No Reverse - 5r55E
About that question "has anybody solved the no reverse problem"?;
Not I, but I've put in a lot of effort on mine, and will wrestle it to the ground eventually. Here's what I have, and have done so far;
99 4wd w/ 5r55e w/ 250 K mi.
Initial problem presented as slow to engage in reverse. As miles piled up, problem got worse. Began to experience problems w/ forward shifts.
Pulled trans to do a rebuild, found brass bushing pieces. Found the source to be the Fwd. clutch cyl. assy, which would not separate due to the direct clutch drum assy friction pads having turned in the housing, which caused the bearings & bushing to become destroyed too. Replaced those hard parts, rebuilt trans, including a new torque converter, rebuilt VB from Central VB (that had all new solenoids, a new EPC, and the pressure check form to prove it was tested), new bands (2 fwd and 1 rev / low), friction and steels throughout, "D" type O rings on the reverse servo, the reverse servo sleeve kit for the smaller bore, new intermediate and front band servos, and as you might have guessed, I also installed a drain bolt to make the ol' "open er up again" routine a little easier. I probably forgot to mention some of the steps, but you get the gist of it. There is no EPC pressure tap (to my knowledge), only a Line Pressure tap that's directly behind the TRS (or DTR, whichever you prefer to call it). My line pressures at an idle of 650 rpm +/-, w/ an ECT of 187 deg. F +/- are; P=74 to 105, R=100, N=75, D=60, 2=60, 1=60. W/ a slight increase in idle, pressures are all in range of ATSG recommendations (pg 24 chart 401). WOT pressures also appear to be within range, although since reverse is weak (breaks loose easily), I let off as soon as it starts slipping.
My next step; the reverse servo extendo pin. Why? Because I'm thinking my reverse servo bore (the outer bore) is perhaps a little worn, bell shaped even, which is either causing the piston to stick, or allowing leakage. So, by putting the pin in, I'll be placing the outer O ring on a straighter, less worn spot on the bore. An alternate to that is to shorten the pin, to accomplish the same "fresh, un-worn bore" goal, but that will allow delayed rev. engagement I think.
Based on what I've read here so far, the more knowledgeable and experienced people have given a lot of good advice. I also think (but don't know for certain) the casing outer reverse servo bore may be what ails some of these "no reverse" issues. I'll keep you posted on what gets my reverse back on-line.