Post a form video.
You could try chains across your shoulders.
I do weighted chinups with a belt and the belt presses against my lumbar spine which makes it hurt. I am not able to hold a dumbbell between my thighs because it slips down. I also can't hold it with my feet, because the pullup bar is so low that I need to curl my legs up to not touch the ground. How can I do painfree chinups? Can anyone show his "setup" that works?
Post a form video.
You could try chains across your shoulders.
Try using a bigger belt? Extreme option, use your normal squat belt, one hole looser, and a normal trousers belt threaded through the hoop to suspend the weight.
That's what I use, btw: a 4-cm high 'normal' belt, and another 1-inch high normal belt, connected by a loop of metal wire.
Hope this helps,
IPB
There are no chains in my gym but maybe I'll buy some. Here is my form.
YouTube