Nice Gauges !!
I used VDO vision series gauges because they are very nice & are very similar to the original Rally cluster. Two reasons why I went with new gauges - #1 The 4T60E transmission does not have a mechanical speedo line output, it is made for electronic speedo's. I could have used a aftermarket deal that spins the mechanical speedo, but I didn't like that idea... and because of reason #2 - 3 of my gauges in the Rally cluster are fried & finding OEM replacements that will last is near impossible. So now I have a complete new set that should endure the life of the car.
As you can see the 4 smaller gauges (Tach, Oil Press, Temp, & Fuel) attach directly to the Bezel. VDO uses this spin lock to mount the gauges so the stress is spread out over the full diameter of the bezel & it sits very flush.
Doing the rewiring.....
This is actually about half cleaned up... it was a maze to say the least. Tyre really knows what he's doing with the wiring.
Senders for gauges:
VDO gauges are proprietary, which like Microsoft means they only like to work with their own senders. The Fuel gauge & the Tachometer are the exceptions. Good thing too, cause it would have been a royal pain in the ass to put a different sender in the gas tank !! The Speedo auto calibrates to Pulse Per Minute (PPM) the caddy computer sends out for electrical speedo's. This leaves the Temp & Oil pressure gauges to be sorted out.
This is the VDO sender for a 0-80 PSI gauge. The caddy 4.9L has a oil pressure sensor / relay mounted in the oil filter housing. The relay is a backup for the fuel pump in the caddy, this way if the fuel pump relay goes out & the engine is cranked to provide oil pressure then the fuel pump will again have power. This relay is not needed & will not be used on my motor. It is important to note because the PROM has to be changed, a NULL value put in so is does not look for the pressure gauge or the relay (engine won't run if puter thinks there is no oil pressure). That all handled this sender can now be installed.
Tucks nicely into place.
The VDO senders have threaded post on them with a textured nut to tighten down on them (see above). I used these eyelets for easy connections. I soldered them for the best contact & longevity.
Birds eye view.
Temp sender:
The Temp gauge was the most difficult to deal with. The VDO gauge won't work with a stock sender, even an OEM sender for a temp gauge. I couldn't replace the sender with a VDO one as I did with the oil because the computer has to have a temp signal.
Temp sender location.
I now needed to find a place to mount a sender if I wanted to have a Temp gauge. Since I used a complete motor that I didn't have to assemble I ruled out tapping another mounting location into the manifold. I decided to find a way to mount a sender inline just past the Thermostat. Beings I married the 2 upper radiator hoses, radiator side from my X & engine side from caddy, I figured it would be a logical place to mount a sender. So off I went trying to find a way to make it work... After talking to an old NAPA guy I went to a local (old fashion) hardware store (nothing against Home Cheapo) & perused the plumbing section...
I ended up getting this Galvanized pipe T junction. It is 1 &1/4 inch diameter with the T bit being 1/2 inch. I also got the two adapter bits to go on either side. They slide into the radiator hose perfectly, and doesn't diminish the flow. Previously I used a solid 1" diameter pipe, but it quite noticeably reduced the inner diameter.
As you can see, the install looks nice & clean. The VDO sender is available is multiple sizes, this one is 1/2" NPT (National Pipe Thread) so it threads directly into the T junction.
Everything back in...
All gauges in & working....