[tamathumper]

How do I know if this release fork is worn? There's a little wear on it, but how much is too much?

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[Ryan]

If these are not cast iron, I bet you could get a weld to fill in the gouge and then grind it to like new profile.

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[MB968]

Since it is fairly easy to replace these, I'd file (with grinding you risk getting it too hot and loosing some of the heat treat/hardness) the profile back into shape. Since you had enough stroke of the clutch slave cylinder before to operate the clutch with the worn away material, you should still have enough cylinder stroke after reshaping/removing the high/unworn areas. Wost case you can later replace with another one. But, I think just reshaping should do the job.



I'm surprised yours is worn that much in just one area. Mine is worn across the complete face. I just stoned mine and will reuse it.

And, at the rod end, do your best to remove all the oxide from the hole before lube. Most oxides are very abrasive. You could take a 3m pad with some oil and scour out the hole taking care not to take out any of the virgin mat'l, jus the oxide.

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[tamathumper]

Well, easy to replace, but surprisingly expensive for a little metal fork. You'd actually shave off more material? Why not just leave it alone if that's the case?

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[MB968]

If I understand your picture correctly, it has only been contacting on the area that is worn down anyway. And I assume that it was functioning OK like this. My concern for using it as is with some new parts incl. needle bearings and fork shaft, is the raised area will keep the fork from using the whole area at the end. So, I'd remove the high spot forcing the full width of the of the end of the fork to be in contact.



That being said look at my pics. I am concerned that there was something amis in the contact between the fork and the throwout bearing mating surface allowing only the small area of contact that you have. You might lay them against one another as I've done in the following pics to understand how only a portion was in contact. As you can see from my pics, the whole width at the end should be in contact with the throwout bearing. You might find that the throwout bearing mating surface isn't correctly machined, or?

       

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[Ryan]

Great pics...really helps explain the mating surfaces.

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[MB968]

Yeah, I've learned a lot from the pics on this site. My compliments to the site owner(s) (I don't know who owns the site of if several people do or just one) for deciding to make it easy to include pictures, they do tell a thousand words.



And after seeing this myself, I'm probably going to rethink the use of the paste lube for these surfaces. I seem to have a bit of fretting corrosion on the mating surfaces, not on the rounded part of the fork, but the side that rubs against the side of the throwout bearing. I'm liking the paste better than a Longlife equivalent.

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[tamathumper]

@MB968, the throwout bearing on my original 964.xx part-numbered pressure plate has smaller (or narrower) "ears" on it, so they only contacted that part of the release fork. The Sachs blue-stripe unit I bought to replace it has much larger (or wider) ears like the one you have pictured, so more (or all) of the release fork is engaged, similar to the picture you've shown.



I have the flywheel back in the car, and the new release fork bearings installed, along with the new release fork cross shaft ready to go, so I'm going to smooth the profile on the fork and see how it goes. (I should have done the filing before putting the new bearings in place, but I can protect them easily enough from the filings and grit, I suppose.)

Regarding the inclusion of pictures - I'm in the habit of always resizing my own pics, uploading them to one of my own web sites, and then referring to them from there... I've lost too many pictures to forums, where I uploaded them thinking they'd always be "safe"... With forum software switches and upgrades, more often than not large batches of pictures and files are lost, never to be seen again.

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[MB968]

[quote name='tamathumper' timestamp='1335015248' post='125811']

@MB968, the throwout bearing on my original 964.xx part-numbered pressure plate has smaller (or narrower) "ears" on it, so they only contacted that part of the release fork. The Sachs blue-stripe unit I bought to replace it has much larger (or wider) ears like the one you have pictured, so more (or all) of the release fork is engaged, similar to the picture you've shown.



. . . but I can protect them easily enough from the filings and grit, I suppose.)



[/quote]



Well that explains the unusual contact pattern.



And, if you just tape up the bearings you shouldn't have any issues keeping them clean.

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[MB968]

[quote name='Ryan' timestamp='1334862693' post='125683']

If these are not cast iron, I bet you could get a weld to fill in the gouge and then grind it to like new profile.

[/quote]

The crossections on the fork are too small to be cast iron. They appear to be forgings, so I suspect you could weld up the worn away areas and grind down to match. You'd just want to use weld mat'l that would end up giving a fairly hard surface.

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[tamathumper]

All buttoned up, and test drive complete. It's raining like hell, so I'll have to wait until the roads are clear before I can get a good feel for it.

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