removing blade hub

[trackfodder]

I have a 4 HP Scamp that served me faithfully many years. It has been replaced by a 6-1/2 HP self propelled one. I want to put the old one on a motorbike but need to remove the blade hub to replace the case seals. I have cut away most of the muffler and can get to the 3 bolts after I remove some of the blade hub. I need to save it so I can reduce the diameter to 1" for a clutch and belt transmission. I have used penetrating oil and a puller with no luck, heated the flange with no luck. Am considering impacting the taper with an air chisel with hammer attachment.. Ideas?

 

[jp1961]

Hello,

You need to heat the hub and strike it with a hammer in the same direction as removing the blade nut. They are hard to remove and you will undoubtably damage it during removal, but they are available new.

Jeff

 

[Lawnboy77]

At this point I would just get the die grinder, or Dremel out and cut it off. It's no good at this point anyway. You can break the tack welds in the plate with a pitman arm puller, or suitable substitute, if the collar comes off with it then you are good to go, but from my experience the welds are more than likely going to break. Once the plate snaps off you can make two cuts 180 degrees apart in the collar, being careful not to get into the crank, then use a hammer and chisel to split it the rest of the way apart.

 

[Two-Stroke]

At this point I would just get the die grinder, or Dremel out and cut it off. It's no good at this point anyway. You can break the tack welds in the plate with a pitman arm puller, or suitable substitute, if the collar comes off with it then you are good to go, but from my experience the welds are more than likely going to break. Once the plate snaps off you can make two cuts 180 degrees apart in the collar, being careful not to get into the crank, then use a hammer and chisel to split it the rest of the way apart.

That's what I've always had to do. I've never been able to get one off without damaging it. The yoke is strong but the plate will bend if you apply just moderate force to it.

This is worth repeating: be super careful not to damage the crank shaft.

I'm not sure if anybody in this thread has noted this but I think the proper name of the part is "blade mount".

 

[fabricgator]

Am I to understand that OMC did not have an approved method to remove this without destroying that part?
Seems like it should be pretty straight forward. Like removing the flywheel, it is just a tapered fit. Try to apply heat to the tapered collar to get the steel to expand while getting as little heat on the shaft so it does not expand. And like JP1961 said, hammer tap it in the direction of the blade track (not off, that would bend it) but in the direction around like the blade track.

 

[fabricgator]

Grind and cut could always be employed if all else fails, but I really believe there should be a mechanics solution to this.

 

[Lawnboy77]

Oh they have procedures to remove that adapter and yes it's just a matter of tapping the corner in the direction of the blade travel, but that's under normal conditions when the blade has been removed periodically for sharpening and exhaust cleaning. It just sounds like you are dealing with the typical mower that has set for years without periodic maintenance performed and the adapter has rusted and seized to the crank. You might be able to get it off in one piece in a usable condition, just depends on the extent of the rusting. Patience, Heat, hammer and penetrating fluid is the way to go. A pitman arm puller is what I use to remove them, but I also use anti-seize compound each time, which will allow it to be removed easily the next time. If it's worth it to you to have it removed in usable condition then I would spray it down with Liquid Wrench and let it set for a day or two, then come back and put a puller on it, apply just enough pressure to not permanently bend the plate, then tap with the ball peen hammer. What really sucks about this is...you may spend hours dealing with this and end up having to replace the adapter anyway, and that's the main reason I suggested just to cut it off, the part is relatively cheap and in good supply, both new and used. Below is a pic of the pitman arm puller that I use, it wraps around the back of the plate to where the tack welds are so much less likely to warp the adapter than a standard puller. It's not a must to have this tool, I'm just sharing my technique. I would imagine we all have different ways to accomplish this task, and all are good.

 

[Two-Stroke]

Am I to understand that OMC did not have an approved method to remove this without destroying that part?
Seems like it should be pretty straight forward. Like removing the flywheel, it is just a tapered fit. Try to apply heat to the tapered collar to get the steel to expand while getting as little heat on the shaft so it does not expand. And like JP1961 said, hammer tap it in the direction of the blade track (not off, that would bend it) but in the direction around like the blade track.

I think the answer is "no". It's a little surprising but the part is cheap.

An ideal tool would be a puller that could grab the collar -- like the tool Lawnboy77 shows but the arms would have to be a little longer and maybe have a custom shape to fit around the collar.

 

[bertsmobile1]

Just as an example, the local mower maker Victa uses a strait shaft and supplied a special puller to remove the blade holder boss from the shaft without damage.
It costs $ 150 and can only be ordered through the whole goods division so you have to be retailer to get your hands on one.
A new engine wholesale was $ 130 so you can make a comparison.
OMC most likely did the same sort of thing to force owners to bring their mowers in for service rather than doing it themselves.


You could also use a bearing puller turned upside down so the flat section is is bearing against the blade boss
But if the boss is real heavily corroded in position there is a better than average chance of mushrooming the end of the shaft.
If you go for a puller, use a rattle gun to tighten it up.
The shock nature of the rotation goes a long way towards breaking the seal.

 

[fabricgator]

... you to have it removed in usable condition then I would spray it down with Liquid Wrench and let it set for a day or two, then come back and put a puller on it, apply just eno...

My penetrant of choice is PB Blaster. We also had a penetrating oil called Mouse Milk that was great also.

Nice picture Lawnboy 77. It almost looks like that tool was built to fit that thing. Too bad it does not reach the round collar where it would really be great. You know what, I bet you could get a piece of steel and cut a U shaped groove in it the size of the shaft. Then slip it over the shaft under the collar, grab it with your wonder tool and V'iola'

As Bert pointed out, the tool cost is prohibitive unless you were doing this regularly. I think the plates are running about 8-10 dollar on FleaBay.... at least for now while there is still a supply of them available. After we cut them all off and they get as scarce as hens teeth, then that tool might look pretty cheap.