Boxerworks.com

Hello everyone,

I have a mutt of an engine which I am transplanting into a Ural frame. Everything has been going smoothly up until yesterday, when I hooked up my clutch cable and tried to disengage the clutch. The clutch-rod moved a few mm, and then stopped. The clutch won't disengage at all. Obviously, in putting the engine together I did something wrong, but I'm not sure what. Before I tear it down to see what I can see, I was hoping y'all could give me some ideas about what might be wrong.

I had to mix-n-match a bunch of parts for this conversion, so here is what I'm using:

R80RT engine (clutch-carrier removed)
/6 Flywheel
/6 Clutch Assembly (with a new spring)
/2 Friction Plate (bought new)

Everything went together fine, and the engine turns over just fine, but something certainly isn't right. Any ideas that y'all might have would be greatly appreciated.

Thanks,

Did you check to see if the /2 friction plate is the same thickness as the /6 plate?

The backing plate should be the cast one with the spacer built in and therefore not a spacing problem such as could occur with the variety of /5 parts.

Hold the brakes, trans in gear, clutch lever pulled in, bump the starter. Sounds like the clutch plate is stuck to the fly wheel. Is the '80 clutch push rod shorter than /6 one? Which one did you put in on assenbly?

Thanks for the suggestions, folks, I think you both might have been right. I don't have the starter hooked up yet, but I went out to the bike, pulled in the clutch and shoved it forward as hard as I could. The clutch did disengage, and I can roll it back and forth, but I can hear a metallic noise coming from the bell-housing when I do roll it, like the friction disc is still making some contact with the backing plate and sliding along it.

Now that I can at least get the bike to roll, I'm thinking that maybe the /2 plate is too thick. Did they come in different thicknesses? The the amount of effort needed to pull in the clutch-lever is also pretty darn high (far more than I've ever experienced on other clutches), could there be some issue with the spring I installed that's making it so I can't fully disengage the pressure plate?

Just looked up what I installed, it was an OEM 9mm friction disk for an r69.

What transmission are you using?

Is the travel provided by the hand lever appropriate for the leverage of the throw out lever? The later clutch disks didn't have specs for thickness but you DO need to be very close to what the rest of the parts are designed for if it is to work. Do you have and can you measure the thickness of the /6 disk that was originally with the clutch?

I think you may be thinking about this too much. Finish putting the bike together and give it a try. I don't think there is a whole lot space on either side of the disk when the clutch is fully disengaged. Everything could be perfect and the disk could be slightly touching the fly wheel or pressure plate, especially at garage rolling speeds. You still may have to pull it back apart but you might not!

John Falconer wrote:What transmission are you using?

Is the travel provided by the hand lever appropriate for the leverage of the throw out lever? The later clutch disks didn't have specs for thickness but you DO need to be very close to what the rest of the parts are designed for if it is to work. Do you have and can you measure the thickness of the /6 disk that was originally with the clutch?

I am using the transmission off of the Ural. The /6 had an (I think) 6mm-ish plate, which may explain my problem. Going back and looking at the instructions I was following for this conversion, I see that I was supposed to use a pre-1955 /2 plate (7mm). At the time, I didn't realize that there were different /2 plates (now I know:) I'll bet the reason the pull feels stiff is that the Ural lever is shorter than the BMW lever. Not sure if there is much I can do about that one.

Thanks for your help!

I am not surprised that you didn't know about the two thicknesses of friction plates for the /2 because very few people knew that one. The thin one was an aftermarket item, not original from BMW. They were sold in the USA by Dixie International in Columbus, Ohio.

Hi everyone,

I just wanted to let y'all know that I finally got around to installing the 7mm friction plate, and voila! My clutch now fully disengages just fine. Thanks for all of your advice.