Replacing a nonworking tachometer in a '78-'93 Mustang is easy with basic hand tools.
We were able to obtain a used replacement tach for our '92 LX 5.0 subject car from Midwest Mustang, which has an extensive inventory of used parts for '79-'04 Mustangs. If you order a tach, specify whether your car is an '87-'89 (no airbag) or a '90-'93 (driver-side airbag). Midwest will also need to know if you have a 5.0 (7,000 rpm scale) or a 2.3L four-cylinder (6,000 rpm scale).
We always try to make our articles helpful and informative. We think this how-to is exactly that: a useful repair-type examination of a procedure we've never covered before.
The cars we're focusing on are the '87-'93 Fox-body Mustangs; the project is the replacement of a factory tachometer. A '92 LX 5.0 hatchback that recently became part of our stable of Mustangs had a tachometer playing the role of a dead fish. At idle, the tach would read 3,000 rpm. During normal driving, the range on the gauge was only about 3,200 rpm with no accuracy throughout the engine's range of operation.
We'd never seen this before in a Fox Mustang, but it's no surprise as little things on these cars stop working on a fairly regular basis. The solution was to replace the tach with another unit from a donor car. Even with our less-than-spectacular mechanical ability, we tackled the project ourselves. The result was a resounding success, as we did it in two to three hours with no more than a few basic hand tools.
A friend introduced us to a valuable source for used Mustang parts. Midwest Mustang in Lawrence, Kansas, graciously supplied a used Fox-body 5.0 tach that worked perfectly once installed in our car. Keep Midwest in mind for any used parts you might need for '79-'04 Mustangs.
1. Accessing the gauge cluster in an '87-'93 Fox Mustang requires the removal of several dashboard components. Begin by removing the toggle switches on each side of the dash binnacle. This is done by pressing the clips out of the way so the switches can be unplugged and removed from the car. | 
2. These clips need to be pressed in to separate the switches from the binnacle. | 
3. Once the switches are out, they can be unplugged. If they're stubborn, careful prying with a screwdriver will help. |
4. Next, detach the lower trim panel from the steering column by removing two screws. Also being removed here is the plastic cover for the anti-submarine panel. Pull the cover firmly and it will come off. The panel underneath is held in place with several screws. | 
5. To access the bolts that retain the gauge-cluster bezel, remove the anti-submarine panel, a metal piece that prevents the driver from being forced underneath the dash in the event of an accident. It's held in place with several fasteners. | 
6. Two bolts up top, along with several bolts underneath the steering wheel, are detached so the bezel can be removed to access the gauge cluster. Although these are Torx bolts, they also accept a standard-size socket. That's helpful since the windshield limts the available space. |
7. Once all the bolts are removed, the gauge-cluster bezel can be lifted out of the car. | 
8. With the bezel detached, the cluster is ready to come out. It lifts free from the dash after removing four bolts with a nut driver or socket. | 
9. The speedometer cable unplugs from the speedometer by pushing the nylon collar to one side. |