So I'm running abone stock 700r4 in my toyota and it's been working great since I got it running and have put around 500 miles or so on it. The TV cable is adjusted perfectly and I've never had a problem before now. It's never got hot or anything. well on friday I changed the filter and fluid in it, whiched looked good, no metal shavings or anything. Put it back together and took it out to pismo all day sat and sunday. Well on the way home the tranny felt like it would go into neutral whenever I'd let off the gas or try and downshift it. It wouldn't go till I got back on the gas then it would rev and thud into gear. I havn't done anything to it and it's full of fluid, any idea what would cause it or how I can fix it. Thanks.

Mine was doing the same thing. Took it to a few transmission shops and they all seemed to have a different reason why it was doing it{none of which thought it was fatal}. Drove it everyday for a little of a year, it was in my Daily Driver. 5 weeks ago i put a new tranny in the car because the input sprag had broken, would still go in reverse, just not forward. The guy that built it said that it had something to do with it because he found nothing else wrong with it. And it works like a champ now.

Input sprag yes, but it should be better when in drive, second, or first. In those three positions the overrun clutch is on, negating the action of the sprag.

I would check you filter for cracks and the filter seal for leaks. You may find a problem with mainline pressure causing this issue, and since you recently changed the filter, I would go back to that first. You may be getting air in the system at low rpms.

the filter doesn't have any cracks and seems to be sealed up just fine. Could it be the torque converter?

sounds like you have no engine braking which would be caused by a problem in the overrun clutches could be a cracked piston bad seal input shaft seal or a prblem in the VB with the overrun circuiit

the input shaft seal is leaking now, could that cause this to happen. and yeah there's no engine breaking at all, like when you get a manual valve body.