Export thread

Sheared bolt on L120 mower deck

#1

M

mikey47

Hey guys, I'm in need of some advice on how to fix the deck on my mower. A bolt that goes through a bracket and holds down a pulley has broken in half. I'm stumped on how to fix it because it doesn't appear that the bracket can be removed from the deck (I think it's welded on) and also the bolt is pretty much rusted into the bracket. If I were able to remove the bolt, I'm not sure how I could get another one back up in there (if I could find a replacement bolt).

My Dad owns the mower and went down to the John Deere store and they told him he needs to buy a new deck for $1000...since the mower is 12 years old, he's about to just go buy a new mower. I myself, love to fix things and am not about to allow him to buy a new mower because of a broken bolt.

I've searched online and have found a repair kit for the idler pulley bracket, but nothing for this one.

Here's are some pictures of the sheared bolt. Feel free to share any ideas you've got!

Pulley sitting on sheared bolt:


Broken bolt and bracket:




#2

M

motoman

Mike, Be sure there is some life left in the rig. Unless you have access to a machine shop you "could" try to repair it yourself, but it requires you to be good with tools and have access to welding equipment. First I would measure the bore of the bearing that holds the shaft (replace the bearing). It looks like a shoulder is used to seat the bearing . You will need to either turn down a bigger od bolt or find a sleeve to provide the seat and weld it in place. Sleeve must be proper height. Get the replacement bolt in a graded strength like grade 5.

Cut off broken stub flush. Center punch and drill. Use a drill jig of some sort to stay at 90 degrees. Pilot drill. Final drill. With the raised position of the shoulder the weld could be "wire weld. " (Room for weld bead) I would prefer braze weld (oxy acetylene) because of the much lower temp and less likelyhood of damage to bolt. New bolt must be held @ 90 degrees during and after welding. All steel must be cleaned free of rust. Fairly advanced stuff , but doable. Good luck.

PS It looks like work hardening broke the bolt. Perhaps under torqued or loosened nut or long time loading on/off of pulley. Check other pulleys


#3

M

mikey47

motoman said:
Mike, Be sure there is some life left in the rig. Unless you have access to a machine shop you "could" try to repair it yourself, but it requires you to be good with tools and have access to welding equipment. First I would measure the bore of the bearing that holds the shaft (replace the bearing),
Click to expand...

Makes sense. Unfortunately, I'm a bit limited on tools. I don't have anything to get the bolt hot enough to work it out, nor do I have welding equipment. Really a bummer that the bolt isn't easier to access.


#4

M

motoman

Mike Read my further ( and improved?) blather.


#5

M

mikey47

motoman said:
Mike Read my further ( and improved?) blather.
Click to expand...

Really appreciate the response! The above is all things I have never done before but will discuss with my Dad.

Thanks again!


#6

M

mikey47

Just thought I'd give an update:

Was doing some thinking yesterday and remembered that our neighbor has the same mower as us. He's an older gentleman and has started hiring a lawn service to take care of his yard. He still had the mower sitting in his shed, so we offered him $500 for it! Problem solved.

Thanks again for the help :)


#7

KrashnKraka

KrashnKraka

mikey47 said:
Just thought I'd give an update:

Was doing some thinking yesterday and remembered that our neighbor has the same mower as us. He's an older gentleman and has started hiring a lawn service to take care of his yard. He still had the mower sitting in his shed, so we offered him $500 for it! Problem solved.

Thanks again for the help :)
Click to expand...

Good One, Mike ;)

If it is exactly the same mower do not dismiss <motoman>'s advice, lightly.
PS It looks like work hardening broke the bolt. Perhaps under torqued or loosened nut or long time loading on/off of pulley. Check other pulleys


#8

S

shiftsuper175607

motoman said:
Mike, Be sure there is some life left in the rig. Unless you have access to a machine shop you "could" try to repair it yourself, but it requires you to be good with tools and have access to welding equipment. First I would measure the bore of the bearing that holds the shaft (replace the bearing). It looks like a shoulder is used to seat the bearing . You will need to either turn down a bigger od bolt or find a sleeve to provide the seat and weld it in place. Sleeve must be proper height. Get the replacement bolt in a graded strength like grade 5.

Cut off broken stub flush. Center punch and drill. Use a drill jig of some sort to stay at 90 degrees. Pilot drill. Final drill. With the raised position of the shoulder the weld could be "wire weld. " (Room for weld bead) I would prefer braze weld (oxy acetylene) because of the much lower temp and less likelyhood of damage to bolt. New bolt must be held @ 90 degrees during and after welding. All steel must be cleaned free of rust. Fairly advanced stuff , but doable. Good luck.

PS It looks like work hardening broke the bolt. Perhaps under torqued or loosened nut or long time loading on/off of pulley. Check other pulleys
Click to expand...


Is that a bushing on top of the bolt?
I believe you could drill it out and use another bolt. You may have to use a lock nut.
The bolt would have the nut on the bottom and you would need washers or a bushing for the bearing of the idler to sit on.

My John Deere has a regular bolt that goes up through the deck and a bushing sits on it and the idler pulley. the bolt is in a slot so as to allow some adjustment.
It would be an inexpensive and simple try to fix it.


Footer Links 1

Top