Stuck bearing

[John Seybold]

Hi,

I'm changing bearings on some MAC 67's that I purchased. The inside bearing on one of the motors won't come out. I heated the case in a toaster oven at 350, tried the torch, this one just doesn't want to come out.

Any ideas???? Thinking about soaking it in some penetrating oil and trying again.

Thanks

 

[Tom Foley]

MAKE TWO SMALL ALUMINUM INSULATORS SO YOU CAN GRAB THE MOUNTING LUGS WITH A LARGE PAIR OF VISE grips (cap lock off now !)

Grab the case very tight on the lug and heat well and evenly with Mapp gas torch and strike the case carefully but firmly on a small piece of 2X4 on the bench . It will come out . Heat is the key 350 F is not enough to get that bearing out . When cool clean the inside of the case with a small piece of red Scotchbrite pad with hot soapy water in the sink , clean completely .

 

[timothy johnson]

Ditto, tried the oven and toaster oven @350 as Tom said not enough heat. A big heavy leather welding glove is your friend, the torch will getter done.

 

[John Seybold]

Thanks guys, added some more heat and it finally came out. Now it's time to get everythig clean and put back together.

 

[Ray Sametz]

MAKE TWO SMALL ALUMINUM INSULATORS SO YOU CAN GRAB THE MOUNTING LUGS WITH A LARGE PAIR OF VISE grips (cap lock off now !)

Grab the case very tight on the lug and heat well and evenly with Mapp gas torch and strike the case carefully but firmly on a small piece of 2X4 on the bench . It will come out . Heat is the key 350 F is not enough to get that bearing out . When cool clean the inside of the case with a small piece of red Scotchbrite pad with hot soapy water in the sink , clean completely .

Duck bill vise grips work great for holding the case without marring.

 

[Tom Foley]

MAKE TWO SMALL ALUMINUM INSULATORS SO YOU CAN GRAB THE MOUNTING LUGS WITH A LARGE PAIR OF VISE grips (cap lock off now !)

Grab the case very tight on the lug and heat well and evenly with Mapp gas torch and strike the case carefully but firmly on a small piece of 2X4 on the bench . It will come out . Heat is the key 350 F is not enough to get that bearing out . When cool clean the inside of the case with a small piece of red Scotchbrite pad with hot soapy water in the sink , clean completely .

Duck bill vise grips work great for holding the case without marring.

Yep , great tool !

 

[Jim Allen]

Most manufactured engines are cast from A 357 silicon aluminum casting alloy. The aging temperature to bring the alloy to a T-6 temper (45,000 psi tensile) is 340*F. The temperature must be held for 4 to 5 hours to reach the T 6 temper. Briefly heating the case to even 450*F will not change the temper.

Jim Allen

 

[Tom Foley]

Good to know ! After I put in bearings I blow it with a blow gun so it cools off a little quicker , always worried about the polyamide retainer melting .

 

[dave roach]

I put the crank and bearings in the freezer over night and when i am ready to put the bearings in I heat the case not as hot when taking them out drop the crank with the big bearing in turn it up side down on a alum rod to hold the crank in the block install the small bearing and cool it off with a little ice.

 

[Jim Allen]

Good to know ! After I put in bearings I blow it with a blow gun so it cools off a little wicker , always worried about the polymide retainer melting .

Tom,

Polyamides are Nylon compounds combined with some types of monomers. Since they are Nylon compounds they could begin to distort at temperatures of approximately 350* F. Your idea of cooling the retainer with air is good if the actual temperature used is unknown.

JA

 

[Brad Christy]

Guys,

I have noticed that 350 degrees, while rarely enough for removal, is usually enough to install bearings. With that last tidbit from Jim, along with Dave's advice about the freezer, you're pretty safe using an oven at 350 degrees to install new bearings without risk of distorting the retainers. Ice cold bearings and the shop air to cool the case immediately following installation should ensure the bearing retainers never reach a harmful temperature.

Thanks. Brad.

Titan Racing Components

BlackJack Hydros

Model Machine And Precision LLC