Bagger Shear Pin on Kubota OEM bagger

[JWR]

The pins are located on either end of the PTO driveline, under the safety shield. Pull the safety shield (using a 7/16" wrench, loosen the two screws holding the covers,) and you will see them going through the spline of the yoke. Just curious, was not familiar with Kubota grass catcher, and the pitfalls of their ownership, and purchased an older model unit to use on my new tractor. For the record, I only use it in the sprint to pick up the dry thatched grass from first mow. Mine does not allow me to fill bags twice before breaking. FYI, mine uses 1/4" grade 8 bolts with a shoulder full length. I will begin tonight, to peen the threads of the bolt to guarantee the locknut does not loosen. Can you guess I also am having this very same problem, 9 years later!

I realize this is an OLD thread with 3 recent posts. I went back and read most of the posts. This whole thing baffles me as to how so many pins are being sheared.
-- The pin I am talking about is the one going through the U-joint half that mounts directly on the input shaft to the bagger. No other pin has ever sheared on mine.
-- I have had mine 14 years. Model GK60BX. Expensive, heavy and worth it's weight in gold for the leaves we have to handle here. Running on a BX2200.
-- In 14 years I had the shear pin go ONCE and that was when the fool operator knew the impeller was plugged and threw the PTO into gear.
-- OK,TWICE because the cheap off the shelf 1/4" bolt I stuck in there lasted one day.

The part is listed in the manual is ｼ-20 x 1 ｽ but that is a strange small round-headed bolt that recesses into the U-joint clevis body and has an Allen key head hole. That u-joint hole is also threaded on one side and larger on the other side to accommodate that round headed bolt. The threads in the clevis are slightly larger than ｼ in size. My guess is that the original intent was to use a special bolt just over ｼ diameter that would thread into the u-joint body rather than have a nut on it. The part number listed is 70050-04158 for the shear bolt.

-- Once I put in a new Kubota shear bolt (which costs $6.19 !! in 2016 $) it has never sheared again and never been a problem.

My GK60BX bagger has been used heavily for 14 years, does not eat shear pins, I do not picture any belts being inside that housing -- I'd be very shocked if there are as it surely seems to be just a geared unit.

I have to think that those talking about replacing 10 or 15 shear bolts are either using hardware store bolts that do not really fit right and not the factory replacement shear bolt. Otherwise, they must have something seriously wrong with the bagger --- binding, plugged up with something, worn out larger than normal holes through the shaft or some cause they have not fixed.

 

[David_Kb7uns]

I realize this is an OLD thread with 3 recent posts. I went back and read most of the posts. This whole thing baffles me as to how so many pins are being sheared.
-- The pin I am talking about is the one going through the U-joint half that mounts directly on the input shaft to the bagger. No other pin has ever sheared on mine.
-- I have had mine 14 years. Model GK60BX. Expensive, heavy and worth it's weight in gold for the leaves we have to handle here. Running on a BX2200.
-- In 14 years I had the shear pin go ONCE and that was when the fool operator knew the impeller was plugged and threw the PTO into gear.
-- OK,TWICE because the cheap off the shelf 1/4" bolt I stuck in there lasted one day.

The part is listed in the manual is ｼ-20 x 1 ｽ but that is a strange small round-headed bolt that recesses into the U-joint clevis body and has an Allen key head hole. That u-joint hole is also threaded on one side and larger on the other side to accommodate that round headed bolt. The threads in the clevis are slightly larger than ｼ in size. My guess is that the original intent was to use a special bolt just over ｼ diameter that would thread into the u-joint body rather than have a nut on it. The part number listed is 70050-04158 for the shear bolt.

-- Once I put in a new Kubota shear bolt (which costs $6.19 !! in 2016 $) it has never sheared again and never been a problem.

My GK60BX bagger has been used heavily for 14 years, does not eat shear pins, I do not picture any belts being inside that housing -- I'd be very shocked if there are as it surely seems to be just a geared unit.

I have to think that those talking about replacing 10 or 15 shear bolts are either using hardware store bolts that do not really fit right and not the factory replacement shear bolt. Otherwise, they must have something seriously wrong with the bagger --- binding, plugged up with something, worn out larger than normal holes through the shaft or some cause they have not fixed.

Not all the allen head bolts are the same, had to track some down after shearing several when starting bagger up and they had them at the local Napa. The hardware store allen bolts had a short shoulder and then threads and sheared off in the threaded area very easily. The ones that Napa had, the shoulder was longer and the shoulder area went through the shaft and the u joint yoke on both sides of the shaft and had a shorter threaded area and did not shear as easily.

David

 

[jfralph]

I approached dealer for the specific shear bolt listed in the manual, my dealer handed me a grade 8 bolt with full shank. In one mowing, I went through two of them. (Never finished mowing) Went to hardware store and bought similar gr 8 bolts, replaced and just to make sure it was not an issue of throwing the locknuts off the bolt, I peened the threads so the new one could not loosen. That was a week ago, waiting for a dry day to try again. All that was being picked up was extremely dry dead grass from last year. Grass had not started to grow yet. This next mowing will be much more challenging, now we have had a week of rain and warm weather, the grass has started to grow. FAST!!! If I have the opportunity, I will finish cleaning up the yard, and then put the mulching blades back on and finish the year with mulching. As far as the bolts are concerned, if they continue to last only minutes, I will drill out shaft and install 5/16' bolt. Unit is worthless if it will not pick up dried grass.

 

[JWR]

jfralph -- of course. Believe me it will pick up serious wet grass, deep piles of leaves, and you if you get in the way. There is something really wrong where these folks are shearing pins all the time ! The only 2 I ever sheared were about 6 years ago and it was my fault. True, the real Kubota replacement pins cost me $6.19 each but they won't shear unless they NEED to shear. Frankly half the dealers are too casual about these pins (and other parts too) and either don't know what they are doing or ?? The dealership I got mine from has been in business for 2 generations, knew exactly what I was talking about with the pin, how I sheared it and which one to use. He certainly was not handing me a bolt that he just thought would work.

 

[jfralph]

JWR,
I am not going to throw my dealer under the bus on this. I did see where a Kubota shear pin was in the $6-8 range last year. This year I went to find the same to order, and not available. (My closest dealer is 100 miles away, I just don't run down to visit and pick up parts.) I made a specific trip to dealership for shear pin, parts man pulled manual and showed me Kubota's spec for the bolt, per my insistence. He insisted he had no other listing for this item. I do believe you may be correct. Upon closer examination of the shaft, the yoke had a 5/16" hole in one side and a 1/4" in other. Not sure what the pinion shaft had, it drilled fairly easily, like it may have already been mostly 5/16" so the factory shear bolt was probably a step design. Regardless, last evening I needed to finish spring cleanup, I drilled out the shaft and yolk and installed a 5/16" bolt as a replacement. Pulled about 50 bushels of grass last night before dark with no more breakage. Tonight I hope to see more ground dry out so that I can cut and bag another 4 acres. My thought on the high failure rate could have been 2 part. 1 was the improper bolt, wrong shank size, and 2, play caused by 1 allowed a shock load on start up the bolt could not handle. Only time will tell how this new arrangement will last, and if the transmission will suffer damage. All I know, the way it was working, it was becoming worthless to me.

 

[JWR]

Yup, you came up with a practical solution. You probably know this, but a critical factor in all shear pins is "how tightly they fit the hole." The slightest bit of looseness and play will cause them to shear prematurely instead of doing their job.

Kind of a side observation: You noted that "Upon closer examination of the shaft, the yoke had a 5/16" hole in one side and a 1/4" in other. Not sure what the pinion shaft had, it drilled fairly easily, like it may have already been mostly 5/16" so the factory shear bolt was probably a step design." I think the small end of the hole is threaded too if I recall correctly. I came away from all that thinking that the yoke had been designed to have the shear bolt screw directly in to it and avoid nuts, etc. Not sure why they did that but the end result is that " a simple bolt that fits the hole" does not work and will soon shear off. Having drilled your own fresh path you should be good-to-go as long as everything is snug and tight.

 

[robertm]

I am very close to buying the newest version of the bagger for my BX2670. I hope this issue has been resolved, as it looks like this shear pin issue is with the old style bagger. My salesman, who I've known for years and bought many tractors from, insists the new bagger is a dream and is a quick hoookup and takeoff, when needed. After watching the youtube videos, it seems some just aren't as mechanically inclined as others.
I've toyed with the Cyclone Rake, but I'm not really digging the extra cost and the overall length.

 

[JWR]

Since you have your clothes off and are almost in bed with that dealer, make him sort out any shear pin issues that occur. My bet is that if you use the manufacturer supplied pins and keep them snug you will never have a problem. Because of the weight of that bagger, etc. it is not quite the dream your dealer describes to take on and off. It is on the edge of being a 2 person job and I don't think the newer ones have changed that circumstance a whole lot. Good lock; give us a report after you're using it.

OBTW, there is "some assembly required."

 

[robertm]

Since you have your clothes off and are almost in bed with that dealer, make him sort out any shear pin issues that occur. My bet is that if you use the manufacturer supplied pins and keep them snug you will never have a problem. Because of the weight of that bagger, etc. it is not quite the dream your dealer describes to take on and off. It is on the edge of being a 2 person job and I don't think the newer ones have changed that circumstance a whole lot. Good lock; give us a report after you're using it.

OBTW, there is "some assembly required."

How did you know we were in bed? I didn't attach a picture.
I'm on the fence. I need to pick up grass in the spring, or if it gets away from me sometimes when I work, and undoubtedly pick up leaves in the fall. We get a fair amount of small branches that fall, ones anybody would drive over when mowing. THAT makes me think that maybe the Cyclone is the better option. I cant possibly pick up every stick, and if the GCK60 can't handle the small sticks without shearing pins, Cyclone claims their unit passed a complete anti-scalp wheel through their impeller without a hiccup (sales gimmick, maybe,). Ugh. Choices. Meanwhile, I rake.

 

[JWR]

I sheared the Kubota OEM replacement shear bolt again in my GK60 bagger. It lasted 10 years which included 11 full seasons of leave bagging. My bagging this year was 40 bags. Always includes countless oak tree twigs and "grenades" or seed pods off the flowering ______ trees in the yard. Those grenades sound like they are breaking through the steel impeller they are so load ! Of course there is regular grass bagging but not all that often.

I'm back out shopping for bolts mainly because I can't find the spares I bought 10 years ago....