When I purchased my Z it had a dead battery (actually it was a fairly new battery from down south where the car was from and we were having an extreme cold snap here in CT, like 2 degrees outside, so I think the New England weather killed the battery) Anyways, I went to Sears and bought a new Diehard Weather Handler. It works well and starts the car fine when charged, but with the battery brack on the negative battery cable barely sits and clamps down on the terminal. I'm afraid it may pop off one of these days.

Any suggestions?

If you have those universal battery clampson there, get rid of them. They are not the best thing; not too efficient & you will get voltage loss. Find yourself a battery place and have them make you a new set of cables.

Since the new battery probably has side termnials too I would just replace the cable with a new side terminal type. I've found that these tend to corrode less that the top terminal type.