Snowblower Shear Bolts failing

[fast*st]

You could torque the bolt and draw a line on the head and tip in line with the rotation. Its possible its shearing front/back versus side/side with sideways being in line with the rotation. Perhaps it needs some modification to the fan to chew up that ice back there, or pam or a good blast of silicone spray


It could be some driveline harmonic that's adding to the shearing as well, perhaps a good slather of grease on the shaft under the blower would help dampen this motion.

-J

 

[andre53]

Good idea, but when the bolts shear the ends disappear... which loses the orientation. I will be finding them all over the yard next spring. I have been looking for them because I would like to look at the fracture surface on the pins to determine whether they are failing in shear/overload or fatigue. I usually can't even find the part of the pin internal to the shaft. When I do, the fractured ends are usually so smeared that you can't make a good assessment of the failure mode. I will mark the orientation and then wrap the ends with duct tape to see if I can recover the pieces next time.

Also, On the GR2728 the fan has a grease fitting so the shaft is very well lubricated. In fact, I have been thinking of trying to use a "stiffer" grease, which is kind of backwards but I am tired of replacing 1or2 shear bolts every time I use the blower.

I do agree, the ice build-up may be creating significant side loading of the pins.

 

[bearbait]

You may want to check out this video. A simple and cheap fix.

http://www.youtube.com/watch?v=EMAgb3QNEE8

 

[fast*st]

Good idea, but when the bolts shear the ends disappear... .

electrical tape?

 

[Snoopy]

I took a look at my sheared bolts, and they were shearing at the head. For those not familiar with the shear bolts used on the GR2728 model snowblower, they are 5/16" bolts with a groove in the top and bottom of the bolt where the inner shaft might touch the bolt. My Kubota guy contacted the company rep and it appears there is a fix where a new inner shaft and new fan will be used. This will have a new 1/4" shear bolt and thus eliminate the grooves in the bolt. The parts should be in this week.

It is believe that part of the issue is that the fan can rotate just a touch compared to the inner shaft due to the groove in the current shear bolt. This small rotation can deliver repeated impacts to the shear bolt at low rpm or if anything is out of balance. It is believed that these impacts cause the bolt to shear. With the new parts installed, the fan and shaft should not have any rotational play in them as the new shear bolt will not be grooved. Finally, my dealer is also going to balance my blower driveshaft to help eliminate any vibration issues.

While I am waiting for the new parts to arrive, I am using a normal grade 2 - 5/16" bolt for my shear bolt and have about 3 hours of snow throwing on that bolt with no issues that I know of.

Peace.

 

[andre53]

I started spraying the back face of the fan tunnel with a silicone spray lubricant before using the blower. I haven't broken a shear bolt since... I was breaking a shear bolt for every hour of use, I am currently up to almost 5 hours on the current bolt.

Inspecting the fan area after blowing, the silcone spray appears to be preventing the ice build up behind the fan, so I think that is probably the root cause of the bolts failing. So I will apply the spray lube before each use.

I never had this problem with my old blower. In looking at some old pictures of the fan on that unit, it was designed to have much more clearance between the fan and the rear face so there was less tendency for the ice to build up in the first place. The way the GR2728 is designed, the snow get packed behind the fan, creating an ice build up that starts loading up the fan until the shear pin breaks.

When summer comes, I will see what I can come up with to eliminate the ice build up problem. I think the problem is that the snow gets behind the fan and has no where to go (it doesn't have a path back into the fan). So as more snow gets jammed into the gap it compacts into solid ice.

 

[OrangeGuy]

finally!!! someone having the same issue as me... my dealer actually tried to tell me it was my style of blowing that was constantly breaking the fan shear pins... I've got less than 10 hrs on this unit and have gone thru about 15 pins... finally I went to the dealer and and used the blower right there in his yard... I went thru 2 pins in about 15 mins... oh and 1 windshield on one of their new tractors They just returned it to me and there is a completely new fan assembly in it... with a hub assembly around the shear pin area... I'll post some pics of this tomorrow

 

[andre53]

OrangeGuy,

I can't wait to see the pictures. I have come to the conclusion that this is a design problem with the GR2728. Despite all of the precautions I am taking this thing is still shearing pins. Yesterday I went thru two in about a half hour... what a pain.

Once I see your pics, I will be on the phone to my dealer.

Thanks,

 

[kubota2360]

Hi guys,
I bought my BX2360 with the snow blower (BX2750D), and loader (LA243), last November, and got a chance to use it with the snow blower a couple weeks ago, and broke 3 shear pins, and one grade 5 bolt (that took me 30 minutes to get it out the way it broke).
I have mostly gravel drive, and a long one, I drop the blower down in float, and then raise it a bit, but still get in some rocks, but not enough to keep breaking the bolts.
I read this post, and last snow I did the silicone thing on mine, and didn’t break a shear pin. While spraying the blower, I noticed 2 blades were bent where a rock got stuck, and the area was worn with groves in it, with only 3 uses. I watched the link about bolting on the rubber flaps to the blades, I think that would get any rocks from wedging under the blades, and think that may just be the way to go, has anyone tried that?
Since it is new, and has only 3 snows on it, I have placed a call to the dealer, and he is checking with Kubota, for what they recommend, I will keep you posted.
I sold my 1840 case with bucket, and plow, (way overkill for my use) for this Kubota, I hope this is the only problem I have with it.

 

[andre53]

I talked with my dealer yesterday and they checked into this for me. Apparently, some GR2728 blowers have excess vibration that leads to premature fan shear bolt failure. This problem is supposed to be unique to serial numbers below 21208089. My unit is in the problem zone. The solution is to update the fan, shear plate and shear bolt.

I will let you know how this comes out.

 

[kubota2360]

My dealer just told me that Kubota said there was a few complaints on broken shear bots, they may have gotten a bad batch, to try a little heavier bolt. I don’t feel that is the problem.

 

[Snoopy]

FYI: Hope this thread is not totally dead. Just got my blower out for the season. I am still having a vibration problem and noticed that my serial number is in the problem range also. At idle RPM, I can see my drive shaft vibrating and lots of noise coming from the unit. If anyone has a smooth running snowblower that is a GR2728, please let me know how it was repaired or if the serial number is above the problem area. This way I will have something to tell my Kubota guy as the unit is still under warranty.

Peace

 

[78Vette]

Check this. Hope it helps. I have a new GR2120 (4 month old) and a new GR2728 blower. Havent used to blower yet but i'll pay attention to vibrating.
http://www.orangetractortalks.com/forums/showthread.php?t=8787
post # 10

 

[Snoopy]

Thanks for the link Vette. You will have to look into getting the cab for it also. It's funner to blow snow around when you don't get it blowing back into your face.

 

[andre53]

Re: Snowblower Shear Bolts failing - 2014 Redux

Well, it seems like the upgraded Kubota fix for the premature shear bolt failures on the GR2728 may not do the job...
I just popped another shear bolt this morning at no load. What is interesting is the bolt that failed is not the shear bolt that is supposed to fail, at least according to the Shear Bolt decal on the blower.

In the GR2728 upgrade, the revised fan has two pieces. The first is a collar that bolts to the snowblower drive shaft. The second piece is the fan assembly that connects to the "secure" collar via a shear bolt (PN 70060-01075). The bolt that failed this morning was the collar bolt, not the shear bolt. What a pain!

Fortunately, I had a bunch of the shear bolts for my old fan assembly and they fit the new collar, so I installed one of those to get me by today. I don't have a parts list for the upgraded fan assembly, so I don't know what the actual part number is for the collar bolt. If anyone has that information it would be appreciated.

It would be nice to finally get this problem fixed because I don't want a repeat of last year where I was replacing the fan shear bolts at the rate of 1 per hour of usage (note: 3 of the bolts broke under no load.)

 

[78Vette]

That sucks. I haven't used the blower yet. Not gonna be happy if i have to deal with that....I'll let you know, if we ever get enough snow.....
Have you called kubota?

 

[andre53]

Snow update: We are having a nice little lake effect snowstorm here. Very localized but leaving us lots of snow. Yesterday, we got between 22-24" of snow at the house. Just a few miles south of us got over 30".

When I got home from work, I had 18" of fresh stuff in the drive. Due to drifting, there were area where the snow was over the top of the blower box. When the shear bolts aren't failing, which they didn't last night, this blower is a beast. It sliced thru everything.

Having the cab was really nice last night as the temp was around 16F and the wind was strong and swirling. Being out of the wind and not getting blasted by blower back wash is outstanding.

Going to have more fun tonight as my wife says we have picked up another 8-10" since this morning. Tomorrow they are predicting another 8-16".

The only additional thing I would ask for on this blower, is some drift cutters as the snow along the drive is already 6" above the top of the blower. Kubota didn't leave any holes on the blower box to attach anything and I really hate to have to drill thru the powder coat to mount them.

 

[78Vette]

Why dont you just make yourself or buy a couple of flat-bars 18 inches long 2 wide 1/4 think at any metalshop and bolt them onto the top/side of the box and paint them? I think you already have a rattlecan of orange, that you painted the weights with. (Mine are black)
We dont get that much snow along the canadian side of lake Erie where i am. Seems to go to the north and south of us. We've had maybe 1 inch in the last couple of days.

 

[78Vette]

Came back from a trip to ohio and found 8 inches of snow in my driveway. Used the blower for the first time. Works pretty good and the weights do the job well

 

[RobGr2020]

Hi
I have the same blower and I found the shear pin on the fan that joins it to the collar on the main shaft was a 1/4 20 bolt right from the factory. It had the orange paint on the nut and bolt to show it had been installed. I put a proper shear pin in and so far so good. At least one hour on this pin