Driven steel plates with holes???

[pudzy]

I just picked up a bunch of parts for a 1973 from the owner as he had sold the bike but, the buyer never came back for the rest of the parts after 8 years. In the parts was a complete clutch assy. that I was wrapping up to store. When I was stacking the plates in the basket, I noticed that all the driven plates had about 8 holes in them. I've never seen this in any plates before. Has anyone else??...

 I'm just wondering if this set-up would/did help with clutch drag or finding neutral?? I kept the clutch out and will see if I can post some pics of them.

Attachment Deleted

[jonesey]

G/Day pudzy
A very interesting clutch You have there. It also looks as if the teeth section is raised slightly as well. Is that so or just a shadow. I've never seen anything like it and the only way to see if it helps the clutch drag issue is to run it
My thoughts are, if the holes fill up with oil then as the clutch separates the oil will be flung out by centrifugal force. if this helps the separation, who knows. Be fun to find out.
The other thought i had was could this be a weight saving idea by someone. It looks like the holes are stamped as part of the Manufacture. Looks Factory or more likely aftermarket. Run it and find out. Lots of Clutch info on the XS 650 Forum as well as the XS has the same drag malady, same clutch too apart from the gear at the back. Best Regards.

[pudzy]

Hey Jonesey,

 Thanks for your reply as I'm surprised its taken this long to hear from someone. The area you are talking about that looks raised is just a thin layer of dirty oil on it. The holes in the plates look like they are from the factory to me also as I checked to see if they had been drilled. They have been stamped for sure as the holes and teeth have the same bevel to them, both on the same side. Strange... I have never seen anything like them before. When the warmer weather gets here, I will try them out and see how they work.

Geo.

[scrambler]

I had the same plates in mine, a very early engine, with around 10k miles. I don`t think it has ever been apart, might be factory made. 

[jonesey]

Don't know why, but this clutch intrigues me. I saw a dismantled Honda GL 1100 clutch the other day and it too had a similar set up but the holes were smaller and more numerous. Still tending towards the weight saving theory.

[scrambler]

The holes in my clutch plates are factory made, for sure, they look identical to the ones on the picture. My guess is that they were replaced by warranty when the clutch was dragging (the bike I took  it out from was all original and had 10k miles in it only). I don`t think Yamaha put too much effort into decreasing weight, on the contrary, they hooked up additional parts onto the bike to make it work.

[scrambler]

Here they are. 

[pudzy]

I'm glad someone else has found the same ones! I see that there are a set on ebay too. My thought on these holes are to help separate the plates like the cushion rings found on early clutches like on the XS1 and YR1's. If I remember correct, the XS650 shares the same fiber and steel plates as the TX750.  I wonder if these models also had plates with holes in them? If not, why just the TX750? I'm sure there is a retired Yamaha engineer that could shed some light on the holes.    

[scrambler]

Just a quick heads up on the steel plates with holes after a few hundred miles: I have no difficulties finding neutral, so the holes may indeed help better separate the discs, but I have nothing to compare it with as I didn`t try shifting with the normal discs. On the other hand, the engagement is very sudden, especially when starting the bike after a few days rest it`s kind of jerky, then it gets better, perhaps due to the holes get filled with oil. So I don`t like it too much, at some pont I`ll put back the original, hole-less plates. 

[tr1ppler]

Those are interesting findings Scrambler. Service News 302A says that if having clutch issues and "clutch operation remains 'jerky', lacking smooth engagement, replace clutch plates with xs2 type. Then it has an image that the tx750 plates have the holes but the xs2 plates do not. That was published in December of 72 so they may have switched to solid plates in later models.

I haven't taken my clutch apart yet so not sure what style I have. I wonder if you mix the 2 styles you will get a happy medium? Very interesting.

[scrambler]

Probably you are right. The bike I took these plates from is a very early edition, from `72. I thought it was a fix, but it seems then it came out from the factory like this. I`ve never seen this bulletin you mentioned.

[tr1ppler]

Its in the service manual I have. Here's a link:
www.tobyfolwick.com/tx750/textual/sb302a_2.php

[scrambler]

Cool, thanks!