Sander Repair – Replacing the [Lower] Armature Bearing (Porter Cable Part # 803854SV)
Sander Repair – Replacing the [Lower] Armature Bearing (Porter Cable Part # 803854SV)

Hi, I’m Mark from In this video, I’m going to show you how to replace the lower motor bearing on a Porter-Cable random orbital sander. The lower motor bearing attaches to the motor’s armature and allows the armature to spin. Like any bearing, eventually it will begin to wear out. The first signs of a bad bearing will be squealing sounds coming from the sander. As the bearing continues to wear, it will start to lock up; and you’ll notice a considerable loss of power from your sander. The lower motor bearing is easy to replace, and I’m going to show you how. Lower motor bearings, as well as many other parts, can be found on our website. Let’s get started. I’ll begin by securing the three screws that secure the sander pad to the sander. Now I can remove the clutch belt. Next, I’ll remove the black sander pad housing. It’s held in place with two screws. With the screws removed, I can separate the two halves of the housing. Now I’ll remove the dust pad housing O-ring. I’ll use a screwdriver to get it started. And then I’ll just pry it away from the housing. Now I’ll remove the sander pad support. I removed the sander pad housing so I’d be able to grab the fan so that the screw doesn’t just rotate as I try to remove it. With the pad support removed, now I can go ahead and remove the fan. The two halves of the motor housing are secured with four screws. I’ll go ahead and remove those now. With the screws removed, now I can split one half of the housing. Now I’ll pull the brush holders away from the armature. With the brush holders out of the way, now I can go ahead and remove the armature. Now I can remove the lower motor bearing. The easiest way to do this is with a bearing puller. However, there’s a very small gap between the bearing and this counterweight. If your puller will fit in between those two… …it will work great. However, my puller is a little thick on the legs, so I won’t be able to use it. Instead, I’ll use a bearing separator and a vise. I’ll place the separator over the bearing. And then go ahead and tighten it up. Now I’ll place the separator on top of the vise jaws. And I’ve opened the jaws wide enough so that the fan on the armature will clear, and won’t get broken as we remove the lower motor bearing. Now we’re ready to remove the bearing. Except, I don’t want to strike the end of the motor shaft with a hammer. because, I’ll damage the threads where the pad support screw goes. So, what I’ll do, is actually take the pad support screw and thread it into the end of the shaft. And that way, I’ll be striking the head of the screw, rather than the shaft itself. And I’ll use the hammer to tap the bearing free from the armature shaft. Now I can install our new lower motor bearing. The bearing gets pressed onto the shaft until it contacts this washer that sits on top of the retaining ring. So, I’ll place the bearing over the shaft. And then I’ll use a socket that has the same diameter as the inner race of the bearing. And I’ll use that to tap the bearing into place. Now we can install the armature back into the sander. There’s an O-ring that fits over the upper motor bearing. And provides some cushion between the armature and the housing. Now I’ll slide the armature through the field. And make sure that that O-ring aligns with the gap in the housing. Now I can install the brush back into the sander. And I’ll do this again on the other side. Now I can reinstall the housing. You might notice this little rubber bumper. And this just goes down in the housing where the bearing attaches. And again, that’s there just to provide a little cushion to the bearing so the bearing has a little room to play. I’ll make one last check of the wires and make sure everything is tucked out of the way so they’re not going to get pinched. And then reattach the housing. And it gets secured with the screws. Now I’ll slide the fan back over the shaft. Now I’ll place the pad support back over the fan and spindle. Next comes the washer The side with the recess should be facing toward you. And I’ll secure it all with the screw. And again, I’ll hold the fan to prevent the motor shaft from spinning as I tighten down the screw. Now I can install the pad housing O-ring. Now I’ll install the pad housings. They just slide over the gray motor housing. And I align the ends with the seam in the motor housing. Both sides, and then I’ll secure it with the screws. Now I can install the clutch belt. First, I’ll wrap it around the fixed pulley. And then around the pad support. And I’ll rotate the pad support… …until the belt’s in place. Now I can install the pad. A trick to make it a little easier to align it is to insert a small screwdriver through one of the holes in the pad. Then I put that same screwdriver in the hole in the pad support. And then I secure it with the screws. And that’s how easy it is to replace the lower motor bearing on a Porter-Cable random orbital sander. If you found this video helpful, be sure to give us a thumbs-up. And leave a comment.

17 thoughts on “Sander Repair – Replacing the [Lower] Armature Bearing (Porter Cable Part # 803854SV)”

  1. shaggy DA says:

    Thank-You for all of those GREAT Video`s  . it takes-out  the guess work I did before!

  2. ali alshra says:

    thank you

  3. Huhyvfbjvv Hhvgvbhv says:


  4. Greg Santos says:

    Thanks! Very informative

  5. Alex Symonette says:

    That demonstration was very helpful and to the point. thanks much

  6. telosfd says:

    Well done. Easy to handle and service this orbit sander!

  7. jose benitez says:

    Gracias por el vídeo

  8. Korgon2013 says:

    3:24–3:27 – nice catch!

  9. Who Me? says:

    Filled out the form on your website for help. All I received generic response saying give us a call. I think help form was there just to collect personal information. I do like the majority videos, fantastic!

  10. Angelo Piacente says:

    seams easy bit i think Is necessary ti do often that job, very appreciated

  11. Made Gede says:


  12. MOHD. AKIR BIN Jokey says:

    Very good explaination

  13. satoshi krab says:

    cool !!!

  14. هشام المنصوري says:


  15. mun kingi says:

    awsome thank you

  16. Ali Simabi says:

    Very useful, and how can remove the other side bearing ?

  17. Rai Manika says:

    Nice super vedio.

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