Auto tranny downshift

[jrpamn21]

A follow-up question regarding my automatic transmission. My auto tranny shifts just fine(both upshift and downshift) but after sometime usually in heavy traffic i experience a jerky downshift from 2nd to 1st gear. This is when i accelerate to 2nd gear and abruptly let go of the gas pedal. The previous owner said he had a transmission oil change and i never got to know if he put the correct ATF viscosity. Could this be the cause of the rough downshift?

[takza]

If your not sure about the ATF in it...probably best to flush it and put in some good stuff? There's a writeup on doing it. Just use the kind recommended for a Toyota. Plus Lubegard if you can find it?

[Petros]

If it otherwise shifts fine in all other conditions, it is not likely the fluid. It could be the linkage that needs adjusting, or the vacuum switch if it has one (check for a vacuum leak). Since auto trans were a relatively new item in small cars it might just be the results of the design of the trans in such a light car. You can make it shift smoother by easing off the throttle rather than just letting it up, once in the habit you will not even notice.

[terkill]

that would happen in my el camino sometimes, its a combination of the fact that you are putting stress on it by hitting the gas the second it downshifts, and that its an older transmission. happens in my friends 1995 Corolla too.

a fix, in my opinion, what i did was i waiting a second after it down-shifts. i used to do it a lot at stop signs since i rarely stop at them unless theirs a car, usually glide through em.

[jrpamn21]

Actually the jerky downshift happens when i happen to be driving for more than twenty minutes(with the engine at normal running temperature), with a cooler running engine it still is a smooth downshift. With our terrible traffic here in Manila, it is always a stop and go situation, meaning just barely taking off and hitting 20 mph and having to step on the brake due to an unintentional sudden stop, sometimes it feels and sounds like running over a pothole.

Thanks for your advise, best to look first into this before going to a tranny specialist.

[takza]

While flushing it and putting in synth ATF plus Lubegard might not solve this problem...it will help the trans last longer. Hot weather and city traffic means an overheated trans. Probably needs adjustment too?

[ARCHINSTL]

I'm just throwing out something, as I've never owned an auto trans car (no, boys and girls, and I got my license in '56...).
Could a reason for the overheating be some blockage of the cooling lines between the radiator and the trans - or sludge accumulation at the bottom of the radiator preventing heat transfer from the lines to the coolant?
Again - just a throw-out.
Tom M.