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valley996

Casper Labs Ceramic IMS Bearing

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We don't have a great deal of data, but what we do have is indicating these cracked , D chunked cylinders you hear about.... are actually a result of the the open deck design combined with the Lokasil liner. On the 2.5 we re-sleeved (remember this engine had a factory Lokasil repair sleeve already), the sleeve had a wall thickness of about .070". I do not remember the total wall thickness, but this was a considerable portion of the total wall. I was able to cut out a ribbon of the Lokasil liner about .020 thick X 1/2 inch wide and half the bore diameter. I polished, etched, and looked at it under the microscope. Those SiC3 particles make the aluminum look like you could drive a truck thru the grain boundary. I then took the ribbon and pressed an edge to the table. It snapped like a popsicle stick. Never saw any alum. alloy do that before..... So, these liners are hard, but they are also very brittle.

Since the exhaust gas is always exiting the cylinder on the lower side, this results in localized heating near the exhaust valve. The top edge of the cylinder has no real heat path but toward crank (because the steel head gasket limits transfer). When top of the cyl gets hot and the bore wants to grow, the locally hottest area near the exh valve grows the most. The bore goes egg shaped. When it cools off, it recovers somewhat. But, each run/off cycle ratchets the egg shape a little bit. That why all these engines have at

least .003" out of round after 20K miles (and why these engine have horrendous blowby).

I have yet to find an engine that has cracked but not destroyed cylinder (but would like one if you have one) because it could prove the failure scenario we theorize. Thermal cycles and egging add up to the point where a crack initiates in the Lockasil. Since a normal Lockasil cylinder is an integral part of the casting, the crack propagates from the liner area right into the base metal. If we can find a cylinder as described, it is a simple mater to section it and crack it open. If the theory is correct, there will be evidence of fatigue along the fracture interface.

The sleeve we made was from a 4032 alum forging (piston alloy) and a full cyl dia. X .25" thick flange was put on the head side. Fitted it .0015" tight with Locktite 620. NiC3 coated b4 installation and decked and diamond honed after. Expensive, time consuming, and probably too good for these engines. Time will tell, but my bet is some other problem will end this engine's life. This engine is probably one that could benefit from some old technology. Put a thin, high strength cast iron liner in every bore. Would really help the egging problem, be low cost, and limit the performance potential. Just a thought.

Ironically, there is actually a kind of benefit to the IMS bearing with the high blowby condition in these engines. All that vapor blowing around the crankcase is perfect for helping to lube a ceramic hybrid bearing (that has neither immersion or oil spray)! If they ever fix the blowby, we may have to make a pressure babbit bearing kit.

We are going to try to "qualify" some shops in Florida by taking an old long block on the road with the IMS kit. Demos/training may help some shops get past initial concern, but this upgrade will never be totally w/o risk. I don't think this is ever going to be work for anyone besides Porsche specialists. A You Tube video will follow.

Note: Valley996 tried to send me a direct email. When we opened it, the text was so small it looked like Morse code. Sorry we could not reply.

BR

Casper Labs, Inc.

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...Put a thin, high strength cast iron liner in every bore. Would really help the egging problem, be low cost, and limit the performance potential. Just a thought...

I've read everything from "we've done this and have a couple cars on the road" to "shouldn't be done, heat and CI is a problem with this engine".

What's your take?

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Porsches are fantastic, I have driven one or another for almost 30 years. Over the years, one great engine (911) played a huge role in making their reputation what it is. There have been a bunch of other engines that they either designed or borrowed from other car makers. None have come close to the air cooled 911. This water boxer engine has more design issues than any one of their engines I can remember. Torsional vibration, weight, IMS, Lokasil, Variocam (early) just to name the big ones. But it is still a very interesting engine,.... that has promise not yet realized. The Variocam system makes it a fantastic sounding engine with the proper exhaust.

It seems doubtful (with the present economy) that this engine will be extensively redesigned. My bet is we will have to wait for a fresh design.

We are going to have to make due with what we have on this engine.

BR

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Bill -thanks for the response .I guess you don't want to get into the Variocam actuator repair business ?

Dave

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To Bill Ryan at Casper: I need to replace the IMS bearing on my 99 but I have mixed feelings at this point. I like the price of yours but I am afraid to be one of the first to use it. I think most would feel this way, but I am sure some felt that way about LN in the beginning. What would say to convince me to use your product over LN's. I plan on replacing mine in the next 3 months. I appreciate your response on the issue.

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I don't know any more about the LN's actual bearing quality program than anybody else out there. We can all count the balls in it, and figure out its basic load/speed rating. I suspect their retired bearing engineer is giving them some pretty good guidance in specing and controling quality. If the bearing was a problem, we would all know by now. If the OEM bearing was not immersed in oil, the failure rate would be a tiny portion of what it is. Remember , this is a $25 bearing. Probably the biggest difference is they have a bar stock machined custom support and center stud. All of our failure analysis and testing has never shown any weakness or design factor in these two parts that contributes to bearing mortality in any way. Therefore, we designed the bearing kit to use as many of the OEM parts as possible. The OEM supports are actually very nice forgings that are much stronger and stiffer than the case they are bolted to (with only three 6mm screws). With the cost of machining anything in the USA today, most of the cost difference is in the extra bits. Bearings cost what they cost, we both get them from bearing mfgrs. With all our products, we strive to make them as affordable as possible without compromising quality. If you overprice your product, the customers go looking for a better deal. Most of our general aviation sales come from our customers,.... who tell their friends. In this economy, no one is looking to spend more than they have to. But, we understand where you are coming from, and even the guy who does 200 of these w/o incident,... could run into a problem on 201. We have been doing this since 2003, and despite the economic slow down, we have steadily increased sales. This business addresses niche markets, we will never be able to promote like Apple Computers.

No plans to O/H Variocam actuators. We prefer to stick with new products, where we have better ability to control quality. The only repairs we do are to our own products.

Bill Ryan

Casper Labs, Inc.

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This has been one very interesting take on our favourite (now infamous) subject........

One thing I didn't realise untill I read Bill's analysis #56 above was that the IMS bearing actually sat in the oil ... must have got under my radar.

It would have been interesting to have been the proverbial fly on the wall when the Budget War for Engineers vs Accountant met to discuss the costing for the (then) new M96 engine - I'll bet there was a lot of unhappy engine men when given the strict $$ budget to work with.

You will find that most engineers will give you a 100 carate design (even when you don't actually need 100 carat job) with scant regard to costing - its those **** bean counters that cut, strip and force inferior goods into production.....

They've been a pain all of my working life !!

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I do this type of work because I love problem solving. When you turn your technical interest into a

business, you find you have to wear hats you never wore before. Finance and sales are big hats.

If you ever worked for a large company as an engineer, you learn that the design or fix you propose

better meet the needs of sales and the money guys. If you don't, you will never get past the first review. It is almost always a compromise, and becomes another level of challenge in getting your idea sold. In this IMS case, it was easy to find a cost advantage because the support and stud are superfluous to the problem.

Guys like Steve Jobs become legends. They know the limits of technolgy, keep the cash flowing, have a sixth sense about what people want before they know what they want, and take calculated risks. Even Steve admitted " I am the only person I know who lost a quarter of a billion dollars."

I drive the Boxster everywhere. Florida to Idaho. For me it was a simple decision to upgrade the IMS

(after figuring out what was the issue), because I can't have the engine fail on a trip. If I just drove 50 miles each way to work every day, having it towed would not be a big deal. All of you are going to have your reasons for decideing to change it or not. Faith in your mechanic's ability should be the primary driver in my opinion.

Bill Ryan

Casper Labs, Inc.

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I've been thinking about your product over the past several days and can't seem to make out how anyone could enter this product space at this point in the game. I'm even wondering if Pelican's offering will ever become viable and the reason why they are delaying it is because as JFP pointed out it just sorta doesn't make sense. You do have a ceramic hybrid bearing and are probably using similar extraction and insertion methods (which BTW have you run into any patent issues?), so that is a plus.

Do you have any estimates on how many units you need to sell before you become profitable? Your guess of 4000 units at $600 per LNE has sold is nothing to laugh about. But at your price of $323, plus the cost of overhead and R&D... is this not too steep hill to climb at this point? I'm wondering if it would make more sense to supply a reputable name (in the Porsche world) such as Pelican.

Edited by logray

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Bill- thank you for the candid input .I believe there is a market for your solution and that it will be sucessful .The theoretical market available is north of 100,000 -LNE's share is in the 2 to 4% range .Plenty of room for multiple suppliers .

Sure wish you would do those actuators ............oh well

Dave

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The Pelican bearing has some other "interesting" elements as well: It is an all steel OEM style replacment with grease and seals. It also only comes in one size, but includes spacers to make up the difference of the larger bearing if the car was a dual row style. It supposedly will sell for $165.

Edited by JFP in PA

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The Pelican bearing has some other "interesting" elements as well: It is an all steel OEM style replacment with grease and seals. It also only comes in one size, but includes spacers to make up the difference of the larger bearing if the car was a dual row style. It supposedly will sell for $165.

And no release date in sight for Pelican!!! I am just trying to make the right choice. I believe LN is the best choice but Casper would save some money. I didn't quite get the answer on why I should purchase Casper over LN. Am I getting as good or better than LN from Casper? Correct me if I am wrong, but there are some savings by Casper using oem parts (support and center stud). This is great if there are no issues. Has anyone ever heard of any issues with the support and stud? Is this just a bearing problem and the support and stud are fine? If that is the case then Casper could be a good choice.

It would still be nice to see a webpage with some photos and installs. LN does have plenty of information on their product. I have about three months before I make my decision. I am still open to all three; LN, Casper or Pelican? I think this would make a nice test article for a magazine.

Edited by valley996
  • Upvote 1

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When this got started in 2008, there was never any intention of making a product offering. Just wanted a more reliable personal car, and was curious why there was so much fuss over these bearings. Having been around them for decades prior, I knew a bearing is a bearing. They fail for a reason. What was it? This project started a life on its own......... with curious fellow owners asking about it.

Just found out today that jury duty becons. At this point, I also am at risk for repeating myself. Time is going to have to be prioritized, and this forum is going to have to be put aside for a few days.

Hope I contributed something you can use in the future. There were some people out there that knew the right questions to ask, and we appreciate the encouragement of those who want to see this work. We are going to make it available, and hopefully the Porsche community will find we have something to offer.

If you have specific technical questions, my direct email is N1WR@juno.com Be aware it may take a bit to get a reply for the near future.

Regards,

BR

Casper Labs, Inc.

.

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" Correct me if I am wrong, but there are some savings by Casper using oem parts (support and center stud). This is great if there are no issues. Has anyone ever heard of any issues with the support and stud? Is this just a bearing problem and the support and stud are fine? If that is the case then Casper could be a good choice. "

LN increased the size of the center bolt to add strength, and removed the OEM under cut for the oring (LN relocated the oring to the flange) as the center bolt has been known to fail by breaking at that point:

imsretrofitbearingsupport.JPG

Edited by JFP in PA
  • Upvote 1

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I think the stud breaks due to the bearing failing not the other way around.

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For the most part, that is correct because the action of the dying bearing overloads it. But there have also been cases where the bolt let go and the bearing was still in reasonable shape.

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Thank you JFP. As for me, I believe I have to lean towards LN on this one. I think for $300 more dollars it seems to be worth buying the LN over the Casper. I'm not too excited about using original parts mixed with new to save a little money. I certainly tried to get a sales spill on why Casper is better than LN but I haven't been convinced, although Casper did provide allot of information. Casper's fix could certainly be as good or better, but as a consumer I'm not convinced yet. LN certainly has plenty of photos and information on their webpage. As far as I can find, Casper just has an ebay ad and some replies on this forum. I'm still listening Casper!

Edited by valley996

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Wow, a lot of information here. I have one of the replacement engines in my car. I am at about 60k miles by my best guess. I purchased the car without records. Is this a problem I have to look forward to and can my engine be serviced with an aftermarket bearing? So far the car is doing well. I put about 7500 miles a year on it.

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Your replcement engine, assuming it has the larger bearing, is only replaceable if the engine is torn almost completely down (aside from the bearing carrier). In other words, BIG bux in labor, more than the cost of a used engine in fact.

The good news is, Porsche "responded" to the IMS bearing issue indirectly by "upgrading" the bearing to a much larger one in your replacement engine which is about as strong as the original dual row, which are less susceptible to failure apparently. Will your bearing fail? Maybe, experts estimate 10% of cars in 90,000 miles. But there is a lack of publicly available real world data on those estimates, so your guess is as good as ours.

You might benefit from the IMS Guardian, which will/can warn you in the event your engine is about to go boom so you can shut it off. A rebuildable core is worth A LOT more than an engine that is not rebuildable and has already exploded.

Anyhow, don't let all this stuff scare you, as pointed out earlier you certinaly read more about the "bad stuff" on the Internet than the success stories.

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The judicial system has decided they can do without my services this time. So,... thought I would check in.

In order to see what the center stud really does, you have to stack up the whole assembly in one half of the case.... and determine the final fit and running positions. First of all, remember all the OEM bearings are radial bearings, meaning they are designed for radial loads only. If you subject them to axial loads, they will quickly fail. In the engine, the various chains provide the radial load, and no axials are present or possible. Without the stud bolt, the IMS just floats between the front face of the plain bearing end (oil pump drive ) and the inside vertical face of the rear support (remember the ID bearing fit is a loose sliding fit). There is just enough axial case clearance to prevent binding. When you tighten the support's center nut it pulls the IMS toward the support's vertical face to set an aft biased IMS running position. The support stub shaft does not bottom on the plug end of the stud. So, as designed, the only load that stud ever sees is the result of the torque you put on the nut! (Unless the bearing dies, and everything starts wobbling and snapping). The stud's structural contribution to carrying the bearing imposed load is ZERO.

The only real danger of breaking that stud (when the bearing is still OK), is when removing the bearing. If, and it is a big if, you end up with a .25 percentile bearing interference fit that is nasty OD tight, you could break the stud in pure tension pulling the bearing. It is a wash if it will break at the base of the threads or the O-ring groove. If it breaks, it is no big deal. One whack with a drift puts it in the IMS tube, you put a blind puller on the bearing, and out it comes. There is also the possibility that some well intentioned person could just "snug up" that center nut (without a torque wrench or even knowing the setting) and radically overload it. We have never broken a stud. The core engine we use for demo has had the bearing pulled at least 35 times on the same stud.

I have to admit I am using you folks as test specimens, but not the way you think. There is so much fear about the IMS bearing. Fear because it is expensive when it fails, because no one has ever really explained why it fails , and because the OEM never addressed the problem. So, the first step is getting people past the fear thru background knowledge. I am hoping your views are typical of the community, and answering your concerns will spread the word.

Question: Is my bearing better than LN's?

Answer: Is a Ford better than a Chevy? There is no answer, ......what is asked for is debate. What I am telling you is that our product is up to the task (if properly installed, the engine does not make metal for some other reason and compromise it, or the lube get contaminated). Bearings are not a big deal for us, we have done the engineering, analysis, and testing. If buying parts you do not need, makes you feel better.............. My advice is to concentrate on hard data, do not ever assume anything. Keep asking yourself if you are making judgements based on facts and logic.

Bill Ryan

Casper Labs, Inc.

I will post tomorrow on the subject of rolling contact stress (Hertz). This is pretty simple factor that is a big player indetermining the bearing's load capacity. It will help develop an understanding of what is behind the 3 types of bearings used over the years, and the risk associated with each.

,

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We have actually seen a 986 that suddenly shut off while at a traffic light, was complaining of a large oil leak under the engine (it was huge) and some strange noises in the transmission area. What we found was part of the IMS center bolt had snapped off where it necks down for the oring, and was lying in the bottom of the bell housing. Prior this this happening, the car had been fine. While the engine was damaged due to valve to piston contact, the IMS bearing was rather loose, but otherwise seemed OK.

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If the nut is over torqued, you run the risk of tensile failure just as you as described. When the stud breaks, the IMS is free to shuck back and forth in the case (that was the noise heard). Since the stud does nothing to support the bearing (just sets the running position) there was no reason to cause bearing damage. The stud's nut is a clinch lock type, and you hold the stud from turning with just a blade screwdriver after the nut is started. The little screw slot's anti-rotation role in tightening the nut should tell people "whoa, why is this here?" And,.....is one reason why the torque spec for the nut is so low. This is why we make a big, bid deal about procedures. I understand your concern, and take your comments seriously. Barring a defect in the original part (which is possible but not likely, and can occur regardless of size) the only scenario that can fail the stud is overtorque. You would think that the limit of holding the screw slot with a screwdriver would limit the installed torque. But in practice, once the nut starts an axial load on the stud, you don't need to hold the slot in position any more on many of these engines. Some turn, and some don't w/o the screwdriver in place. This is what makes the "tweaking" possible. Nobody likes tasks that are awkward or difficult. Learning the technique to hold the slot and tighten the nut takes practice, and I understand why you guys don't like it. But it was done for a reason.

The OEM stud actually has a couple advantages over a "beefed up" stud. 1) If things don't go together right, it limits the load you can put on the inner race. When you are

pulling on the inner race, it creates a load path thru the balls. Remember the discussion yesterday about bearing design for radial only loads. If you pull too hard, the races can get indented from the balls, and they are ruined. 2) The more material that goes into the stud dia., the less available to actually support the bearing ID. If the support flexes, it won't be long b4 other problems start.

While on the subject of odd ball failures............. When you guys come across strange failure modes, we would love to see the parts. Send them to us, or give us a call.

We can look at them in the lab, and tell a bunch of things not apparent to the naked eye.

BR

Casper Labs, Inc

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Here's the post I promised yesterday.

When you start a project that involves a ball bearing, the first steps are to figure out the loads and speed the bearing will operate under. The loads will be used to determine the rolling contact stress. Intuitively, you might think the peak contact stress to be directly at the point of ball contact, but actually it is just forward of the ball and below the surface. It is easy to visualize if you think of a heavily loaded wheel-barrow tire rolling over soft earth. The wheel pushes forward soil, so it is like the wheel is always trying to "climb out" of a depression. As long as the contact stress is below the material yield point, the bearing survives. From a practical standpoint, the higher the contact stress, the more distortion. The more distortion, the more heat generated. Heat makes the steel softer. So, when designing for big loads, you need bearings with either lots of balls…. or big balls to keep heat down. Speed factors determine which approach is used.

When you see a ball race that is pitted or flaking, the allowable contact stress limt was exceeded. It could be dirt. lube, or overload that caused the problem.

Now we need to move back in time. Here is a guess as to how the bearing ended up submerged. The engine was designed wet sump, the first Porsche boxer engine with that approach since the 912/356. When they started testing it in the prototype 996, they found the oil pick-up was sucking air instead of oil (with the new suspension and great tires under high lateral "G’s"). When sump baffling changes did not fix it, they added a couple liters of oil to the sump. Cheap fix, new dipstick. But, the bearing (which was designed dry) was now wet when not running. Well,….. someone had to sign off the engineering change forms, including the impact of the change assessment. Now we have a paper trail to the guilty. When the bearing problems started, the cover up began.

So, the guy who messed up ….either found a way to get it blamed on the least liked guy in the group (and is now the area manager), or…..he has long since left Stuggart, and made a career making weinerschnitzel in the Black Forest. You might laugh, but this happens all the time in big organizations. The case everybody remembers ……..is the space shuttle o-ring disaster.

When we do the math on the grease lubed (but not immersed) dual row bearing, it looks really good . Lots of load margin, and the combination of small OD and small balls keeps the ball speed and centrifugal loads down. No problem at all grease lubed. The problems start when the grease is gone.

The second generation single row bearing is simply the dual row cut in half. It is really that basic. Same ID and OD, half the ball count. So the contact stresses are doubled. We now have a bearing that is far more likely to overheat and die. Based on the failures seen , this is exactly what is happening. These engines should have the hybrid ceramic upgrade done now, don't wait for the clutch to go.

You can’t admit you made a mistake and go backward , so……..you make a third design! You fix the contact stress by putting this big single row bearing in place. The load capacity math on this bearing looks fine, but the limiting speed is very questionable. The increased diameter makes a big jump in ball speed (speed varies as the square of the radius) because the OD of this bearing spins. The balls are large and heavy, making high centrifugal force that wipes lube off the race. If you are driving around town, and rarely redline the engine, it is OK. Endurance running this design at sustained high rpm is asking for trouble. We have not completed the analysis on the impact of just changing the balls to ceramic on this bearing. With the ceramic ball’s weight reduction, it will help the centrifugal issue quite a bit. (We do have a ceramic ball version of this big bearing on the road, but it is far to early to tell if the solution is adequate. All indications are it is an improvement, and we can custom make one of these for you if you really want it.) Question is, will it be enough. Since you have to tear the engine down to service this bearing, we are considering making the shaft go back to the (field service capable) dual row. It will require a very precise, cylindrically ground spacer sleeve to make it happen. We would have to do the upgrade in-house to control the fit. More work is needed on this one. Since every engine has to be torn down to fix this bearing, we don’t expect very many sales for a period of years.

So, all this probably happened because ……….no one wanted to tell the boss a $300 bearing was needed to fix it, or the business people could not make a case for spending the money.

BR

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...in practice, once the nut starts an axial load on the stud, you don't need to hold the slot in position any more on many of these engines. Some turn, and some don't w/o the screwdriver in place...

This is interesting. When I recently tore my engine down, I ran into a snag with the LNE bearing while removing the center nut. During bearing installation I followed the suggested 25 ft lbs (IIRC), which didn't seem like much. I am always a "good german" and follow directions when provided, especially because I have a habit of over tightening if I don't get torque specs. Perhaps the difficulty removing the center nut was from the recommended use of green loctite, but I could not for the life of me get the nut to turn off the stud. It was "frozen" for a lack of better terms. I continued with engine disassembly, and once the tube was on the bench I was able to get a better hold on the center stud and turn the nut with a deep box end wrench. But in the process it ruined the threads and nut. So I had to extract the bearing in order to put on a new stud (which only had about 10k miles on it) and had it sent off to LNE for examination. Unfortunately the advice was given to replace the bearing, perhaps in relation to the issues with the stud, or perhaps I damaged it during extraction - which I was very careful to use the LNE bearing puller with modified threads for the LNE stud. So long story to ask a question but...

On your kit, what is the recommendation for use of sealants and thread lockers during installation? And do you also recommend a specific torque value for the center stud nut?

Also, it seems like this area could be designed better, I had to fabribate a special tool in order to place the recommended torque on the nut. If the center nut is supposed to be just "good n' tight" or "25 ft lbs", how about putting a wing nut on there or some other type of fastener that is easier to turn with perhaps a cotter pin to hold correct position and anti-rotation?

Edited by logray

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...Since you have to tear the engine down to service this bearing, we are considering making the shaft go back to the (field service capable) dual row. It will require a very precise, cylindrically ground spacer sleeve to make it happen. We would have to do the upgrade in-house to control the fit. More work is needed on this one. Since every engine has to be torn down to fix this bearing, we don’t expect very many sales for a period of years...

Hah, try not many at all, if any... I can't remember the last time (at all) where I've read about the Porsche revised single row being replaced just for the sake of the bearing... without other engine work already being done, since you have to remove the bearing carrier in order to get to the tube.

p.s. you might want to fix the font size and remove italics in your post, very hard to read without manipulation.

Edited by logray

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