RA40 3spd Automatic Trans Issue

[PhillC]

I have a 1980 Celica RA40 3-speed automatic.

From when I bought the car until just recently the transmission always had firm gear changes as it normally should.

However around 2 days ago the transmission started acting differently. The way it changed gears was not unlike having a badly slipping clutch in a manual.

First gear engages with no issues, but the trans "slips" into second gear and nearly all of the drive disappears, and third gear is unrecognizable. Putting my foot down the engine RPM climbs an amount, but then seems to get bogged down with no real noticeable increase in speed.

In addition, step-down from 3rd doesn't seem to happen - again, RPM increases but there is no real noticeable increase in speed, and no "kick down" which I always experienced - just like a badly slipping clutch in a manual car feels like.

One possible cause I have thought of is a throttle linkage that is faulty in some way, and limiting the amount of power the engine can produce which is messing with the changes. However the engine still revs happily when not in gear using the pedal. Does anyone have experience with this issue?

I have changed out the transmission fluid with new stuff, but that has had absolutely no effect. I did not notice any metal in the discarded fluid, so I do not believe there is any physical damage to the gearbox.

I'm not terribly good at explaining things like this - but the best I can come up with is it feels like punching into a slush puppie.