Author Topic: A method for loosening dissimilar connections threaded or interference fit.  (Read 433 times)

Offline Dan Case

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A method for loosening dissimilar connections, corroded threaded connections, or interference fits.

I cannot take credit for this method. Dick Roush in Washington state gave me the answer I was lacking.

A few years ago I was trying to dismantle the drive end of the original alternator for our black car. The ball bearing was rapidly becoming an issue that could not be ignored. I was doing fine until the carbon steel bearing race would not let go of the die cast aluminum drive end case. Over weeks of time I tried soaking the interface in every kind of "penetrating oil" I had plus a couple I bought, no joy.

I tried heating the case to make it expand, no joy. I tried ice cooling the rotor shaft and bearing while heating the case, no joy. I tried low weight dead blow hammers of increasing size, no joy. I tried gentle press pressure left over night, no joy. Then I talked with Dick by telephone one day.

Dick told me to get some natural honey bee wax, a heat gun, and a way to measure temperature. I had the wax, it is used for lubricating wood screw threads here. I had a heat gun and I had an infrared non-contact temperature sensing device.  He said put wax chips around the connection you want apart and slowly heat to 250F. He said using an oven would be okay for most assemblies that were temperature safe too large to use a heat gun on.  He told me to try separating pieces when 250F was reached. It worked! The bearing came right out of the case with ease and then the bearing slipped on the rotor shaft easily also.

I was happy, the original alternator for our car went back in the car with a new drive end bearing.

Since then I have used variations of the method with more heat to get secondary stop grub screws out of Ford and Holley brand 4V carburetors and with a small torch to get hopelessly rusted in exhaust manifold studs out I had given up on before;  plus other devices I had thought impossible to unthread.
Dan
1964 Cobra owner since 1983, Cobra crazy since I saw my first one in the mid 1960s in Huntsville, AL.