BX2750 Blower - can I upgrade the fan shearing

[darkeagle10x]

I've ran a BX2750B for many years and although my gravel driveway would shear a pin now and then it has been a great blower.

The driveway was re-done this fall and I was expecting a few more sheared pins with the loose stone. To my surprise I had no issues at all - until today.

We had a thaw so the driveway got some ruts, then 6 inches of snow overnight. My blower was trying to level the driveway even with the skids all the way down. It was threw a lot of stones until it sheared the fan pin. No problem I thought, just another pin BUT I can't drive the piece out because the fan is no longer aligned. It doesn't help that there is very little room in there to swing a hammer and punch. The fan normally has a clip that holds from moving forward on the shaft but the clip is no longer doing the job so the fan is too far forward to align the pin to drive out and put in the new one.

In my search for help I found a few posts showing a newer design for the shear pin. There is a flange now and the pin is not through the shaft it is 90 degrees to the shaft using the collar.

All that is to get to the question - can I simply buy the newer designed fan and flange and use it on my current shaft to eliminate this problem in the future? There is already a hole through the shaft that looks like it would be the correct location for the new flange style setup.

 

[sagor]

Answer is "maybe". The key would be if the gearbox drive shaft is the same or not. I've had both blowers, the one with the Gr8 shear bolt on the fan, and the newer one with the Gr5 shear bolt on the flange. The old blower had a similar problem as yours, the shaft/fan were not aligned any longer. I could try to force the shaft/auger forward with a 2x4 and then the fan bolt would slip into the hole, but it was a struggle. I gave up on it and bought the new style blower.
New blower design uses a 5/16x2" Gr8 bolt to hold the shear plate onto the drive shaft. Old blower used 5/16x2-1/4" Gr8 bolt, so that suggests the hole in the two model drive shafts may be the same, but unknown is the alignment or setback. The gearbox part numbers are the same on both models (old and new), 70060-02191 and that part number includes the driveshaft.
New model fan with bushing is 70060-02757, fan alone is 70060-02191. The flange for the new blower is 70060-01287 and is called a shear plate which has that 5/16" x 2" Gr8 bolt through the gearbox driveshaft and uses the 1/4"x 1-1/4" Gr5 flange shearbolt to the fan. The length of that is the critical part, that length gives enough solid body for shearing (not in the threaded portion)

Good luck

 

[darkeagle10x]

Thanks sagor. I think this will be a summer project but want to order parts if it's do-able. Sounds like a good chance it would work. I have a machine shop and welder so modification is always possible too but prefer to use stock parts if possible.

 

[DustyRusty]

My BX2750 had a tab and used a grade 5 bolt and nut as the shear pin, and when I had it out, I installed a grease fitting into the fan so I didn't have to be concerned with the fan rusting to the shaft. My guess is that if you use a 2"x4" piece of wood, you should be able to push the fan back in place and install a new shear bolt. You can buy a new fan, however at $200 + it will be a very expensive upgrade that really isn't necessary. Most likely, the unit will need to come apart and have everything reset back to its original tollerances. Most likely, when you hit the stone, it jammed in the impeller and it might be that you damaged the chain drive mechanism. These snow blowers are easy to work on, and I would recommend replacing bearings if you have used the blower a lot in the past. Nothing lives forever without some service, including our bodies! If you can put the blower facing the sun, the snow should melt away, and it will be easier to diagnose the problem. The cover that covers the chain is removed by taking out the two very long bolts and lifting the cover. Once the cover is off, you can see the gears and the shaft. If the gear is moved on the shaft, then it needs to come apart for an overhaul and reset. It is more time than hard work, so if you can hold off till the summer, it will be a lot easier.

 

[darkeagle10x]

Thanks DustyRusty. Once things warm up I plan to take a good look at things. Using the 2x4 as you mentioned to push it back into place, possibly I can put a pin or bolt in the extra shaft hole and then make a spacer that will keep the impeller from moving forward. More robust than the clip that won't stay in place now. Then I would be back to the shear pin in the shaft original setup. I do want to take a good look at the hole and shaft to be sure it's not wearing badly. If it is, then going to the newer style might be the best option as that will prevent any further wear of the shaft and fan shear area.

 

[sagor]

My earlier point about the 2x4 was that I could not push the fan back any farther in the old blower. I had to try and "pull" the drive shaft forward by pulling the auger/gearbox forward with a wedged 2x4 against the box, before the Gr8 shear bolt would fit. It was just a half of a 1/16" I think, not much. I figure that the old blower (was used when I got it) had some other incident before I got it, and somehow something got screwed up with the shaft.
It was easier for me to buy the newer model of blower, and move the old accessories to it (hydraulic chute turner and old chute).
I still have the old blower, for spare parts. Seems the gearbox and augers and other parts are the same.

 

[darkeagle10x]

OK, we are expecting a week of warm days so this snow should melt and I can take a closer look at what actually moved. No fun doing it with wind and single digit temps.

 

[darkeagle10x]

We got a warmer day so I jumped on this. First tried prying the fan back but couldn't manage to get it aligned well enough so then I took off the chain guard and although it looked proper I knew the shaft had to go forward a little so I put a hydraulic scissor between the mount and the shaft. Took very little to give me the extra I needed to get the old pin out and new one in.

My concern at this point was the extra tension on the shear bolt once I released the hydraulics. As mentioned previously there was a clip that no longer kept the fan in place on the shaft but there was an extra hole in the shaft. So, I spun up a couple of spacers and held them in place with a bolt in the extra hole. This should work much better than the clip ever did. I probably should have made them with flats but the stock I grabbed was just the right size so we will see how this goes.

I may not get to try it until next season but I think the idea is sound. Only concern I have now is that there is more play in the shear pin hole in the shaft than I would like. It has definitely worn the shaft hole and the fan hole over the years.

Maybe I should pursue the flange shear idea before next season? I would hate to have the shear pin snap the shaft in the dead of winter. This currently uses a grade 8 bolt. Maybe change to a 5? Opinions/thoughts going into the future?

 

[GreensvilleJay]

When you do work on it, be sure to use LOTS of neverseize/and/or grease when putting the blower back on.ANY water in between it and the shaft WILL form rust and 'weld' the two together,making it 'challenging' to get off next time....