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Crankshaft disassemblyTake your crank apart - the set upSo I am trying to share my progress which will be in this and two following posts.
While my kids were growing up I used to tell them, “Education is always expensive.” They sure had a smart Dad. The adventure begins. The first pic below is the end of my crank that is bad. PO apparently rode it a ways while the starter clutch had insufficient oil. Must have made a God-awful noise. You can barely see the oil hole in the reflection line. It is about closed up. On close inspection I found that the shaft is cracked out from that oil hole. CL72 shop manual says the end counterweight pieces are made of carbon steel. The second pic is the jig I made in action in a 12 ton press. Jig is resting on a new cross-bar that I made up. You need a 1/8" spacer for the end that goes farthest into the jig because the inside surface of the counterwieght is not flat. Got some good pressure on it and then hit it with a 3 pound drilling hammer. It moved a little and then the press did the rest of the work. Have someone catch the rest of the crank or the con rod could come off and scatter those little roller bearings to Kingdom come. I caught both this and the donor crank, and avoided that problem, but did briefly lose one of the rollers from the donor crank. They are pretty small.
Last edited by conbs on Sat Jun 11, 2011 12:42 pm, edited 2 times in total.
Press a crank apart - What I foundAssuming you have used the method from my prior post and dial gauged all bearings on your crank to shop maunal specs and inspected for tight spots and rust/binding, you will still want to see what the insides of the bearings are like. Here's what I found.
First pic is the con rod shaft. I got just a little bit of crud out of the oil holes. When you use carb cleaner I think it flushes a little of the crud out and and softens the next layer each time you shoot it into the crank, so if you start that process, probably a good idea to do it a number of times over several days. The last couple of times I sprayed the carb cleaner, what came out looked pretty clear. I am not sure how you can tell when you are “done”. Third picture is the inner bearing next to the cam chain sprocket. Next to it is the annular groove that Teazer talked about. You can actually get at it fairly well and clean it out. I had run a lot of carb cleaner through this bearing so the crud was fairly soft and easy to remove. You can clean out this groove even if you don’t take the crank apart, but remember you are disturbing crud that your bearings won’t like so be thorough in shooting carb cleaner from every angle to flush everything until it is really clean. The starter sprocket oil hole does NOT go back directly into the con rod bearing, so squirting from there will not make it back into this bearing or into the con rod bearing. Last picture is what came out of the crank after gouging out the impacted crud and spraying carb cleaner through the con rod shaft, annular groove and inner bearing. I got a little dirt and 2 metal pieces and I am not at all sure where these came from, but likely from a piston that came apart early in this motor's life and repaired by the PO. If that is the source they went through the oil pump and inner roller bearing without causing any significant damage and I think were caught in the annular ring so they didn’t make it into the con rod bearing. Simple, but effective Japanese engineering. When you start loosening this crud up, it can send metal like this through your motor. It may be that my prior question about whether it is just better to leave this stuff compacted and in place may be the better way to go. I haven’t decided what I think yet. If you loosen it up it could go through the motor. If you leave it in place there may not be any room left in the annular ring to catch the next piece of metal. In either case, it seems like the annular groove was designed to catch and hold crud and metal and, if doing its job, it will fill up again at some point.
Last edited by conbs on Sat Jun 11, 2011 12:45 pm, edited 2 times in total.
Dream crank disassembly - The patient needs a transplantSo when I went to put the crank back together again you probably all heard the very loud “DOH!” no matter where you live. I have the early crank that was used in ’60 and the first 1,050 bikes in ’61 for CA77's. Apparently about 40,000 bikes worldwide though between between C/CA and 72/77's.
I knew it was a '60 motor before I started, but didn't connect the dots. It uses 3x14.5 rollers. Everything after that first 1,050 bikes in ’61 uses 2.5x13.5 rollers. Rods are the same for either crank. So…..the con rod shaft in the early crank is smaller (0.984”) to allow for the bigger rollers and when I tried to put the counter weight from the later crank shaft on my early crank the hole in the counterweight was too big (1.024”). DOH! Or, as Agent Maxwell Smart would say, “Missed it by that much” In this case I missed it by .040. Education is always expensive. So, if some kind soul has a starter end counterweight from an early crank they will part with, I can put this remarkably good crank back together. If not, I guess my grand adventure will have come to an end. I know I can use a later crank but will have to change the clutch basket because of a change in the splines on that end and I am not sure what else. In the mean time, the patient will remain on life support awaiting a transplant. The motor I am working on (and crank) is from a 1960 bike and I would like to keep it as original as possible. I plan to run it for a while, but will be building another motor to put on my bike, which is a 1964. The '60 motor has a serial number below 100 and I think someone may want it at some point for restoring one of the first wet-sump 305’s ever produced. It has a couple issues in the lower case, but will otherwise be in pretty good shape and will be very functional with the correct parts. I am trying to revive and preserve a little piece of 305 history. So, there’s my pitch. Anyone willing to help out? BTW you don't have to take the crank apart to measure the con rod shaft. The hole for it goes all the way through the couterweight so you can measure it from the starter sprocket end. Thanks to all who have helped along the way. May the adventure continue. Posting BluesIs there really no way to post a picture as an attachment and then continue text below that until you post the next picture?
Last edited by conbs on Sat Jun 11, 2011 11:55 am, edited 1 time in total.
Bill
I have a rusty 1960 crank which is one of the ones that I was going to play with. If I can rebuild my 1960 C72 without needing any parts from it you can have that part. It will take me a while to get to it so you may have to be a little patient! Did you recall how many tons it took to push your crank apart? G '60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160 '66 Matchless 350 '67 CL77 '67 S90 '77 CB400F
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