I have a 94 Pontiac firebird lt1 automatic that seems to have alot more front brakes compared to rear. When stopping in snow, or gravel the rear tires just been spinning with the brake pedal pushed to the floor. Could this be a proportion valve issue or just need bled? Any ideas would be great thanks!

 

Obviously the first thing to check would be pads and rotors.

 

You may have "upgraded" front brake pads on the car and worn out or not-so-great pads on the rear, do you know the history of the pads or have you fiddled with them at all? The front brake calipers are obviously much bigger and provide a majority of your stopping power.

 

Yea it's been like this since I got the car about a year and a half ago. I replaced the front brakes awhile back but never the rear which and probably about half pad.

 

Brake pads make a bigger difference in braking performance than most people give credit to, so you may just want to upgrade to some quality rear pads anyay. While you have the car up in the air, climb underneath and inspect the brake lines and make sure nothing looks out of the norm (no failed attempts at a home-made line lock, pinched lines, ect from the previous owner).