My brakes are kinda soft after installing new calipers up front. I bled the whole system, no improvement, so I bled them again. The weird thing is they feel good and solid when the parking brake is on. I am stumped. Is it an issue with the proportioner valve? Any advise would be appreciated.

Did you do an entire 4 wheel bleed or just the front? 

Bled them all the way around, starting on the rear driver's side

Did you bleed the LSPV?

If the brakes feel good when the handbrake is up, that would suggest the problem relates to the rear brakes - maybe you should inspect those and see if they need adjustment.

sound like you need new brake shoes,or adjust on rear

I had a lingering problem with soft brakes on my truck. Never went away until I completely flushed all of the old brake fluid out. Wouldn't you know it on the last line some gunk came out i'm guessing it was floating around the system causing things like the porportioning valve to not function properly etc.   

To do it I did the same procedure as bleeding the lines except I sucked as much as I could out of the resevour before I started and then I just kept pumping fluid through the line until I could tell there was fresh fluid being pumped out.  Went fast and cost $5 for brake fluid. Now I change brake fluid when I do pads.

im having the same issue you are. I just purchased my trackkick. The brakes have been like that since i bought it. I vacuum bled the whole system and ran about a quart and a half through the system with no luck. I pulled the drums off the rear and collapsed my adjuster all the way then had them automatic adjust once i put them back together. That didnt help. So it seems like its either the proprortioning valve or master cylinder to me. Its strange cause if I pull the ebrake up the brakes feel normal as well. Hopefully we can get this figured out soon. I will let you know if anything I try works this week.

Just did my rears and used a Mityvac to bleed them (it). Nice solid pedal.

Not just the rear pads, check your drums and make sure they aren't beyond or at the wear limit. You'll get a spongy feel from the rear brake cylinders trying to move the pads too far. If your pedal feels firmer with the handbrake up I'd look at the whole rear brake system including the drums for wear.

Well, I tightened up the parking brake, and the pedal came back. Now that wheeling season is done, I'll put the rear brakes on the list, along with replacing the front third member with a steel one. Gotta try to find one of a GV, or get one off a sami and weld on a mounting tab.

I can almost bet your rear drums are worn out. And when Is wheeling season ever done? 

 

I can almost bet your rear drums are worn out. And when Is wheeling season ever done?