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Quote:
Originally Posted by feelyx View Post
Ok, after more research and finally being able to have a disassembled engine that didn't suffer a IMS failure, a few things stand out.
1. The IM shaft was approx. 1/3 filled with oil, not motor oil but it appears to be syn. gear oil by feel. I won't know for sure until a sample is tested.



2. The bearing has BOTH seals on it, I have confirmed earlier with NSK that the bearing was shipped with only ONE seal and no lube. I have written proof of this thru Emails with Eng.'s from NSK.



3. After a quick inspection, the inside of the bearing is like new, smooth rolling, but very little lube (oil) inside, no grease anywhere, as I am pretty sure porsche did not use grease, as no bearing yet has been found with grease.



4. Which leads me to this new theory.... Porsche filled the IMS with an oil, which was to lube and cool the bearing, but, for some reason Porsche filled the bearing with oil and put the other seal on the side missing one and installed the bearing.

5. So... did the original design of the IMS require the inside seal to be removed from the bearing and have the IM shaft 1/3 full of oil to lube and cool the bearing while having it sealed from the engine oil?

6. To me, it appears Porsche had a break down between Designing and Production of the engine. Somewhere something was changed to the bearing.

7. After handling a perfect IMS, I have no doubt that the oil in the IMS design with the inside seal removed, would be trouble free if installed correctly. But who am I to say?

8. Unless my microscope finds damage or I come across more info contradicting this theory, this is how I will intall THIS bearing or mine if it is in the same condition into my '98. (no seal on the inside and IMS 1/3 full of oil.)
Interesting; questions:

-I'm unfamiliar with just how the bearing and the IMS fit together so here goes:If the IMS is 1/3 full of oil, how does this oil get to the bearing to lube and cool it?

-Since this is not engine oil, it stays in the IMS for the life of the assembly, right?

--Maybe the LN reps can chime in here--has anyone else reported the IMS being filled with oil? With all the work they;ve done I would think they would have seen this.
Old 03-09-2012, 06:19 AM
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Being filled with oil...sure. If the inner seal allows hot oil in and the "grease" initially installed gradually leaks out. Depending on the quality of the oil in the sump and the type of driving the car has been doing, the oil has been frequently been reported as seriously degraded and smelling as overworked oil will. There have been numerous online pictures of removed bearings dumping this gunk with descriptions from the person who removed the bearing. They show this obviously compromised lubrication.

I don't recall any of the folks trying to introduce a replacement bearing describing any other phenomena. So look at the LN, Casper, Hartech and Pelical sites and see wht they say after probably looking at more samples than the average mechanic might see.
Old 03-09-2012, 06:54 AM
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Quote:
Originally Posted by MikenOH View Post
Interesting; questions:

-I'm unfamiliar with just how the bearing and the IMS fit together so here goes:If the IMS is 1/3 full of oil, how does this oil get to the bearing to lube and cool it?

-Since this is not engine oil, it stays in the IMS for the life of the assembly, right?

--Maybe the LN reps can chime in here--has anyone else reported the IMS being filled with oil? With all the work they;ve done I would think they would have seen this.
Exactly the question I had also with 2 seals on the bearing, I believe the inner seal was originally not sa'pose to be there in the first place.

correct, there is no place for the oil to go except to the bearing.

That would be great if they did, as Mikefocke posted above, there are plenty of reports of the oily mess running out of changed bearings.
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Last edited by feelyx; 03-09-2012 at 07:43 AM..
Old 03-09-2012, 07:29 AM
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Quote:
Originally Posted by mikefocke View Post
Being filled with oil...sure. If the inner seal allows hot oil in and the "grease" initially installed gradually leaks out. Depending on the quality of the oil in the sump and the type of driving the car has been doing, the oil has been frequently been reported as seriously degraded and smelling as overworked oil will. There have been numerous online pictures of removed bearings dumping this gunk with descriptions from the person who removed the bearing. They show this obviously compromised lubrication.

I don't recall any of the folks trying to introduce a replacement bearing describing any other phenomena. So look at the LN, Casper, Hartech and Pelical sites and see wht they say after probably looking at more samples than the average mechanic might see.
Has anyone actually reported finding any grease?
Yes, smelly, degraded oil..... ever smell gear oil during a change?
You should heat up grease and oil and mix it, and see what you get...
Sometimes the obvious isn't what it seems.

Yep.... your right the earth is flat, and we should believe what we are told because we are just average nobodies.
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Old 03-09-2012, 07:42 AM
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Quote:
Originally Posted by howe00 View Post
A sealed bearing back in 2001 ie ( 2RS) was never intended to seal against the ingress of oil, it was only required to handle grease and was about 30% full of grease. A new sealed bearing such as the SKF ..RSH series however, with a line contact seal on the inner race will have a far better chance to seal against oil ingress than the old RS series.
Just a suggestion

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Howe00 I agree with you about the rs is a grease seal and not intended to keep oil out just the grease in. I also agree the grease should be approx. 30%. But Porsche did not use a rs seal, the seal type is a DUA17. We know what the 6204 stands for. The BD20-17 on the bearing itself is a proprietary number used for Porsche designed bearing built by NSK. Its 2ea. 6204 bearings side by side with the innerside seal mounts removed from each bearing. That is why the odd size width deminsion of 23.75mm and isn't available.

Back to the seal, DUA17. Maybe you could help me out with your experience, could you find out what it exactly means? It does not look or feel like the typical rubber seal. Any help there would be great.
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Old 03-09-2012, 04:46 PM
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If you can imagine the IM shaft as a "holding tank" for oil and only an outside seal on the bearing to retain that oil, I think you will see what I see.
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Old 03-09-2012, 05:19 PM
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Hi feelyx,
I may one day see a IMS shaft and fully understand the detail of the bearing mounting but from what I have seen from photos etc makes me wonder.
a) placing 2 x 6204 bearings side by side is a no no. The deflection due to loads will cause the shaft to bend place a moment on the inner and outer bearing which they were never designed for. The only way to overcome is to use a self aligning bearing, maybe a sinle row spherical roller but then you have problems with sealing.One would have thougth if P engineers asked for a special arrangement it would have been signed off by the bearing supplier? This a very interesting topic, but my peace of mind... unscrew your oil filter evey 3000 klm or less and look at the filter, ALL OIL that goes through the engine must PASS through the filter first. How cheap is that?
Old 03-10-2012, 02:22 AM
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Quote:
Originally Posted by howe00 View Post
Hi feelyx,
I may one day see a IMS shaft and fully understand the detail of the bearing mounting but from what I have seen from photos etc makes me wonder.
a) placing 2 x 6204 bearings side by side is a no no. The deflection due to loads will cause the shaft to bend place a moment on the inner and outer bearing which they were never designed for. The only way to overcome is to use a self aligning bearing, maybe a sinle row spherical roller but then you have problems with sealing.One would have thougth if P engineers asked for a special arrangement it would have been signed off by the bearing supplier? This a very interesting topic, but my peace of mind... unscrew your oil filter evey 3000 klm or less and look at the filter, ALL OIL that goes through the engine must PASS through the filter first. How cheap is that?
Hi Howe00,
Very good info, so the natural response for Porsche's problem would be to stop using the double row bearings and go to a single row bearing? Which Porsche did in 2000, but now they would have a seal issue which in turn caused a bearing issue? Although it was a deep groove ball bearing not a roller or self aligning, as I think they have some side loading they were trying to control with so many chains trying to align themselves running off 1 shaft. Do you think if the seal was seperate like a rms type seal 20x47x7 with a single row bearing might of had a better chance of sealing?
I wish you well with the filter search, but remember if you do find metal, it will most likely be too late.
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Old 03-10-2012, 08:00 AM
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Agree felix,
If there is enough space to fit a separate conventional seal, as per the crankshaft seal,this would be a better sealing option. Given the choice between a spherical roller and a deep groove ball, the SR will win hands down w.r.t dynamic capacity, axial capacity,and misalignment due to shaft deflection etc, and hence life. Another issue which could cause failure:- there has to be a interference fit on the OD of the outer race, as it is has a rotating outer ring load, if I was replacing the bearing this would be the first thing to check. It depends on the type and class of bearing.
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Yes, there is plenty of space for a conventional seal, Would you suggest a bearing like this? NJ204 Cylindrical Roller Bearing 20x47x14 Cylindrical Bearings

Also, the seal size is 20x47x7 that I am looking at here...
Oil Seals Metric Sizes Table 6 of 26

Which seal design would you suggest? also, Viton or PTFE?

I am going to put this together and run at speed from my lathe, with the tube a 1/3 full of oil just as I found it. Even though I don't know exactly which oil is in the tube, I've a pretty good idea that it is Mobil 625 or 629 gearbox oil.
I don't know yet how to replicate the back and forth motion of the oil in the tube to represent accellerating/decellerating of the the car. I will also will be able measure any deflection at the center of the shaft at max speed of 3500 rpms..
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Old 03-11-2012, 02:17 PM
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here is a couple more pics...






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Old 03-11-2012, 04:10 PM
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Old 03-11-2012, 04:11 PM
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Old 03-11-2012, 04:13 PM
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Can't find a single or double row spherical roller to suit the OD x ID dimensions,so the cylindrical roller NJ204 would have to do. The SR is more desirable because it is self aligning where as the CR is not, but given the OEM was DGB this also is not self aligning so maybe not such an issue. As far as the seal goes pick the one which has the best operating temperature and the linear shaft contact speed is not exceeded.

Not sure what you mean by measuring shaft deflection as the loading on the shaft comes from the chain tangential force loads which would be difficult to replicate in the lathe.
Old 03-12-2012, 03:21 AM
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Yeah I couldn't find one either, the seal is ordered and should be here this week as with the bearing. I figure I will need to run this bearing at 3500rpm for 214 days 24/7 for the test to be successfull. That would be equivalent to running the engine at redline for 214 days straight.
I won't be able to replicate the chain forces, Porsche "should of" already had that covered, but, my concern is the tube with fluid spinning at 3500rpms causing an imbalance in the shaft, that is why I will be measuring flex in the center of the shaft.
I will do a video on start up, and throughout the testing period.
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Old 03-12-2012, 12:09 PM
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Feelyx - I hadn't been over here in a while. Great updates! Your bearing looks just like mine. I wish I had kept the oil inside the tube so it could be determined exactly what the contents were. It was old and smelly, the interesting thing as I explained to you is my bearing was full of clean oil. When I took my bearing out I was shocked how much oil came out of the tube. Keep up the good work! I've since moved on to new suspension components...the car drives like a dream now.
Old 03-12-2012, 06:57 PM
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Hi Whip, My oil was black and didn't have any type of odor to it. Makes me wonder if the oil was black to begin with, as the oil is clean with high viscosity. Would you say your tube was about a 1/3 full?
I bought a M030 suspension kit but have yet to get it on the car, oh well, someday soon I hope.
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Old 03-12-2012, 08:47 PM
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The factory bearings are grease filled. Here is a factory bearing, new, never run, pulled from a new intermediate shaft. We have purchased many intermediate shafts over the years and this has never changed. Here is a pic.
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Old 03-13-2012, 06:11 PM
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Thanks Charles, can you post a pic of the seal numbers? also do you have a pic of an original double bearing with grease? and did you purchase any of these bearings in 1997-1998?
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Old 03-13-2012, 06:22 PM
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Unfortunately, all I have here currently are new 6305s from 3rd revision replacement intermediate shafts as currently provided by Porsche. I tossed the seals and bearings from the last batch of intermediate shafts we purchased, so I don't have the seal to photograph.
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Old 03-13-2012, 06:44 PM
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