Corolla Automatic Transmission Shifting

You did not mention whether you have an automatic or a manual transmission, but since you are implying that it is an automatic, I'll give my 2 cents assuming that it is an automatic.

What is the condition of the automatic transmission fluid (ATF)? Is it red, brown, or black? What it the level of the ATF?

Assuming that the ATF level and condition are satisfactory, my guess is that the accumulators are worn. Automatic transmissions have a pump that is turned by the input shaft, and as engine RPM increases, pump output pressure increases. At higher RPM, shifts will be harsher due to the higher pressure, and accumulators act as a shock absorber to reduce shift shock, kind of like slipping the clutch a little on a manual transmission instead of popping the clutch.

The increased shift shock is not harmful, and is actually a little better in terms of internal friction surface wear but if you want to reduce the shift shock, a competent technician should be able to change the accumulator without too much trouble, as long as there is good access to the transmission pan and valve body.

Hi Ray,

Yes, it is automatic. The fluid is in good shape, and its always been changed every 35-40,000 miles.

Just some further info,it happens only when in third gear. There also a noticeable, but slight "bump-bump" when downshifting (and a quick "bump-bump" when accellerating).

These patterns have all fix the discription of 'shift-shock' I've read about, and otherwise the car drives great.

Tom

Keep an eye on the condition of the ATF, and if it doesn't bother you, don't worry.