Thread Number: 35654  /  Tag: 50s/60s/70s Vacuum Cleaners
Convertible Maintenance Questions
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Post# 383005   12/22/2017 at 10:36 (211 days old) by hooveru4089 (CT)        

I am going to be replacing the top sleeve bearing on an older Convertible with the original 2-speed motor. Would you advise lubricating with 3-in-1 before installing or are they ready to go out-of-box? Also, I keep losing the small triangular spring clips that hold the brushroll bearings in place. I have been making some out of old springs with pliers and wire cutters but I was just wondering if snap rings would work.


Post# 383018 , Reply# 1   12/22/2017 at 17:52 (211 days old) by bnsd60m9200 (Ponder,TX)        

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dont replace the bearing. just oil it. ive serviced many convertibles over the years and i find original top sleeve bearing to be better quality and less friction than the new replacements. i would only replace it if the bearing is scored from grease or a bent armature (both ive seen but extremely rare cases)

Post# 383024 , Reply# 2   12/22/2017 at 20:15 (211 days old) by hooverU4089 (CT)        
Interesting piece of advice!

This is actually a follow-up of an older thread in which other members recommended replacing the bearing since the top shaft of the armature appeared to many of them to have overheated.


Post# 383025 , Reply# 3   12/22/2017 at 20:18 (211 days old) by hooverU4089 (CT)        

I should also mention that I will be replacing the carbon brushes. I noticed that the new ones have ridges on the seating surface. Do these just seat themselves while running? This is my first time replacing brushes on an electric motor before so I am curious.

Post# 383043 , Reply# 4   12/23/2017 at 04:57 (211 days old) by broomvac (N/A)        

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Are you working on the same machine you discussed in your link? I didn't read the entire thread, but I gathered that you are trying to eliminate unexpected motor noises after the vacuum sits unused for a while.

My experience has been that the culprit for such a noise is usually the ball bearing, not the brass sleeve bearing. I know it's always tempting to try to lube or replace the sleeve bearing (because it's cheap/easy, right?) but after doing so, I find the unwanted noise usually persists.

The best solution I have come up with for addressing the noise, then, is to either lube or replace the sealed ball bearing. On Hoover vacuums, this usually involves drilling out the rivets which hold on the steel retaining plate and replacing the ball bearing. Simply drill out the rivets and slide out the bearing.

Now that the bearing is free, you can pry off both the rubber seals, blast the bearing with break cleaner, dry it thoroughly, re-pack it with high-temperature grease, and press the seals back on. This will fix the noise, however you still can't "roll back the miles" that were put on the bearing--it will never be as good as new. Much better is to simply go to a bearing shop (or shop online) to buy an identical replacement for only a few dollars. If you look hard enough, you will spot a combination of a few numbers/letters on the bearing. This is the bearing's "size." It is standardized; you do NOT have to buy a "Hoover" brand bearing. Hoover doesn't even manufacture their own bearings. They simply buy from a bearing supplier just like you.

Popping in a brand new bearing is the way to make it work like new again. Now simply find suitable rivets or screws which can re-fasten the lower bearing retainer plate and...voila! Smooth operation again!

See below for some pics. I have done this to my Concept One U3317, and I suspect the same can be done for you Convertible. I put in a brand new sealed ball bearing and three new blind rivets. Washers were added as reinforcement to keep the rivets from possibly pulling through the bearing retainer plate as I installed the new rivets.

Disclaimer: Attempt this only if you are sure you can drill out the rivets without ruining the base or bearing retainer plate AND if you are sure you have the correct hardware to re-assemble everything. You do run the risk of ruining things if you do it wrong, however, if properly executed, this service produces great results. I know it sounds like a lot of work, but if you have the right tools and hardware, you can get it done in a matter of minutes.

Good luck, and let us know how it works out.

  Photos...       <              >      Photo 1 of 3         View Full Size
Post# 383056 , Reply# 5   12/23/2017 at 14:02 (210 days old) by hooverU4089 (CT)        

Yes, this is regarding the same unit.

In the thread, I posted a picture of the bottom bearing from inside the motor. The bearing does turn freely and does not have any noticeable play from side to side.

I do believe this machine has not been used much as the outer bag has no major rips and the zipper and base paint are almost immaculate.

The best way I can describe the noise is that it sounds like there are pieces of sand or tiny pebbles occasionally scraping the armature. This is why others' speculations of bad carbon brushes made sense to me. I have pictures of them in the other thread as well. As I said, other than this, the machine runs absolutely perfect.

Post# 383059 , Reply# 6   12/23/2017 at 14:26 (210 days old) by Real1shep (Walla Walla, WA)        

 The brushes will have to seat themselves and unless you use an armature/commutator 'stone' there will be a lot of carbon dust all over.  You can Youtube the process, as it's not hard to do...just have to be mindful of the LIVE current in the armature.



Post# 383065 , Reply# 7   12/23/2017 at 17:07 (210 days old) by hooverU4089 (CT)        

Good to know!

I just checked some videos out. Most of them demonstrated the method of turning the armature by hand with sandpaper wrapped around the commutator to sand the brushes to shape while a few described the process of turning the motor on a lathe or running it. Which is more appropriate for these motors?

Post# 383072 , Reply# 8   12/23/2017 at 19:08 (210 days old) by Real1shep (Walla Walla, WA)        

It's more accurate to chuck them on a drill and use emery cloth. You don't need to spin really fact you really don't want high RPM's until you've done this a lot. And like you saw in the vids, don't let the space between the commutator bars fill with trash....clean them out. 


When your brushes seat themselves, they will generate a lot of carbon on the commutator....sometimes enough that it looks like you never cleaned the commutator. That's why I suggested seating the brushes and then coming back and cleaning the commutator again. 


Basically, you want the brushes seated and the commutator shinny. That's your goal and can be done in different ways.



Post# 383075 , Reply# 9   12/23/2017 at 19:33 (210 days old) by hooveru4089 (CT)        
I'll give the drill a try!

Interesting that you recommend using emery paper. Most other suggestions have been to avoid emery and only use garnet or wet/dry as they do not contain aluminum. I do have 180 grit garnet, which I hope is not too coarse but I'd be interested to hear your take on using emery paper.

Also, are you suggesting that the commutator be sanded again after the brush seating or should I use solvents to clean it?

Post# 383090 , Reply# 10   12/24/2017 at 14:11 (209 days old) by bnsd60m9200 (Ponder,TX)        

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180 grit anything is FAR too coarse to polish a commutator. 2000 grit wet dry sandpaper or use the seating stone and put the armature into a drill chuck and spin it that way. if you use anything under 1000 grit to polish a commutator, itll score it and keep the carbons from making proper contact!

Post# 383095 , Reply# 11   12/24/2017 at 16:35 (209 days old) by Vaclover (Freestate, Virginia, South Africa)        
Grease or oil?

The top of my Hoover U4006 is a sleeve bearing. Do i oil or grease it? I greased mine and it sounds better.

Post# 383097 , Reply# 12   12/24/2017 at 17:10 (209 days old) by Real1shep (Walla Walla, WA)        

Absolutely, nothing coarser than 1000 grit wet & dry paper. Use the stone and you won't have to worry about the paper/type.


You can clean things with denatured don't want to remove any potting finish on the armature itself.





Post# 383135 , Reply# 13   12/26/2017 at 14:46 (207 days old) by hooveru4089 (CT)        
Thanks for the tips!

I did use 220 at first just to remove residue, but I will finish it off with 1000+ before seating the new brushes.

Is denatured alcohol the same as isopropyl?

Post# 383157 , Reply# 14   12/27/2017 at 10:57 (206 days old) by Real1shep (Walla Walla, WA)        

No, it's a lot stonger. You can find denatured alcohol at places that sell painting supplies or a good hardware stores....pretty common chem.  Cleans up vacs especially well, even the cord.



Post# 383159 , Reply# 15   12/27/2017 at 11:25 (206 days old) by hooverU4089 (CT)        

I'll have to get my hands on that stuff. Do you soak the commutator in it or apply it with a paintbrush or likewise?

Post# 383160 , Reply# 16   12/27/2017 at 12:02 (206 days old) by jade_angel (Newport News, VA)        

Denatured alcohol is pretty much just ethanol with enough methanol, pyridine or other chemicals added to make it toxic. Home Depot should carry it. 91% isopropyl alcohol or 91% ethyl rubbing alcohol should serve roughly the same purpose.

Post# 383161 , Reply# 17   12/27/2017 at 12:09 (206 days old) by Real1shep (Walla Walla, WA)        

There's no comparison between the cleaning properties of isopropyl alcohol and denatured alcohol. Just ask anyone who has cleaned tape deck heads with various chemicals.


No, don't soak the armature in denatured alcohol......paintbrush would be fine....always test the potting finish to make sure it doesn't start to come shouldn't if it was done thickly.


Use the mechanic nitrile gloves when using chems...they're skintight and offer excellent flexibility.



Post# 383165 , Reply# 18   12/27/2017 at 14:23 (206 days old) by jade_angel (Newport News, VA)        

I did a little more looking into it, and yeah, I was all wet. Disregard my post.

Post# 383273 , Reply# 19   12/30/2017 at 03:17 (204 days old) by tolivac (Greenville,NC)        

Tape head cleaners----CAUTION!!!!WARNING!!!!DO NOT USE DENATURED ALCHOHOL to clean tape heads will cause head laminations to come apart and the head mount to the head block to come off,too.Use ISopropol alchohol for tape deck cleaning its safer for the parts.I don't think I would use denatured on motor parts,either-could damage the insulation.

Post# 383279 , Reply# 20   12/30/2017 at 09:12 (203 days old) by Real1shep (Walla Walla, WA)        

Not true and you would be at odds with almost the entire tape community I belong to which is over 3,000 members...including EE's and past studio technicians of analog. MEK, acetone and some other strong chems, definitely not to use.


Denatured alcohol is fine for tape heads and I've been using it for over 40 yrs without incident. It's harder and harder to find 99% isopropyl alcohol....anything less and you're using too much water in the formula for tape head cleaning.  



Post# 383300 , Reply# 21   12/30/2017 at 18:38 (203 days old) by hooveru4089 (CT)        

I have taken some of your suggestions and done some work.

I sanded the commutator w/ 1500 grit wet/dry, seated the brushes with a drill on low speed, and lubed the motor bearings.

The motor runs smooth, but it does sound a bit noisier than before. I did also lubricate the brushroll bearings, replace the belt and bag.

Is this extra noise something I should be concerned with?

Post# 383323 , Reply# 22   12/31/2017 at 00:56 (203 days old) by tolivac (Greenville,NC)        

Most tape head manufacturers recommend AGAINST using denatured alcohol for cleaning.Use Isopropol instead.Being doing this for 40 yrs,too.I have had to order replacement heads that get worn out during the older days when RR machines were used all the time in broadcast work.Save the denatured stuff for cleaning insulators in the transmitter-and transmitter tube envelopes,vacuum cap envelops.Works good for these.

Post# 383331 , Reply# 23   12/31/2017 at 07:32 (203 days old) by Real1shep (Walla Walla, WA)        

Well, I couldn't disagree more on the denatured alcohol for tape heads and I have almost an entire tape communnity to back me up, plus over 40 yrs using as you wish. I guess we agree to disagree.


@hoover4089   As far as the noise, you're going to have to be more specific? New brushes will be a bit noisier than old ones for awhile. The spark is what's important should be even, low and not shooting out one side unevenly from the two brushes.



This post was last edited 12/31/2017 at 08:49
Post# 383338 , Reply# 24   12/31/2017 at 09:18 (202 days old) by hooveru4089 (CT)        


What I'm hearing now is not dried bearing noises and the previous scraping noise is now gone. The motor itself just sounds a little noisier. Perhaps I could keep using it for a while to see if it will run quieter after the brushes fully seat.

I did take the motor apart a couple of times after running with the new brushes to clean the commutator with isopropyl.

The motor turned perfectly smooth by hand after I lubricated the bearings. However, it took at least 12 hours for the top sleeve bearing to completely soak the few drops of 3-in-1 oil I applied to it. I had seen some videos on lubricating these bearings and was informed that they should drink the oil immediately.

The top bearing also seemed more difficult to slide back on the shaft. I did sand the bearing surface on the shaft, first with 220 and then with 1500.

Thanks again for all of your suggestions. If this information still leaves you with questions, I could post a video or audio clip of the cleaner running.

Post# 383343 , Reply# 25   12/31/2017 at 10:22 (202 days old) by Real1shep (Walla Walla, WA)        

My old ears aren't the videos don't usually work for person is still the only way I can hear trouble.


The noise could just be increased rpm from a cleaned motor.....hence the motor is louder. I rebuilt/cleaned a truck starter once and it was quite noisy afterward. Like a motor on steroids.....but it worked great and lasted.



Post# 383346 , Reply# 26   12/31/2017 at 11:15 (202 days old) by hooveru4089 (CT)        

@Real1shep: The motor is running at the same rpm as before, just sounds a little more raspy. I think you could be right about the brushes needing to break in a little.

As for the bearing, do the symptoms I have described in my last post suggest that it would be good to replace. The first user to reply to this thread recommended against it but I've heard numerous suggestions in other threads to replace if lubrication is unsuccessful.

I will try to clean it thoroughly again and see if it takes oil.

Post# 383351 , Reply# 27   12/31/2017 at 15:05 (202 days old) by Real1shep (Walla Walla, WA)        

If you're dealing with a sintered bushing that won't take oil from a wick after being thoroughly cleaned, then yes, replace the bushing.  I've actually seen this guess is that the porousity of the sintered bushing is ruined.


New brushes often do make a lot of noise when first used. Watch the sparks though when the motor is running to determine if they are seating properly. If you've got more spark shooting out one side of the brush than the other at the commutator, they're not seated well.



Post# 383458 , Reply# 28   1/2/2018 at 16:36 (200 days old) by hooverU4089 (CT)        

I have done an extra thorough cleaning of the bearing with rubbing alcohol and it subsequently took about 12 drops of oil. I then put a drop on the bearing itself after sanding both the inside of the bearing and the shaft with 1500 grit.

The bearing went on a little smoother and the motor, little by little, is starting to quiet down.

Post# 383482 , Reply# 29   1/3/2018 at 02:50 (200 days old) by broomvac (N/A)        
Hate to say it.

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I would not have sanded the upper bearing surface on the shaft. Not only will the diameter be smaller now (more play), but the shaft surface will likely never be as true or as smooth as it was before. If the surface is not as smooth as it was before, any bearing, new or used, lubricated or not, has the potential to wear out the bearing more quickly now.

But do not panic. Although it may be less than ideal, I'm sure it will last just fine. Replace the upper bearing if you want, but If you have already lubricated the original one and it doesn't sound or look terrible, the original should work just fine too.

The honest truth is, it's a pretty robust vacuum motor that is likely never going to see enough use to wear out any of its components ever again. Use it to your heart's content, let the motor break in after all the work you have performed on it, and enjoy your Hoover. I would be surprised if it ever failed you.

Post# 383490 , Reply# 30   1/3/2018 at 08:54 (199 days old) by Real1shep (Walla Walla, WA)        

You need to burnish a shaft, rather than sand it, I agree.  But putting a blackened shaft end back in from long use is not ideal either. It's easy enough to mic a shaft too, to tell if you've taken off material residue or actual shaft material. The real wear is most likely in the sintered bushing....considered sacrificial by design.


I doubt however if the tolerances in this case are that critical.





Post# 383494 , Reply# 31   1/3/2018 at 09:27 (199 days old) by vacuumlad1650 (Chicago Suburbs)        

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The reason an upper bearing will be stiff is it has not been seated. The original bearings wear down from Round to an Egg shape. You don't want to give an armature spinning at 7000rpm the opportunity to shift back and forth.
Install the new upper bearing, and then rotate the fan by hand. Then, while spinning the fan as fast as you can, give the upper bearing some decent smacks with a rubber mallet. This will seat it, and allow the motor to freely spin with no resistance. Make sure the felt pads around the bearing were soaked with the proper oil (i use 3-in-1 MOTOR oil) so it will continue to self lubricate.

Post# 383559 , Reply# 32   1/4/2018 at 15:41 (198 days old) by hooverU4089 (CT)        

I take it that I need to lubricate the new bearing before installing. Is that correct?

Once again, thanks for all your help.

Post# 383592 , Reply# 33   1/4/2018 at 23:19 (198 days old) by vacuumlad1650 (Chicago Suburbs)        

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I always put 2 drops of the 3-in-1 MOTOR oil in for good measure. Just allow it to soak into the bronze for a few minutes before installing it.

Post# 383601 , Reply# 34   1/5/2018 at 09:15 (197 days old) by Real1shep (Walla Walla, WA)        

Agreed...always 'prime' a sintered bearing like that....then the wick oil will take over. Just make sure the new sintered bushing you use isn't the 'dry' lubricated type.





Post# 383736 , Reply# 35   1/7/2018 at 09:56 (195 days old) by hooverU4089 (CT)        
Here's another update:

I replaced the top motor bearing temporarily with a known good used one and lubricated it. The motor is even noisier now. It sounds like a sick cow.

While running, I turned the lights off in the room to look at the sparks on the brushes. One brush is shooting sparks like an angle grinder on metal while I can't quite see anything from the other brush.

Post# 383797 , Reply# 36   1/7/2018 at 23:19 (195 days old) by Real1shep (Walla Walla, WA)        

I thought you replaced the sintered bushing with a new one? Or are you talking about greased bearing? Sintered bushings wear in relation to their can't usually pop one out of another motor and put on a different shaft....or at least it's not good practice. 


I think most of the noise sounds like it's might be coming from your brushes....they're not seated correctly if you have sparks coming out one side more than another. You can buy a commutator stone online for about $5. I just bought two from a dealer who sells Kirby stuff online. But you have to use it with the motor running for best results and depending on the motor access, that can be a bit, you have to be mindful not to touch any part of the motor with your hand near the brushes because of the shock potential.


You really need an Elmer in this to show you the ropes....keyboards don't get it. That's probably why some here said to leave things alone.





Post# 383833 , Reply# 37   1/8/2018 at 10:21 (194 days old) by hooveru4089 (CT)        

Commutator stones would indeed be tricky. It looks like the only way to do this would be to run the motor with only 1 brush. My only other option would be to connect a drill to the armature and run that, as I had done seating the brushes.

Post# 383877 , Reply# 38   1/8/2018 at 17:05 (194 days old) by hooverU4089 (CT)        

Check out the first picture in this thread. What do you think of this?


Post# 383939 , Reply# 39   1/9/2018 at 12:32 (193 days old) by Real1shep (Walla Walla, WA)        

Best way is to access the commutator while everything is in place.  Stonning it that way works to seat the brushes. Maybe that's why that hole was drilled...dunno. If you can get to the commutator somehow by shaping the stone or drilling a hole....that would be the best way. Stones are like $5 for small ones.



Post# 384148 , Reply# 40   1/12/2018 at 14:11 (190 days old) by hooverU4089 (CT)        

Where in particular are they most readily available online? I've seen few listings on Amazon for bulk quantities but not much.

I think I will probably end up drilling a hole and plugging it up somehow with a plastic plug or cap.

Post# 384166 , Reply# 41   1/12/2018 at 22:10 (190 days old) by Real1shep (Walla Walla, WA)        

Curiously, they are now $8.90ea...they were around $5ea just a few weeks ago. Plastic or rubber plug-great idea for the hole.







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