IMS - Going with SKF hybrid

[Silber]

Originally Posted by Gelbster

The freeze plug & grease washout.I don't understand.
The fundamental problem is that conventional IMSB wisdom suggests the bearing seals deteriorate because of heat.

I am not sure this is entirely right, I think the main problem is the heat cycles of the air in the IMS tube sucking oil past the seals. I am trying to solve that issue.

So, I am correcting the problem I think to be the root cause of the issue. I can see heat deteriorating the seals to some degree, perhaps a bearing with Viton seals would be ideal. If heat deterioration was the only issue, why would the oil run into the IMS tube, but not come back out?

I am leaning toward the pelican bearing with the freeze plug rather than a fancy ceramic bearing, not sure if I really believe ceramic is needed at this point especially if I change them every time I change the clutch. Standard 6204's are around US $6-10 each. Porsche thought they were a lifetime solution and if I can fix the oil ingress issue, I can probably make 75k miles or so.

Silber

P.S. - Here was where I explain my theory IMS - Going with SKF hybrid

[Smallblock454]

Hello,

for those that are interested in i found the english version of the SKF bearing catalogue. Lots of infos:
Library

Overview of all 6204 SKF bearings available:
SearchResult

And this might be interesting for all that want to go deeper in this topic:
SearchResult

@ Silber: think the pelican bearing is OK for shure. Most important part is very careful de- / installation.

@ Gelbster: I recommend to read the introduction of the SKF catalogue about what types of bearings are available and what are the differences in detail. Chapter A to H. I'm pretty shure you'll find some interesting facts.

Regards, Markus

[Smallblock454]

Sorry, double posting.

[Smallblock454]

I think there are more parameters than seal deterioration.

Type of bearing and capability to handle axial force, torsion and vibrations.
Type of cage.
Type of grease if you have a sealed one - heat resistancy.
Type of sealing and seal material.
Misalignment IMS and ISMB.
Rotation Per Minute / Friction inside the IMSB.
Amount of contamination the IMSB can handle. hc
Heat and heat cycles.
Maybe fast up and downcycling when motor revs up or down.

And again. If you have a bearing that was designed to run as a sealed bearing and you remove the sealing, you have no specification, because the bearing wasn't designed for that.

There are bearings that are designed to run in oil. These might be the right choice if you want to run an open bearing,

Regards, Markus

[Smallblock454]

Hello Silber,

there are 3 different types of IMS for the 986 available - depends on bearing and engine type. Make shure you get the right one for you car, because there are differences.

Regards, Markus

[Silber]

Markus,

I am just planning to plug the end of the spare IMS and test how much pressure is generated by heating it up. Will not actually be installed on my car, so doesn't really matter which version it is.

Steve

[Silber]

Thought I would update this thread with what I finally decided to do.

Since I ultimately decided to prepare my car to SCCA STR class rules, I am only allowed to put in the part that is either the Porsche original part, or the most closely similar available part. Since Porsche does not offer an IMS bearing separately, the most similar part available that I could find was the pelican parts IMS kit. Any other part would likely get me protested and I would lose.

If I had not been preparing to autocross class rules I would’ve put in a freeze plug, but since I am that is not an option.

Regards,

Silber