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Topic-icon Kuh Thunk! 1970 R75/5 Clutch flywheel transmission

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2 months 6 days ago #4591 by blind lemon pie
Last September I was riding back home to San Clemente, California on a 1990 Honda Transalp I had found on Craigslist in Rochester New York. My Clutch cable broke coming into South Dakota and I was waiting in Deadwood for the new one to arrive when I stumbled across a white 1970 R75/5 toaster with just over 32,000 miles on it and fell in love and purchased it. I joined the ABC and have used many of the fantastic Wobbly articles on carburetor and valve adjustment. After putting about 1500 miles on it since October, my wife and I decided to ride over the Ortega Hwy into Corona to watch a friend play his Sax with a reggae band.. We wanted to leave on time to make it back over the mountain before dark. While cruising down the 15 at about 70mph I felt through the footpads (and heard) a violent kuh thunk. I pulled in the clutch turned off the engine and coated to safety. I kicked it through with the ignition off a few times and it felt alright so I kick started it and heard an audible rattle rattle clank clank so I turned it off. AAA picked us up and brought is home. The next morning I pulled the valve covers and the valve were close to spec and the engine turned over easy with the spark plugs removed. I then pulled the pan and found no metal in the sump or oil pickup. I think the next step is to pull the transmission and inspect the flywheel and clutch to see what might have happened. Any help or clues to what might have happened would be greatly appreciated. I have a workshop manual. Today I will drain the transmission and look for metal. Thank you all out there in advance for any help. (I wish that I could have made the "Ralley in the alley tech day in San Diego!)

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2 months 3 days ago #4597 by 15087
Sounds similar to an incident I had, one of the bolts came loose off the clutch plate and rattled around till it lodged at the bottom. If you remove the timing rubber plug, with a lite you may be able to see if that is the issue.

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2 months 3 days ago #4599 by blind lemon pie
Replied by blind lemon pie on topic Kuh Thunk! 1970 R75/5 Clutch flywheel transmission
Thank you for the suggestion. I turned the engine over slowly at the alternator and looked into the timing hole and the outside of the flywheel seems to be intact, however, the hole is to small to see very much. I will be pulling the transmission to inspect. It looks like I will need a turned down 27mm socket to remove the swing arm and a clutch alignment tool. Any other special tools?

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2 months 3 days ago #4600 by 15087
I'm thinking that this posting will be moved to 'Technical Discussions' where someone more tech wise than I will assist you further. Be patient, there are some very skilled mechanics here.

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2 months 3 days ago #4601 by blind lemon pie
Replied by blind lemon pie on topic Kuh Thunk! 1970 R75/5 Clutch flywheel transmission
I drained the transmission today in preparation for removing it and found a gear tooth 13mm in width. I removed the transmission breather bolt that holds in the speedometer drive cable and it lifts about 3mm out of the transmission but will not come out, any tips? Are those torx head bolts that attach the U-joint?

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2 months 3 days ago #4602 by 8166
First, I've moved your post to the more appropriate "My Airhead Needs Help" topic so that others will have an easier time finding it.

Sorry you found metal on the drain plug. There are several reliable rebuilders in the US; the job requires specialized knowledge and tools most of us don't have.

The sleeve around the speedo cable can be removed only when the hollow hex bolt is completely removed. Even then, you may have to pry a little because if the sleeve isn't oriented properly, the when the bolt is installed it will raise a burr on the sleeve that keeps it from easily coming out of the transmission.

The four flange bolts are 12 point, and will fit nicely in any 12 point 10mm ring wrench, the longer the better. Loosen those bolts before you remove the rear wheel and swing arm, and you can put the transmission in gear and use the rear brake to prevent the output flange from moving.

There are several transmission and drive shaft articles in the Tech Articles section of this website that may help you with the job ahead.

8166 Scot Marburger, This email address is being protected from spambots. You need JavaScript enabled to view it.
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