fitting an off the shelf SKF bearing for IMS
 

Im taking the trans off the car next week primarily for a clutch job.

I have decided on using a simple SKF/NSK bearing as one has been in there for 100k miles so far no problem, and the main reason is that the engine will be removed also in about a year to swap in another engine I am building.....so I dont want to spend a fortune on a mega bearing upgrade for this engine for a short time.

My questions are....

. should I get standard clearance bearing or a C3?

Assuming I cant get any oil into the IMS, should I leave both rubber seals in situ on the bearing....maybe remove one seal and repack with grease before refitting both seals??

Thanks

1) A C3 bearing is the "standard" clearance. I would clarify with the bearing manufacturer what he would recommend with the engine operating @ 100 deg C + under normal operating conditions, but I think that a C3 is only good for up to +/- 75 deg C.
2) Why do you want to repack the bearing - they come from the factory with enough grease for normal operation. Normally. a deep groove bearing requires less the 30% grease fill, any more and it will overheat and expel the grease out of the seals.
3) Read up on just removing the seals and let the oil "splash" system lubricate the bearing.

Jim,
If you plan to use a sealed bearing(1 row or 2???) - consider specifying a hybrid ceramic bearing with a high temperature rating including Viton seals. There was some discussion about venting the seals to prevent the seals being forced open when the grease gets hot . Some of these bearings are already vented. .The temperature rating of the seals and grease is more important than the ABEC/DIN number Imho.
Yemv

Thanks both.

Do you have any links or reference numbers for any ceramic ones?

First I've not heard of punching holes in the seals. seems like that opens them to the oil more than they already are. Some thoughts on running ceramic bearings without seals front or back. No seal in front allows the bearing to see splash oil. No seal in the back prevents oil entrapment in the IMS tube.

If youre dead set on going that route, Porsche sells the original IMS bearing for about $112.

Well today after much homework and talking to guys whom know bearings; I have found a number for a hybrid ceramic SKF bearing that is off the shelf.

SKF 6204-2rsltn9/hc5c3wt

A chap on BOXA net in the UK dragged a bearing from his 2.5 with this number, so did his car have a ceramic update at some point?!

It is obviously a 6204 but with high temp, high speed, better seals, ceramic balls and composite cages.

They retail for about £70GBP here in UK

The standard 62042RS is about £3.50 - £4 GBP, so quite a jump.

Ive gone for an uprated over standard so high temp and speed, but not ceramic, £16GBP.

Will be sufficient for the time I will have this engine in the car.

An equivalent to the standard bearing can be sourced for about $6. It's a standard 6204 as found in electric motors, lawnmower decks and alternators. In general, steel deep groove ball bearings are cheap unless it says "Porsche" on the box. :\

Most of us seem to fit LN but enjoy contemplating alternatives.
More info here:
I'm Going in ALONE....LNE Retrofit bearing - Page 5 - Rennlist Discussion Forums
and just google ; IMS SKF 6204-2rsltn9/hc5c3wt
Please be sure you need a single row. The part number you gave is single row. And be sure to confirm Viton seals, not Buna.
Good Luck.

Wow, how to reply? Have you been drinking Gelbster? Well, if not, don't worry about it, I drink enough for both of us. :D I guess the best approach is to answer numerically, (sort of) starting with the text included with my reply.

1) Never saw it. Please post a link, I'm intrigued.

2) it gets splashed continuously when the engine is running. It's between 1/3 to 1/2 submerged when the engine is level and not running. You do realize the seal on the bearing is spinning right? there is no "high point" to put a hole in.

As for the next 3 (well, 4 actually) let's take those numerically as well:

1) The seal being "intact" does not mean it is a pressure seal, it isn't. It is a sliding seal between the inner bearing race and the bearing cover. Changes in pressure between the inside of the IMS tube and the inside of the engine due to temperature changes easily pushes oil past this "seal". Both in and out of the IMS tube. In some bearings rated for higher speed, the seal is only close to the inner race without actually sealing it.

2) I like DOF if the oil is not stolen from the right hand cams, the oil is filtered, preferably cooled and supplied as a light mist, and not randomly squirted at the bearing. If I can't have that (and I can't) then I'd go with splash.

3) There's no such thing as a high point vent, and if there were I'd not put a hole in the bearing shield that would allow communication between the bearing grease and the oil. That would defeat the purpose of the seal.

4 (or 3 prime if you prefer)) LN does make good products from everything I've seen. If I weren't such a cheap..., well you know the rest...

The "I'm going it alone" post reminds me of me. My car is still running great too.

I'd be careful of the bearing being discussed here. Everything I've seen has been steel race and silicon carbide composite. This has "ceramic" races and balls. What kind of ceramic? Needs to be silicon carbide, and the fact it's full ceramic would run me off. ;)

HOLY COW! Ever since getting my wife her 99' Boxster in October, I have been doing my due diligence, and reading up as much as I can on the things I need/want to do. the IMS issue is of course always on my mind. I just received my first Blackstone Labs oil analysis (can not recommend them enough) to start a baseline, as I had no idea, what type of oil was in her, or even when the last time it was changed. The report showed higher than normal aluminum, iron, and copper in the sample, which could be due to a contaminated sample, or just being in the car for a looong time, with sub-standard oil. regardless this has caused me alarm, and I am trying to decide my next step concerning the IMS.

The information here, as well as other forums concerning IMS replacement/upgrade is MIND NUMBING! LN vs. Pelican vs. Factory vs. everyone else, off the shelf bearings, hybrid ceramic bearings, roller bearings, and the list goes on and on. The waters get muddied further by people jumping on one bandwagon or another and starting flame wars which do nothing to really answer questions. Jeez! What's a guy to do?

Keep reading . . . You ain't seen nothin' yet!!!! Try the 986 Forum over on Rennlist . . .

Different strokes for different folks.

We all differently balance risk versus expense versus the desire to do it our way.

When the most knowledgeable/experienced are also those with a financial incentive in a product's acceptance, the trust factor comes into play.

Recall Porsche with all their engineers and test mules got it wrong several times and only realized after many cars, years and miles had accumulated. A few cars and a few miles is IMNSHO an unimpressive and unconvincing sample.

Oh I have!! It is THUNDERDOME!!

Has anyone fitted an off the shelf dual row? Most of the discussion I've read focuses on single row engines. I remember reading a thread (can't find it now), where someone did use an off the shelf bearing, however it required some kind of special washer IIRC...

Ask about the 5204 (not 6204)
Start by googling this:
SKF 3204 A-2RS1TN9/MT33
Angular contact ball bearings, double row

But recognize that a lot of very smart fellows who have these generic part numbers have still chosen to use the LN kit .

All thats been offered is an updated IMS Shaft with bearing. The original bearing has no Porsche part # by its self.

There is a reason for that. For some unknown rationale, people keep trying to replicate the LN ceramic hybrid bearing using off the shelf units. I can assure you that the real LN bearing is not an off the shelf item, it is made for them, exclusively. They went through the effort to hire a bearing engineer to help them design a workable product, tested it repeatedly in running engines, and then modified or replace various components before bringing the final product to market. The result is a well designed replacement bearing whose shear number of successful installations speaks for itself.

And people still try to find a cheap way out by experimenting with unknown and unproven bearings at the risk of a very expensive engine, all in the hope of saving a couple of bucks. Sorry. but I just do not understand this.

And the last time I looked, that OEM shaft assembly was nearly $1K at retail.

When the bearing part itself is only a small part of the total cost.

You could have added the failures LN/Flat6 went through with off the shelf items and even one of their early designs had to be redone after the first dozens were out there and they got some more experience on them. But forum posters think that specs are everything and trumpet their "success" after a few miles. I hope they don't have as many failed test engines as LN/Flat6 did before they got it right.

Another difference is the kit contains other improved parts beyond the bearing itself. From flange to bolts to seals to ....

You put a new IMS in to reduce risk.

Recall how many test mules Porsche had and they still got it wrong several times.