EPS IMS Bearing Upgrade Kit

[fanguy]

This link gives info on ball vs roller bearings.

What

[JFP in PA]

Originally Posted by ksjohn

One other thought:

One thing that attracted me to the EPS bearing system was ability to modify the oil pump drive shaft and the IMS so that oil would be continuously pumped to the bearing. I know this oil source is not cooled or filtered which is ideal, but still it is a continuous oil supply.

Why could you not combine this feature with a simple, non-sealed single row ball bearing? A ball bearing may be a better solution than a roller bearing and the cost could be minimal depending on the source of the bearing.

I have never seen this option discussed anywhere.

Perhaps because the oil pump drives in these engine's are already notoriously weak before you grind a slot in them, punching a hole with a hammer in the pump end shaft seal may not be the best way to control oil flow, and running a flooded IMS shaft may not be the best approach to extending bearing life.

[fanguy]

I am glad to see this discussion develop into technical dialog.

There seems to be 3 very different approaches to delivering oil to the IMSB. List in alphabetical order.
1. EPS (IMS Bearing Upgrade Kit) Cylindrical Roller bearing oil delivered through the oil pump shaft by modifying the shaft during installation.
2. Flat6/L&N, and Jake Raby (IMS Solution) Has removed the Bearing and oil delivered from spin on oil filter to IMSB flange through braided line.
3. Pedro’s (DOF) Roller bearing, from unused port in engine casing to IMSB flange through braided line.

I was very curious about the difference between Jake Raby’s and Pedro’s. Both deliver oil through braided line to the flange but from completely places. Last weekend I sent Jake an email asking why he choose his design as the DOF seemed a simpler way to get oil to the flange. He responded back rather quickly which was impressive. Here is his response to why do he pulls the oil from the filter.

I developed a system similar to the DOF many years ago, it never impressed me, and therefore it was not marketed.
That said, the oil that I collect for the IMS Solution is taken directly from the oil filter, it is JUST FILTERED OIL, and it has the highest volume, fastest priming, and highest pressure of any portion of the engine, because this post is the first orifice past the main engine oil pump. The DOF takes oil from where it does, because my first US Patent includes the Spin on Filter Adaptor method, so the DOF had to source oil elsewhere to reduce the infringement possibilities on this Patent.
United States Patent: 9416697

Review this here:
Layshaft end bearing retrofit with external positive oil pressure delivery
Single Document


That said, the reason I pick up oil where I do, is because I understand the fundamentals of this engine much more than the oil system diagram from Porsche. Pulling oil from the cylinder head is a way to see oil pressure which has already been reduced by the bypass system, and to collect unfiltered oil that has already passed dynamic components. This is NOT just filtered oil; therefore, it can present, and feed directly into the IMS Bearing, debris laden oil. Been there, done that years before anyone else had even extracted an IMS Bearing.

[ksjohn]

Originally Posted by JFP in PA

Perhaps because the oil pump drives in these engine's are already notoriously weak before you grind a slot in them, punching a hole with a hammer in the pump end shaft seal may not be the best way to control oil flow, and running a flooded IMS shaft may not be the best approach to extending bearing life.

I can agree with some of your point, but not entirely.

I have wondered if Porsche had originally sealed the end of the IMS as opposed to leaving it open might have made failing IMSBs a non-issue. But then that depends on what the majority mode of bearing failure is, rancid, acidic oil in the shaft eating at the bearing or simple failure due to stress.

But, the fact remains that the IM shaft does fill with oil on many/most cars and the oil has no means of escape, creating an oil flooded IMS. It seems to me that the EPS bearing being open allows the oil in the shaft to spin out past the bearing especially when subjected to centrifugal forces of a running engine, minimizing the amount of oil in the shaft while running. And new oil being metered through the pump shaft will provide continual lubrication for the bearing.

Regarding the oil drive shaft, I don't think it is a stock shaft with a groove cut in it. I looked, and they do not spell out how the shaft is manufactured. (which would be nice to see). But I am going to make the assumption that it has been engineered to account for the strength required in light of the groove. That is entirely an assumption. But then I have not read of any of these parts failing either.

I agree with you regarding the punch used to open a hole in the end of the IMS. It should be manufactured with a flange to prevent you from making the hole too big.

Now all of this is simply my understanding of the product and how it works. Many people here have vastly more knowledge than me regarding these engines.

But still, I pose the question: would their oil feed system and a standard un-sealed single row ball bearing be a viable option?

[JFP in PA]

Originally Posted by ksjohn

I can agree with some of your point, but not entirely.

I have wondered if Porsche had originally sealed the end of the IMS as opposed to leaving it open might have made failing IMSBs a non-issue. But then that depends on what the majority mode of bearing failure is, rancid, acidic oil in the shaft eating at the bearing or simple failure due to stress.

But, the fact remains that the IM shaft does fill with oil on many/most cars and the oil has no means of escape, creating an oil flooded IMS. It seems to me that the EPS bearing being open allows the oil in the shaft to spin out past the bearing especially when subjected to centrifugal forces of a running engine, minimizing the amount of oil in the shaft while running. And new oil being metered through the pump shaft will provide continual lubrication for the bearing.

Regarding the oil drive shaft, I don't think it is a stock shaft with a groove cut in it. I looked, and they do not spell out how the shaft is manufactured. (which would be nice to see). But I am going to make the assumption that it has been engineered to account for the strength required in light of the groove. That is entirely an assumption. But then I have not read of any of these parts failing either.

I agree with you regarding the punch used to open a hole in the end of the IMS. It should be manufactured with a flange to prevent you from making the hole too big.

Now all of this is simply my understanding of the product and how it works. Many people here have vastly more knowledge than me regarding these engines.

But still, I pose the question: would their oil feed system and a standard un-sealed single row ball bearing be a viable option?

One thing you may be overlooking is that many, in fact most, IMS shafts do not run true. This means there is some inherent "wobble" in the factory shaft even when is dry. On engines that have suffered IMS failures at low mileage, the amount of this nonconcentric movement is often profound, and is believed to have played a role in the early demise of the IMS bearings as they were simply being beaten to death by the wobble in the shaft, as well as the loss of the grease. As I have mentioned on more than one occasion, we always find the shafts at least partially filled with oil when doing an IMS retrofit, and a common comment we get from car owners after we install an IMS Solution (with the shaft now dry and plugged behind the bearing area) is that the car now seems to run and idle smoother. As we have not changed the amount of inherent wobble in the shaft, but have removed any collected oil and prevented any new intrusion, those observation may be the direct result of there not being any oil inside the IMS shaft to exacerbate the existing wobble inherent to the shaft from the factory. We have also observed that some Porsche engine builders often drill small holes into the IMS shaft, specifically to allow collected oil to escape.

So if oil inside the shaft seems to be an issue with multiple solutions, why would you specifically introduce it in the first place?

[wogin]

I just put the EPS roller bearing in a month ago. After researching this issue to death I ended up deciding to put this particular bearing in based on the following:

1) Roller bearing has a higher radial of load capacity than a ball bearing. I read estimates that the failure rate of single row ball bearings is as high as 10% before 100k miles but that the double row bearings had failure rates closer to 1-2%. The dual row bearing has more balls to distribute the radio load. This results in lower cyclic contact stresses in the balls and the races. In fatigue failure, even small decreases in stresses can dramatically increase the average time to failure of a part. A roller bearing distributes its load along the line of contact rather than a point. This design feature means that roller bearings will see much lower cyclic stress levels than a ball bearing of the same form factor. I chose a roller bearing over dual row ball bearing because I believe the cyclic stress level will be lower in the roller bearing than in a dual row bearing.
2) In reviewing pictures of the of the Boxster‘s engine’s internals, and the support configuration for the intermediate shaft, I did not see any sources of significant thrust load on the shaft. Given the lack of thrust loading, I concluded that the EPS bearings thrust washers would probably be sufficient to manage a inertial thrust loads.
3) I called EPS and spoke with them, and although they have not sold as many Bearings as The alternative suppliers on the market, they have not had a single reported failure. On the other hand I have read about failures on ball bearing retrofits (and The manufacture simply blamed installation rather than Entertaining the possibility that they supplied a defective product..)
4) cost. The EPS bearing was cheaper than a ceramic ball bearing retrofit, and the manufacturer claims it will last the life of the engine. Contrast that to the ceramic ball bearing that costs more and should be replaced every 40k miles. If I had all the money in the world to throw at this problem I would buy the Journal bearing retrofit kit, but for me it was just crazy to drop $1.7k on a 10% chance my $6k engine would blow up.
4) the speed of the ims shaft is compatible with the rated speed of a roller bearing of this size.

Finally, if I had a dual row bearing already in my car from the factory... I probably would have just left it alone... 2% failure rate isn’t high enough to justify the expense and hassle of replacing the bearing.

Please excuse typos. I wrote this on my phone and dictated some of it to Siri... she doesn’t hear me well sometimes.

Not looking to debate what solution is best, just throwing out the reason I made the choice I did in case it helps others with this decision.

[Gelbster]

Thanks for sharing your thoughtful analysis.
Having chosen the roller bearing option, why EPS and not RND ?
Roller Bearing IMS Retrofit Kit – RND Engines

[wogin]

Originally Posted by Gelbster

Thanks for sharing your thoughtful analysis.
Having chosen the roller bearing option, why EPS and not RND ?
Roller Bearing IMS Retrofit Kit – RND Engines

Actually did compare those two bearings. Although the thrust loads on the roller bearing should be very low. The EPS bearing seemed to me to have a better way of controlling those thrust loads. On the EPS bearing the thrust loads are transferred between the outside of the External race and the retaining washer faces on either side of the bearing. This ensures the ends of the rollers will not be the primary wearing surface. In the RND bearing appears to be an off the shelf rollerbearing that is simply axial retained by rigidly connecting its internal race to the cover/flange. Thrust loads would be between the roller ends and the internal edges of the bearing race... effectively loading the off the shelf bearing in a way that it is not designed to be. .... while this may be technically acceptable if the thrust loads are low enough, I just didn’t want to risk it. EPS seemed like a better thought out design.

[dsallean]

Originally Posted by Gelbster

Thanks for sharing your thoughtful analysis.
Having chosen the roller bearing option, why EPS and not RND ?
Roller Bearing IMS Retrofit Kit – RND Engines

Gelbster I know your question was directed at Wogin and his detailed post but I will add that when I was considering replacement of my IMS I searched the interwebs and I read everything I could find and came to my own personal preference for the roller bearing option. I was leaning toward the EPS version but the oiling system modifications kept me from pulling the trigger. It just didn't compute to punch a hole. It just nagged at me. So when RND came out with theirs and no oiling system requirements I pretty much knew that was the way I was going to go.

I really was in no hurry to replace my dual row IMSB and it ultimately came out in excellent condition. The replacement was accelerated after my Indy said the IMS was toast and I needed an engine replacement. Turned out it was a variocam puking green O-ring bits and the plastic variocam pads were worn. It was time for a new clutch and DM flywheel anyway

Dave
2001S

[paulofto]

Originally Posted by dsallean

The replacement was accelerated after my Indy said the IMS was toast and I needed an engine replacement. Turned out it was a variocam puking green O-ring bits and the plastic variocam pads were worn. It was time for a new clutch and DM flywheel anyway

Remember rule #1 with any Boxster or 911 from 1997 to 2004. If anything is wrong with your car, I mean anything, it is the fault of a failing IMS bearing. Period.

[Gelbster]

Two other supporting aspects for JFP's comments:
1.When this modified driveshaft was first introduced we voiced alarm at the deliberate weakening of an already weak part. Subsequently , it seems the depth of the groove in it has been reduced to the point where it is difficult to imagine any significant amount of oil can travel along the groove. So while you are in there, why not fit an upgraded drive shaft ?
2. The oil in the IMS tube. The premium IMSB replacement product has a plug to completely seal the tube. Why would they bother with this if it was not a problem ?
I am puzzled why the RND roller bearing product does not include this seal for the IMS tube.It would have been an easily added premium feature ?

[JFP in PA]

Originally Posted by Gelbster

2. The oil in the IMS tube. The premium IMSB replacement product has a plug to completely seal the tube. Why would they bother with this if it was not a problem ?
I am puzzled why the RND roller bearing product does not include this seal for the IMS tube.It would have been an easily added premium feature ?

Two possible reasons:

1. The RND bearing may be open on the flywheel side to mist lubrication, much like the LN ceramic hybrid bearings, and therefore does not need the pressure lubrication.
2. Use of a plug in the rear of the IMS shaft may already be covered in a patent.

[Gelbster]

"would their oil feed system and a standard un-sealed single row ball bearing be a viable option?"
Probably should distinguish between single/double row ? If it is double, there is less incentive to go with any roller bearing kit?
Another option in this theme would be to use Pedro's DOF because his bearing is sealed on the inside and may minimize oil intrusion to the IMS tube. In theory you could use Pedro's DOF & the roller bearing? Ask Pedro. That may be attractive for cars originally fitted with a single row IMSB.

[JFP in PA]

Originally Posted by Gelbster

"would their oil feed system and a standard un-sealed single row ball bearing be a viable option?"
Probably should distinguish between single/double row ? If it is double, there is less incentive to go with any roller bearing kit?
Another option in this theme would be to use Pedro's DOF because his bearing is sealed on the inside and may minimize oil intrusion to the IMS tube. In theory you could use Pedro's DOF & the roller bearing? Ask Pedro. That may be attractive for cars originally fitted with a single row IMSB.

Actually, introducing pressurized oil from the flywheel side has multiple potential issues. First, just how much oil is necessary? LN's history of more than 25K units successfully running on just the oil mist inside the engine say that not much is needed. Bearing engineers have chimed in to say that while some is good, a lot is not so good as it can induce "skidding" rather than rolling in the bearing balls, which they say is not a good thing. It is also common for shops to remove the rear seal from the third generation IMS bearings which cannot be easily retrofitted, and to my knowledge, there have been no reports of any of the oversized bearings run this way subsequently failing. Add in that it is well known that the factory bearings leak oil into the shaft behind the bearings without any induced pressure, pressurizing them is going to accelerate this process. Lastly, as Jake has already noted, where you source the pressurized oil from is critical; you want the oil to be clean and as cool as possible, while not short changing any other pressure lubricated components. With oil from the cylinder head being one of the hottest, as well as the dirtiest sources, and there have been multiple reports of both valve noise and VarioCam problems on engine's using the cylinder head oil to lube the IMS which promptly disappeared when the oil lines were plugged, you have to ask yourself if this is really someplace you want to go.

[mikefocke]

Originally Posted by JFP in PA

With oil from the cylinder head being one of the hottest, as well as the dirtiest sources, and there have been multiple reports of both valve noise and VarioCam problems on engine's using the cylinder head oil to lube the IMS which promptly disappeared when the oil lines were plugged, you have to ask yourself if this is really someplace you want to go.

I've seen one report but not multiple ones. ???

[JFP in PA]

Originally Posted by mikefocke

I've seen one report but not multiple ones. ???

We have had two in the shop ourselves, plus what we have heard from other shops, in addition what has been talked about on the web. Unfortunately, reports or threads about this online tend to be attacked by those with direct interest in the product, usually ending the conversation quickly rather than exploring it further.

[Boxtaboy]

What I want to know is how someone like MarcW can get over 300k miles (and still going) on his 02 Boxster with original IMS. I thought it's not a matter of if, but when.

[JFP in PA]

Originally Posted by Boxtaboy

What I want to know is how someone like MarcW can get over 300k miles (and still going) on his 02 Boxster with original IMS. I thought it's not a matter of if, but when.

For some it is, others not so much. We also have customers that have gone well over 200K with the factory bearings, and others have not made it to 50K. As with all production mechanical systems, some will go on nearly forever, but others will die prematurely for various reasons. But one inescapable is the Porsche's own data from the lawsuit: Of the single row engines produced between 2000 and 2006, approximately one in ten won't make it, and for the earlier dual rows the odds are somewhat better at 1-2% (no real hard numbers are known for the third generation bearings as they were not part of the legal action).

So it comes down to individual's risk tolerance levels; we have had customers trade in cars because of their concern, others have chosen to take preventative steps, and others simply decided to ignore it. All a mater of personal choices.

[mikefocke]

The failure rate for the 2nd generation single row bearings that was admitted to by Porsche was as of several years ago. I'd presume the percentage of failures would increase with time so it would be higher today?

[JFP in PA]

Originally Posted by mikefocke

The failure rate for the 2nd generation single row bearings that was admitted to by Porsche was as of several years ago. I'd presume the percentage of failures would increase with time so it would be higher today?

There was some discussion on this point a while back, but I cannot pinpoint the exact thread now. From a numerical standpoint, there were more single row engines (2001-2005) produced than dual rows (1997-2000), and the single rows were (from from Porshce's original litigation data) much more prone to failure than the dual rows, so it is a reasonable assumption. Unfortunately, once the litigation was settled, there has not been detailed additional hard data released, only occasional "snippets". With the legal action over, and all of the potential cars long out of warranty, the final numbers will probably never be known.