Bng replacement

[Bill Eilers]

Tip.. don't use open flame 2 warm case removing bngs. As a machinest 4-35 years aluminum does not like open flame.set case on a 150 w light bulb. 15 min or so.

 

[Bill Eilers]

The general idea

 

[Al Hobbs]

I use a table top toaster oven to heat engines and parts. I do get the engine cases hotter than you do to drop out the crankshaft bearings.

Temperature is our friend when dis-assembling or assembling model engines.

Al Hobbs

 

[timothy johnson]

Al, what temp and for how long. I have watched many people at boat races use a torch to remove and replace bearing's. Jim Allen, Feb 13, 2016 said " Briefly heating the case to even 450 F will not change the temper" Comments from a post about removing a stuck bearing in a case, 2016

 

[Bill Eilers]

Yes a toaster oven is an excellent way to heat a case. Any thing but an open flame. Open flame directly on any metal introduces a molecular change on top of being very dramatic uneven heat that can change and warp the base metal

 

[Al Hobbs]

A toaster oven heats the entire crankcase evenly, with no hotter areas and colder areas to distort the crankcase itself. You can damage the case if you do not heat the crankcase evenly.

I heat the crankcase to 300 degrees and let it remain in the oven for at least 20 minutes. Then the bearings should just drop out with no difficulty. If the big bearing does not come out easily, I set it on a board with the open end flat on the board. Then I rap the engine against the board a few times and the bearing should just fall out.

Be careful so you do not burn your fingers! I use an insulated glove.

The engine does not have to be that hot when installing new bearings.

Al Hobbs

 

[K F Wheeler]

Thank you, AL!!!
Ken

 

[Jeff Lutz]

As a machinist and pump rebuilder and SKF certified, never never heat the case over 250 degrees when installing the bearings. Really only 220-230 is well hot enough. Over 250 will cause damage to the bearings. Jeff Lutz

 

[SayMikey]

Have you ever used the Nova Rossi bearing remover and installer? Amazing how it will remove and install with no heat at all. And I might add you can push the bearing in with your hands using this tool.

 

[Rick Doane]

The bearing remover/installer tools made by the manufacturer(s) are great for their specific engines and may or may not fit other makers. Hudy makes these for .12-.21 motors and may fit a larger range of makers. However, I have not been able to find these available for the larger motors and with different crankshaft designs, so I have made the ones needed for the work I do. I do not like to have to heat the case to remove bearings but will use heat to install them. The installation procedure I use for the single counterbalance crankshaft, is to make a mandrel for the crank to sit on with the rear (large) bearing on the crank. The heated case (another discussion topic) is slid onto the mandrel which holds the crankshaft/rear bearing in the correct position for assembly. The front (small) bearing can then be slid onto the crankshaft to its seat and then the flywheel cone, flywheel, and finger tightened collet. The motor is removed from the mandrel and sat in a vice or fixture until cool. This sinks the heat away very quickly have never had any bearing damage.

I will make another post showing the different sizes of bearing pullers.

Rd

 

[Rick Doane]

These were supposed to be attached to the last post.

 

[Rick Doane]

These are the various sizes made to remove and install bearings from .21-1.01 CI motors.

 

[ALLAN YUEN]

These are the various sizes made to remove and install bearings from .21-1.01 CI motors.

Hi Rick I wonder that how much will bearing tool kits for CMB 21 EVO ? Let me know thanks

 

[K F Wheeler]

...So nice to have the perfect tools to do a job the way it should be done!
Ken

 

[James Schmidt]

Have you ever used the Nova Rossi bearing remover and installer? Amazing how it will remove and install with no heat at all. And I might add you can push the bearing in with your hands using this tool.

I have one of those, they are awesome. To bad is dose not work for my CMB engines lol.

 

[Bill Eilers]

I use a table top toaster oven to heat engines and parts. I do get the engine cases hotter than you do to drop out the crankshaft bearings.

Temperature is our friend when dis-assembling or assembling model engines.

Al Hobbs

Mr Hobes. Thanks for all the contbution.

 

[bermudadude]

lets all remember (or learn) NEVER remove or instal bearings without heating the case. we should all know this ..its 2022 and ..the internet.

for the full size mechanics ,yea im [self taught -descendant of mechanic] one too ,these are model engines that take 100 times the beating of a full size comercial or industrial engine.

the bearing seat interference fit is NOT meant to be a press fit i.e its not permanent. e.g i never changed bearings on my 50cc bikes i owned cause the whole shabang didnt last long enough. a model engine goes through a half dozen sets at least before its dead. IF u want to re-use ur case u have to heat it so u dont remove metal [yes ..again ,its high skool stuff] ,,once u do it dry the bearing is no longer sitting square or even in the right place . u SHOULD notice the loss in performance BUT if ur slow anyway ......idk ....i can hear the difference.
the fit of the case also affects the expansion/shape of the bearing . this also explains why the first set lasts 4 gallons the second 2 gallons the 3rd 1 gallon etc.

f.y.i thats why most engines are for sale stating - only 1 tank on new bearings [sorry lol]

 

[Rick Doane]

These are the various sizes made to remove and install bearings from .21-1.01 CI motors.

EDIT: I want to edit this post to include the statement that some of the bearing tools pictured in this post were built by the late, great Jim Wilson. Still miss his wisdom.

 

[shoboat]

Rick,

I am with you about missing Jim’s wisdom.

Thanks,

Mark Sholund

 

[Danny King]

Have you ever used the Nova Rossi bearing remover and installer? Amazing how it will remove and install with no heat at all. And I might add you can push the bearing in with your hands using this tool.

Yes the removal tool and installation tools work awesome with zero heat.