Model #917270910 Craftsman lawn, tractor

Question and Answers


How to replace mower deck mandrel with broken blade


If you are trying to replace the lower mandrel bearing, you will have to replace the shaft as the bearing comes already pressed onto the shaft. If you need to replace the upper bearing; the shaft will still have to be removed. I will describe how to take the whole thing apart so you will have a better understanding of how to get into it. It’s a fairly simple process and since you’re even asking, I’m sure you will be able to do it with little to no problem.

The very first thing you want to do, even before you get parts, is make sure that nothing is wrong with the mandrel housing. There are 3 “legs” on the mandrel housing. The bolts that hold the mandrel assembly onto the deck thread into these legs. If any of the legs are cracked, the entire mandrel assembly will be the way to go since you also are in need of bearings. Part 130794 is the complete assembly. It is the housing, the shaft, and bearings.

Once you determine that the housing is in good order, you can proceed. You will need to remove the belt from the mandrel pulley. Then remove the nut on top of the pulley. I use leather work gloves to hold the blade and an impact wrench to loosen the nut. If you don’t have an impact wrench you should be able to rent an electric impact at your local rental shop. You can also bring the deck to a local auto repair shop. I am sure a technician would remove the nut for you.

Once you remove the nut, you should be able to remove the pulley. Make sure the splines on the shaft and matching splines on the pulley are both good. If in question, replace the shaft and pulley as you do not want to get it back together only to have to take it down again and add more parts. Once you have the pulley off, there will be a washer that sits beneath it. Make sure you hold onto that washer. When you put this all back together, that washer absolutely must be under the pulley or it will get into the upper housing and destroy it.

Now that you have the nut removed, the pulley removed, and the washer removed you can screw the nut back onto the shaft a few turns and smack it with a hammer to knock the shaft out of the housing. If the lower bearing stays in the housing and doesn’t come out with the shaft, you will have to get a shaft assembly. It is virtually impossible to press that bearing back onto the shaft.

Now that the shaft is out, chances are the upper bearing is still sitting in the housing. Go into the housing from the bottom side with a punch and knock the top bearing out. Again, check the housing for any sort of damage. If everything looks good, you can go ahead and start putting everything back together.

Set the top bearing into its seat on top of the housing. If the bearing doesn’t want to sit right down into its seat, you can tap it (do not beat it into place) with a hammer to get it into place. Then slide the shaft (and lower bearing) into place. Here, it gets a little tricky because nothing wants to stay in place and if you don’t have an assistant with you it can be a bit trying (to say the least). When you get the shaft into place go ahead and put the blade onto the shaft. Have your assistant hold the blade (remember to watch sharp edges) and push up so everything is in place. Then put the washer on the top end of the shaft and put the pulley on to of that. After that go ahead and put the nut on the shaft. Screw it down and make sure you get it tight. Remember how hard it was to get that nut to break loose; it needs to be on the shaft tight. If it’s not tight enough the pulley will work loose and you will end up having to do all this again because the splines on the pulley and shaft will get damaged. I just can’t say enough about that nut being tight.

Things to know

  1. Mandrel Nut: 75 foot pounds torque
  2. Blade bolt: 27-35 foot pounds torque
  3. Mandrel housing mounting holes are not threaded. The bolts are self-tapping, you can use the bolt to tap them before you mount the housing.

Part numbers you may need to know

  • Top bearing: 110485X
  • Bottom bearing and shaft: 137646 (this will have both bearings, shaft, and nut)
  • Complete mandrel assembly: 130794 (this will have bearings, shaft, hardware, and housing)
  • Mandrel pulley: 173436
  • Bolts for mandrel housing: 173984
  • Mandrel housing: 128774

You can go HERE to order any parts you may need or to look up any others you find yourself in need of.

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Mark T -
Sears Technician
April 16, 2012

I miss spoke in my response. If the blade was missing, I held the pulley with a gloved hand and used an impact wrench to remove the nut. You can also use a strap wrench to hold the pulley. Wrap the strap around the pulley and feed the strap through the handle of the wrench. This will hold the pulley but I think you will still need an impact wrench to remove the nut.

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Mark T -
Sears Technician
April 17, 2012
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