I have a plastic covered dead blow for that task as well as a spinner socket that can be used.. I forget the weight of the hammer, but I think it was a couple of pounds.. I will look today after services and post here..
Here's a different idea. Get your hands on a solid alum rod about 2 1/2 -3" in diameter and a couple of feet long. Then use it as a drift and place one end on the knock off and hit the other with whatever you like.
A few things here. One, is that you no longer need to "reach" into the wheel with your swing therefor reducing the possibility of hitting the wheel with the hammer. Two, is that you can stand more upright as you make your swing. Lastly you can use a nice steel hammer. They are cheap, smaller for the same weight, and don't get deformed in use. 2-3 pounds is enough weight for the hammer.
I am still waiting to get time to work on my cars but have purchased a 3 pound lead hammer mold.
The hammer takes up less space than a deadblow and is fun to make.
And with having a mold when it gets beat up it can just be recast.
Did my own lead hammer, recycling old lead fishing sinkers... cast in a coca-cola aluminum can (cutted and removed after casting), with a metal shaft fitted through the can (If you wanna try that, just mind the lead vapour, which are toxic...heat and cast lead in open air only, wearing a proper mask).
I used 3kg of lead (more or less 6Lbs), lighter would be useless IMHO.
Cheap and easy to do (with the additionnal pleasure to be able to say : I did it myself ) :laugh:! Heavy, i.e efficient and unlikely to damage the rim or the spinner due to softness of lead and no back bouncing effect. Works perfect !
Of course subject to shape distortion when used, but easy to shape back in re-hammering it (I used the same one since five years, periodically reshaped...)