Dual clutch plates

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olebmw
Posts: 33
Joined: Fri Oct 27, 2006 3:00 am

Dual clutch plates

Post by olebmw »

When I was working on my R42 last winter I was given some incorrect information on how thick the fiber clutch disc material should be. I was told that it should be 6mm and 1/4" should work. Not so,I ended up using 3/16" thick material to get things to work correctly. I suppose that my clutch could have been altered at some point and that is the reason the 6mm material wouldn't work?

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Darryl.Richman
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Joined: Fri Oct 27, 2006 3:00 am

Dual clutch plates

Post by Darryl.Richman »

Well, I continue to prove to myself what an idiot I am. My R52 has only a single clutch plate.

The clutch measures only 5.7mm thick right now, and seems to be down close to the rivets. Anyone know how thick an original is? (The parts manual doesn't say.)

Holman2106, are you saying that you put new material that was 3/16" onto both sides of the clutch? That would make your clutch over 9mm thick, without counting the actual steel plate sandwiched in the middle. That's thicker than even the thickest /2 clutch I've read about...
--Darryl Richman

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Darryl.Richman
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Joined: Fri Oct 27, 2006 3:00 am

Dual clutch plates

Post by Darryl.Richman »

I took a look at the clutch area again yesterday. There's a lot of room in there for clutch material! It depends mostly on how much the 6 coil springs can be compressed without binding up.

As you may recall, I also have an R62 motor that's apart. The clutch is not apart, still installed in the flywheel. I was able to measure the thickness of the material on one side of the clutch plate, it was about 2.7mm. Of course, I have no idea what the original spec was. But on my R52, the thickest material is only about 2.3-2.4mm.
--Darryl Richman

olebmw
Posts: 33
Joined: Fri Oct 27, 2006 3:00 am

Dual clutch plates

Post by olebmw »

Daryl, I removed the carb to look at the clutch material thickness on my R42 to make sure I wasn't having a senior moment. It is impossible to measure accurately, but it appears to be around 3/16" thick. I started out with 1/4" material and that was to thick for the clutch to go together. I mounted both plates (one at a time ) in the lathe and took a skim cut off the clutch material. After several attempts I had clutch action thru-out the range of the lever travel. Then I had to remove the rivets and counter sink the heads some more.The original clutch material on my R42 measured around .157" +or -. That should have thrown up a red flag that the recommended .250" may be to thick....but it didn't.

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VBMWMO
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Joined: Sun Aug 23, 2009 7:49 pm

Dual clutch plates

Post by VBMWMO »

The good news: I finished reassembling my 1928 R52 this past weekend. It started on the second kick! Also, with the new pertinax and nylon gears in the gear train, the motor is significantly quieter and less rattly up front.

The bad news: I went to take a test ride, but found that when I released the clutch in 1st gear, I didn't get much power and there was also a tinny, metallic noise. I think I must have only gotten one of the two clutch plates into mesh on the transmission input spline.

I will take this apart and find out what's really going on, but getting even the 1st plate to mesh (if that's what my trouble is) was pretty finicky. Does anyone know a trick or two about reassembling the motor and tranny on these bikes?
Dedicated to the Preservation of Classic and Antique BMW Motorcycles.

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