One of the things that just makes a car is the gauge cluster. We're big on driving our vintage rides, and with 30 or more years on the odometer, it's rare to have all of our gauges even work, let alone look good. Functional gauges are essential for a driver, but faded numbers, dull faces, hazed lenses, and faded-out needles just look shabby. Staring at faded gauges that have an erratic or noisy speedo needle just sort of takes the shine off a pleasant drive.
For our non-running, long-term projects that have more items missing than not, we tend to snatch up parts as we come across them, throwing bits and pieces on the shelf in the hope we'll eventually have enough to put together one good "whatever" from the pile of carcasses.
That was exactly the case with our Second-Gen Trans Am gauges. When we gathered up the pieces to send to AutoInstruments in Collinsville, Virginia, we had a little of this, a little of that, and none of it very good.
The core of our set was a late 100-mph speedo cluster, but we wanted the earlier 160-mph speedo. We found one, but it had been "converted" by someone to include a trip odometer, cutting the 160-mph speedo face to accommodate it (with a can opener, from the looks of it). The rest of the gauge faces were rusty, the lens faces were hazy, and the printed circuit on the back was torn and mangled. We didn't expect any of the gauges to function.
This is what we provided to...
This is what we provided to AutoInstruments. "Not pretty" only scratches the surface. At least nothing was cracked in half! Notice the 100-mph speedo gauge face. See how it has two openings at the bottom for the Fasten Seatbelts light and Brake light? This type of face was installed in '75-to-'79 Birds. The earlier '70 1/2-'72 160-mph gauge face only has a small rectangular opening for the Brake light, as you can see here. We want the 160-mph markings on the two-opening gauge faces as on the '73-'74.
Here's the gem of the collection-someone...
Here's the gem of the collection-someone put a trip odometer in a 160-mph speedo by cutting the window for it. It was butchered.
We called AutoInstruments and explained what we had, what we wanted to do-restore them all and convert to the 160-mph speedo-and asked if we needed to find better cores. We were told the speedo conversion is one of the company's most popular upgrades, and the mess we were sending wasn't a problem. "We restored Hurricane Katrina gauges every week for over a year and a half," owner Gentry Zentmeyer told us. "We had instrument clusters that were submerged in muddy salt water for weeks; then left to rust and mold before being sent to us. Your gauges won't be a problem."
We felt a little better about sending them off, but not much. Salt baths or no, we expected a call back telling us to hunt for better cores. It never happened. We cover the restoration and modification of these gauges, so you can see much of what goes into the process.
When the instrument cluster was completed, we were shocked-the gauges looked perfect. The 160-mph speedo conversion looked like it was shipped that way from the factory, the clock was updated with a quartz movement, the instrument faces looked brand-new, and the plastic lens was crystal clear.
Let's cover the highlights of how it was all done.
The first order of business...
The first order of business is to strip down everything and evaluate it. Note the gauges are marked (Top Fuel, Top Volts) to identify each one and its orientation in the cluster; it can be tough to tell once the faceplates have been removed.
A special IC puller, as used...
A special IC puller, as used in the computer industry, is required to get the pointers off the instruments. Without these pliers, the mechanisms can be ruined.
The temperature and fuel gauges,...
The temperature and fuel gauges, and voltmeter housings are riveted to the faceplate. The rivet heads are cut off and the unit is opened up. After the gauge is restored, new rivets are installed and set to look just like the originals.
In this pile of parts everything...
In this pile of parts everything is stripped down to its bare essentials. This is taking it past how Pontiac did it-this is how Pontiac's suppliers put them together.
These are the internals from...
These are the internals from our original speedometer. Rusted and dirty, the original lubrication is caked and some parts are broken. The important parts are the frame, which houses a bronze bushing (upper left); the speed cup with hairspring (lower center); the speed cup housing (lower left); and the speedo drive and magnet (upper right). When a speedometer needle is acting erratically, bouncing, and/or squealing, if it's not a lubrication issue with the cable then there is excessive clearance between the speedometer frame's bronze bushing and the steel shaft of the speedometer drive. Since none of these parts are available new, AutoInstruments has an extensive morgue of donor clusters and NOS drives and parts.
The speedometer drive mechanism...
The speedometer drive mechanism in the previous picture nests inside this speed cup. As the mechanism spins, magnets at the wide end of it cause the cup to rotate on an axle. The faster the magnet spins, the more magnetism it makes. The speedometer's pointer is attached to the shaft coming out of the center of the speed cup. When the hairspring shown here breaks from being slammed around by the erratic movement of a worn drive and/or bushing, the needle stops moving. The spring is delicate and will break very shortly after the speedo starts squealing and bouncing. In order to save this part, disconnect the drive cable and run without a speedo as soon as yours starts doing that until you can get it repaired. These aren't being reproduced either.