IMS - Going with SKF hybrid

[Silber]

Originally Posted by mikefocke

To reveal my bias for quantity testing, I come from a background where millions of test cycles were a minimum.)

I have great faith an SKF's testing methodology. My challenge is to make sure that the bearing has conditions that are acceptable. I think the best way to do that is with a freeze plug. Preventing oil from washing out the bearing will enable me to get the SKF rated service like from my chosen bearing.

I am definitely going out on a limb, at least as far as the Porsche community is concerned. You're right, Time will tell.

As to the cautionary tale of KK, he was trying to use a cheaper bearing with inferior ratings to do the job. I am trying to use a top notch bearing with exceptional ratings to do a hopefully better job than what is currently available on the market.

Absolutely without pioneers I would not be in a position where I could take this experiment and have any minimal chance of success. The work of others has put me in a position where I can possibly even incrementally improve the IMS situation.

What I want is a lifetime solution, and I'm going to do my darndest to get as close to that as humanly possible.

And, I reserve the right to cancel my experiment and go with a proven quantity if that is what I determine to be the best course of action. So far my plan still looks good, but I'm always open to being proven incorrect.

Regards,

Silber

[thom4782]

Originally Posted by Silber

What I want is a lifetime solution, and I'm going to do my darndest to get as close to that as humanly possible. Silber

The IMS Solution is the closest you'll get to a 'lifetime solution' It's just that simple.

[particlewave]

Originally Posted by thom4782

The IMS Solution is the closest you'll get to a 'lifetime solution' It's just that simple.

It's not that simple and there is exactly zero data to back that up. Plain bearings are not permanent and do wear/fail. It's just a fact. That's why you replace them when rebuilding an engine.

Until many have been pulled and measured for wear after 50k, 75k, 100k miles, and until many of them have done years of service without failure, it's all just guessing and marketing hype.

I would trust it more than a single row ball bearing, but the price is ridiculous.
I'm glad I have a dual row that will only be replaced with the same.

[Gelbster]

KK used a Ceramic Hybrid bearing and removed both seals.That bearing is more 'expensive' than the usual $3 steel bearing, not cheaper.
Nothing wrong with the bearing spec but it failed in his engine.
https://rennlist.com/forums/996-forum/750825-different-approach-to-diy-imsb-retro-parts-and-pics.html

"As to the cautionary tale of KK, he was trying to use a cheaper bearing with inferior ratings to do the job."

[Silber]

KK used a Ceramic Hybrid bearing and removed both seals.That bearing is more 'expensive' than the usual steel bearing, not cheaper.
Nothing wrong with the bearing spec but it failed in his engine.

I looked up the bearing he used. From what I can tell, it was a $60 or so ceramic hybrid bearing, where the SKF hybrid is $150. It was a cheap hybrid, maybe price wise above a steel bearing, but effectively you would be worse off with that bearing as compared to an SKF steel one. Fatigue limits for his bearing were very poor, not a bearing suited for an engine.

Silber

[Gelbster]

There is way more to this subject than the merely the specs of the bearing or discussing load vs lube.This is just conventional M96 wisdom.I am not an expert . 6204 & 5204 are just a dimension code. the Abec rating is a useful spec but C3 seems adequate.Tight clearances like 5+ may be a disadvantage ? then there is cage, seal, hybrids etc.
M96 engines may have different IMSB-related defects and to varying degrees. So are we discussing a better spec for a specific engine, a specific tye of bearing/year model or a panacea for all M96 ?
Let's exclude the collateral/ FOM damage failures because they are unrelated to IMSB specs.

Until you know the IMS-related defects(if any) in a specific engine ,how will you propose a solution for that engine ? And how does that spec apply to all M96 ?
For example -if Runout of the tube and/or sproket is the problem, tweaking ball bearing specs won't fix it. A plain bearing or a roller bearing might up to a limit . But what runout limit ?
If there are no IMS related defects in an engine , a1RS $3 OEM-spec bearing would probably be O.K. - particularly if the original bearing did not fail even after 100k miles. In such a case a superior spec bearing could be installed and after another 100k miles it would also be in good condition. Which would prove what about "better" bearing specs.?
Perhaps the best justification for using a "better" spec is that the upgrade costs little and does no harm - as long as you remove only 1 seal. 1RS seals do not seem to fail.Why?
The wisdom of using a plug in the IMS tube like "The Solution: has been reviewed and dismissed in previous discussions. For deep groove ball bearings and roller bearings 1RS works well in thousands of applications, so what additional benefits would the IMS Tube plug offer?
Note that seal failure often precedes IMSB failure. In which case, the primary cause of failure is seal spec/placement not bearing spec.
After years of participating in such discussions I have learned how much I/we do not know about this subject and just follow what works for people who install or warranty hundreds or even thousand of these bearings.Some of them still try to help in these Threads but it is futile.

[Gelbster]

Originally Posted by Silber

I looked up the bearing he used. From what I can tell, it was a $60 or so ceramic hybrid bearing, where the SKF hybrid is $150. It was a cheap hybrid, maybe price wise above a steel bearing, but effectively you would be worse off with that bearing as compared to an SKF steel one. Fatigue limits for his bearing were very poor, not a bearing suited for an engine.

Silber

But what about the Installation or Pre-Qualification ?
For example - CH bearings are brittle compared to steel and therefore vulnerable to Installation mistakes.
Maybe the CH bearing was also knock-off like some NSK reputedly may have been ? - There is way more to this than just bearing specs.

[Silber]

I'm thinking it may be beneficial to post some of my thoughts about this, so if you don't like rambling skip this post.

Porsche had some of the best engineers in the world designing this engine. They looked at the numbers for the bearings, and their load data, and came up with their bearing being a lifetime solution. These were smart guys, they didn't just go to a bearing catalog and pick something at random.

But, obviously, they made some sort of mistake or we wouldn't see the failure rates we do. What was their mistake? I think it was the open tube inside the IMS shaft. Thing is, that tube acts like a small lung. Every time your car heats up, the air inside it expands and it "exhales" through the seals of the IMS bearing. Then when you stop your car and it cools it "inhales" oil from the sump through the IMS bearing seals and into the IMS tube as it cools and the air contracts.

So, I think the enemy of the IMS bearing is heat cycles. Every time the car heats up and cools down, a little bit of grease gets washed out of the bearing. Does evidence support my theory? The bearings have the grease washed out, the IMS tube is usually full of oil. At least some evidence exists. Sealed bearings running in an oily environment don't normally wash out as bad as these IMS bearings do, by a long shot. Reading some Machining forums sealed bearings in oil is fairly common and not problematic.

So, I think the Porsche engineers got it right, in that the bearings they specified, if kept intact, will work as long as they thought. They did not predict the lung effect.

I think the lung effect can be countered by plugging the IMS shaft tube with a freeze plug. Your lung will go from the size of a small dog's lung, to the size of a gerbil's. Not near as much, if any, oil will get pulled through the bearing. This allows the 2rs seals to do their job of keeping the grease intact and allowing the bearing to live to its rated service life.

Is this theory a good one? I think so. The bearing washout and oil getting into the IMS tube in the quantities it does has to be explained somehow. Will my solution (2rs + Freeze plug) actually work? I think so, but you are all right, it has to be proven, as unproven it is nothing more than ramblings of an internet nobody.

Silber

[thom4782]

Originally Posted by particlewave

It's not that simple and there is exactly zero data to back that up. Plain bearings are not permanent and do wear/fail. It's just a fact. That's why you replace them when rebuilding an engine.

Until many have been pulled and measured for wear after 50k, 75k, 100k miles, and until many of them have done years of service without failure, it's all just guessing and marketing hype.

I would trust it more than a single row ball bearing, but the price is ridiculous.
I'm glad I have a dual row that will only be replaced with the same.

Yes, everything fails in time, but if you read closely Silber's goal, he's looking for the solution that will last the longest. From the known data of ISMB replacements, the LN single row and double row replacements have the fewest failures. While the IMS Solution has sold fewer units and less actual data, there are no reported failures. It information such as this that leads to informed decision in light of imperfect data. That's not guessing nor is it marketing hype. To say so is disingenuous.