We were experiencing a slight reverse slam in our 1999 SW1. A reverse slam is the “clunk” of changing the gears in an automatic transmission from reverse to any other gear. In Saturn S-Series cars, this is a common problem – usually the culprit of not maintaining the maintenance schedule of the automatic transmission.

After reading countless stories and fixes for the Saturn automatic reverse slam problem, I did it today on our SW1.

Here are the steps:

Get the right fluids for the job. Standard ATF fluid, an additive, and an OEM auto transmission filter from Saturn. DO NOT use a standard auto filter.

The fluids required

Put the car up on ramps.

Put the saturn up on the ramps

Loosen and/or remove the air box. This will give you easy access to the transmission filter.

Remove the air box

Un-tighten the transmission drain plug.

Unscrew the transmission plug

Let the fluid drain in a pan.

Let the transmission fluid drain out

Check the fluid colour as it drains.

Check the colour of the transmission fluid

Make sure you let it dribble to the end.

Make sure you let all of the transmission fluid drain out

Clean up the drips.

Clean up the mess

Check the fluid colour in the pan for problems.

Inspect the fluid

Take off the old filter. A filter wrench will help.

Take off the old transmission filter If you remove the entire air box, it is easier to get at the tranny filter

The old filter.

The old crappy transmission filter

Apply a thin coat of transmission fluid to the new filter seal. Just like an oil filter.

Apply a thin coat of the transmission fluid to the rubber seal

Make sure you watch the transmission sensors and sensor wires when you put the new filter on.

Mind the transmission sensor wires when you put the new filter on

Pour in your additive of choice. Then pour in the ATF.

Put in the additive

Take the car off the ramps and chalk the back tires with the ramps.

Chalk the tires with the ramps, and put it in reverse for 30 minutes Chalk the tires with the ramps, and put it in reverse for 30 minutes

Put the car in reverse with the parking break on. Let the car sit in reverse for 30 minutes – I just used my stove timer to keep track of the minutes. While waiting, this is a good time to clean up the mess, and to check the tire pressure, clean the wind sheild, etc. etc. DO NOT LEAVE THE CAR UNATTENDED WHILE IN REVERSE! Stick around for any problems.

After the 30 minutes, take it out for a spin around the neighborhood. Try regular driving, …backing up, …3-point turns. Anything that will mimic regular driving.

I did this procedure, and our reverse slam was reduced by 95%. I’m hoping this will postpone a valve body replacement for a year or so. In some cases it will completely make the reverse slam problem go away.