Another IMS bearing thread

[tonysilver986]

Hey guys,
I've been lurking around for 12 months or so gaining lots of info on my purchase last year, a '99 model 2.5 silver Boxster.
I shopped in my 4.0L V8 TVR Wedge to join the 986 brigade as I'd always fancied one, even after owning a 320bhp BMW Z3m. (which my son redesigned quite badly)

Although the IMS bearing is a potential issue, it is not at the front of my thoughts all the time. But I follow all the threads related to it on hear. I do and always have done all my own maintenance, from oil changes to engine rebuilds. (because I am too tight in the wallet department :ah:.)
I have a clutch waiting to go in at some point, although it isn't slipping but my RMS is leaking so it is to be taken apart sometime soon. So I will fit an IMSB of some kind while in there.


So to my point, I don't recall seeing the below item mentioned on here>>

Porsche IMS Intermediate Shaft Bearing Repair ETERNAL FIX (ebay no. 181254668411)



As you can see, (hopefully picture uploaded) it is a roller bearing as apposed to ball bearing.
Has this slipped by people or is it an unproven source? Or even worse, has it slipped by me and all you guys already know about it

And just because I can, a photo

[Jamesp]

A man after my own heart with the tight in the wallet department comment. Also I just don't trust anybody but me to work on my cars - too many bad experiences in that department. From what I've seen roller bearings demand that the rotating shaft be aligned axially very, very closely. Ball bearings allow much more misalignment which appears appropriate with the IMS. I put a new IMS bearing in yesterday evening. I used a sealed Nachi greased ball bearing with a vented IMS shaft. I'll tell you I'm way out in the wilderness on this one as I made it up myself, but I'm sure enough that its right to bet my engine on it.

[ppbon]

Originally Posted by Jamesp

I used a sealed Nachi greased ball bearing with a vented IMS shaft. I'll tell you I'm way out in the wilderness on this one as I made it up myself, but I'm sure enough that its right to bet my engine on it.

Do you have any pics of the vented IMS.
That was one of our routes to solve the issue, but was not further developed because it requires engine tear-down.
Good luck
Happy Boxstering
Pedro

[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

[Kirk]

Yes, I believe thrust or axial load handling is the big issue with the Eternal Fix roller bearing. However, according to their website that is now updated with more information, they say that they have a patent-pending way of dealing with thrust. But they don't give any technical details. They do refer to their bearing as a "thrust" roller bearing... I don't know... I'll believe it when I see it. I'd want specific technical details as to how they overcame the poor thrust handling of a roller bearing. I really question it because bearing companies have not be able to overcome this issue for decades! So I'd like to know how an aftermarket, cheap (as in low cost and sometimes low quality) parts manufacturer like Vertex cracked the code that the big bearing makers could not.

Kirk Bristol

[tonysilver986]

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

So I haven't stumbled across an eternal fix then, damn and blast.

This is what I shopped in to join the Pcar club. Had various ones for 12 years or so but this was the best.
As said, 4.0L v8, tubular chassis and fibreglass body and only 1100kg

[BobRickel]

My local indy mechanic has been working on these cars for years. His fix is the EPS fix shown in this video:
He charges $1400 to do this on cars with Tiptronic, which includes all parts and includes changing out the AOS, belt, and plugs.

[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.

[Walter White]

My local Porsche dealer parts department was very helpful when I called about the bolt. He said it is pressed into the bearing and sold under one part number.

So I am wondering if Porsche did this to help conduct heat away from the inner race of the bearing.

[Jamesp]

Originally Posted by ppbon

Do you have any pics of the vented IMS.
That was one of our routes to solve the issue, but was not further developed because it requires engine tear-down.
Good luck
Happy Boxstering
Pedro

These videos explain my thoughts on why all IMS bearings run in oil, and not grease, and what to do about it. It's simply PV=nRT, with the pressure venting through the bearing seal. For those who don't speak perfect gas law, as the air temperature inside the shaft goes up when the car runs, air is forced from the inside of the shaft through the bearing grease seal, when the engine cools, air is forced back into the IMS through the bearing grease seal. The videos show that problem and the solution, and it could be done with the shaft in, but would take cleverly designed custom designed tooling to do it.

I used the pelican parts bolt (Thanks Wayne!) but chose a Nachi 6204 NSE s - the seal material is Viton instead of Buna-n - a little better material and it is a sealed bearing.

1 986 IMS Bearing Failure Mode - YouTube

3 Eliminating 986 IMSB Differential Pressure - YouTube

7 My IMS forward plan - YouTube

[Walter White]

Originally Posted by Jamesp

I used the pelican parts bolt (Thanks Wayne!) but chose a Nachi 6204 NSE s - the seal material is Viton instead of Buna-n - a little better material and it is a sealed bearing.

I have been doing my oil seal test on a Nachi 6204 NSE. After 24 hours it shows no sign of leaking. This is the best result I have seen so far. Some bearings fill with oil after only a few minutes, like the one below, just 3 minutes into test.



I have an NSK DDU on order.

[Jake Raby]

Originally Posted by Walter White

I have been doing my oil seal test on a Nachi 6204 NSE. After 24 hours it shows no sign of leaking. This is the best result I have seen so far. Some bearings fill with oil after only a few minutes, like the one below, just 3 minutes into test.



I have an NSK DDU on order.

Add an oil to the mix thats highly concentrated with chlorinated paraffin… Then heat it to 240*, then thermal cycle it hundreds of times, then add 1.5-3% fuel intrusion, then…..

Of course, I'd hope that you know about a durometer and how to use it, and why. We were doing the tests that you are now way back in 2007 and they continue as we develop oils with Joe Gibbs Driven Racing Oils, from scratch.

Jake - Any update on Gen 2 release? If already posted elsewhere missed it. I'm waiting to do a single row 3.2L until I can learn more.

It has been released to our distributors for some time now and their purchase orders are being filled. We are waiting until the time is right and distributors have units in stock (a few hundred per distributor) before the big release.

We are waiting as long as we can after the holidays… However I did recently spill the beans about it in a 5 page interview in a certain publication. :-)

Trust that Gen 2 is NOT "better" than the IMS Solution; nothing will be, because nothing else removes the wear components from the equation. Gen 2 is better than Gen 1, and is a mid price point thats far superior to anything else at the same price. In fact, Gen 2 is the same cost as it could cost to simply "spray oil" onto your OEM bearing and accepting all the compromises that come with that.

[Jamesp]

Originally Posted by Walter White

I have been doing my oil seal test on a Nachi 6204 NSE. After 24 hours it shows no sign of leaking. This is the best result I have seen so far. Some bearings fill with oil after only a few minutes, like the one below, just 3 minutes into test.



I have an NSK DDU on order.

That is why I chose the NSE. In some bearings the rubber seal comes close to, but does not seal the inner race. The Nachi 6204 NSE seals the inner race, and uses higher temp non metallics than the standard bearing. I specifically did not use a bearing that does not completely seal the inner race. Check out the bearing manufacturers spec sheets to tell one from the other, they look similar. The pressure differential between the inside and outside of a non vented IMS will be much higher than the centimeter or so of oil pressure you are seeing in your test. The differential pressure with a vented IMS will be ~zero.

[Walter White]

The thinking is to just try to keep a low level of oil behind the bearing, just a supplement to the oil feed the engineers already provide. This would be a very low pressure, low volume pump. I imagine much less than 1 psi and on the order of 1 liter per hour. I drew the seal a little better to show how it is trimmed near the center race to hold oil until it reaches a certain level.
I am looking at this as more of a drip system, not a fire hose.

[thom4782]

Spallation seems to be the primary cause for IMS failures. Installing unsealed dual row ceramic bearings reduces it to nil. Although close, the same would be true for single row bearing installations if they had greater load carrying capacity.

So Walter what problem are you trying to solve here?

Are you trying to find a lower cost alternative to the IMS Solution which fixes the IMS problem for single row cars because it distributes dynamic loads over a very large area?

[moresquirt]

James,i think your on to something and obviously Pedro agrees,but how do u make drill those holes without splitting the motor and if it is possible what about the 06 thru 08 models with there bearing installed from inside the case on assembly.Again great info and well documented

[Jamesp]

Originally Posted by moresquirt

James,i think your on to something and obviously Pedro agrees,but how do u make drill those holes without splitting the motor and if it is possible what about the 06 thru 08 models with there bearing installed from inside the case on assembly.Again great info and well documented

I have not looked at the larger bearing, but from what I've seen in passing there is little problem with them in the base, thought some say their reliability can be improved by removing the grease seal and relying on splash or DOF. If I had one of them I'd be tempted to leave it alone. When replacing my IMS I searched a long time to replace it with a shaft using the 6204 bearing so it could be serviced. I'm not sure that was the best choice. As far as drilling the hole with the shaft in the engine, for the removable (6204) bearing, with the bearing removed a very small 90 degree drill bit drive with a predetermined set back would need to be built. Not impossible, but not easy either. Milwaukee makes one commercially that is close, but I think it would be custom tooling to drill from the inside of the shaft.

[pjq]

James P, your theory seems to be based on the pressure difference that can occur within the tube, why does the simple solution of removing the IMS bearing grease seals non't address this issue?

[Jamesp]

Originally Posted by pjq

James P, your theory seems to be based on the pressure difference that can occur within the tube, why does the simple solution of removing the IMS bearing grease seals non't address this issue?

The lubrication properties of oil and grease are completely different. Splash oil on an open 6204 steel bearing would be dicey at best. The same bearing with grease is fine. The trick is keeping the grease in the bearing.