Removing front wheel bearings

Atlas Commando · Dec 19, 2020

I searched the forum with my question with no luck. I'm removing and replacing the bearings on the front wheel of a disc brake '72 Combat. Per the manual, I am supposed to gently heat the hub with boiling water. I'm looking for a drier way to heat the hub and knock the bearings out. The wheel won't fit in our oven and I don't want to buy a bearing heater. Has anybody had any luck with a heat gun? I'm contemplating using our iron. Or, if I remove the tire, I might be able to get the wheel into my garage sink and pour a boiling kettle or two over the hub. It's tempting to put some gentle heat on it with a propane torch. I do have a temperature gun so could monitor the temperature rise.
How are the cool kids doing this? Thanks for your time.

texasSlick · Dec 19, 2020

I have a professional heat gun. I am sure it would be adequate to drop the bearings out of a wheel hub, although when I did mine a few years ago, I used the propane torch ...... gently.

I am not sure my wife's hair dryer is equal to the heat gun.

Slick

Bernhard · Dec 19, 2020

Boiling hot water is the safest way to heat alloy.
Just remember to put your new bearings in the freezer over night before inserting them into the pre heated wheel hub, I've done this loads of times, it's the recommended way - so what's your problem?
You are pouring the hot water around the alloy hub, tilted down wards, not the old wheel bearing, which would defeat the object of trying to keep them cool.

Time Warp · Dec 19, 2020

I just use a heat gun.
It is probably more important to drive the bearings out without cocking them in the bore and to draw them in at installation, seated on the locking ring side and drawing the other side up to the spacer (with a disc that covers both the inner and outer race)

I did machine the inner spacer to suit a wider commonly available off the shelf 5203-2RS bearing (no more felts) which the hub was all but designed to take given the depth of the hub bore.
That depth makes it importance to draw the stock width bearing in to avoid excessive preload to one race or the other. (imho)

Tornado · Dec 19, 2020

Electric heat gun should be fine. No harm to the ally unless you go crazy.

Lots of top bike mechs use propane to head cyl heads, gearboxes etc to release bearings. Usual rec is to heat so that a drop of spit or water sizzles away.

Torontonian · Dec 19, 2020

I just use an electric heat gun too. Very safe and handy for the layshaft bearing upgrade , bushes , etc.
An idea is to drop an ice cube onto the bearing just before the pull out. Yes to freezing the new bearing before drawing it into the hot alloy hub. The bearing must go in straight , never at any angle. There are sealed wheel bearings available now .

Atlas Commando · Dec 20, 2020

Thanks for the advice everyone! I lost a heat gun in the fire, and this is a good excuse to replace it. Engine and gearbox cases fit in my barbeque grill, but a wheel is a bit more of a challenge. I'll set up an appropriate draw-in system for the new bearings and put pressure on the outer races only. I think I've got enough threaded rod, large washers and appropriate sockets.

CanukNortonNut · Dec 20, 2020

I use a small propane torch. Fast heat and does the job.

EstuaryBoy · Dec 20, 2020

I believe there is another train of thought that eschews freezing the bearing on refitting, as that can hasten the localised contraction of the heated hub at a time when you don't need it.....

Torontonian · Dec 20, 2020

EstuaryBoy said:
I believe there is another train of thought that eschews freezing the bearing on refitting, as that can hasten the localised contraction of the heated hub at a time when you don't need it.....

First I've heard of it. Heat the aluminum , freeze the bearing. Work fast. Time is critical.

EstuaryBoy · Dec 20, 2020

Torontonian said:
First I've heard of it. Heat the aluminum , freeze the bearing. Work fast. Time is critical.

'à chacun ses goûts', as our Gallic friends might say..... Unless fish are involved, of course

Time Warp · Dec 20, 2020

EstuaryBoy said:
I believe there is another train of thought that eschews freezing the bearing on refitting, as that can hasten the localised contraction of the heated hub at a time when you don't need it.....

You might note I mentioned nothing about cooling the bearing (beyond room temperature)

norton bob · Dec 21, 2020

In years gone by, an old parafin blow lamp , the kitchen gas hob, now i have a propane roofers torch, an electric heat gun , a gas camping burner , a gas barbeque , a plumbers torch. A Halogen flood light. DIY gone mad !!.

Atlas Commando · Dec 21, 2020

I found a heat gun yesterday at Home Depot for $23. It has 2 settings, 750f and 1100f. I should easily get that hub up to sizzling spit temperature. The Norton is in intense competition for my time and attention this month, but ideally I'll get a chance to try it today.
When it comes to installing new bearings, I find that freezing the new ones doesn't seem to do much versus heating the new home. I had to install my new Super Blends in my engine cases twice (can't remember why but I am quite certain it was something stupid) and went without freezing the second time with no problem at all.

EstuaryBoy · Dec 21, 2020

Time Warp said:
You might note I mentioned nothing about cooling the bearing (beyond room temperature)

I was responding to #3 and #6....
Thing is, we all have the means to add large amounts of heat via ovens, torches et al, yet unless a liquid gas is used most cooling methods (the domestic freezer/icebox) won't reduce temperatures by anywhere near a similar amount.
Does anyone know size reduction involved? If any?? Is the expansion/contraction linear? And we're usually concerned with two different metals as well. I seem to remember from first year physics that water had an anomalous expansion rate, though that was close to it changing form (liquid to solid), so may be irrelevant here.
Ramble over

Removing front wheel bearings

Atlas Commando

texasSlick

Bernhard

Time Warp

.......back to the 70's.

Tornado

Torontonian

Atlas Commando

CanukNortonNut

EstuaryBoy

Torontonian

EstuaryBoy

Time Warp

.......back to the 70's.

norton bob

Atlas Commando

EstuaryBoy

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