Quote:
Originally Posted by Smallblock454
Hello,
Hi Gelbster,
well first of all there is a myth that the IMSB never was designed to be replaced while the engine is in the car. Because there is no official Porsche special tool offered? Simple question: would some shurely not too dumb engineers would have designed the mount and bearing this way?
Best solution:
There are different aspects. I think everybody has to decide himself what he or she wants to do and what amount of investment and risk to take.
Pre qualification: i completely understand why there is that process. If you have hard metal debree in a soft full aluminium engine with Lokasil coated cylinders you have a major problem. Some of these engines will still run for some time (maybe if you're lucky and the metal debree amount wasn't high forever), but sooner or later you can run into problems. A new IMSB will not solve the problem. And as said there are a lot more causes why the engines can fail.
Cost:
Does it make sense to put a 2K-3K solution in a 10K car? Would you think one minute if it would be a 100K car?
On the other side:
A 986 engine rebuilt in Germany starts at about 12K Euros and grows up to about 15-20K Euros for a more optimized engine.
An used 986 engine is available at about. 3-4K Euros. But you'll never know what you get. And to make it a good one you also have to put some additional money into it precautionary.
Installation:
From my personal POV an installation can definitely go wrong if not done properly.
Perfection / perfect world:
If you want to make 100% shure that there is no problem you have to rebuilt the engine every 50K miles.  But as always - also a rebuilt engine can fail sometimes.
Conclusion:
I don't have a solution for that.
My personal opinion:
A proper installed high quality roller ISMB with every clutch replacement. And if your DMF is worn even if the clutch isn't, replace the DMF, clutch and IMSB all together. And: if the engine fails, it fails - there are a lot of causes why the engine can fail. IMSB is only one.
As for installation and quality tests.
@ JFP in PA: If you have got new parts from Porsche that are out of tolerance, sent them back, tell them what you found and ask them to sent you a new part.
I see a lot of causes why a new part can be out of tolerance. Example: i lately ordered some Brembo brake pads in Italy (around 600 miles to my home). I asked kindly to package everything very safely before shipping. What did the idiots do. They throwed the OEM packaged brake pads (just put in a card box) in another card box and shipped them this way. The result is expensive garbage you can throw into a trashcan.
Also there are tolerances. These engine parts are mass production. Pistons and rods are not equally weighted before installation. Crankshafts are not finely balanced… If you want a 100% perfect spec engine you'll need to bring it to the 100% perfection yourself or by somebody else. Not to mention you'll need the machinery and know how to do it – in your case i have no doubts that you can do it.
@****Gelbster: For the DIY man who is doing a repair or engine rebuild in you own garage (like you did) i don't think there is a simple way to get everything perfect. Shure with time, know how and patience you can build a really good engine. But you need very expensive machinery and also know how to do and test some things. One solution could be to bring the parts to a local machinery shop and let them do the tests and optimization for you.
@ flaps10. That is what i've wrote / meant. The aluminium engine case is made by an aluminium cast. Then it was CNC machined. Then it was Lokasil coated. Think i've wrote that, no problem at all. If there is something misleading or not understandable just ask. My english skills are just the way they are. Always a problem to be exact and precise for me.
I agree that CNC machining doesn't mean there can be faults and errors. But if you take a look at modern engine production plants you'll find the processes everywhere. Also every 986/996 engine at Porsche were assembled by skilled and educated mechanics. So there was a quality control by eye and also by machines that controlled the results - shurely not at todays standards.
I could go more further in that production process, but i think that would be much to much for that post and honestly it would take me a long time to translate the terms and processes precisely.
@ JFP in PA: These are interesting aspects.
Let's calculate some things:
LN premium solution: $1700 plus professional installation or premium tool $600 and plus cam locking… tools plus DIY. I would estimate 2.5K plus.
Conventional high quality ball bearing plus new updated mount: $200 plus materials for tools made yourself $50. I would estimate $ 250 plus.
Clutch needed around every 60-70K miles. AT-car - other calculation.
IMS run out:
I'm not an engine engineer, but i think it's an interesting aspect. Is a ball bearing capable to handle more IMS tolerances than a plain bearing? I did a research and from what i understood i would say yes.
@ all / for those who are interest in bearing technologies and want to get more into it:
Some infos about bearings in general (english language)
Schaeffler Germany | Products & Services | Rolling and Plain Bearings
Some infos about roller bearings (sorry, only german language)
Technische Grundlagen
Regards, Markus
PS: If you have access to a spare engine and a 3D scanner and a 3D construction program you can do funny things. |
OK, let’s look at your comments, point by point:
The “myth”: The reason for the “myth” that the IMS bearing cannot be changed without disassembling the engine happened because Porsche notified US dealers in writing that this was the factory’s official position on the subject. US dealers had been pleading with the factory for a fix for what was rapidly becoming a major issue influencing North American sales, with many pointing to Jake Raby and LN Engineering’s then newly announced retrofit system. The factory said no, it simply would not work, and the rest as they say is history. So the “myth” is indeed a fact that many dealers here still adhere to even today.
Prequalification procedures: What you are looking for is one of two conditions, the presence of quantities of ferrous particulates, or large amounts of alloy flakes. Ferrous materials are serious and probably an already dying IMS. Alloy flakes are always present in these engines, but usually is small amounts. When you start see them is large amounts, something is wrong, and installing an expensive IMS bearing that is open to oil lubrication is asking for a premature bearing failure due to debris ingestion.
Replacing the IMS with a low cost off the shelf all steel bearing every time you do the clutch: This idea sounds fine until you look at expected clutch life. We have customers that are still on their factory clutch at 200K miles, and a few at or over 300K. Like the Tiptronic cars, these would have never been retrofitted using your approach. But all of them were, and the original clutch was reinstalled either because it still looked fine, or the customer insisted on it.
Roller bearings: We do not install them for a multitude of reasons. They do not offer any significantly higher load carrying capacity than ceramic hybrid bearings, and some of the kits installation techniques are questionable at best. They also have a very limited performance history. As my shop’s reputation is on the line with every retrofit, we go with what we know has a proven record of over 25K installs with no issues. And quite plainly, they are not that much cheaper than the ceramic hybrids, and in any case the parts costs are only a small fraction of the total installed cost to the customer.
Returning defective parts: A nice idea, but what do you do when you send one back because its run out is too high, and the replacement you get is even worse? And you can only buy an assembled shaft with an oversized IMS bearing in it from the factory, at over $1K my cost, and to fully test the shaft you have to remove the factory bearing, which kills it. Jake has the luxury of having a pile of shafts to go through and select the good ones to put on the shelf for future engine builds. I do not have that luxury, we are always under time constraints to get the car back on the road ASAP.
CNC variations: How do you explain the issue if you can take one shaft out and put in one with little or no run out and the problem goes away? It may be the cases in some situations, but the shafts in the M96 engines decidedly have a problem all their own that is quickly solved by using a different shaft in the same cases.
IMS Solution costs: One Solution cost about as much as two ceramic hybrids, just for the parts. And with the exception of a small amount of additional labor to notch the bell housing to accept the oil line, the costs to do the Solution are exactly the same as the hybrid bearings. But the Solution is also a permanent life of the engine retrofit. So if an owner expects to keep the car for a bit, or sell it 60K miles down the road they would actually be ahead of the game when the first retrofit would have come up for subsequent replacement, and history has already shown that the Solution being permanent holds its value at resale while the hybrid is discounted for mileage since install. And to put an incorrect idea away, once and for all, you can install the Solution using the original tool kit, but will need the supplemental tool kit to install the IMS shaft plug behind the bearing on a Solution install. Most shops have the supplemental kit as it contains additional parts needed to do the later designed bearing, like the Single Row Pro. And many shops went to the Faultless tool as soon as it became available, simply because it makes any extraction or installation a quicker turn around, plus it eliminates any chance of a cocked single row installation, and is an absolute requirement for the Single Row Pro bearing. Using the Faultless tool, you shorten the time and reduce issues, which is every shops dream.
Sales of Solution installs also speak volumes; the demand for them has exceeded the supply nearly all of this year. Early this year, the wait time from order to delivery was exceeding 90 days. And we have more inquiries for the Solution than any other style retrofit bearing.
Ball bearings are more tolerant to run out than solid bearings: Jake’s experience is just the opposite. People seem to forget that, being an innovator, he relishes testing things to destruction to learn more. He has taken shafts with considerable run out that had factory steel bearings showing the telltale signs of shaft wobble and put a Solution in them and put them back in the engine. Then he ran the Hell out them and pulled them out for examination. While the solid bearing showed some polishing on the run out side, it was otherwise fine. If you have ever had the chance to hold an IMS Solution in your hand, and in particular the dual row version, the total contact area of continuously oiled surface is utterly immense when compared with the available contact patch of any type of ball or roller bearing. And because the solid bearing surface is both lubricated and cooled by twin oil ports and an annular oil channel, the Solution is a happy camper in situations that would be fatal to other types of bearings.
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