soverystout

Uh, I think that's a double row bearing. It's got a snap ring on it (no snap ring on the single row) and unless the picture is distorted, it looks too wide to be a single row bearing.

dnitake

Did the "while your in there" thing and popped for a light weight flywheel and clutch. Yes, it'll be nice on the track when I go next, and their is a subtle accel diff. Risk/reward calculus said do it, but hope not to be pushing my luck. But that's another well worn thread.

dnitake

Soverystout,
Not sure which way it went. My mechanic has a '99. It worked out he got one, and I got the other. Thought the 99's were double row.

street rod

99's all have the dual row bearings. 2000 and 2001 some had single row and some had dual row. My 2001 happened to have the dual row when I got the retrofit done. Your pic does look like a dual row but if you say it was single than maybe the angle of the pic is playing tricks on us. Either way great to hear that you caught it and always nice to have a good outcome. The retrofit is cheap insurance especially if you are getting a clutch anyway.

trapperdog

Pry the bearing apart and let's have a look.

dnitake

Your wish is my command. Double row bearing. Wonder what my mechanic did?

OGWGFIW

Can't be real, IMS bearings don't fail.

dnitake

Outer race could be more damaged than it looks, but no visually obvious pitting.

dotframe

silotwo

Mechanic at the Porsche dealer that did the PPI on my C4S told me that although he had not yet seen an IMSB failure in his 17 years as a Porsche mechanic, he was aware of the issue. One thought he had was that cars that are not driven to full operating temperature have more problems because of moisture related issues. He did to tell me that no one really knows why these bearing fail but that the failure rate is far less than internet discussions suggest.

That said, I have finally made up my mind and my local dealer is ordering the LNE IMSB and I will replace it when they do the clutch. Decision finally made.

Thanks for sharing your experience of a good outcome.

Byprodriver

I hope you got the flywheel balanced...

dnitake

>> I hope you got the flywheel balanced...
OK, do you mean as part of the crank, or as an individual unit. You can see where they balanced as a unit w/ drill outs. It's an AASCO unit if that helps to explain what you mean. I have read about the cracked cranks from LWFW's in web searches, but my mech has 30 or so in the field and track w/ good reliability so far.

Byprodriver

I mean precision balanced to a tolerance of a gram or two imbalance since there is no longer anything to absorb harmonic vibrations.

trapperdog

Was there noticeable wobble in the shaft and did all the bearings look as bad as this one? How was the cage? Thanks for pics btw.

dnitake

>Was there noticeable wobble in the shaft and did all the bearings look as bad as this one? How was the >cage? Thanks for pics btw.

Yes there was some wobble. Maybe around 50 mils at the tip of the bolt. The pic was the worst ball, but they all looked bad. Cage was fine.