEM means it has a C3 tolerance to account for thermal expansion. The OEM bearing had C3 tolerances too since the bearing operates in a hot environment, so I stuck with that. The OEM bearing was from the NSK brand, but I prefer and predominantly use SKF at work.

Kirk Bristol

[ganseg]

Originally Posted by Kirk

SKF 6204 RSH JEM single row bearing. 2RSH means it has two seals, but obviously I removed one seal. The "RSH"is SKF's new and improved seal. JEM means it has a C3 tolerance to account for thermal expansion. The OEM bearing had C3 tolerances too since the bearing operates in a hot environment, so I stuck with that. The OEM bearing was from the NSK brand, but I prefer and predominantly use SKF at work.

Kirk Bristol

Thanks for the answer, Kirk. I will be looking at the same task in my 2002 S. If possible, please come back to this thread with updates on your actual experience in the future.

I have learned a lot in this thread! Thanks to all who have contributed!

[Jake Raby]

Jake, I hear what you're saying, but at the same time I use exactly the same tools to work on a M96 engine as I do an air cooled 2.7L as I do my wife's LS2 in her GTO. There is no vodoo magic to the workings of the Porsche engines. They are indeed machines and are just as subject to the laws of physics and science that make the machines in my factory work.

There's one issue with what I've quoted above... The fact hat you lack the direct, personal M96 engine assembly experience to state this.

Tear down and assemble a complete M96 engine, make it leak free, make it noise free and make it issue free on your very first attempt, then we'll talk.

If this engine was so damn simple and so easy to manipulate I'd not have 986/987/996/997 vehicles at my facility from 27 states today, the majority of which have been shipped to us from other repair facilities across the US and Canada.

My day was good... The first part of a 3 part series in Panorama feature focused on our DFI 9a1 engines was shot today :-)

[Jamesp]

Hi Jake,

That's my intent, and having researched the build every way I can, I'd agree it is a very different beast from say a GM V8 straight 6, Volkswagon, Triumph (self unthreading connecting rod bolts and dual Zenith Stromberg carbs Ugh!), Ford or Chiseler V8, or even the venerable Corvair. Any tips you'd care to PM me would be appreciated.

[mikefocke]

What was the history of the engine and the condition of the rest of the engine on the LN IMS bearing Pedro showed? Might they have influenced the condition of the bearing? Why have so many survived so much longer? Beware the sample qty 1 conclusion.

And I'd bet Charles and Jake have said that installing any bearing in a contaminated engine or having some other failure in the engine would compromise any bearing over time, even a better bearing.

I think we have to be really careful to separate in our discussions the single and double row removable bearings.

[mikefocke]

But LN isn't saying all LN bearings should be replaced at 40-50k like you said, just the single row ones. They were cautious with their claims in the beginning and waited until time and miles and reports gave credence to any thoughts of longer life.

What evidence is there in similar mileage cars of the effect of the DOF? How many 40-50k bearings have been pulled after being used in real world cars for several years with a DOF and what are the reported results? Oh, I forgot, the DOF folk won't even reveal the extent of their testing. And there hasn't been a single person yet posting "I've had the DOF installed with XYZ bearing for 3 years and 30k miles and this is my experience". How do we know it helps or hurts until that level of experience is exposed? I think some people's enthusiasm for the next new thing has outrun the evidence.

How many new medicines have been introduced with much hoopla only to have us learn a few years later they aren't as good or they have really bad side effects. My doctor believes in using ones that have a long history because the benefits and risks are better understood.

[Kirk]

Originally Posted by mikefocke

But LN isn't saying all LN bearings should be replaced at 40-50k like you said, just the single row ones.

That's not what's on their website, imsretrofit.com

Typically replacement of the IMS bearing takes 10-14 hours (with exception of some Tiptronic 911 models) and is usually serviced at the same time the clutch is being replaced, or every 50,000 miles (for 4 years, like a timing belt on many modern engines).

In the context of this statement they are talking about both double and single row bearings.

Kirk

[Steve Tinker]

With the music you listen to, no way ......

[DennisAN]

Rather than start up yet another IMS bearing thread....

I've read through all the arguments and theories in this thread. I'd like to add one more that hasn't been discussed at all.

It's known throughout the ball bearing industry that there's a lot of counterfeiting going on. Cheap bearings are marked with "brand name" markings such as from SKF, Timken, et al. The counterfeiters are very clever at making both the bearings and the packaging look identical to the real thing. The only difference is that the fake counterfeit bearings simply have a short working life.

Porsche uses NSK brand bearings for the IMS bearing. However, NSK experienced a rash of counterfeit bearings in the German market just about covering the time frame of the IMS bearings at issue. Product: Resolving of counterfeit problem | NSK

I wonder whether Porsche got a percentage of counterfeit NSK bearings in from suppliers. IIUC the IMS with bearing already installed is received as a complete subassembly from Porsche's suppliers, so Porsche doesn't directly buy the bearings from NSK. A random scattering of counterfeit NSK bearings would explain the somewhat random failures of IMS bearings. There have been many theories proposed as to why certain cars experience IMS bearing failures and why others survive to a ripe old age. Counterfeit bearings could be one significant reason. Porsche engineers may have correctly designed the engine when genuine bearings are used, but did not anticipate inferior counterfeit bearings entering the supply chain.

Guys like Jake Raby have examined thousands of IMS bearings, but it would be interesting to see if even he could tell a genuine bearing from a fake counterfeit part.

[mikefocke]

Jake isn't a bearing engineer but Ed is and I'd bet that he has looked at a lot of the failed bearings that were OEM. I've seen his analysis and even his comments on the original bearings specs pointed to a potential problem so even if they were genuine ....

Bearings aren't just polished balls but a complex assembly of races. seals, packaging, initial lubrication, etc. designed and specified for the loads and environment that they will operate in. And, of the products that have been out there the longest, even LN had one of theirs that had to be redesigned specifically for them (which is why you can't buy one off the shelf and assume it is the same). This after it showed too much wear in the first few that were installed and then were pulled for analysis.

[Walter White]

I have a theory that the cage or separator on the earlier single row bearings may have been the cause of early failures, and possibly many of the higher mileage failures. I believe that poor lubrication allows excessive vibration of the cage leading to its failure. I think that added lubrication helps dampen the vibration, possibly leading to reduced failure incidents of the cage.