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Crank bearing installation

Sawyer94

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Hey all,

Cut to the chase, I’m wondering the fastest and easiest way to install bearings and then install the crank in my Frankenstein 660 I’m building. I see videos of everyone just dropping them in with heat. I have heated the cases up and have no luck with the bearings sliding in. Any advice would be appreciated as I haven’t installed many bearings before. Is there a type of press used to push the bearings in from the shop?

Thanks!
 

Squareground3691

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Hey all,

Cut to the chase, I’m wondering the fastest and easiest way to install bearings and then install the crank in my Frankenstein 660 I’m building. I see videos of everyone just dropping them in with heat. I have heated the cases up and have no luck with the bearings sliding in. Any advice would be appreciated as I haven’t installed many bearings before. Is there a type of press used to push the bearings in from the shop?

Thanks!
Are you heating the cases hot enough, and placing bearings in the cold ,
 

Sawyer94

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Yeah I don’t have a temp gun so I can’t ID 250°F. It must just be that I am not heating it enough because I never got the cases smoking hot.
 

Sawyer94

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The times I have tried the bearing slides in but stops maybe 1/8” down.
 

Stump Shot

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For an easy way to do this with heat, first put the bearings on the crankshaft. I like to use the microwave method as you can not overheat a bearing. Simply take about four wet paper towels and wrap the bearing in them. place in the mic for about 3-4 minutes(the towel should be starting to get dry) take out and slide on all the way, making sure if not identical to have them orientated correctly. I also have a driver handy just in case one were to hitch up half way, then it can be tapped on the inner race the rest of the way if necessary. Usually if I have it ready I don't need it and just the reverse if I don't.
Now take your loaded crank and drop into a heated mag side case half, it should just drop right in and bottom out, Get your gasket on the alignment pins(I like a little grease to help hold it) and heat the pto side half and drop on, the alignment pins are going to slow it down, I like a plastic faced hammer to tap it in smartly until flush. Working fastly here is a plus. Place case bolts and tighten evenly.
Lastly there may be a bit of side tension on the bearings from being installed. Again working fast tap the crank with a brass hammer until the bearings are free without friction. If you flick the crank with your finger it should not go a little and just stop, rather rack back and forth a bit before coming to rest.
Trim the gasket with a razor blade and get to building that saw! :)
 

Stump Shot

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Yeah I don’t have a temp gun so I can’t ID 250°F. It must just be that I am not heating it enough because I never got the cases smoking hot.
I started with a heat gun and noticed the case was smoking every time it got hot enough, so I gave up on the gun and just wait for smoke to appear.
Put bearings in freezer, and get cases up in heat ,
You can if you like.
 

Sawyer94

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For an easy way to do this with heat, first put the bearings on the crankshaft. I like to use the microwave method as you can not overheat a bearing. Simply take about four wet paper towels and wrap the bearing in them. place in the mic for about 3-4 minutes(the towel should be starting to get dry) take out and slide on all the way, making sure if not identical to have them orientated correctly. I also have a driver handy just in case one were to hitch up half way, then it can be tapped on the inner race the rest of the way if necessary. Usually if I have it ready I don't need it and just the reverse if I don't.
Now take your loaded crank and drop into a heated mag side case half, it should just drop right in and bottom out, Get your gasket on the alignment pins(I like a little grease to help hold it) and heat the pto side half and drop on, the alignment pins are going to slow it down, I like a plastic faced hammer to tap it in smartly until flush. Working fastly here is a plus. Place case bolts and tighten evenly.
Lastly there may be a bit of side tension on the bearings from being installed. Again working fast tap the crank with a brass hammer until the bearings are free without friction. If you flick the crank with your finger it should not go a little and just stop, rather rack back and forth a bit before coming to rest.
Trim the gasket with a razor blade and get to building that saw! :)

Awesome! That helps a bunch. I really appreciate you and everyone else taking their time to stop and drop a comment. I will most likely give your method a shot or a variation of it. I assume I haven’t been getting the cases hot enough but would rather be safe than sorry.

The microwave way doesn’t damage the micro or the bearings at all? My lady would probably kill me if I managed that. Bad enough I’ll have to sneak a pair of bearings into the micro. Haha
 

Deputyrpa

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When I say smoke, it should be from oil soaked into the metal pores, not the paint. I use a mapp torch and the paint stays fine.
Yep. I used a heat gun on a thoroughly cleaned case. The 034 I did last week was clean and didn't smoke, but I got it hot enough to slip in easily. I installed the oil pump as a stop and dropped the plastic-caged clutch side bearing in the hot case and cooled it quickly with air, then the crank into that bearing and cooled it fast again, then I dropped the flywheel bearing onto the crank, and lastly the other case half onto that bearing. I fingered it was the best method to avoid melting the plastic cage. Would the plastic cage bearing survive the microwave?
 

Stump Shot

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Awesome! That helps a bunch. I really appreciate you and everyone else taking their time to stop and drop a comment. I will most likely give your method a shot or a variation of it. I assume I haven’t been getting the cases hot enough but would rather be safe than sorry.

The microwave way doesn’t damage the micro or the bearings at all? My lady would probably kill me if I managed that. Bad enough I’ll have to sneak a pair of bearings into the micro. Haha
The wet paper towel shields the microwaves from the metal bearing.
Yep. I used a heat gun on a thoroughly cleaned case. The 034 I did last week was clean and didn't smoke, but I got it hot enough to slip in easily. I installed the oil pump as a stop and dropped the plastic-caged clutch side bearing in the hot case and cooled it quickly with air, then the crank into that bearing and cooled it fast again, then I dropped the flywheel bearing onto the crank, and lastly the other case half onto that bearing. I fingered it was the best method to avoid melting the plastic cage. Would the plastic cage bearing survive the microwave?
The steam from the wet paper towel does the heating so, no it will not overheat a bearing in any fashion. I've done dozens and dozens and it's the easiest way I've found.
There's still oil in the pores of the metal case that will come out and smoke when heated properly, no matter how clean it is.
I don't know why you would put it in the blind side(pto) first when the other side(mag) will index it, I guess that's just me. As long as it is right in the end that's all that really matters.
 

cuinrearview

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I press the bearings on the crank with an arbor press then toss the assembly in the freezer. I heat the cases with a heat gun. I usually get enough engagement the first time to get case bolts involved, then pull everything together. 550xps don't particularly care for this method though.
 

Deputyrpa

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The wet paper towel shields the microwaves from the metal bearing.

The steam from the wet paper towel does the heating so, no it will not overheat a bearing in any fashion. I've done dozens and dozens and it's the easiest way I've found.
There's still oil in the pores of the metal case that will come out and smoke when heated properly, no matter how clean it is.
I don't know why you would put it in the blind side(pto) first when the other side(mag) will index it, I guess that's just me. As long as it is right in the end that's all that really matters.
I did it that way to minimize the heat put upon the plastic cage bearing. The oil pimp also indexes the bearing. Messing up on step one is easiest to correct as well. Next time I'll try the microwave method. Thanks for the tips.
 

Al Smith

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Another option of heating the inner race is use a large soldering iron .
 

Sawyer94

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The wet paper towel shields the microwaves from the metal bearing.

The steam from the wet paper towel does the heating so, no it will not overheat a bearing in any fashion. I've done dozens and dozens and it's the easiest way I've found.
There's still oil in the pores of the metal case that will come out and smoke when heated properly, no matter how clean it is.
I don't know why you would put it in the blind side(pto) first when the other side(mag) will index it, I guess that's just me. As long as it is right in the end that's all that really matters.
Hey would you mind clarifying that last part about how flywheel side will index it? That’s also a concern I have because the pto side case half has no stop.
 
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