'89-97 Tbird/Cougar/Mark VIII Speedometer -Odometer Gear Replacement

Replacement odo gears can be found under the "Hoods / Body Kits / Miscellaneous" sections of www.SuperCoupePerformance.com

See this link: HERE TO PURCHASE

You can purchase online or call 513-697-6501 to order.

Failure of the 1989-97 Thunderbird Odometer Gear happens due to excessive heat and age.
You can see the damage caused by the heat.
The plastic gears got so hot the surface shows bubbles which weakened the gears and eventually
caused the gear or gears to break and the odometer to stop working.

The odometer part of the speedometer has a small electric motor which drives a 16 tooth cam gear also called carrier
gear which then drives a 20 tooth intermediate gear which drives the odometer and trip odometer.

16 tooth Carrier Gear


20 tooth Intermediate Gear

Now that you know what the cause of the odometer failure is lets take you through replacing these gears.


Removal of the instrument cluster bezel surrounding the cluster is necessary.
Removal of the instrument cluster from the car is not necessary.
You will need to remove the clear plastic instrument cluster cover first.
Once this cover is off you can just pluck the speedometer assembly from the car
Before you start you need to refer to the Ford Shop Manual for removal instructions.

In addition to the Ford Shop Manual here are a few tips.

Remove the lower panel below the steering wheel.

Remove the vent ducting behind the lower panel.

Loosen the 4 nuts holding the steering column to the dash frame. Lower the steering column about 1 inch.
Remove two retaining screws at top of cluster opening and the three below.

NOTE:  It is NOT necessary to remove the entire cluster as shown in the picture below. 
Remove cluster finish panel by disengaging the 10 retaining clips around cluster finish panel.

Disconnect the rear window defroster switch. Remove the Cluster Bezel from the dash.
We recommend you leave the instrument cluster in the car and simply remove the 7 screws holding the
clear plastic lens cover to the instrument cluster. Shown with black arrows.

Be careful not to scratch the plastic lens when removing it.
Replacement covers are still available from ford for 1994-97 cars. Part number F4SZ-10887-A
Note: Put the plastic lens cover back over the cluster while working on the speedometer this will keep
any dust from getting inside the instrument cluster.

If you are removing the instrument cluster from the dash (which is NOT RECOMMENDED) then remove
the 4 screws holding the cluster to the dash. Shown with red arrows.

Tilt the cluster and remove the two electrical connectors and boost vacuum line (Supercharged only)
going into the back of the cluster.

The speedometer is held in place by three pressure contacts. Grab the speedo and pull it out of the cluster.
Once you have removed the speedo find a flat clean area to work.


Note: Before you remove the needle move it by hand until it stops and using a pencil mark the location of the needle.

Begin by removing the speedometer needle.  You can attempt to use a fork to gently pry upwards to remove the
needle. If there is any resistance we suggest you stop this and remove the reset assembly by unclipping from the
back side of the unit and remove it.  Once removed you can rotate the needle in either direction and it should loosen
easily and come off the shaft.

After the needle is removed flip it over and remove the 3 screws holding the plastic housing to the faceplate.
Shown with black arrows.

Note: The trip odometer spring will fall out when you separate the face plate from the housing so do not loose it.

Once the speedometer housing is removed from the speedometer faceplate you can optionally remove the 4 screws
holding the green board to the housing. This step is not necessary to replacing the Odometer gears. Shown with red arrows.

Next remove the 2 screws holding the Odometer motor to the housing.
Once you remove the screws be careful of the two wires, blue and black. Shown with black arrows.
Using a pick or small flat blade screwdriver disconnect the wires from the housing.

When you lift the Odometer motor off you will see two gears.

Remove the two gears and install the new gears as shown.

Rotate the gear until it seats in the housing.

When installing the Odometer motor make sure the gears mesh together.

Reinstall the two screws holding the Odometer motor onto the housing.
Reconnect the Odometer motor electrical connector.
Install the green board back on the housing with the 4 screws if you removed it.
Before reconnecting the Faceplate and housing back together verify the trip odometer is working.
Pull back on the lever that resets the trip odometer. It should reset without binding.
Any problems with resetting the trip odometer and you have misaligned the gears when you put it back together.
Go back and verify the gears are seated and fully meshed.
Install the trip odometer reset spring over the lever as shown.

Then align the trip odometer reset lever pin and lever back together.

Reconnect the 3 screws holding the housing to the faceplate.
Note: Do not over tighten the screws as you will strip the plastic threads in the faceplate. Snug but not too tight.

Now we reattach the speedometer needle. Press the needle over the pin as shown.
Then adjust the needle so it stops back at your pencil mark.

Reinstall speedometer back in the instrument cluster.
Then re-install the cluster bezel and tighten the steering back up. Re-install the duct and lower plate.
Take the car for a test drive and verify the odometer and trip odometer are working again.

Additional speedometer calibration procedure:

Before you reinstall the faceplate and the bezel an additional speedometer calibration verification procedure can be done.
Note: Tighten the 4 steering nuts back before you drive the car.
Using a GPS like the one shown, or a friend to help you, one can verify MPH speed between the GPS and your speedometer needle.
Drive the car over a level road for 1/2 mile at a 30mph while your friend watches the GPS display it's MPH.
If your MPH is off then stop, shut off the car and pull the speedometer out of the instrument cluster.
If the GPS displayed 35mph while you kept the car at a steady 30mph you will adjust the needle forward 5mph.
Using a thin screw driver inserted behind the faceplate to hold the needle from rotating adjust the speedometer
needle to any hash mark and push the needle up 5mph. Reinstall the speedometer back into the cluster and retest.
The shop manual lists a speedometer error factor. The odometer cannot be recalibrated or adjusted. 

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