bearing removal

[reg]

guys i need to remove the mains on an aw 250, i read some where that you put the cases in the oven ? and said bearings
will hopefully drop out.
Question are ,  what temp and for how long, do i pre heat oven or just turn it on and bake ?

Thanks...reg

[maico police]

I put the oven on about 160 and leave 'em in there until they're a bit too hot to hang onto by hand and then drop the case onto a wooden bench. If one hangs in there I might use a puller or press rather than beltin' the bejezzuz out of them. I do the opposite putting them in except I might put the bearings in the fridge for a while.

[PCMAX]

For bearing installation I prefer to freeze the gearings overnight and then locally heat the case (around the brg cutout) with a butane torch prior to dropping the frozen bearing in.

[Stevo17]

I pulled the mains out of my Spider today and just stuck the cases in the oven at about 120 celcius. Just long enough for them to reach temp, maybe 10 minutes at the most.  Then I just knocked the bearings out easliy with a hammer and socket.

[reg]

thanks guys, give it a go this arvo

[shelpi]

std procedure is to heat cases in a oven to 120 deg C + if bearings do not drop out gently persuade, i usually have some ice cubes to cool the bearing it helps to shrink and fall out and or slight tap, of coarse cases are supported nicely on hard wood timbers. 
Reverse (assemble) heat cases in oven, have timber supports for the cases to sit on all nice and straight each side of the bearing location on a good firm surface with no bounce or give and if need be tap bearing in with the use of some hard wood driff just under the o.d of bearing, if you have a press even better.
p.s the driff is also good for your seals to be put in with, just make sure the timber redwood, jarrah is of smooth straight unblemished surface finish and coat them with oil, and coat the bearing location too.

if bearing is super loose in the (boss) location you may need bearing locktite

oh yer on assembly of crank shaft and crank halves, warm cases and cool crank shaft ass with oil on surfaces all nicely supported on those timbers high enough so the shafts miss the bench

[brent j]

If you heat the cases you should heat the entire case evenly.
If you just heat the bearing area the bearing bore can decrease in size. If you just heat the bearing area the metal will heat up and expand. If the metal around the heated area is still cold it will not allow the heated metal to expand outwards so the only place it can go is in.
Different case designs will have different effects as things like material thickness and ribs will play their part.

I measured the bearing bore of a large radial engine then heated the centre of the case only. The bore closed up 7 thou (on 10" dia) the only way to get the bore to open up was to heat the entire crank case.

[cappra]

Buy a hot plate. One burner hot plates are about ten dollars. Cheaper than making the wife
pissed off about using the oven! I also stick the bearings in the freezer for a couple of days.
Heat the cases until a drop of water "dances" on the aluminum.

[holeshot buddy]

draw a line in texta on the case
heat it up on a burner when the line
starts to disappear its ready

[shelpi]

  Yer learnt how to piss the missus off use here oven to bake on that nice paint job  :'( me now  has a second hand old stove in the shed on LPG and I have not seen the wife sneek in once and and bake those stinky cookies, and hey anyone want a cuppa.

[tony27]

An old family friend used to use his oven for stove enameling parts for his brit bikes while his wife was at church & told us cooking a good curry hid the smell by the time she got home 

[shelpi]

Damn could have saved myself all that mucking around putting in a stove and had a curry and a nice beer  hey could i cook a curry and heat me cases at the same time

[Nathan S]

A pot of boiling water is an idiot-proof way of heating stuff without ever over-heating it.
Obviously, the water can be a corrosion issue sometimes, but still a useful technique.

[pancho]

 Rather than annoy 'er indoors by stinking up the oven you can sneek in to the boudoir and purloin m'ladies hair drier. Just be sure to wipe off any greasy fingerprints and PUT IT BACK.
 If you want to get real technical you can check the temp. attained with some temp test crayon available from bearing speciallists.
 cheers pancho.

[CRTAD313]

Used this for main bearings on a cr500 today worked a treat.I put bearings in the freezer for a few hours warmed cases at 120c for about 15mins then just palced the bearings in no tools required, great tip guys. cheers.