[Fred Kiehl]

My first guess is that there is a bad circuit board on the cluster. If the speedo works and the odos do not, it means the board is getting a signal from the VSS, but it is not getting to the odos. If you need a board, I have a couple.

The fender is easiest to do if you get one with the brace (not wheelhouse) and the hood hinge attached. You have to unbolt the hood on the side to be swapped, detach the hood strut at the fender (brace the hood), remove the two rows of screws around the wheelhouse 10 & 13mm, the corner of the core support 10mm, bumper cover 10mm, remove the headlight mount 10mm, two beside the vapor cylinder 13mm, one at the rear trianglulators 13mm, one under the foam at the end of the rear hood seal 13mm, one screw under the fender Phillips, and the two at the door hinges 13/15mm (open the door). Make sure you save the shims. You may have to loosen/remove the wheelhouse extension 7/10mm to get the bumper cover low enough to get the fender off.

 

[Fred Kiehl]

If you need a wheelhouse, get the fender with it attached. You only have to remove the two bolts behind the wheel, and the three around the vapor canister, and the accessories on the wheelhouse. Be careful with the ABS connector, they are generally fragile, and will often crumble in your hand. You can splice another one in, if it does. To replace the wheelhouse with the fender, you do not have to remove the 10mm bolts around the wheel opening or the 13mm ones between the fender brace and wheelhouse.

The fender can come from any year, but the wheelhouse is 91-93 specific, but can come from a Caprice sedan or any 91-93 wagon.

 

[Fred Kiehl]

Replacing the wheelhouse is not a big step from replacing the fender. The one you have could be worked back into shape with a hammer and dolly. If you have one, I would just replace it.

The circuit board is fairly easy to replace, you just have to be careful putting the screws back into the plastic. They have a dual thread trace, and if you get the large one in the small track, it will strip the plastic. You can tell if you have them in correctly because they will thread in with your fingers until they are almost completely installed. I believe the issue is with the circuit board, because both of the odos are not working and the speedo is, which means that the signal is good to the cluster. The speedo and the odos use the same signal.

I can sell you a board for $30, or a complete cluster for $55. You will have to swap your cumulative odometer to the donor part, or take the one in the donor apart and adjust the mileage. It is a simple Geneva mechanism.

 

[Fred Kiehl]

I have not had the replacement boards fail. I do not know if they can be repaired, but if you know what is wrong with it, I assume it can be. Figuring out what is wrong with it is the main problem. There are some resistors that get hot, and could be the culprit, but you would have to know the value of the resistor.

 

[Fred Kiehl]

Once you have the cluster out, there are a lot of gold colored screws around the perimeter of the board. Protect the face, and remove all of the gold screws, then you can lift the black cover, and pull the board off of the pins of the gauge motors. Work carefully from the top and bottom, and do not overly bend the board. There is a black cover over the back that needs to be retained. Unplug the odometers, and you have it off. The cumulative odometer is screwed to the face from the back, and can be removed to swap with the donor, or the donor can be disassembled and the mileage changed to match the original in your car. As stated prior, make sure you put the screws in the correct traces, because they will strip if you do not. Use your fingers to turn them in almost all of the way. If they will not go in with your fingers, they are in the wrong trace (once in a while they will be a little stiff to turn). When reassembling, make sure you wipe any fingerprints off of the face before installing the cluster.

 

[Fred Kiehl]

To remove the dash, you have a lot of screws to take out, and you need a 7mm socket. First remove the two screws that hold the column access panel to the support at the bottom. Next carefully remove the column access panel. Next tilt the steering wheel in the full down position and remove the tilt lever if you can. Remove the 4 screws that hold the glove box door and remove the glove box door. There is one screw under the dash at the brake release, one at the driver's side of the glove box, and 5 across the underside of the dash pad. Chock the wheels, and shift the car into 1st gear. You can now gently pull the dash off of its clips. It may take some wiggling to get it past the steering column, the bottom of the dash pad, and other assorted pieces that interfere with it. There are a couple of receptacles for the column access cover clips that like to catch on the bottom of the support. You can put the gear shift lever back in park once you have the dash out.

The cluster comes out with 4 7mm screws, and be careful to remove the gear position indicator cable from the left side of the rotating part of the column. The cluster comes out by rotating the bottom toward you and removing it to the left. The shift lever can be in park, and you can still get it out, although you may find it easier with the shift lever in 1st.

You need a 5.5 mm socket or a small torx bit to remove the screws on the back of the cluster. The caution in removing and installation of the circuit board is that you get the dual trace screws in the correct tracks in the plastic when reassembling, or you will strip the plastic. The traces are different sizes. You should be able to turn the screws at least half way in with your fingers. If they are tight, you have remove them, and get them to go in the other track.

When reinstalling, the cluster in the dash, remember to hook the gear indicator cable up to the column, and adjust it so that it shows evenly in neutral window with a little white in each dot on both sides of the top of the neutral window.

 

[Fred Kiehl]

The change may be related to why the other parts did not work. If the odometers had a bad circuit it may have influenced the speedo. My speedos have always run high by about 3 at 50 MPH with the stock tires. Your odometer probably runs a little fast as well. I put 29 inch tires on my white OCC (stock is 28 inch), and the speedo is about correct. The nature of the 91-93 VSS makes it almost impossible to get it exactly correct. You could change the driven gear by making it one tooth smaller, but the gears are almost impossible to find. What gears do you have in your car (SPID code G??, and your tire size)? If you know the gear ratio, you can look for the gear you need. An electronic pulse modifier is available if you want to correct it easily without having to look for the gear.

 

[Fred Kiehl]

GM8 is a 2.56 ratio, and should have a light green 34 tooth driven gear. I do not think GM makes a 33 tooth gear, so you would have to get a pulse modifier to correct it, or get bigger tires. I would vote against the tire size change because of the gearing. The pulse modifier is cheaper than the tires as well.

If you can find a GU4 or 5 rear, you could put a green gear (42 teeth) in it with 225 70s. If you use 325s with a GU5, you will be looking for a 43 tooth gear that is impossible to find. I have one of the gears, but I am not willing to part with it at this time. I think I am going to frame, and display it. To the best of my knowledge, it is the only one not in a car anywhere in the world. There are some other quirky things about changing driven gears...39 and under teeth uses a different VSS than 40 and over.