Triple Black

This thread is getting better by the second!

Cuda911

Whew...and here I was, thinking I was a moron for not being able to envision a non-spherical ball bearing. Thanks, SG, I'm feeling less moronic now.

P.S. Why has JR not yet chimed in here? Long overdue MIA.

Maybe he's just swamped returning calls to all the people that didn't buy any of his products or services.

Chiamac

How would a clip make it more robust? It's not like it would hold it super tight (you'd still have to get it off somehow), it wouldn't prevent it spinning like a tighter fit along with the locktight, and you wouldn't want much pressure (I wouldn't think?) on a clip anyway - it's just there to keep it in place.

Again I don't totally understand the situation, but it doesn't seem like the bearing is going to fall out or move around all that much.

Chiamac

Or he is busy taking calls about this product vs his.

Speaking of, I should write LN and ask to see if I could my old bearing back or have a decent dual row back. Don't have the money to plate it now, but that sounds like something super fun to have around.

Sneaky Pete

Food for thought....transmissions use ball bearings for thrust control. Look at the pics below for example. Rod......in what type of situation are they not used for thrust control?

gnat

There was a guy on eBay selling used bearings awhile back. Maybe check to see if he is still around.

I think it's fun, but my wife and co-workers that have to listen to it spinning incessantly all day long seem to have a different view

Showed it to the guys at the shop that pulled it this morning when I had to pick the BMW up. I got the distinct impression that at least some of the laughing was AT rather than WITH...

Chiamac

Well, if all the fears on here are true then it will fall apart sometime in the near future and you will have to replace it with a LN, or the option we're talking about here - but in your case I'm thinking the solution or this permanent upgrade is a little overkill.

5CHN3LL

I admit I don't really get burning several hundred bucks for the plating, but I bought a 911 on a whim and thus don't have much room to disparage the kettle.

I can understand why some of the mechanics might not "get it" - probably takes a day or two to earn what it cost to gold-plate a junk bearing on a whim.

If you start lighting your Swisher Sweets with rolled-up 50's, you'll be banished to the 993 forum.

dxflyer

I recently picked up 1999 C2 996 with 155K miles on it. It runs well but with all the information about the ims failing I decided to replace it and do a lot of work on it as well. So I did an engine out service on the car. It does have a double row bearing it. Previous owner replaced ims at 110K miles with oem. As you can see from the pictures the old bearing was in great condition.

I decided to go with the vertex bearing. So I will let you guys know how it holds up and if my engine goes south, well 155K is already a lot already, then I will do I rebuild. If I can get another 20K on the engine then I will be happy. I plan to rebuild the engine anyways.

From what I see in terms of the thrust... the washer and the outer race is taken all the grunt of the thrust so from what I can gather the cylinder bearing has very little thrust forces on it. Disclosoure: I am no expert on bearings....

I did do the hole in the ims shaft and also change the hex driver with the one provided in the kit.

Schnell Gelb

One last try.
Yes, Rod's technical content is gibberish but one more try because he has some clever Mechanics in his support team despite the vague engineering claims .
I have great respect for mechanics solutions to engineering problems. Raby on that subject in Helos would be an interesting off-topic conversation.
IMHO this is not a mechanics problem. It is engineering -with lots of instrumented testing and dyno+road required.
I used to work with an OEM and we did all this and still failed in the 'field' sometimes. But the part that failed 'field' use was always way better than the hack-ups we initially tried as initial experiments.The difference was all that tedious engineering data collection of prototypes. The difficult question always was: "Is it better than the current Industry benchmark ?"The Solution ,in this case ?

But wait ,there is more.
Raby & Martin need some competition so let's encourage Rod. So Rod ,please address the thrust/misalignment concerns, describe the testing. The Marketing waffle just harms his product - which is a pity.
What really worries me is that the Vertex bearing may in fact outlive clutch changes !
It could be that all the objections to the roller bearing while theoretically legitimate are not the limiting factor(s).
These limiting factors are the fundamental disagreement that is unresolved(no consensus-yet).
Is it LOAD, Lubrication, seal failure+contamination,metallic debris or some other combination/sequence ??
As an engineer I need to know "Why". As a mechanic "how" but as an owner just "what works?".
Better to forget the engineering with this Vertex product and settle for 'what works' ?

eastcoastcab996

I occasionally get IBS while driving my 996...

5CHN3LL

Welcome to the 996 forum of Rennlist, Rod.

Ben Z

That was the gist of my point. If there was a 25-50-75% failure rate of the OEM bearing then it would be easier to suss out the relative efficacy of the various aftermaket upgrades. But the fact only 8% of the weakest, worst-designed bearing application fail implies that a fairly small improvement in specs is all it takes to bring the failure rate close to or at zero.

If none of Flat6's The Solution have failed, none of Vertex's bearings have failed, and none of LN's dual-row and single-row-pro have failed, then the only way to prove which one is better would be to subject them to conditions or loads beyond what they will ever see in service, and what's really the point of that other than a urination contest between competitors? Only a dozen or so original LN's (which have sold probably ten times the number of Vertex's) have failed and most of those can be attributed to pilot error in installation or failure to properly assess the condition of the engine. In fact in the early days I recall (I think it was Hartech) "solving" the IMS failure problem by replacing the OEM bearing with a new identical but unsealed one (or if the original bearing was in perfect shape, pull the seal off) and a stronger stud. I think Pelican was selling a similar unit at one time. I would be curious if any of those have failed.

RodVertex

Everyone, thank you for your comments. In response to the question about the retaining circlip and loctite. The forces necessary to move the IMS bearing from the IMS shaft are huge. A specially designed extraction tool is required to remove the bearing from its cavity, because the IMS is embedded by pressure in the cavity it resides. The forces that embed or hold the bearing in the IMS gear are so large that it will not move even without its retaining clip or without loctite.

As you know, Porsche made three attempts at correcting the IMSB design flaw and all had subsequent failures. OEM revisions continued using the sealed ball bearing design. It was a frustrating and expensive process understanding the origins of the IMSB failure. After installing Porsche-upgraded and aftermarket IMSBs in our customers’ cars and in our rebuild program, failures persisted.



The efforts made to determine the root causes of the IMS ball bearing failures have been a daunting task. This is because when failures occur the damage is so severe that any evidence for its failure has been destroyed. It was during a service in one of our customer’s vehicles that we were fortunate to have captured a bearing failure in its first stages. This opportunity gave us a better understanding of the existing wear and causes of bearing failure. Please go to to see actual bearing damage. The video provides further insight into the ball bearing IMS failure. With the combined loads exerted on the bearings we expected greater surface area wear. You will note the limited surface contact area the ***** ride in. The area the bearing rides in is practically a pinpoint and the images highlight the very limited surface area contact the ball bearings are required to work. Having such a small area of load bearing will eventually cause the surface to shatter and ultimately catastrophic bearing failure.


Changing the ball bearing IMS with another ball bearing IMS will yield the same results, e.g. failure! In order to fix the problem one must make a paradigm shift. Others have knowingly developed a different approach to solving the IMSB problem but those efforts have been commercially impractical. The fact that others have developed journal bearings alerts us that they have conceded to the impracticality of ball bearings in the IMSB application.


From the facts gathered about the IMS ball bearing having a very limited load bearing area we can conclude this to be the cause of the failures. Knowing this, one must change to the type of bearing that provides a large surface area of contact to distribute its load. To solve this problem the bearing of choice with the highest load bearing capacity and largest surface area is the cylindrical roller bearing. Thrust control is for the purpose of keeping the chains /shaft aligned and has no influence over the failure of the IMS. Cylindrical roller bearings lack thrust control.



Since cylindrical roller bearings have thrust control they can be applied to solve the IMS problem. To further explain the IMS bearing problem where there is no room for failure, two objectives need to be satisfied. The first is the bearing must have thrust control and second and most important the bearing must have a large surface area of contact to distribute the load. A cylindrical roller bearing with thrust control satisfies these criteria and in 2013 a US patent was awarded to Mesa, et. al. for the cylindrical roller bearing with thrust control.



We have concluded that within the IMSB application ball bearings properly lubricated fail, different size ball bearings fail, different numbers of rows fail, closed cage ball bearings fail, and ceramic hardened open cage ball bearings fail. Knowing this we directed our efforts in a different direction to identify the problem. It is not lubrication, it is not the size, it is not the numbers of rows, and it is not the hardness of the ball. The common denominator is the ball bearing. We exhausted our attempts to improve in all areas of the ball bearing and all have failed. Leading us to conclude that this type of bearing and its application is not only the problem but a dead end.

5CHN3LL

The engineers in the house are going to freak out due to the lack of proper terminology in your posts and video...like cracking and spalling in lieu of "pieces of the chrome [sic] are flaking off."

Has there been any finite element analysis or other solid-model analysis of the aftermarket bearings? I have to assume that Porsche performed extensive FEA as they were trying to cook up their "final" solution of the larger non-removable bearing; it would be interesting (and reassuring) to see some plots from FEA for the various retrofit solutions if they're available.

The IMS would not be a complicated finite element model. If the forces applied to the shaft are known, adding the necessary degrees of freedom to the model and then testing the various bearing solutions would be nearly trivial and much more reliable than some of the "science" I've seen (i.e. "we used the biggest bearing that would fit").

Anyway, a guy can dream. I'm not suggesting that Vertex should be the one doing more sophisticated analyses on the IMS - but given how cheap FEA modeling has gotten in the past 20 years, and how costly it is to be wrong, it seems like at least one of the aftermarket suppliers would have gone this route...