sourdough

So my new to me 99,000 mile 1985 4x4 trucks automatic is clunking into Overdrive. ATF fluid smells and looks fine and driveshaft u-joints are good and that's about all I know. Shifts 1,2 and 3 seems fine. It's just the 4 gear change that's clunking but is good once engaged. Kinda bummed as it was shifting OK a couple weeks ago when I bought it and drove 120 miles home. If I need to get a rebuild, who's the best, Marlin Crawler?

patches1045

Mine was doing this to but it would shutter/wobble at part throttle going down a hill really bad. I took the d-shaft off output put shaft of transfercase the t-case flange was warn slightly on the splines. Undid the center nut cleaned and retotorqued totally mint. This is the 2nd 1 I've had to do that with.

sourdough

I've been searching for a DIY repair and found zero info. I have found the transmission is an A43D and has a shift Solenoid. I believe the O.D. Solenoid is working because transmission shifts in/out of O.D.. I have yet to find out why the in/out shift is so abrupt. So much so that I keep the O.D. button off around town at speeds under 45 MPH. More discovery to come. BTW, this site seems to have too many open threads, ones with the O.P. posting and no follow up. Anytime I start a thread I will post a conclusion.

patches1045

Yeah it's definitely working. Could be fluid ,filter,disconnect the battery buy grounding out positive. Never had 2 in old stuff newer but if everything else checks it ain't gonna hurt anything.

sourdough

Help me understand. Disconnect the battery and ground the vehicles positive cable to , ? discharge the system. Is that like a reboot ? I was thinking the OD solenoid was hydraulic,but I'm learning. I just replace bushings on the front axle torque rod. Got a good look at the transmission. The pan was cleaner than everything around and looks like someone had it off recently. Also saw the OD solenoid was external and that the pan has a drain plug. I will be draining the ATF(looks pink)and adding a cleaner. I read a drain refill only takes 2.5 Qts., so might do this a couple times hoping it does magic

patches1045

The discharge of the computer memory probably won't do anything more like checking all the boxed. Yes the solenoid is on the outside drivers side. I don't know exactly the amount of trans fluid but in positive its more than 2.5 qrts. I think there about that just for the overdrive. I worked at a trans shop and never met a single person in multiple shops that have ever been inside of 1 cause they usually rot away before the trans dies. The other thing u can check is the tv/kick down cable make sure its not to tight or to lose that would do it to.

2ToyGuy

Actually, the whole "Grounding" thing takes no more than pulling the negative lead off the battery for a couple of minutes. You shouldn't need to do anything to the positive lead. At MOST, if you want to, you can pull the positive lead off, and then touch it to bare metal someplace. That will discharge any static charges that have built up. Personally, I wouldn't touch the positive lead to bare metal while the negative lead is connected, but it shouldn't hurt anything. As long as you wait at least 90 seconds before you do. The airbag system has a back-up power supply that holds a charge that long. It's just a safety thing to not suddenly discharge it.

Bare metal is any bare, clean, unpainted metal. The body metal, the engine metal, and so forth. Even putting a wire on one of the ground points of the engine, and touching it to the positive lead, as long as it's off the battery. Do NOT touch the positive lead to bare metal with the negative lead still attached. It's just not safe.

Does that answer your questions?
Pat☺

sourdough

Haha, thread kinda got off onto electronic controlled transmissions, of which my 85's is not. Anyway, that YouTube guy Scotty K. had me worrying cause he said if your transmission shift rough in/out of O.D., it's failing. Maybe I should consider myself lucky. I have done a drain and fill including a bottle of Lucas transmission additive, which improved O.D. shifting during 100 miles of driving.