Nicole

I recently had my garage remodeled and upgraded (gas line, electric wiring, lighting, and EV charger). Now I'm trying to better organize all the parts I collected over the many years of 928 ownership.

I found two bearings SKF type 6201-2RSJEM in original, sealed packages, but so far, no search has allowed me to associate them with the 928.

Does anybody know what this bearing is for?

The only reason I can think of for buying these bearings would be for the timing belt rollers.

Thanks!

Nicole

Just found this:
https://rennlist.com/forums/928-foru...idler-arm.html - post 28 provides the answer.

We probably ordered those for the TB project and didn't use them last time. I'll keep them ready for next time.

17prospective buyer

You can buy the timing belt roller bearings separately? What about flappy bearings?

Mrmerlin

Flappy bearings are also available.
NOTE Roger has the newer style of double sealed Flappy bearings

Ed Scherer

The two bearings I used when I replaced the idle roller bearings (probably unnecessarily, given that there's a PKsn'r doing the tensioning now) were NACHI 6201NSE. You can make out that part number if you click the following photo and look at the large version.





Yup... INA HK10122RSFPMDK (or HK 1012.2RS FPM DK B; it seems to show up with different product codes based on where you look) needle bearing. You can see the seals on both sides, as Stan just mentioned in the previous post.

Nicole

Is there a specific reason why you used the NACHI instead of the SKF referenced in your other post? Are they interchangeable?

Thanks much!

Hilton

As noted its the crank pulleys above.

You can also use a 62012RS in the S4 Bosch alternator - the rear bearing

Ed Scherer

That's what 928's R Us was carrying at the time. Yes, they were/are interchangeable.

Jerry Feather

It looks like the mounting hole on the right of Ed's idler body is kind of wallowed out. I have found that, and much worse, on all of the S4 idlers I have removed. What does anyone do about that, if anything, and how? Just curious.

Ed Scherer

I assumed that these might have been drilled a little off the first time and then re-bored (but not just with a bigger hole, since these aren't bolted down; probably don't want them rattling around too much) a little to fix the problem. The whole piece looks like a pretty darn crude casting.

BTW, I just fixed the link on the photo of it in post #5; it now takes you to the large version of the photo like I originally said it did. If you look at the eccentric hole, it appears that it has been machined, not hammered during use (edge of eccentric part of hole looks clean, not what you'd expect if it just been hammered in use).

Jerry Feather

Hi Ed. I am pretty sure that there is some kind of severe vibration of this idler body, particularly on the "downstream" side, that causes this hole to wallow out. The ones I have had to deal with were much more wallowed than your's is. The odd thing is that one might expect that the other hole is the fulcrum for the wallow and that the wallow would be in an arch around that hole, but your's and mine were, or seem to have been, wallowed in a different arch. I can't explain that.

However, even though the part appears to be a crude casting, many castings are crude, but they are usually finished very accurately.

I have never seen anything on this Forum about repair or replacement of this part, because of this, so I 'm just wondering what others are doing about it, if anything.

Ed Scherer

Jerry, did you inspect the pins for wear? I don't remember for sure if I did (it was 3½ years ago). But I'm almost sure I would have noticed filings or other signs of extreme wear (aside from the elongated hole) if there were any.

I was under the impression that these rollers are rarely if ever touched by the belt. Given the condition of the bearings on mine before I replaced them (IIRC, one of them was either frozen or nearly frozen, yet I didn't see evidence of the roller surface being polished by the belt), I suspect they weren't even touched. That's not to say that the whole assembly might not shake around anyway.

I believe some people who installed PKsn'r tensioners just remove these rollers. I didn't know that at the time.

James Bailey

For some reason I was under the impression that one of those mounting holes was deliberately oversized.......perhaps from seeing new mounting brackets and rollers many years ago ..

Rob Edwards

Back in 2006 when I was a bigger newb than I am now, I bought a timing belt R&R kit straight off the 928 Specialists website. Not knowing that you could just replace the bearings, I ended up buying a whole new idler. And then read through the archives, and the common wisdom at the time was that no one ever changed these out, so I didnt when I did the TB on the GT.

The upshot of which is that I have a new idler here in a little green Porsche bag, somewhere. Will find it and check the bores for eccentricity.

Darn you DR, and your slick and effective sales interface!

Ed Scherer

Let me get this straight: you have a brand new, cool looking 928 part, and you didn't yet get a photo of it to add to your collection?

You're slipping, Rob.