Got my muffler situation figured out and now I'm moving onto the BBC issues on my 1984 Model 7271.
Sorry in advance as I don't know some of the terminology associated with these mowers.
FYI - the blade on my mower is always engaged.
The lever that moves under the engine which engages and disengages the clutch seems to be working okay. I can move it with my hands and the spring works okay.
I think there must be something wrong with the cable system leading from the deck to the handlebar controls.
I've taken apart the controls and tried to lube the cable with WD-40 but I can't get the cable to budge. Is it possible the cable is rusted so badly that it is frozen in the housing?
Here's what the controls look like from the outside -
Remove the 1/4 inch bolt holding the cable end the the BBC lever that sticks up through the deck. Then run the motor and see if the blade is still engaged. If it is not engaged then the clutch is ok, and the problem is just the cable. To free up the cable, try flexing it through out it's whole length to try freeing it, and more WD40.
#3
secaII4884
I'll have to give this a try. The lever moves from front to back okay.
Can you give me the correct orientation? If the lever is to the front of the mower should the blade be engaged or disengaged?
OK, standing at the rear of the mower looking forward the lever(BBC lever pointing up through the top of the deck) should be to the left in the slot of the deck and the blade disengaged/ bail in the released position(forward away from the handle). With the bail pulled back to the handle(blade engaged position) and the blade engaged the BBC lever would be to the right in the slot. NOTE: If the cable is not adjusted properly the clutch or the brake may not be engaged at the correct time or properly. A locked up bearing of which there are two can also cause engagement of the blade or brake at the wrong time.
Liquid Wrench also works well to free up stuck cables, then motor oil once it's free.
Jeff
#6
secaII4884
No luck
FYI - found out my LB is a 1983 model 7270, not a 1984 model as previously stated. Did some searching for parts and the handlebar mounted controls confirm that the LB is an 83 model.
Got the mower running today and tried to disengage the BBC. No luck. The blade is engaged at all times and moving the lever from left to right that actuates the BBC does not work. My guess, something is seriously wrong with the BBC.
How hard is it to get inside the BBC unit? It looks like I'll need some sort of puller to get it apart.
Any thoughts.
#7
d_sharier
I am glad that the muffler worked out for you. Here is a link for the BBC information. It isn't to bad it you have the right tools.
Sounds like the bottom bearing is locked up. Remove the blade and then you can see the bearing just above the blade. Using a ice pick or small flat blade screw driver pry out the grease cover on the side of the bearing and see if it is all rust inside. If it is there is no way to replace this bearing without the factory tools and jig used at assembly to preload the tension on the large spring. You would need to find a BBC clutch assembly to replace yours.
#9
secaII4884
Yeah, I've been wondering about the specialized tool thing.
I've read over the manual that d_sharier posted. It states that once the blade is removed, you would remove the socket head screw (in the middle of the housing) and then install a clutch retaining tool.
This is where I'm lost. I've had the socket head screw out but nothing from there. I don't have a clutch retaining tool and have no idea if its worth trying to find one. I'm pretty sure I could locate a decent puller but the BBC unit is under 150 pounds of tension.
LB8210 - the bearings you are talking about, I'm a little confused on where they are located and where I should be looking.
The clutch retaining tool is needed to stop the clutch from hitting you when removing the assy. which is two halves pressed together containing the large spring under tension that if the press fit holding the two halves lets go you better be out of the way. If the upper half sticks tighter to the crankshaft than the press fit then the puller that attaches to the lower half and then when you pull on the lower half it may come apart. To get to the lower bearing, remove the two bolts holding the blade to the clutch. Do not remove the allen bolt in the center it holds the two halves of the clutch together containing the spring under tension. With the blade off you can see the bottom bearing. Use a small screw driver and pry out the plastic cover from the bearing. Go easy as you will need to reinstall reuse the cover by snapping it back in place. If it is rusty and the bearing is stuck you will need to find replacement clutch, this bottom bearing is not a replaceable part except as part of the complete clutch, trying to will cause the two parts of the clutch to come apart releasing the spring tension. If that happens and you are not hurt you will not be able to reassemble the clutch and preload the spring tension. The factory had a jig that was used to build the clutch assembly. Not serviceable in the field.
2 comments. First, the Lawnboy models with the BBC had a heavier flywheel, so the engine could be started with the blade disengaged. Second, if your BBC is stuck in the engaged position, it is really no big deal, as the mower will then act like any "regular" mower and you can cut grass.
#12
secaII4884
Agreed, the mower does work as any normal mower would. I thought it would be nice if I could get the clutch working for sh%@s and giggles. I'm not planning on restoring the mower, I'll just continue using as my primary mower. As long as it's running right, I'm good.
Initially, I thought with the cable being seized, I could replace the cable and the clutch would work. Now - knowing the clutch isn't working anyway - I'm thinking about leaving this alone.
I don't have the tools to service the existing clutch and a replacement would probably be costly although I have checked.
