Pedros Techno DOF IMS fix?

[cnavarro]

Originally Posted by Kirk

So Jake... if we guess this super secret factor will you confirm if it is correct or not? I have seen Charles Navarro of LN state that he would take this secret to his grave!

I am going to throw out my guess and I am going to bet that I am spot on.

The issue is that in the design of the intermediate shaft the ball bearing application is compromised (not optimal) and the magic number (or constant) that it is compromised by is 20%. We state load numbers for the 6204 bearing based on manufacturer's numbers, but those numbers assume that the inner race of the bearing is turning. In most applications the inner race is fitted to a shaft through an interference fit, the shaft rotates, the inner race rotates, and the outer race is held in place in a fixed housing. Bearing load numbers are based on this scenario.

This is not what happens on the intermediate shaft though. That scenario is exactly the opposite. The inner race is fixed and it is the outer race that is pressed INSIDE the intermediate shaft that rotates.

So who cares if it's the outer race that rotates rather than the inner race? Engineers care because this one little difference has a significant impact on how much load the bearing can take. The general rule that is used in bearing calculations is that the impact is a 20% decrease in load. Decreased load effects calculated bearing life and failure rates.

Is this significant then? 20%? Damn straight that is significant. So how to address this? LN went to a stronger ceramic bearing with a much higher load rating than OEM. But eventually LN went to a plain bearing with significantly different load characteristics altogether.

So what do you say Jake? Do I get the gold star??? :dance:

Kirk Bristol

This is just another piece of the very complicated puzzle. When we first started looking at this problem, the use of the bearing in outer race rotation was one of the first problems I knew exactly how to tackle. That's the reason for a ceramic hybrid bearing with sintered silicon nitride balls to be specific.

Jake and I have been using sintered silicon nitride for various components including lifters in pushrod Porsche engines primarily for their wear performance, but the added weight savings is huge.

Now consider the reduced mass of the ceramic balls and how that relates to the loads exerted on the races during the constantly varying acceleration and deceleration of the IMS bearing. This is even more important considering the load on the IMS bearing isn't even across the whole circumference of the races. Since the sintered silicon nitride balls are only 40% of the weight of equivalent steel balls, centrifugal force is lower - the lower weight of silicon nitride balls enables rapid accelerations and decelerations with reduced wear.

At any given time a very small surface area of the bearing is carrying all the load. To simplify what's happening, the balls are slung round 3/4 of the circumference of the bearing and they go from unloaded to fully loaded with only 1 to 2 balls carrying all the load. This is why we see flat spotting of the balls and skidding in the races leading to pitting and eventually complete bearing failure.

Integrated Reliability Solutions

Considering the bearing is in outer race rotation and already prone to skidding, this is just one of the reasons we chose against roller bearings from the very beginning and focused on ceramic hybrid bearings.

However, I will clarify that just going to a ceramic hybrid doesn't give you a higher load capacity than an equivalent conventional bearing but their benefits certainly outweigh the cost.

Hybrid Ceramic Bearings | Applied.com

PS. George is my dad. He used to work in the aerospace field in sales and he came to LN a few years ago to help my wife and I.

[Kirk]

Originally Posted by cnavarro

However, I will clarify that just going to a ceramic hybrid doesn't give you a higher load capacity than an equivalent conventional bearing but their benefits certainly outweigh the cost.

Hybrid Ceramic Bearings | Applied.com

Thanks Charles, the information you provided is very helpful!!!

I do have one question that has been bugging me. Looking at the Applied website that you provided you will see that they recommend grease first and foremost for ceramic bearings, but that's not practical in our application as the grease would need to be changed very regularly. In that situation they recommend oil lubrication and they note that a ceramic bearing does not need as much oil as a steel bearing. However, lubrication is still key. The LN Retrofit relies on oil bath and oil splash lubrication, which Applied notes is fine in some applications. However, they also note that oil jet and circulating oil are also acceptable.

So what if someone does not feel comfortable with the LN Retrofit approach? What if they think that oil bath/splash in this application of high RPM's and high heat is marginal and that a more consistent oil flow is better? What would be the problem with a direct oil feed to a bearing like the LN Retrofit? The LN Retrofit website discourages this practice:

"The LN Engineering IMS Retrofit kit should not be used with any forced oiling products for which they were not designed for."

But ceramic bearings in general are designed for all forms of oil lubrication. Since you are providing some technical detail regarding your ceramic bearing would you mind providing some better detail on why the LN Retrofit does not work with direct oil feed?

Kirk Bristol

[Jamesp]

Kirk,

I'm not trying to design anything to sell. I'm just looking for an IMS redesign that provides adequate bearing life and addresses the root cause of the bearing lubrication failure. Your 20% discussion points to inadequate design by Porsche. Doing the calc on the existing bearing answers the L10 question.

[Kirk]

Originally Posted by Jamesp

Kirk,

I'm not trying to design anything to sell. I'm just looking for an IMS redesign that provides adequate bearing life and addresses the root cause of the bearing lubrication failure. Your 20% discussion points to inadequate design by Porsche. Doing the calc on the existing bearing answers the L10 question.

I am with you. Okay, I think I will do some calculations this next week too. We know the load ratings for the NSK stock bearing. I posted on Pelican Parts a link to the SKF bearing calculator that makes it easy to get an L10 calc. This assumes that the inner race is moving though. I suspect you can just multiply the results by 0.8 to get an answer for the outer race rotating.

SKF Bearing Calculator

You can use the numbers from the stock bearing to compare to other options. I believe I have seen LN post their ceramic bearing load figures in a forum post. You will have to "assume" a certain level of radial and axial loads. Thus you won't get a definitive answer, but you will get calculations that you can use to compare the options available.

The one variable I don't know is what TuneRS is using for their ceramic bearing. What is the load capacity of that option? Does it use a nylon cage? I plan to call Mike at TuneRS next week to ask these questions and add it to the mix for comparison. I want to include them because, although I am still investigating, my gut feel right now is that the TuneRS DOF with ceramic bearing is the best "bang for buck" option that I can install myself in my own shop. If the radial load rating of their bearing is good and you've got consistent oil feed, then it seems that this solution would address the major failings of the stock bearing.

Kirk Bristol

[Jake Raby]

the best "bang for buck" option that I can install myself in my own shop.

The things that motivate the DIY installer are quite different than those who are looking for an installation program and a Certified Installer to carry out the process. The majority of those reading these threads do not have the proper resources to carry out a DIY IMS intervention process, no matter which of the technologies will be employed.

We made the decision long ago not to support DIY installations and to do whatever possible to have Certified Installers apply our technology. Its no fun having to travel across North America as a WTI Instructor, and its much less fun to host my "M96 102" classes here at the Flat 6 Innovations 2-3 times per year to train the installers and evaluate them. It puts such a hiatus on R&D and engine assembly that I am having to build yet another training center off site to support these classes.

While there are other technologies on the market now, none of the others offer a true program for the installers.

Kirk, you are a fairly sharp individual. You are one of the few who I believe could carry out a successful DIY of most any IMSR intervention. I don't hand out compliments, they have to be earned.

[cnavarro]

Originally Posted by Kirk

I am with you. Okay, I think I will do some calculations this next week too. We know the load ratings for the NSK stock bearing. I posted on Pelican Parts a link to the SKF bearing calculator that makes it easy to get an L10 calc. This assumes that the inner race is moving though. I suspect you can just multiply the results by 0.8 to get an answer for the outer race rotating.

SKF Bearing Calculator

You can use the numbers from the stock bearing to compare to other options. I believe I have seen LN post their ceramic bearing load figures in a forum post. You will have to "assume" a certain level of radial and axial loads. Thus you won't get a definitive answer, but you will get calculations that you can use to compare the options available.

L10 life of the 6204 bearing is 90,000 miles assuming an average speed of 60 mph in top gear (the speed mph isn't really what is important - it's the engine RPM that is as engine rpm is directly related to IMS rpm to ball bearing life). Driving habits play directly to this.

The one variable I don't know is what TuneRS is using for their ceramic bearing. What is the load capacity of that option? Does it use a nylon cage? I plan to call Mike at TuneRS next week to ask these questions and add it to the mix for comparison. I want to include them because, although I am still investigating, my gut feel right now is that the TuneRS DOF with ceramic bearing is the best "bang for buck" option that I can install myself in my own shop. If the radial load rating of their bearing is good and you've got consistent oil feed, then it seems that this solution would address the major failings of the stock bearing.

How does adding more oil to a bearing that is already submerged address the major failing of the stock bearing and furthermore constitute being the best bang for the buck?

[Kirk]

Originally Posted by Kirk

But ceramic bearings in general are designed for all forms of oil lubrication. Since you are providing some technical detail regarding your ceramic bearing would you mind providing some better detail on why the LN Retrofit does not work with direct oil feed?

Given my last post with the photos I will pose this question again... if I don't feel comfortable relying just on oil bath and oil splash lubrication, what is wrong with direct oil feed to a ceramic ball bearing - specifically the LN Engineering bearing??? Wouldn't the DOF allow the bearing to run with less wear and cooler? Wouldn't it remove variable lubrication and make it more consistent? These all seem like good things to me, and I really can't see aeration and system pressure losses as being significant down sides. So what exactly is the problem with DOF on a ceramic bearing?

Kirk Bristol

[Jake Raby]

I really can't see aeration and system pressure losses as being significant down sides.

Time and studies will tell.

Kirk, It sounds like you've made your mind up. I believe that decisiveness is a key to anything, so it looks like stage 1 is complete for you.

Charles and I had our version of the DOF in 2007, the studies that we did then, and the data that we collected are the reasons why we do not support a DOF when being utilized with the LN Ceramic hybrid bearing. We did this when having a difficult time extracting OEM dual row bearings, hoping that it would be an alternative to a retrofit, which at the time seemed was not an easy process.

The mistake we made then was not patenting the procedure. We've learned from our mistakes, and trust that from this point forward we'll not only protect the things that we plan to bring to market, but also competing technologies, even if we don't prefer them, or have any plan to bring them to market.

Let us know how the DOF install goes.

What is more, your new 'solution' is also not supported by a large number of installations over long periods of time.

Been there and done that before... Remember, we were the guys getting chastised here on the forums for "a retrofit" back in the day. Back then any retrofit wasn't accepted and people basically made these same statements about anything that we did. Thats what happens when you pioneer something.

[Kirk]

Originally Posted by Jake Raby

Kirk, It sounds like you've made your mind up. I believe that decisiveness is a key to anything, so it looks like stage 1 is complete for you.

Charles and I had our version of the DOF in 2007, the studies that we did then, and the data that we collected are the reasons why we do not support a DOF when being utilized with the LN Ceramic hybrid bearing.

Jake, you are right that my mind is made up about the DOF. What I do will most definitely include the DOF. My big question is what kind of bearing will the DOF be spraying oil on??? I called Mike at TuneRS today and I am awaiting bearing data from him for what he offers. He made it clear though that he is not trying to sell a bearing solution. He is trying to sell a lubrication solution and leaving the bearing question mostly up to others. Your response though still leaves me looking for an answer. So you tested the DOF and found it unsuitable for your ceramic bearing, but WHY, WHY, WHY??? What is the reason, what did the data show? Doesn't the quote that Charles Navarro gave apply here?

Christopher Hitchens - "That which can be asserted without evidence, can be dismissed without evidence."

You make me think that there is no good reason not to do this by not supplying one.

Kirk Bristol

[Jake Raby]

Sharing the things that we know about spraying uncontrolled oil inside the crankcase would be targeting and would be frowned upon.

What we did was not a DOF, as that is the name that they have chosen for their specific product. Essentially it was the same thing, and there are more than a few ways to do it, some better than others.

I was simply stating that we have first hand experience with this form of potential increased bearing life. That's where our standing comes from, not just saying "Don't apply the pressure fed oiling to an LN bearing because we said so".

Like anything else, time will tell.. In fact you may experience some of the things that we did yourself. Just pay attention and share your findings fair and balanced, good or bad. Don't stop analyzing after the install, watch oil consumption, fuel consumption and pull the hose from your AOS after a hard drive before and after the intervention. Pay attention to every noise and every smell. In fact remove the hose from the AOS and block off the port on the intake and see what happens after a hard drive before and after.

Moreover, run your engine at 6,000 RPM for 10 minutes and drain the oil immediately after it shuts off, then do the same test and install a cut off valve in the line feeding the oil flange. Then shut that valve off and do the same test at the same RPM and drain your oil and see what you notice. Then carry out UOA and compare before and after.

The majority of development is just paying attention; listen to the engine as it doesn't know how to lie and it will tell you what it wants and what it likes. Throw the engine on an engine dyno, or the car on a chassis dyno and shut the valve off and on between runs, or utilize an inline electronic fuel shut off to kill the flow of oil at WOT during a run and see what happens. When you do that you can integrate some transducers in the exhaust system and wee what you find then. Maybe you'll see something, maybe you won't and you have to be looking for issues when doing this, because everything is guilty until proven innocent- right?

You might waste your time and thousands of dollars, or you might find something that someone else hasn't.

What I stated here barely scratch the surface of the things that one would need to pay attention to when carrying out this sort of development. These kinds of things are all I do, all day everyday and it is enough to drive someone crazy. Fortunately I was already crazy before I started all of this.

You make me think that there is no good reason not to do this by not supplying one.

Exactky. Your mind was made up before you even started posting.

[thom4782]

The decision to reduce IMSB risk with what technology would be an easy one in a world of perfect information. That world doesn't exist for the Boxster community today and will not exist for years to come if ever. Owners can only rely today on the available empirical information and the opinions of the developers and other community members.

My calculus is simple...

1. The differential IMSB bearing failure rates documented in the class action law suit make it more likely than not that single row bearing weakness is the root cause of the majority of IMSB failures.

2. The LN Retrofit dual row real world experience over many years and thousands of miles make it more likely than not that it is a life of the engine fix as Charles opines.

3. The LN Retrofit single row experience suggests it is a long term fix, at least 50,000 miles, but its developers caution about inherent single row bearing weakness suggests it is a wear item that one should consider replacing at the 50,000 mile mark.

4. DOF may extend the worry free lifetimes of single row ceramic bearings far beyond wear intervals, but there is no empirical experience or developer opinion to suggest by how much.

For me, the above is more than enough to make an informed decision regarding how to mitigate risk. I don't find further hypotheses about possible failure mechanisms or the merits of one technology versus another helpful. They are speculative and their degree of correctness is unknowable without more data. And that's the beauty and curse of the scientific method - hypotheses are just informed guesses that beg confirmation through laboratory or real world observations before they are proved correct or not.

At the end of the day, each owner must look at the data, opinions and speculations that lie before him or her and decide for themselves if, when and how to deal with the IMSB risk problem.