crankcase in the oven

[ROOFCOCK]

so i split my cases and cleaned and inspected everything. (putting in a 4mm long rod crank) when i noticed the bearing in the upper case half....where the clutch arm goes through was hard to turn and missing 3 needles. i am having trouble removing the race. so i was looking through my oem manual and in the water pump section it stated you could put the cover in the oven and bring it to about 200 degrees to assist in bearing removal. can i do this with the crankcase as well or will it distort its shape. we all know this project isnt cheap and i dont want a $10 bearing turning this into a mess. any help would be greatly appreciated

[brock_fuzzy_69]

thats the method our local shop uses

its what he suggested for removing a case bearing on a dirt bike i had

 

he puts a piece of plywood down on the floor and gently slaps the case onto it and the bearing usually falls out

 

has the new bearing handy and frozen then slides it right in

 

i would say that there is plenty of material in that case to keep it from any distortion

[Nightrider]

I don't think you'll be able to get the bearing out that way.To remove a bearing with heat,you have to apply the heat very quickly to the area outside the bearing,you have a very small window to work with as the heat will soak into the bearing itself and begin to expand the bearing race.Aluminum has one of the highest heat transfer rates and ovens heat too slowly for bearing removal.

 

Using a Benzomatic(with a good tip) start heating far from the bore,move quickly and work your way in using circular patterns.You'll get to a point where the bearing will probably fall out if you turn it on its side or gently tap it out making sure it stays fairly square in its bore.

 

Now as for installing,The oven trick works good,since the aluminum is expanded and the bearing is room temp.The bearing should slide right in,but be careful if you get it stuck and it gets cocked badly,get it out fast.The heat will begin to soak in quickly since the transfer rate is very high on aluminum.The case could be distorted if the bearing is badly cocked and allowed to cool.

 

Aluminum,steel,and bronze can be heated this way for fast removal of parts,but cast iron is a different animal and will crack if certain precautions are not taken

Edited October 3, 2004 by Nightrider

[SICK BOY]

That's the way I remove crank bearing in the old Triumph bikes.Heat the case up in a oven,and then slide the new frozen bearing in.Works like a $2 whore.

Edited October 4, 2004 by SICK BOY

[Nightrider]

Sick Boy,you don't look like the Triumph type,more like Harley.What gives?

[SICK BOY]

I love old Brit bikes Triumph,Norton,BSA.I've owned one Harley,and when I sold it I went and bought a 72 Triumph Tiger.

[brock_fuzzy_69]

gotta luv the sound of those single hole triumph's

[SICK BOY]

I prefer the twins.

[ROOFCOCK]

thanks for the input. i am waiting for the bearing in the mail since my local stealer didnt have it...of course

[thebloker]

You might just have to cut the bearing out with a dremel, or even drill down the side of the case where the bearing sits. I couldn't get mine out and had to take it to a machine shop. I tried everything, heating while freezing the bearing, slapping it, pulling on it with everything I could imagine, and it just wouldn't budge. It eventually was cut out by drilling down the side of the case. Getting it back in was just as hard, I tried to freeze it with dry ice while heating the case and even that didn't work. Had to take it back to the shop to have them press it in and they didn't even get it all the way down. You would be surprised at how big of a pain in the ass that little roller bearing can be.

[stu]

i had this problem on my cbr400 with the rear wheel bearings. i was told by the engineer across the street from me that there is one easy way to solve it:

 

we put a ring of weld round the inside of the bearing, put loads on so you can get a bar/hammer to it. when the weld cools down the bearing contracts and with a few gentle hits of the hammer drops straight out. it was sooo easy. id recommend this method to everyone.

 

stu

[superchicken]

i pulled mine out with a 4 inch 1/4-20 bolt and nut,a 1 inch socket and two washers.pounded the two washers though the top of the bearing so they sit inside that little lip,plased the socket over the bearing ran the bolt through and put a nut on the inside of the bearing below the washers.tighten the bolt up slowly and shell come out.i took pics cause i know it would come up one day.ill try to find them and post them