These are notorious for rusting on. You can try heating the snot out of it, but you may end up replacing the clutch. Price out the mounting plate as well if this is the case and make your life easier. Can you get in close enough to cut the shaft and press it off? Depends on what chipper you have.

Just out of curiosity, what model of Mighty Mac do you have and why are you replacing the motor ? I have a 12pt10 and have had to make several modifications but, so far, the motor is fine.

tomplum: thanks for the suggestions. I may be able to pop it loose, maybe with heat, then use a lifter-puller tool to gently pull it straight off. I intend to use the old engine for a different application, so don't want to harm the shaft or the slip clutch.

ubique: I have the same model Mighty Mac, a terrific machine. The B&S 1100 series engine has given me some headaches, though, including head gasket replacement (plus the first one they sent with the MM had a cracked head and wouldn't hold oil; they immediately sent a replacement). The main problem has been with the muffler; I've had three replacements so far, finally installed a helicoil in the head, but no luck. It's a bad design (machine screws into the muffler exhaust especially; the new 1150 series has a modified and better design).

I got the new engine without realizing I'd have to get the slip clutch assembly onto the new shaft. Another problem! The one I'm working on the at the moment. If any other ideas on how to get this done occur to you, shoot 'em on over.

Gary

Call or write MacKissic. they have a website that will direct you. They have knowledgeable tech people there who will answer questions.