Are you talking about the direct clutch in the overdrive unit? If so, then yes, it can cause a no reverse with forward gears working
so if I overhaul the overdrive unit being the main trans air ck good that should fix it
Well, I don't want to guarantee anything, of course but given the synmptoms and what you have already checked, it's goijng to be the most likely cause of the problem. Just to double check, we are talking about a complete reverse failure and not just slipping, right? Here is a list of possibilities of a reverse failure with forward gears working. Let me know if this is enough info for you,1. Gearshift linkage/cable misadjusted/damaged.(Repair or replace linkage as needed)2. Park Sprag sticking.(Replace OD annulus gear)3. Rear band misadjusted/worn(Adjust band or replace, but you already checked this)4. Valve body malfunction(Since this is not checked by air pressure, it might be worthwhile looking in to for worn valves and/or bores) 5. Rear servo malfunction(You already checked this-the band did tighten around the drum, right?)6. Direct clutch in OD worn.(This is the one I was talking about, but it involves disassembling the OD and replacing worn or damaged clutch parts as required, so I'm reluctant to send you down this road without checking other possibilities)7. Front clutch burnt.(This one also involves major work, namely disassembling the transmission and replacing worn or damaged parts)
Thank you for your help,I will go through the overdrive and go from there.