Griso Grimeca clutch cylinder screws revisited

[Moto]

This is an old issue first raised by boatdetective who got bit by it. The clutch slave cylinder is attached with flange head screws, while the cylinder itself is machined for countersunk flat head screws. Read about what can happen here:

http://wildguzzi.com/forum/index.php?topic=92204.msg1455540#msg1455540

I have a couple of things to add on this, and a question. First the question. Has anybody ever seen a reason to put flange head screws in countersunk bores? Hard to imagine.





Now my additions. Flange head screws are specifically called for in the parts diagram of both the 1100 and 1200 Griso: "Screw w/ flange M6x16." So it's not really just Luigi's doing on the assembly line. My slave cylinder (above) and every picture of one I've been able to find on eBay has counterbored seats. So I think all versions of the Griso would have this feature. No doubt Brevas too, and probably some other CARCs.

I'm about to order some McMaster-Carr number 93395A357 316 stainless hex drive flat head screws for my cylinder.

Since they come 25 per box, I'm happy to send three of them to any Wildguzzi member who wants a set. No charge, domestic shipping included, assuming the post office will take them in a first class envelope. While they last. (Send me a PM.)

This seems to be a very rare problem, and I wouldn't lose any sleep over it. But if you've got the cylinder exposed during swingarm service, it seems worth a little trouble, as boatdetective has long maintained, based on his sad experience.

Moto

[Moto]

Update: I just installed my new flathead screws, and noticed that the original screws had some thread locking compound on them, from the factory. That should have been enough to keep them from backing out, and may explain why the mismatch between the heads and the seats doesn't seem to have created a widespread problem.

Maybe Luigi forgot the thread lock on boatdetective's bike and any others that may have had a failure.

Moto

[Moto]

M6 countersunk fasteners with hex or slot are a little fragile especially with Loctite.

These could be used with the flanged bolt perhaps.

Well, that's interesting. Thanks. I don't see why it would be true, but I'm no expert of course.

Could be the explanation for why the flanged bolts were used in the first place, with a thread locker like Loctite.

This could have been a wild goose chase after all.

Would you recommend I not use the Allen-socket flat heads?

Moto