Ok, so in the last installment, I had successfully removed the stock dash instrument cluster from the truck. The stock instrument dash has a 'blank' pod that appears to be the same-ish size as a new gauge I want to install as a tuning tool for my new engine build, i.e. an Air / Fuel ratio gauge which is part of the WidebandCommander O2 kit I am in the middle on installing.
I had previously acquired an almost identical to stock instrument cluster from ebay, which also had a 100MPH speedo instead of my stock 85MPH one, which I intended to swap over as part of the A/F gauge installation.
I decided to take the ebay spare cluster to bits first, so I didn't have to worry as much about breaking it while taking it to bits as practice for the stock one out of my truck.
First then, take one ebay instrument cluster:
Unbolt the transparent plastic cover:
Unbolt the metal cover:
Unbolt the individual gauges:
Gauges on their own:
A closer look at the speedo. Fancy a bit of very easy mileage 'clocking' anyone? Don't trust an old-body-style odometer reading ever again! This is the 100MPH speedo I intended to use in my truck.
Ok, so now I knew taking the cluster to bits isn't difficult, so it was time to take the 'real' one from my truck to bits. Start again:
Take the transparent cover and black backing off:
Now, the black cover in the ebay cluster was a really nice pressed metal item. The one out of my truck is a horrible plastic one!! As you can see it has a 'blank' pod in it, which is just plastic. Rather than mess about drilling ot cutting it, I would use the nice metal one instead, as it already has a hole in correct place for the new gauge.
The rear of the cluster from my truck has an 'extra' set of connections at the back:
I had already guessed that these connectors are for the ECU in my truck as the first year (1987) of computer controlled TBI engines. The connectors are for the Vehicle Speed Sensor (VSS), which is tacked onto the previous year style speedometer.
Comparing the VSS-enabled 85MPH speedo and the non-VSS 100MPH speedo together:
The 100MPH speed doesn't have the correct backing plate for the VSS sensor, so I decided to leave it and keep the 85MPH speedo. Looking carefully here, you can see the VSS sensor is just a some form of light reflecting/reading device that counts the speedo spinning:
Ok, so on with fitting the new WidebandCommander A/F gauge. First I offered up the gauge to the metal backing plate:
It was very close in size, but didn't quite fit. After a LOT of messing around with a grinder and a file, I managed to enlarge the hole to allow the gauge to slide into place:
View from the back:
The metal backing plate is a nice snug fit for the gauge, which means it won't move about at all. Now obviously, the wiring for the new gauge needs to exit from the back of the instrument cluster so it can be wired in. So I had to cut into the back of the cluster:
I had to make the hole a bit bigger than in the picture in the end, to allow the illumination bulb of the new gauge to sit right. Now for a test fit of the cluster and metal plate:
Then I made a test fit of the front transparent plastic cover on top of that. Ooops! As the new gauge sits proud with its silver bezel, the clear plastic cover couldn't be bolted on top. No problem though, I just cut a hole in it, big enough for the gauge body, but not the bezel, with the idea for the gauge to sit proud of the cover when finished.
Cut cover:
Sit the A/F gauge in it from the outside:
Then slide through the metal cover (again, a snug fit to grip it well):
Finally, I can put it all back together!! A view from the back to see the wiring looms:
And the finished artlicle:
Now I can put the cluster back into the truck!! Pics to follow
