Replacing IMS with Original bearing
 

Has anyone replaced the IMS with the original part? Sorry if this is a repeat. Searched and couldn't find anything. Going to drop the trans and inspect the IMS, RMS and the clutch and am trying to narrow down my options. Have oil dripping between the engine and the trans.

My dilemma is that even with the LN kit, it's no guarantee there will be no failure. Since the failure rate is not clearly documented - original or LN, I'm thinking the IMS guardian would be a better peace of mind either with original bearing (new) or LN one. But since the LN bearing is ceramic balls would the Guardian really be able to catch it in time. Being a magnetic based monitoring system?

Also if anyone has a cost comparison between the two bearings it would be great to know. Thanks.

I was in your position last year, and I went with LN engineering's bearing. If you need a good local shop to change it for you, shoot me a PM

First of all, if you go to Porsche, all you can buy in the “final solution” IMS shaft with the bearing already in it; this is the unit you have to disassemble the engine to install. And it is expensive as Hell, more than twice the cost of an LN update unit……. Your only alternative here is the OEM style replacement Wayne has developed, but it is my understanding that he will be recommending replacing it every 30K miles, which will rapidly escalate its “cost of ownership” way outside that of the LN unit.

Both Jake and Charles have been very upfront in how their upgrade has been doing; the last I read was a total of four LN bearing failures out of more than a couple thousand installations. Three of the four failures were suspect (poor installation technique, or the IMS destroyed by debris from a different type of engine component failure), leaving only one that failed for unexplained reasons.

Regardless of the bearing materials, ceramic hybrid or steel, when the bearing starts to go, there will still be a ton of ferrous debris circulating in the engine; so the Guardian will function as designed.

There are no guarantees in this life; engines break for all sorts or reasons, the IMS is only one of them. You could install the best IMS replacement available, and spin a rod bearing the next day. Instead of looking for “iron clad” assurances, you should be looking at an IMS update the way most owners look at oil; you want to get the best possible product in the car in order to eliminate as many possible problems as you can.

Did you research the original bearing at all. What was the cost difference if I may ask.

As for the shop I'm going to tackle it myself. Though frustrating sometimes it is fun to work on the car. Thanks for the offer to recommend.

Love it when the answers are spot on. Thanks JFP.

Hartech in England is doing original material IMS bearings but removing the inner seal so the method of lubrication is the same as the LN bearing. Installation difficulty/risk the same. Probably much better materials in the LN bearing.

For now Charles is being cautious on any claims of longevity until there are more high mileage examples of the replaced LN bearing returned to he (and Ed, the bearing engineer) for analysis. Their expectation is the longevity will be actually much longer than the 30k. But until the sample gets big enough and the analysis is done, who can be sure.

There is wear and failure in every rotating part. Some fail earlier than others, some later.

The original mfg. of the IMS bearing was a NSK. The bearing # is 6204 2rs. Email tech support and ask them what is the recommeded lube would be for the bearing in the engine/conditions/temp and rpm of the bearing (1/2 max engine rpm), and how long that bearing will last in those conditions. You could also ask if the ceramic bearing would be better, S6204 2rs. It will take them a couple of days to get back to you.

+1,

And the experience? ...priceless

.

Exactly! I would love to put the LN one and be done with it. The 600 bucks is not my concern. I'll still not be at peace unless I put the Guardian to watch over me! So, with the LN really not proven statistically or otherwise I think it's the same risk as the original bearings. At least at this time.

Checked Hartech website and didn't see anything on the IMS bearing. So, sent them an email.

Let's see where all this ends. Maybe when I drop the tranny I'll find that the PO replaced my IMS bearing with a one made of diamonds! Would that reduce the failure rate? Well at least my wife can have a necklace out of the debris!!! :rolleyes:

I want to say that even LN is recommending replacement at clutch changes

I read the SKF bearing book on bearing design from cover to cover and bearings have a tendency to fail unpredictably if not operated within their original design specifications. The IMS bearing is of the deep groove design and is designed to be grease lubricated not oil lubricated. If the seals fail or are removed the bearing isn't correctly lubricated and service life becomes unpredictable. The later model m97 engines in the 987 from 2006 used a larger diameter bearing ( so turn slower) than the earlier m96 so the crank case is a different design and they cannot be retro fitted without machining. Personally I think there is no discussion, fit the LN bearing wherever possible , it's not only specified for oil lubrication , it's also better at higher temps. It is not however without it's limitations , as it has lower load ratings and speed ratings than the oem unit , hence the hesitance to stipulate it's 100% guaranteed.

When you say lower load and speed ratings what do you mean? Sorry, not that savvy. Am I looking at driving like Grandma? :(

Bala...
What berty is alluding to is the fact that ball bearings in general are limited to several factors determining their suitability - some of which are lubrication, rotational speed / loading and temperature.
With the IMS bearing, the "load" is coming from the tensioning pull of the chain(s) operating the camshafts, so I would think that that kind of lightish loading is well within the design parameters of a deep groove ball bearing.
Rotating speeds @ 50% of engine revs (lets say 4,000 rpm max) @ 100 deg C also shouldn't be a problem as long as the lubrication is constant, clean and of good quality - but that of course could be the achilles' heel of this system.
Ceramic composite bearings have excellent wear characteristics over steel (especially in questionable lubrication areas) but do not have as high a load rating.
Roller bearings (where the balls are replaced with cylindrical shaped rollers instead of spherical balls) have a much higher load rating, but much lower speed tolerance, so would be unsuitable in the IMS application.

As a side note, the grease used for bearing lubrication is really only a lubricant enclosed in a carrier to prevent it being flung off at high rotational speeds - the push fit RS (rubber seals) each side of the bearing also helping retain the lube. Most bearings are "filled" with less that 30% grease (if I remember correctly) during manufacture, any more and there is a real chance the bearing will overheat before it can squeeze out the excess...
I'm sure Navarro, Raby and their bearing engineer have had all these bases well covered in the initial design stage, so you don't have to drive like Miss Daisy.....

The IMSG can be co-applied with the ceramic hybrid IMSR bearing. We actually sell a combo of both from time to time.
BTW driving like Grandma is the worst thing for the factory bearing~

Jake,

The IMSG is a chip detector, an electronic instrument that attracts ferromagnetic particles. Your IMSR bearing is ceramic right? If your bearing fails, how does the IMSG detect it since ceramic is non-ferromagnetic?

Expert please enlighten me. Love to stuff my brain with interesting information.

The IMSR is less load rated than the oem one. It is also less speed rated then the oem one. All the reading I have done from the forum here and advice from previous owners are that These cars need to be driven like grandma on steroids! ;) One seller even told me that at each gear it should be taken upto 6k rpm before shifting. That maybe overkill but i can say that it makes my stupid grin wider. :) And i dont mean redlining it.

So, am i looking at moving to a conservative driving style with the IMSR compared to oem given load and speed ratings? And also have the same question as Jaxonalden below. These ferrous bit that are present prior to the failure are from the balls or the casing? What actually goes first and lights the fuse? And how do both differ in that process?

Jake,
Do you have any statistics as of this time as to how many have been deployed and how many failed and the causes for failure? Sorry if it has been published and i missed it.

Thanks

The LN IMSR had a total of 3000+ installs as of late last year according to Charles. That of course includes both 986s and 996s. Failed bearings returned to Charles are sent to Ed for analysis.

Aren't we lucky to see so many P-car owners working together to come up with the best solutions they can for us.

JFP said about 4-5 failures. Out of 3000? That is good.

You are right about the owners working together. This collective effort and support is what makes owning this car fun and possible. Without this collective effort (and the members of this forum) I wouldn't touch this car with a 10 foot pole.

:cheers:

I think the big question here is whether it's better to rely on the seals of the original bearing to keep the grease in and contaminants out , or a ceramic bearing relying on clean oil to keep it lubricated.

Statistics can't be accurately gathered for the factory bearing because the numbers to complete the equation can't be gathered.
This week we received one engine with a failed bearing, it was a late style 06 and later bearing. It's the "featured failure" in this months newsletter that I am working on today because of how collateral damage is what killed that engine.

I received 3 other failure calls this week, two were IMS and one intermix.

Of the cars we have retrofitted here (215 all serialized) we have not had any failures. This is due to the procedure that we employ coupled to the after install support and engine oil that is used.

The factory seals might be fine if they stayed sealed, thanks to oil temps and oils that sees heavy fuel intrusion, they don't.

I wanted to address this separately.
The races and cages of the ceramic IMSR are still ferromagnetic and will trigger an IMS Alert. We have carried out this specific testing all through 2011.

BUT in applications where the IMSR is employed the IMSG is more useful in alerting the driver of the other ferromagnetic wear metals within the engine.

Sorry if I wasn't clearly asking the question. I meant to ask you about the statistics of the LN bearing not the factory ones. But, mike and jfp have indicated the figures. You don't have to answer if the numbers are right. Thanks,

That's a gamble as well isn't it? Considering that ferrous bits can come from other sources and affect the LN bearing which is not sealed.

Wonder if the magnetic drain plug might actually help in drawing and keeping the bits confined in one area and away from the bearing to some extent.

Won't the heavy metal cage be slower accelerating/decelerating than the ball bearing itself? Causing the ball to bang the against the cage, accelerating wear on the cage? Eventually banging chips in the ball itself as the ceramic ball sharpens the the edges of the metal cage?

I think that is why bearing companies use nylon or Teflon cages with ceramic balls as they are lighter and can keep speed with the ball itself.

Sorry, you are wrong..
The cage is there to only lightly retain the balls (the balls run in the so called "deep groove" of the bearing), and they dont come into contact because the lubricant (grease or oil film) acts as a buffer - the gap between the cage and balls is measured in microns.
The weight of the cage is measured in milligrams - the speeding up or slowing down would be insignificant unless your grease was so thick it caused drag.

Sorry,, but you are wrong,, They are using oil lubrication in the LN bearing and very thin at that. It will be like a knife being sharpened with a oil film against a ceramic sharpener. The cage weight will matter even in the milligrams when you jump on the accelerator or slamming on the brakes. Anyways, I will look up the link on the bearing site I read it on, and post the link.

Log onto www.rentech.org.Forums and under heading for 996 Series (Carrera, Carrera 4, Carrera 4S, Targa
see Casper Labs Ceramic IMS Bearing.
The whole gambit is interesting but especially post #39, on page 2 from Casper Labs head honcho regarding steel vs plastic cages and ceramics in general. Casper are Aero engineers have been trialling an alternative IMS bearing application.
Bill Ryan is far more experienced than I am in detailing the respective materials....


Our production bearings will be shipped with steel ball cages. We have tested two types of steel designs, nylon, and an exotic made of a low density phenolic. The phenolic one is put in a bell jar immersed in Mobil 1. You pull a vacuum on it, and the oil gets sucked into the phenolic. It will wick enough oil for years of dead storage to start-up lube a ceramic hybrid...... even if the sump oil level is below the bearing. These have to be custom CNC machined, and double the bearing cost. If you really want the phenolic cages, we can special order them (2 week delivery).

Why did we pick steel as the baseline? Many reasons, 1) steel cages are fitted more loosely to the balls due to the limitations of forming sheet metal. This gives the consumer the perception of a lack of quality in a precision device. They move around a bit relative to the ball. Does not hurt the bearing, but perception can be a difficult thing to get around. 2) Nylon nests the balls precisely and has slightly better capillary attraction for the oil film between the ball and cage (providing more oil "storage"). 3) If either of these cage materials gets some level of damage, the nylon will not damage the OD race when the hard ball rolls over a piece of it. 4) From a temperature standpoint, steel cages have the highest rating. The phenolic is second highest (about 350F), and nylon the lowest. The highest temperature rated nylons are just too close to this boxer engine's red line coolant temp (remember this engine uses a coolant/oil heat exchanger). We never encountered this problem, but it is too significant to consider production worthy. If this really catches on, we may consider investing in the tooling to mold out of a higher temp plastic, none are available now in this size.

We ship the bearing with a very, very light lube that really lets you feel the rolling action. If anything gets in the bearing during assembly, you will feel it. Once we are certain it is clean, we take a veterinary's large animal syringe (.040" needle) and inject some engine oil supplement to both rows of balls before slipping the support in place. This is where the looser fitting steel cage comes in handy, you can get the needle past the first row of balls.

Billl Ryan
Casper Labs, Inc.

Steve, All this says is.... nylon "could" melt if you cook your engine but didn't give the temp. Phenolic was too expensive, but is suited for the job (350F) BUT, nylon and phenolic are NOT steel. Also it states they only tested 2. He also states... the cage won't damage the ball, but I don't see where the the ball won't damage the cage. Plus, he is talking about assembly of the bearing here, not a test of accelerating/decelerating of the ball damaging the cage.

Ceramic balls are lighter and harder than steel and will move much faster than the steel cage causing wear within the cage. The bearings life will be shortened with steel cages, and its a wait and see at this point until bearings do fail.... as the root cause, it is an unknown at this point. And I hope it is shared with the group.

Maybe thats why the gaurdian came into play?

No, the IMSG came into play because of the huge plunge in Boxster and 996 values that could make a retrofit process worth almost half as much as a car and if a failure occurs the engine could cost twice as much as the car is worth to repair.

The IMSG is seamless and integrates into the car as a simple DIY process, not requiring any special tools or knowledge. The installer also doesn't risk making a mistake that can cost them an engine if the process isn't carried out correctly.

The IMSG isn't appreciated by everyone, but it has gained respect from its installers thus far.

It has gained my respect for sure. Though I am not happy about the cost. But that's just me.

I drained the oil and found maybe 3-4 tiny metal bits. The filter had a few small black plastic bits as well. Very tiny. My clutch is fine but, there is slight oil leaking from the bottom of where the engine mates to the tranny. So am going to wait it out with the IMSG installed. The way I see it I will not be totally confident with the IMSR alone installed. So, will need the IMSG as well and this will be one step closer to a good night's sleep.

Thanks all for the discussion. Very informative and helpful.

http://986forum.com/forums/uploads01...1330384030.jpg

We make bundle packages with IMSR and IMSG quite often, it saves a little money.

Jake,
i ordered the guardian. Honestly I want to wait for Pelican kit to compare as I'm still on the wall with the ceramic factor. PP kit is 3-6 weeks away is what I'm told. Anyway it gives me some time to drive around with my new buddy Guardian.

Removed the oil pan to prepare for IMSG install and surprise! Metal pieces in the pan. They look like someone left some aluminum tray inside that got chewed up. I'll post pics tomorrow but at this time I am not a happy person. Need to drop tranny and take a look at the ims. since the entire suspension, axle is out better to do it now than later. :mad:

Run a magnet around the metal and see if the pieces stick to the magnet.

A bearing filled with grease does always have a specific limited lifetime compared to bearings that are lubricated by oil. Guess that Porsche knows the lifetime here but this is of course only possible to calculate if the grease is kept inside the bearing.
However , original intention must have been a lifetime well beyond 200,000km

In Mr Rabys solution lifetime will probably be very good as long as there is no loose debris entering the bearing which cant be guaranteed. Just look inside your oilfilter every oilchange.

I guess that no double row bearing with the grease kept in place has failed yet.
The single row bearing was probably some kind of costcutting project as the IMS failures where uncommon the first years and there was room for lower spec of the bearing.

When it is time for my next clutch I will,( if they exist) use a standard bearing but with upgraded seal spec and grease that can take more than 120 degrees C.
This will be done in combination with a low temp thermostat and 10/40W oil

Until then I will feel very safe with the IMS guardian.

I am in a similar boat. I can't justify another $600 on this engine. I went down to the local bearing shop and bought a bearing for $17. The bearing in both the failed engine and the replacement engine we bought were both good.

John

One thing I don't understand (or not educated on) is why am I finding the metal pieces at the bottom - oil pan. These should have gone thru the filter and actually should be in the filter no? Don't think those pieces just came loose when I turned off the car and then proceeded to drain the oil and removed the pan.

Just tried feelyx's suggestion and used a magnet. NONE of the pieces stick. There are also some tiny pieces black in color. Plastic maybe?

So, if the LN bearing is not sealed and is lubricated by oil, and the contaminants (metal) can come from elsewhere, there is a high probability that it can damage that bearing as well. So, a sealed one is much better bet not considering lubrication factor? Your take on an upgraded seal bearing makes a lot of sense to me. Of course the IMSG would allow just in time intervention if a disaster was going to happen in all cases. But, no such bearing exists does it. Can a OEM bearing be purchased, upgraded lubrication and upgraded seal be made to order?

Reading up on bearing failures it's normally a result of the race guide or the balls suffering damage. Typically this damage is caused by either foreign particles entering the bearing races or the bearing race/balls fragmenting as a result of excessive heat from running at too high a speed /load or with insufficient lubrication. The advantage of ceramic or composite materials is they are less affected by temperature or foreign particles. Assuming Porshe specced the bearing correctly for speed and temperature the only realistic cause of failure is that the lubrication is washed away or that foreign particles enter the bearing causing deterioration. Either way, there is a very strong case for fitting a bearing that can operate with less lubrication or oil lubrication rather than grease and that is more resilient to foreign particles in the race guides.

A question for Jake and flat six innovations at this point. With full ceramic bearings available , why is the solution offered using a hybrid rather than full ceramic ? Is there an issue with full ceramic bearings in terms of load or shock resistance that is required in this application ?
For instance the bearing listed below meets the temp requirements for the application
6204 Full Ceramic Bearing 20x47x14 Ball Bearings

Or the full compliment Silicon nitride bearing
6204 Full Complement Ceramic Bearing 20x47x14 Si3N4 Ball Bearings

I assume the bearing offered currently is something like this ?
6204-2RS Hybrid Ceramic Sealed Bearing 20x47x14 Ball Bearings
SKF - Product data

Feelyx,
Thanks for the suggestion. The pieces are not sticking to the magnet. What am I supposed to conclude from this?