QuadraFire 802-4400 Exhaust Fan Bearing

[maraakate]

I had to get a new blower motor for my Quad Santa Fe (PN: 812-4400) because one of the two bearings on the shaft were starting to get loud. The fan is over 15 years old so I think it's done well. Anyways, I kept the old one because the only thing wrong with it is the bearing.

The bearing in question is 608S made by NMB. You can probably replace it with a 608-2RS and it will be fine. The ones on mine were actually a rubber shield with metal reinforced on the inside so you can pop them off and re-oil. Doing this made them spin a lot easier, but there's still too much side to side play so it still makes a sewing machine noise.

Not sure who makes good bearings besides FAG? I'd probably avoid buying the cheapest skateboard bearings you can find, or any of the really cheap 10 packs on amazon.

 

[Mt Bob]

Last time I got a few, I used the bay, and looked for expensive ones. Basically quality ones cost lots more. I searched for Japan or German made. BUT, you have to watch out,also,as some Japan and German suppliers also rebox China ones. Honest sellers will list all the pertinent information.

 

[Washed-Up]

NSK is another good quality bearing manufacturer. As Bob said, buying the cheaper ones is a roll of the dice.

Home | Ball Bearings | Roller Bearings | Linear Components | Automotive Components

NSK Americas | Bearings - leading manufacturers of bearings. Ball Bearings, roller bearings, automotive parts, automotive components, bearing units, hub bearings, steering columns, precision bearings

www.nskamericas.com

 

[zrock]

Look at the ABEC rating of the bearing, do some research on what the ABEC rating means..

 

[maraakate]

Look at the ABEC rating of the bearing, do some research on what the ABEC rating means..

Yes, but ebay and Amazon anyone can claim whatever. Just curious on reputable brands that ideally I can order locally or direct.

 

[Mt Bob]

There are many brand name good retailers on the bay, you just have to know what to look for. The last ones I got were German, came in a box marked as such, the ABEC numbers were right. They might even have been marked German, but I am not going to go dig them out, until I need them. Which reminded s me, I picked up an old style Harman motor cheap,as it only had a noisy brg. Will prob. dig it out and do it over the winter.

 

[zrock]

You just have to look at the sellers reviews and sales.... I have gotten some good quality bearings off ebay and Amazon

 

[maraakate]

Update to this, my convection blower bearing started getting noisey. Took it apart and cleaned it, but ordered a new one in the mean time. New one showed up today and the the newer convection blower has steel shield bearings. The old one uses the same NMB 608S. Getting the fan blades off was kind of tricky. Had to carefully use a prybar and some penetrating oil but it did come off without breaking.

 

[gfreek]

So the 608 bearing has a common ID of 8mm, OD 22mm, Width 7mm. Be sure you measure your bearing and shaft, The bearings I had to get for my Harman exhaust blower were 608-ZZ-3123-C3 with a ID of 7.9mm....

https://www.motionindustries.com/products/sku/02717956

 

[maraakate]

Yeah I was planning in these which I think will be good replacements https://www.ebay.com/itm/194031106842

 

[maraakate]

The 608ZZ FAG bearings are slightly too larger on the inner diameter so it won't work with interference fit. Anyone got a known good drop in replacement?

 

[gfreek]

So the 608 bearing has a common ID of 8mm, OD 22mm, Width 7mm. Be sure you measure your bearing and shaft, The bearings I had to get for my Harman exhaust blower were 608-ZZ-3123-C3 with a ID of 7.9mm....

https://www.motionindustries.com/products/sku/02717956

Measure the diameter of your shaft with a caliper. The ones above are what I had to use on my Harman . The bearing ID is smaller than normal 608 bearing

 

[maraakate]

I haven't measured yet, but it appears to be about 0.1mm off so it probably is 7.9mm. I was thinking it might be possible to make a shim out of a soda can before I try to do anything else.

 

[maraakate]

Also, this is for the convection blower. But they use the same bearings. I haven't attempted to get the exhaust blower apart as the set screw is rusted in there and the set screw is slightly rounded off. I'll have to get a drill press and carefully get that out at some point.

 

[Mt Bob]

People still don't get it.
608 is a generic class size designation.
Low or no ABEC classification bearings quality can have broad variations in dimensions.These would be for such crap as your kids skates.Or cheap china power tools. ABEC 5 and above would be what real skaters and tool makers use.
Dimensions can be ordered different for any 608,or other bearing. Sometimes for a better fit,better longevity, sometimes to make the product less desirable to be repaired.
To quote-
"Where a more precise fit is desired, bearings can be obtained that are cali-
brated into narrower bore and O.D. tolerance groups. These can be
matched to similarly calibrated shafts and housings to cut the fit tolerance
range by 50% or more."

 

[maraakate]

Admittedly, I am pretty ignorant to it. I do know there are ABEC ratings. I tried to order higher quality bearings thinking I'd be doing the blower a favour, but did not check the ID exactly so that is my fault.

This is the first time I've ever done this. I've read up on how to do it many times and understand the basic concepts. I bought a vice and a jaw puller set to carefully remove the bearings. And I do know to put the new bearing on you'll have to put the shaft in the freezer and heat the bearings and it should just slide on if you work quickly.

I was going to try a soda can shim, and it's just too thick to pull it off. I had the shaft in the freezer over night and heated the bearings to 250F for about 45 minutes, but it's just not happening.

I'll probably just go to a bearing house locally and see what they can find. The peer bearing that gfreek listed is probably exactly what I need but I think $20 per bearing is a bit overkill for our application, but if there's no other option then I'll have to go with that.

 

[gfreek]

Admittedly, I am pretty ignorant to it. I do know there are ABEC ratings. I tried to order higher quality bearings thinking I'd be doing the blower a favour, but did not check the ID exactly so that is my fault.

This is the first time I've ever done this. I've read up on how to do it many times and understand the basic concepts. I bought a vice and a jaw puller set to carefully remove the bearings. And I do know to put the new bearing on you'll have to put the shaft in the freezer and heat the bearings and it should just slide on if you work quickly.

I was going to try a soda can shim, and it's just too thick to pull it off. I had the shaft in the freezer over night and heated the bearings to 250F for about 45 minutes, but it's just not happening.

I'll probably just go to a bearing house locally and see what they can find. The peer bearing that gfreek listed is probably exactly what I need but I think $20 per bearing is a bit overkill for our application, but if there's no other option then I'll have to go with that.

OK, for installing, putting the shaft in the freezer and heating the bearing, I've done this a few times and did not need to do either....That bearing is most likely special order. For removal I used this but smaller to remove the bearings and a brass hammer or brass punch for the shaft. https://www.harborfreight.com/bearing-separator-63662.html
As for install, Tubing or pipe the exact same diameter as the inner race of the bearing, but able to fit over the shaft to tap it on, at least thats how I did it.

 

[maraakate]

I thought you wanted to tap on the outer race when installing as the inner race will damage the bearing?

 

[Washed-Up]

You’re risking brinelling every time it has some sort of shock…for installing on a motor shaft ,the inner ring of the bearing will require a press fit and the outer ring will be a line-to-line or a clearance fit. Tapping it gently lessens the risk of brinelling the bearing.

 

[maraakate]

I'm a little ignorant to all of this, but when I did motorcycle wheel bearings a couple of years ago (in an actual shop, with someone supervising me) they had a tool that basically was like a socket of the same size you use to drive it in and kept pressure on the outer race, tapping lightly and checking to make sure its driving in evenly.

I'll end up doing the hot/cold method as it's not a big deal for me to do so instead of potentially goofing it up via driving it in.

However, I am curious is it more appropriate to drive it in from the outer race?

 

[Mt Bob]

You drive on the race that is being "fitted" "contained". On a m/c it is tight in the hub, but axle slides in loose.So you tap on the outer. Driving a brg onto a shaft, you tap on the inner. In certain situations, drivers are made to drive in from both races.

 

[maraakate]

Just a small update to do this: I had to get a new blower motor sometime around February or so as it started getting loud and annoying. Well, true to what has been mentioned here before, the newer OEM parts have crappy grease in those bearings too. During my maintenance of first fire of this season I noticed the new blower motor was getting loud. This time around, they changed it to NMB 608Z. It's the same as before, except it has a steel shield instead of rubber. The newer design has a circlip and there's a small amount where the shaft is wider where the bearing seats so it doesn't need much to drive it in as opposed to the old design.

The interesting thing with the new design is the FAG bearings fit properly on the newer shafts. They also got rid of the rubber grommets the bearings sit in.

On my older shaft, I tried taking it to a bearing supply house and they couldn't find any 608's that would fit it. I ended up taking a 0.1mm or similar feeler gauge to make a spacer and put the new FAG bearings on it. Put that back together and that one is currently in the stove and works just fine. So, it appears there has been some small updates here and there between them.

I never got around to getting the exhaust blower apart as the allen is really rusted on there. Need to get a torch to heat that up to get it out and likely retap. Maybe this year, we'll see. Otherwise, stove has been working just fine.