Scooterotica

Anyone tried putting the case with all bolts etc removed, ready to split, in a hot oven for awhile? Seems the aluminum case would expand at a faster rate than the steel in the bearing assemblies thus easing the task.

Likewise, putting the ready to assemble case assembly in the oven and the penetrating parts - crankshaft etc - in a freezer could make reassembly easier.

If you've done theses what temperatures?

Not going to do much good on the pre split phase. There are internal connections that need to come apart before you can get to the bearings. Stripping apart a hot motor is no fun. Just remove as much as you can at room temperature. When you get to the bearings, just use a propane torch. Most of the time after about 5 min the bearing should fall right out.

Freezing parts is a waste of time and will introduce moisture between the alloy and steel.

What kind of motor?

I would have thought that putting an assembly of any type into an oven would allow heat to soak into all of the parts, meaning you were reliant on relevant expansion rates, and probably not a great idea.
however applying heat and cold to mating interference parts to allow them to be assembled is common practice in engineering. I have frozen bearings, and heated cases with blow torches many times. If you are worried about moisture condensing on the cold surfaces, oil the bearings before freezing them.

Grumpy225 wrote:
Freezing parts is a waste of time and will introduce moisture between the alloy and steel.

What kind of motor?

+1

A home freezer is so close to ambient temperature that it barely makes a difference. Say 18 degrees ambient and -10 in the freezer, but you can easily raise the temperature to 300 with a heatgun. So that's about 10 times more effective.

We reduce bearing temperatures at work because we can't heat the things they're going into ('kin big lifting devices) but we do it using dry ice.

hendy wrote:

Grumpy225 wrote:
Freezing parts is a waste of time and will introduce moisture between the alloy and steel.

What kind of motor?

+1

A home freezer is so close to ambient temperature that it barely makes a difference. Say 18 degrees ambient and -10 in the freezer, but you can easily raise the temperature to 300 with a heatgun. So that's about 10 times more effective.

We reduce bearing temperatures at work because we can't heat the things they're going into ('kin big lifting devices) but we do it using dry ice.

Thats fair comment, we used to use liquid nitrogen, but I would steel freeze the bearings at home. I agree that the greater effect is from the blow torch on the casing,as aluminium has typically twice the thermal expansion rate of steel, but the greater the temperature differential the better. If your ambient is 20 degrees C and you achieve -20 degrees C, a 40 degrees differential is worth having.

It all depends on the fit to start with.

Its a simple case of BS4500 Vs Coefficients of Thermal Expansion