Another IMS bearing thread

[BudmanV24]

Originally Posted by southernstar

Yes Tony, the Vertex roller bearing replacement has been discussed here previously and the consensus seems to be that, in spite of the obviously greater surface area of roller bearings, they are ill-suited to the IMS application: roller bearings are not intended for, nor are they capable of dealing with the thrust loads that the IMS is subjected to.

Brad

A couple of thoughts that I have on this.

No I do not think that the above pictured IMS bearing is a quality, well thought out piece of equipment. Yet, I do want to add to Brad's comment about roller bearings not being designed for thrust loads. While this is true it appears that this product has integrated plain bearing style thrust washers into the bearing races.

Do I think their design will work? Probably not because they look like low grade, 5 cent parts. But, I'd sure love to hear someone try it and so I can see the pieces when their engine goes.

On another note, I have 4 engines sitting in my garage with spun bearings or d-chunked cylinders. Not a single one has a bad ims bearing. I've pulled several ims bearings and never found a single one that exhibited any play. While yes the IMS bearing is something that goes out on some cars, I think if you drive these things hard the IMS bearing is the least of your worries.

Anyone ever seen the bearing at the front of the ims shaft go out? Of course not, its a plain bearing. All it is, is the steel ims shaft riding in the aluminum casting of the oil pump.

I think from a releability stand point Raby's IMS Solution (the one that utilizes a plain bearing that is force fed oil) is the best idea to date. It's not a coincidence that the only ball bearing in these engines is commonly a failure point. Ball bearings require less lubrication and provide less drag, but wear out faster in my experience and are more susceptible to debris. So then the only problem with the IMS solution is is it's cost. But I guess that's up to the consumer to gauge the value of their engine.

[Walter White]

Originally Posted by BudmanV24

A couple of thoughts that I have on this.
While yes the IMS bearing is something that goes out on some cars, I think if you drive these things hard the IMS bearing is the least of your worries.

I have heard this many times and while I do not disagree at all, I think it may very well be a matter of the chains throwing much more oil around and creating much more oil mist in the area of the IMS bearing at high RPMs. At low RPMs, the oil that the chains pick up stay on the chains. So it may still come down to just lubrication.
Chain saw bar oil has ingredients in it that keep the oil on the chain, and not flying off at high RPMs. On our Porsche motors, we want the opposite.

One thing I have thought about. How many ball bearings do you see fail in transmissions, wheel bearings, motor cycle engines, the way IMS bearing fail . While they may wear to a point of needing replacement, I don't recall seeing the complete failures in these bearings that the IMS bearing seems to exhibit. When the bearings are bathed in grease or oil, complete or catastrophic failures are very rare.

[Jake Raby]

Originally Posted by Walter White

I have heard this many times and while I do not disagree at all, I think it may very well be a matter of the chains throwing much more oil around and creating much more oil mist in the area of the IMS bearing at high RPMs. At low RPMs, the oil that the chains pick up stay on the chains. So it may still come down to just lubrication.
Chain saw bar oil has ingredients in it that keep the oil on the chain, and not flying off at high RPMs. On our Porsche motors, we want the opposite.

One thing I have thought about. How many ball bearings do you see fail in transmissions, wheel bearings, motor cycle engines, the way IMS bearing fail . While they may wear to a point of needing replacement, I don't recall seeing the complete failures in these bearings that the IMS bearing seems to exhibit. When the bearings are bathed in grease or oil, complete or catastrophic failures are very rare.

But Pedro's video shows centrifugal force throwing oil AWAY from the IMSB area? Not that I agree with that, but your hypothesis states the opposite.

The M96 bearings LOVE RPM because it helps unload them, the M97 bearings hate it because the components spin too fast. M96 bearings fail on the street, M97 bearings fail on the track and seldom on the street, very seldom. Load is the evil constant.

[trimer]

For Jake R...and just out of shear curiosity, you have put in so much time with these engines. I have the upgrade you all developed and glad I did it. That was 1,000 miles ago. We see a lot of talk in a lot of our threads about these neat little cars never being collectible. I am curious what your thoughts are on that topic. I assume most wont replace the IMS and we will start seeing a ton of failures from this as well as other parts, but do you eventually think the early survivors might actually start to hold some value? Again..just curious. You have a ton invested in these motors and realize they are not just boxster specific motors...

[Jake Raby]

Originally Posted by trimer

For Jake R...and just out of shear curiosity, you have put in so much time with these engines. I have the upgrade you all developed and glad I did it. That was 1,000 miles ago. We see a lot of talk in a lot of our threads about these neat little cars never being collectible. I am curious what your thoughts are on that topic. I assume most wont replace the IMS and we will start seeing a ton of failures from this as well as other parts, but do you eventually think the early survivors might actually start to hold some value? Again..just curious. You have a ton invested in these motors and realize they are not just boxster specific motors...

Its so hard to say what will happen with the value of these cars. The IMS issues and all the other deficiencies have scarred them heavily. I'd like to think that the cars will have price increases over time, especially with fixes for the major issues easily attainable today.

I can't imagine a "vintage Boxster" and out of the 32 cars that we have on our schedule for engine reconstructions only two of them are Boxsters, the rest are 996/997 or Caymans. Thats much different than the old days when we started this, back then it was rare to see a 996 here. hell, I can't imagine a "vintage 996" either.

I am not betting on the cars holding value, so in the December issue of Panorama you'll be introduced to "Cayman X" and our DFI (post 2009) engine program thats now 4 years in the making. Its always about getting into the next big thing before the next guy :-)

Thats why we went straight to 4.2 liters from the factory 3.4!

[trimer]

Originally Posted by Jake Raby

Its so hard to say what will happen with the value of these cars. The IMS issues and all the other deficiencies have scarred them heavily. I'd like to think that the cars will have price increases over time, especially with fixes for the major issues easily attainable today.

I can't imagine a "vintage Boxster" and out of the 32 cars that we have on our schedule for engine reconstructions only two of them are Boxsters, the rest are 996/997 or Caymans. Thats much different than the old days when we started this, back then it was rare to see a 996 here. hell, I can't imagine a "vintage 996" either.

I am not betting on the cars holding value, so in the December issue of Panorama you'll be introduced to "Cayman X" and our DFI (post 2009) engine program thats now 4 years in the making. Its always about getting into the next big thing before the next guy :-)

Thats why we went straight to 4.2 liters from the factory 3.4!

Thanks for your insight. I didnt buy mine to collect but will keep it in as great of shape as possible...seems like the only thing to do is keep it bone stock and enjoy and move on or build a big ass motor and really enjoy it for what it is.

[Porsche9]

In the early 80's no one gave much thought to vintage 914s. They were just used cars. Time will tell.

[Walter White]

Originally Posted by Jake Raby

But Pedro's video shows centrifugal force throwing oil AWAY from the IMSB area? Not that I agree with that, but your hypothesis states the opposite.

The M96 bearings LOVE RPM because it helps unload them, the M97 bearings hate it because the components spin too fast. M96 bearings fail on the street, M97 bearings fail on the track and seldom on the street, very seldom. Load is the evil constant.

I am not familiar with the video you mentioned, but it would be nice if the oil would sling off the chains, but stick to the bearing.
When I was experimenting with getting oil to a bearing spinning at 4 - 6K RPMs, I was getting the idea that the bearing wasn't getting any oil at all. I would drop a drop of oil into the race of the spinning bearing and it would instantly vaporize. I don't think the oil ever even got to the contact surfaces.

[Jake Raby]

Originally Posted by Walter White

I am not familiar with the video you mentioned, but it would be nice if the oil would sling off the chains, but stick to the bearing.

He's posted it in several threads. In all your research I can't believe that you haven't found it.

[thom4782]

Originally Posted by Walter White

Is the bearing under load while accelerating?

Can you ask a more specific question? The following will clarify why I am asking.

It seems to me that the bearing is under load so long as the engine drive chains are moving. I would think the substantive issue is just how much load does the bearing bear under different operating conditions. The hypothesis I am about to advance is pure educated guessing on my part.

My theory is that forces create load - centripetal due to rotation and vibrational. At constant RPM, the bearing experiences some degree of load, say X. As acceleration increases RPMs, I think the loading increases as the chains increase rotational speed of engine components. At higher RPMs, however, the vibrational loading component decreases because vibrational amplitudes don't have time to reach their full heights.

[Walter White]

Originally Posted by thom4782

Can you ask a more specific question? The following will clarify why I am asking.

It seems to me that the bearing is under load so long as the engine drive chains are moving. I would think the substantive issue is just how much load does the bearing bear under different operating conditions. The hypothesis I am about to advance is pure educated guessing on my part.

My theory is that forces create load - centripetal due to rotation and vibrational. At constant RPM, the bearing experiences some degree of load, say X. As acceleration increases RPMs, I think the loading increases as the chains increase rotational speed of engine components. At higher RPMs, however, the vibrational loading component decreases because vibrational amplitudes don't have time to reach their full heights.

I am not clear on the vibration part. Is that vibration of the IM shaft, or the bearing components.

Here is some information I found that touches on rpm and lubrication-

"The engineer’s initial thoughts were that the ball-separator failure led to bearing collapse, but after analysis of said IMS bearings, it would appear that bearing wear/fatigue spalls lead to separator wear and outer race failure. Separator failure and bearing collapse causes catastrophic failure of the mounting bolt(s) and IMS/timing chain components. The first recommendation was to use a bearing without seals and secondly to use a higher viscosity oil (with greater film strength). More frequent changes will also improve lubrication quality. An oil with extreme pressure additives like Moly might also further assist in increasing bearing life. Higher rpms also increases bearing life as this lessens the viscosity requirements of the lubricant to maintain EHD lubrication, also providing a reasonable explanation of the lack of IMS failures in tracked cars or those driven "like they were stolen." Likewise, far more failures are found in engines with low mileage that are garage queens and never driven to their full protential."

Source: PORSCHE Intermediate shaft upgrade kit for PORSCHE BOXSTER ENGINE 986 AND PORSCHE 911 996 ENGINE

I have to admit I am stuck on rolling bearings for the IM shaft. I just keep asking myself why Porsche insisted on using a rolling bearing for so long. Was it because it was the best fit for handling dynamic forces that they were not able to engineer out of their production parts.

[BudmanV24]

Originally Posted by Walter White

I am not familiar with the video you mentioned, but it would be nice if the oil would sling off the chains, but stick to the bearing.
When I was experimenting with getting oil to a bearing spinning at 4 - 6K RPMs, I was getting the idea that the bearing wasn't getting any oil at all. I would drop a drop of oil into the race of the spinning bearing and it would instantly vaporize. I don't think the oil ever even got to the contact surfaces.

At high rpms, ball bearings prefer an oil vapor. Take a look at ball bearing turbos, albeit at a much higher rpm, they fog the bearings.

[Jamesp]

Originally Posted by BudmanV24

At high rpms, ball bearings prefer an oil vapor. Take a look at ball bearing turbos, albeit at a much higher rpm, they fog the bearings.

Reading bearing manufacturer data on lubrication shows that high rpm requires lower viscosity (thinner) lubrication, and low RPM requires higher viscosity lubrication. It was explained that that the lubrication has to "be in the way" when needed, and also be able to "get out of the way" so the bearing elements can pass. This supports longer bearing life in aggressively driven cars that have engine oil in the bearing. So to the folks out there with 200K+ on their cars, we know how you drive.

[Steve Tinker]

Originally Posted by Jamesp

Reading bearing manufacturer data on lubrication shows that high rpm requires lower viscosity (thinner) lubrication, and low RPM requires higher viscosity lubrication. So to the folks out there with 200K+ on their cars, we know how you drive.

Or they drive at really low revs with really thick oil......