Try using a extra thick BB for DL holds, shrugs, etc or all your exercise for that matter. Great for cleans/Hi-pulls. Reverse curls comes to mind as one with a thick bar, using a false grip at times. Extra thick bars are hard to come by so you might get some heavy plumber pipe. Select the size you think is demanding enought for your grip. Cut or have them at the store cut it for you. Get a Allen or hex wrentch and remove one of the collars on the bar. Slide the pipe unto the bar. Replace the collar that you removed. Now lift. Can also do this with a pair of DB's. Works well on a chinning bar or even a lat machine. You will get a very strong and improved grip using extra thick handles. And usually in a very short time.
Work out at one of those fussy commerical chain gym/spa's? Too bad for you, but here are a couple of suggestions. One practical way may be to get some extra heavy industrial hose material; water, steam, etc. Cut to size (may need a fine tooth saw or box cutter), which would probably be 7-8 inches, or so. Slit the hoses (long way), open it up and place it or wrap it around the bar. These will be your new gripping handles. Another way is to use roll material, like a karate belt, and wrapp it around the bar and grip these as you lift. Good Luck.
