3 Speed Transmission in a 4 speed Car

It’s pretty obvious that someone dropped the ball somewhere. If you paid for a four-speed transmission and the shop installed a three-speed, it’s quite obvious where the fault is. It is up to the shop to make good with the proper transmission.

The trouble is — if you had just provided a bit more information it really would have been helpful — that, although your question implied they installed the wrong transmission, it is never really stated so it’s like working on a transmission in a closed shop with the lights off and only a tiny candle for light, instead of even a worklight.

So, assuming that you contracted for the proper transmission, the shop should have installed the proper one. It is not that a three-speed transmission won’t work in a four-speed, it is just that there are some parts that may have to be adjusted like the half-shafts in the transaxle, the transaxle itself, the bellhousing, the locations of various cooling hoses and such.

You will also have to adjust the three-speed shift console, the linkages and any electronic control modules that may be affected by the four to three swap.

From the performance of the transmission you just had installed, it is obvious that the shop may not have correctly adjusted the clutches and bands and it is also obvious that they may have misjudged the amount of transmission fluid that had to be installed as it seems like your tranny’s performance indicates low fluid.

These are just broad-brush strokes of the problem. If it isn’t fixed soon, it is quite possible your Corolla will need another replacement transnmission soon. This time, though, the shop will likely have to pay for it.