I have been chasing this issue - literally - for years. I have a "93 Ford E350 Motorhome with front disc and rear drum brakes (RABS). I have had a very spongy, soft pedal and I'm almost positive I've been stopping this coach with only the front brakes. Recently pulled the rear duallys and changed out everything - new drums, hardware, wheel cylinders, shoes...
And I still have the same issue. Today, I've pulled the rear wheels again trying to adjust the brakes. I have spent several hours trying to get them adjusted but I still have no real brake in the rear wheels to speak of. My wife was in the coach, pressing the brakes and I was still able to turn the drums by hand (no tires installed yet) with the brake pedal depressed.
Also, I changed out the master cylinder last year and I have bled the **** out of these brakes!
Any thoughts? My only thought is I still have a hydraulic problem - although the front disc brakes seem to work, OR I still have not gotten these rear shoes adjusted properly to the drums.
Please help! Thanks!
ryan