Replacing Tach Gear Drive Oil Seal

Been getting oil leakage from my mechanical tachometer drive (‘81 XJ650 Maxim), so I decided to replace the oil seal. I got the mechanism off the bike no problem, but I am now struggling to remove the part that allows access to the oil seal. Tried penetrating oil, tried heat, nothing seems to work. Also tried screwing in both directions, in case it unscrews clockwise or something.



To make matters worse, my largest screwdriver barely fits here, so it has been prone to stripping little bits out of the thing.



Anyone ever had trouble getting one of these unscrewed? Any tips?

 

If you have the body of it clamped in the vice, you're tightening the grip of the body threads.
Try grasping the body with strap type of thing and heat it a bit.
Also, put a thin blade on edge across the slots.

 

Yes, they can be a beast to remove. Dave's suggestions are good, also some penetrating oil will be helpful as well as a few moderate whacks with a hammer on the threaded stud can be useful in breaking the seizure.

 

Dave, your suggestion was right on the money. I still used the vice, but I moved the clamp down to below the threaded portion, and it made all the difference. I also was able to source a flat blade socket that was wide enough to span the gap, which helped a lot with avoiding stripping the thing.