Odometer Repair
Procedure for diagnosing and repairing failed or slipped odometer drive gears on early and late 944 models and the 968, including gear selection table and disassembly sequence.
Tools
- Phillips head screwdriver
- Cyanoacrylate adhesive (super glue)
Parts
Replacement odometer drive gears are available from odometer gear specialty suppliers. Search for suppliers using your model year and gear tooth count (see table below).
Other Procedures Needed
- ELECT-07 — Removing Late 944 (1985.5 and Newer) Gauge Cluster
- ELECT-06 — Removing Early 944 Gauges
Introduction
Most odometer problems on the 944 result from resetting the trip odometer while the vehicle is moving. Never reset the trip odometer while moving — bring the car to a complete stop first.
The repair procedure is nearly identical for early and late gauge clusters; the primary difference is gauge cluster removal and gaining access to the speedometer internals.
Procedure
-
Remove the instrument cluster per ELECT-07 (1985.5 and newer) or ELECT-06 (pre-1985.5).
-
For early 944s (pre-1985.5):
a. Push the speedometer out of the front of the cluster from the back. b. Remove the bezel from the front of the speedometer by prying up around the back lip with a small flat-tip screwdriver, working around the circumference until the bezel is free. c. Remove the screws on the back of the housing; the speedometer internals will slide out.
-
For late 944s (1985.5 and newer):
a. Remove the gauge cluster front cover by removing the nine Phillips head screws along the back edge of the cluster.
b. Remove the four screws on the back of the instrument cluster directly behind the speedometer. This allows the speedometer to be removed from the gauge cluster chassis.
-
From this point, the repair is the same for both early and late cars.
-
Hold the speedometer facing away from you and look at the left side for a worm gear — a white plastic screw-shaped gear. There should be a small gear engaging this worm gear to drive the odometer. In most cases this gear has either slid along its shaft and disengaged, worn to the point its teeth no longer mesh effectively, or broken.
-
If the gear has simply slid off the worm gear, use a small flat-tip screwdriver to move it back along the shaft until it engages. Place a drop of cyanoacrylate adhesive on the shaft where it passes through the gear to prevent future slipping.
-
If the gear is not broken or worn, reassemble the gauge cluster — the repair is complete.
-
If the gear is worn or broken, the speedometer must be further disassembled to replace the gear. If you are not comfortable proceeding, the speedometer can be sent to an authorized VDO repair facility or speedometer specialist for service.
Odometer Gear Selection Table
| Model | Odometer Type | Gear (# Teeth) |
|---|---|---|
| 1982–1985 944 USA | Mechanical | 17 |
| 1985.5–on 944 USA | Electronic | 20 × 21 * |
| 1985.5–on 944 USA | Electronic | 20 × 22 * |
| 911 USA | Electronic | 20 × 30 |
| 968 All | Mechanical | 15 |
* Most 944s with electronic speedometers/odometers use the 20 × 21 tooth gear. A small number use 20 × 22. Disassemble the speedometer first to determine which gear is installed. If the old gear is destroyed beyond identification, obtain both sizes and test-fit each.
- After obtaining the replacement gear, disassemble the speedometer to access the gear train.
- If the speedometer has a mechanical stop (pin) at 0 mph (early 944 gauges), gently lift the needle over the stop and let it come to its natural resting position. Mark the full-stop position on the gauge face with a pencil or other easily removed marker. If there is no mechanical stop, proceed to the next step.
- Gently pry the speedometer needle upward to remove it from its shaft.
- Remove the two screws holding the face plate on the speedometer.
- Under the face plate, four screws separate the two speedometer halves. Remove these screws.
- With the halves separated, access the odometer gear train. Most gears must be removed to reach the failed gear.
- The outermost gear (farthest from the gear to be replaced) is held by a pin that can be pushed out with a small jeweler's screwdriver or a straightened paperclip.
- Remaining gears are held by small E-clips, which can be removed carefully. Reinstalling E-clips requires patience.
- After replacing the failed gear, assemble in reverse order.