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Flywheel ring gear

Al Johnson

Northwoods Hillbilly
VIP
I have one in the oven at 400°F, will take it out in half an hour. Flywheel has been in the freezer for several hours. Will they go together?

Or am I :owned: ?
 

Al Johnson

Northwoods Hillbilly
VIP
What are ya making?
Trying to make a new ring gear go on a flywheel.

More specifically, a rebuilt/warmed up 1986 Ford 5.0 motor, which will either go into the Jeep or the Falcon. But right now I just want the parts together so I only have to move one item instead of two.

:beerchug:
 

Glenn

Desert Dweller
VIP
Should squeeze on. I remember putting gears on VW crankshafts the same way years ago.

But because it is you, I am sure you will manage to screw it up. :shush:
 

Al Johnson

Northwoods Hillbilly
VIP
I did manage to screw it up. Guess the temperature difference was inadequate. Ring gear still too small to fit on the flywheel. Acetylene torch is the next step. Have to be careful not to get it so hot it loses temper, but how hot is that? Crap.
 

Avid

:avid:
VIP
I froze the flywheel and heated the ring with a propane torch. Greased with assembly grease then used a block of wood and a hammer to do some light tapping. Didn't take much.
 

Jays89YJ

Udaho
VIP
When symmetrically heating a steel part like Al did, that's not already installed on a shaft, the steel will expand in all directions. It doesn't magically know there's a hole in the middle and to only expand away from the hole. Therefore the hole shrank. I could see heating the outer portion of the ring gear which in theory would expand and pull the cooler, inner portion (the hole) out with it.

I believe the most effective way to fit the part is to dry ice the "shaft" part, like Twindows said, and press it in an ambient "hole" part. I've successfully pressed many parts this way.
 

GreenGeep

Timber Baron
VIP
I always heat my hubs and freeze my bearings on my dirt bikes.








End up beating them in with a BFH anyway......:owned:
 

Al Johnson

Northwoods Hillbilly
VIP
When symmetrically heating a steel part like Al did, that's not already installed on a shaft, the steel will expand in all directions. It doesn't magically know there's a hole in the middle and to only expand away from the hole. Therefore the hole shrank. I could see heating the outer portion of the ring gear which in theory would expand and pull the cooler, inner portion (the hole) out with it.

I believe the most effective way to fit the part is to dry ice the "shaft" part, like Twindows said, and press it in an ambient "hole" part. I've successfully pressed many parts this way.
Your premise is correct, but not the conclusion. The steel will indeed expand equally in all directions, by a percentage per degree. So, across the width of the gear, you will get, say, 5% expansion for a certain temperature rise. Same with the thickness. The other dimension of a ring, though, is circumference, and you will get the same 5% expansion of the entire circumference. That will make the hole bigger, by a lot, because the circumference is by far the largest dimension of the part, so you get the largest amount of expansion for the given %. Make sense?

Too bad it wasn't enough to get the ring onto the flywheel.
:woe:
 

Jays89YJ

Udaho
VIP
So you're saying the uniform heat will expand the hole because its circumference is smaller than the outside diameter (ring gear teeth portion) circumference?
 

Al Johnson

Northwoods Hillbilly
VIP
So you're saying the uniform heat will expand the hole because its circumference is smaller than the outside diameter (ring gear teeth portion) circumference?
Not really. What I'm saying is that the metal expands by a uniform percentage in all dimensions, and the longest dimension will have the greatest amount of expansion for a given percentage. (5% of 100 is a lot more than 5% of 2.) The longest dimension of the ring is the circumference, being analogous to the length of a long skinny part. So the largest absolute amount of change occurs at the circumference. Yes, the outside circumference will change by a bit more than the inner circumference, but this is inconsequential. Of course by the nature of circles, a change in circumference is directly related to a change in diameter.
 

Al Johnson

Northwoods Hillbilly
VIP
Thermal expansion equation. I'd still not bother heating the gear and dry ice the shaft part.
Due to my failure with about a 400°F difference in temperature, I'd probably like to try the dry ice for the flywheel, and still heat the ring gear to 400 in the oven. I need as much temperature difference as I can get.
:shrug:

I'm not familiar with the thermal expansion equation. But I'll Google it.
:beerchug:
 
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