O-200 Motor Mount Bolts

[atypicalguy]

I guess I dont really u derstand the conical mounts very well. The bolt axis is largely constrained, so the motor is pretty tightly constrained radially about that axis. The cones only provide motion along the bolt axis, fore and aft.

[6643]

I'm not sure I understand what you're getting at. The point of either mount is to reduce the engine vibrations transmitted to the airframe, not to facilitate any movement of the engine.

[atypicalguy]

They are the same thing. The way the transmission of vibrations to the airframe is reduced is by allowing the motor to move independently of the mount.

I guess there is more movement required along the long axis of the motor mount bolts due to the prop thrust/drag. Movement along the other two axes is more limited.

[atypicalguy]

Ok so what does the normal early mount look like with the conical rubber bushings? They must have a conical surface to land on and a washer on the outsides to smash both rubber bits into the conical mating surfaces. So what was the stock Cessna setup for the conical mating surfaces for those rubber pieces?

No, the mounting surface is the same. The only difference is the 140a mount is about an inch shorter from the firewall to the mounting surface.

The "conical" comes from the shape of the surfaces in the engine mounting ears.

lords_on_the_left_208.jpgConical mount.jpgLord mount.jpg

Those Lord mounts look quite a bit better from a fundamental engineering standpoint than the conical stuff I have going on. I should probably just switch everything to Lord. Do the Lord bushings require a different engine mount/frame?

[atypicalguy]

Ok so what does the normal early mount look like with the conical rubber bushings? They must have a conical surface to land on and a washer on the outsides to smash both rubber bits into the conical mating surfaces. So what was the stock Cessna setup for the conical mating surfaces for those rubber pieces?

No, the mounting surface is the same. The only difference is the 140a mount is about an inch shorter from the firewall to the mounting surface.

The "conical" comes from the shape of the surfaces in the engine mounting ears.

lords_on_the_left_208.jpgConical mount.jpgLord mount.jpg

Those Lord mounts look quite a bit better from a fundamental engineering standpoint than the conical stuff I have going on. I should probably just switch everything to Lord. Do the Lord bushings require a different engine mount/frame? - -edit- Nevermind I see you mentioned the 140a frame is about an inch shorter from the firewall to account for the thicker Lord mount.

[6643]

Do the Lord bushings require a different engine mount/frame?

The engine case is different. The C85-14F and O-200 engines take lord mounts. The Lord mounts extend an additional half inch or so aft so the engine mount has to be shorter by the same amount.