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How to install crank main bearings?

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I split my cases to install a new crank and main bearings. Everything is going smoothly soo far, but I'm having trouble installing the main bearings. I'm practicing on the old bearing so I don't screw up my new bearings. But I put the case in the oven(and another time I used a torch) at 250 degrees for 15 minutes then I freeze the bearings for 2 hours. And everytime I try to put them in, they don't really drop in, i kinda slightly push them alittle then they stop 1/2 through. And I tried this like 4x today.

What should I do? Is there any way to make sure they go completely straight? Is there any thing in my technique I should change? Any tips or anything would be helpful.

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I heated the oven up to 280. I dunno if that would make that much of a difference though. seems like you're doing everything right though. I would see if autozone has a bearing installer that they rent out.

After I heated the cases, I just tapped it in with a large socket that fit on the outer bearing diameter with out touching the crankcase.

you could go to home depot or harbor freight and bring in the bearing and crank case and just buy a socket that fits.

two things: be careful on heating crankcases with a torch!! I've heard warping it is pretty easy to do. also, only light tapping should be necessary with a heated case and frozen bearings.

my 2 cents

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No need to bake the cases. Put the bearings and crank in the freezer for 5 hours. Then with a map gas torch heat the bearing race in the case until it starts to sweat then pull the bearings from the freezer and they will go in with a little help. Don't beat the shit out of them or you will damage the bearings and cases. I have a 12 ton press that makes the job easy. I spent $135 for it at harbor freight. Then once the bearings are in the cases use a brass plumbing fitting that sit's in the inner bearing race and heat just the fitting with the map gas and when it starts to sweat pull the crank from the freezer and it will drop into the bearing. Then while it's still cold put the other case half on and use the case halve bolts to draw the cases together alternating all the bolts to evenly pull them together.

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freeze and heat like u were doing and if they still wont go in take it to a machine shop with a press it doesnt take very much pressure to put them in place

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No need to bake the cases. Put the bearings and crank in the freezer for 5 hours. Then with a map gas torch heat the bearing race in the case until it starts to sweat then pull the bearings from the freezer and they will go in with a little help. Don't beat the shit out of them or you will damage the bearings and cases. I have a 12 ton press that makes the job easy. I spent $135 for it at harbor freight. Then once the bearings are in the cases use a brass plumbing fitting that sit's in the inner bearing race and heat just the fitting with the map gas and when it starts to sweat pull the crank from the freezer and it will drop into the bearing. Then while it's still cold put the other case half on and use the case halve bolts to draw the cases together alternating all the bolts to evenly pull them together.

When pulling the crank into the bearing you should not be using the case bolts to pull it together. You should be pulling the crank through the bearing with the crank puller hard against the inner bearing race where you want it seated.

If you do it the other way you will be loading the bearing which could cause the main bearing to bind.

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Do what your doing but lightly tap the outer race when it's halfway in and it will easily go in.

You have to work quickly!

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So i used dry ice for the bearings this time and then set the oven at 250 degrees. The flywheel side bearing went in perfect. The clutch side bearing didn't fully go in straight and got stuck. So instead of paying $40 for a new bearing. I'm gonna go check to see what the bearing supplier has. Then I'm just gonna have a dealer install the bearing like I should have done in the first place.

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Edit: take it to your local machine shop and have them press it in. I'm sure it'll be a lot cheaper than the local moto chop charges @ #100+ an hour.

Or look on Craigslist for a hyd. press and you'll own the proper tool for the rest of your life.

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