Clutch rod oil seal

[jleewebb]

Hi y'all, could use some help/advice here...folks who know me know I'm a reluctant wrench at best.

The story: after returning from a brisk ride around the neighborhood Saturday, I noticed (first) oil specks on the back of the seat. Then on the flipper, then mass quantities on the right muffler, swing arm, and tire (!)...Dodged a bullet there, I'd been zipping around twisties like I was 19 years old just a few minutes before. Oil dripping out on the floor, too, from bottom/back of right cover.

I eventually pulled the cover, another big gloop of oil hit the floor. First thing I noticed was the clutch rod seal was standing a little proud of the sprocket nut. I just pushed it back into place with my finger. Question 1: could it have been stuck to the clutch lifter and pulled out a little when I pulled the case? Or is something else going on?


DSC_0456 by Lee's CB, on Flickr
That grape looking thing is a Jujube fruit from a nearby tree; there were four or five in there.

DSC_0468a by Lee's CB, on Flickr
Cleaned up with clutch rod seal pushed back into place.


Question 2: I discovered I could wiggle (rock) the sprocket just a little, a mm or less. I'm thinking it needs to be tighter than that, right? I had a similar, smaller leak on my Hodaka that I solved by tightening up the sprocket nut.

I've got it cleaned up, it was much nastier in there than the photos suggest. I'm going to pull the sprocket and inspect the seal behind it for visible damage, but before I do I'd like to turn the motor over without starting it to see if I can spot the leak for sure. I'd drop the float bowls to assure it wouldn't start; I think cranking with plug wires pulled might be hard on the electronic ignition. Questions 3: Any problem with cranking engine (with electric starter) with the cover removed? Wouldn't the clutch rod seal leak without the lifter holding it in place? And will the oil pump generate enough pressure to make the leak show up?

Engine was rebuilt by LM with new seals seven years, 2800 miles ago. So question 4: If inspection reveals no visible damage to the sprocket seal, would I be safe just tightening up the sprocket nut or should I be thinking about replacing with a new one just in case?

Which leads to question 5: just how big a deal would it be to replace that seal? My experience is that if there's a wrong way to do something, that's how I'll do it, at least the first time. I've searched forum posts without finding and actual step-by-step.

I'd certainly appreciate any insight that more knowleable members here have to share. Thanks, Lee

[G-Man]

It looks like the clutch pushrod seal has popped out and it should be possible to clean up the oil, dry everything off and push it back in.

The sprocket just slides on its splines and is retained by the little locking plate with the two bolts. Sprockets are rarely a tight fit on the shaft and cannot be tightened.

It should be OK to run the engine with the cover off. You won't have control of the clutch as the lifter is inside the cover.

Cappelini make a little aluminum retainer to hold that seal in place.

http://www.cappellinimoto.it/index.php? ... 12&lang=en

G

Hi y'all, could use some help/advice here...folks who know me know I'm a reluctant wrench at best.

The story: after returning from a brisk ride around the neighborhood Saturday, I noticed (first) oil specks on the back of the seat. Then on the flipper, then mass quantities on the right muffler, swing arm, and tire (!)...Dodged a bullet there, I'd been zipping around twisties like I was 19 years old just a few minutes before. Oil dripping out on the floor, too, from bottom/back of right cover.

I eventually pulled the cover, another big gloop of oil hit the floor. First thing I noticed was the clutch rod seal was standing a little proud of the sprocket nut. I just pushed it back into place with my finger. Question 1: could it have been stuck to the clutch lifter and pulled out a little when I pulled the case? Or is something else going on?


DSC_0456 by Lee's CB, on Flickr
That grape looking thing is a Jujube fruit from a nearby tree; there were four or five in there.

DSC_0468a by Lee's CB, on Flickr
Cleaned up with clutch rod seal pushed back into place.


Question 2: I discovered I could wiggle (rock) the sprocket just a little, a mm or less. I'm thinking it needs to be tighter than that, right? I had a similar, smaller leak on my Hodaka that I solved by tightening up the sprocket nut.

I've got it cleaned up, it was much nastier in there than the photos suggest. I'm going to pull the sprocket and inspect the seal behind it for visible damage, but before I do I'd like to turn the motor over without starting it to see if I can spot the leak for sure. I'd drop the float bowls to assure it wouldn't start; I think cranking with plug wires pulled might be hard on the electronic ignition. Questions 3: Any problem with cranking engine (with electric starter) with the cover removed? Wouldn't the clutch rod seal leak without the lifter holding it in place? And will the oil pump generate enough pressure to make the leak show up?

Engine was rebuilt by LM with new seals seven years, 2800 miles ago. So question 4: If inspection reveals no visible damage to the sprocket seal, would I be safe just tightening up the sprocket nut or should I be thinking about replacing with a new one just in case?

Which leads to question 5: just how big a deal would it be to replace that seal? My experience is that if there's a wrong way to do something, that's how I'll do it, at least the first time. I've searched forum posts without finding and actual step-by-step.

I'd certainly appreciate any insight that more knowleable members here have to share. Thanks, Lee

[PhilD]

Hi jlee,
The clutch push rod oil seal is prone to popping out if crank case pressure is too high. I had one come out whilst riding up the M6 to collect parts from Bill Heads many years ago when a piston ring broke up. Not a nice experience and a long push back to the Wirral. Suggest you check the engine breather whilst running when you've put the seal back as G-man advises.
PhilD

[G-Man]

Phil

Interesting. I note that Cappellini reccommend the little seal holder when using their high-capacity oil pumps, suggesting the extra flow and resultant pressure can pop the seal.

I wonder if the cause is crankcase pressure, oil pressure or a combination of the two? If it is crankcase pressure, then Dreams ought to have a bigger problem with two pistons rising and falling together. I like these little mysteries.....

Did your problem happen again when you put the seal back in?

G

Hi jlee,
The clutch push rod oil seal is prone to popping out if crank case pressure is too high. I had one come out whilst riding up the M6 to collect parts from Bill Heads many years ago when a piston ring broke up. Not a nice experience and a long push back to the Wirral. Suggest you check the engine breather whilst running when you've put the seal back as G-man advises.
PhilD

[PhilD]

G-man,
In my case it was obvious after replacing the seal and refilling with oil that something serious was wrong as the top end sounded horribly noisy and oil and smoke were pumping out of the engine breather at tick over. A top end strip revealed two broken compression rings on one cylinder which required reboring to repair. This was on a friend's bike and is the only time in nearly 70,000 miles on CBs that I was immobilised by engine failure whilst on the road, a testament to their reliability and Honda engineering. With hindsight I suspect that the timing was too advanced and a partial seizure occurred whilst at full throttle on the motorway. I suspect excess crankcase pressure can cause the seal to blow out as a similar thing happened on another friend's CB77 which had a Read Titan 350 big bore conversion. I remember the piston rings were very difficult to compress into the cylinders as over boring had removed the chamfer from the bottom of the liners. He had a clutch oil seal pop out after a rebuild in which we had broken one of the rings during reassembly.
PhilD

[G-Man]

Phil

Great information. Thank you.

My brother's CB72, which I had a go on when I was 14, holed a piston and poured smoke out of the breather. Not while I was riding it, though.....

G

[jleewebb]

Thanks Phil and G-man for your prompt and informative replies. I obviously had no idea what I was looking at (a CB77 is nothing like a Hodaka) and you gave me confidence to proceed.

I went ahead and pulled the sprocket off for curiosity and peace of mind. The seal behind it was clean and dry, so that's a relief.

When I noticed the clutch rod seal protruding I thought, "that doesn't look right" and immediately poked it back flush with my finger...didn't take much pressure. Probably not my brightest idea. At this point it shows no sign or wanting to come back out with gentle prying with a dental tool or a small screwdriver.

I re-installed the exhaust pipe and started the bike yesterday, ran at fast idle until it was well warmed up, no leak, no movement of seal. It's tempting to just button it up and ride it, but I'm thinking that since apparently all that holds the seal in place is friction, if there's enough lube between the seal and inside of shaft that I can re-seat it with finger pressure, it'll likely push back out again sooner or later. I obviously need to follow your advice, remove the seal, clean things up and reassemble.

So is there a trick to getting that seal out without destroying it? Can I pull the clutch rod out without displacing something at the other end and getting into more trouble? (Or do I need to?) Do you use any kind of sealant on the seal or just install it clean and dry?

On the other hand. that Cappellini seal holder looks interesting...Looking at a better pic here: http://www.ebay.com/itm/Honda-CB72-CB77 ... 257fe23979 it looks like the holder goes on over the sprocket plate...wonder if I could get away with just slapping this puppy on over the existing installed seal. Think it would ooze?

Phil, I pulled the crankcase breather tube out and held the end in a cup of water briefly with the engine running/reving. Got a healthy but not excessive stream of bubbles, no oil, no smoke. No unusual noises from engine, either. I thought about holding my finger over end of the tube to build up crankcase pressure to push the seal out but decided that might not be good for the other seals. I tried blowing into the tube with my mouth, it held pressure; there's a check valve up at the other end, right, like a PCV?

I really appreciate you both putting up with my ignorance and verbosity. I'll keep you posted on my progress. Thanks again, Lee