First off, the car - 1988 GT 5 speed Getrag.
Modification - 97 Riviera 3800SC II (stock).

How to replace the factory tachometer with a Sunbird's Tachometer (with boost gauge):
In the past, this info has been hard to locate.
I got most of my information from this thread.
Install a Turbo Sunbird tach/boost gauge with me by SCCA Fiero.
As good as it was, I like to have things dumbed down for me a little more than that.
So I'm going to work through it here.

Here is the gauge:


Here is the circuit board on the back of the gauge:


Here is an electrical diagram of the modifications to be made:


Here is a picture of the trimmer: (I bought 3 just becaause they were $0.75 each)



The following areas are the parts that aren't clear to me:
1 - How and where to connect the four wires to the Fiero's wiring
2 - Where to trim the gauge and the cluster housing
3 - How to hook both gauges up at the same time in order to calibrate the tachometer
4 - Where the guage gets backlit from *** Lit from factory dash light in stock location *** Thanks Phonedawgs
5 - What MAP sensor wire gets connected to the existing green wire

I don't think any of this will be too hard though. I will document everything with pictures as I go along.

[This message has been edited by 2002z28ssconv (edited 07-24-2010).]

I'll take the easy one - the lights are alreay in the dash plastic body. If they end up being in the way and you have to move them, then you will also have to figure how to power them

quote Originally posted by 2002z28ssconv: 5 - What MAP sensor wire gets connected to the existing green wire

It should be the center wire, which ironically is green.

You probably already know this, but in order to register boost, you'll need a 2-Bar MAP sensor. The one that came with the 3800 SC engine should work.

I made a little progress today.

I soldered a thin piece of solid core wire to the trimmer.
I squoze each pin on the trimmer with a pair of needle nose plyers.
Then I wrapped the wire tightly around a needle.
Then I slid the trimmer's pins inside the wire loops.
Hopefully the ridges created by the plyers will help to hold the solder.

I did some reading about trimmers and most sites said that the third pole didn't need to be connected.
Hopefully it didn't matter which end I left off.
The center one has to be connected though.


Then I added some heat shrink to cover up any bare wire.


Then I soldered the wires to the circuit board and gave it the same heat shrink treatment as before.
Once the trimmer is adjusted, I'll cover the entire trimmer with heat shrink.


You can clearly see where I cut the circuit board with a razor.
It's not very visible with just eyes, but for some reason my crappy camera really caught that detail nicely.

Tomorrow... the cluster...

Adding this one to Favs!!

Thanks for sharing the information regarding the tach. I had been struggling with my install. A '86 Sunbird instrument cluster but w/o the turbo boost gauge.

Quick question, does anyone have the wiring diagrams for the complete instrument cluster?


Thanks for your assistance in advance.

Mike

Well... This is BIG!
I have started and finished a project in the same weekend.
I don't think... no I KNOW... this has NEVER happened to me before.
So here's "the rest of the story."

I pulled the instrument cluster from the car. I didn't snap any pictures of this as it's common knowledge.






So here is the back of the cluster after it has been removed from the suround.
I have marked the ignition, coil and ground locations.

Remove the lense and the metal plate.


Remove the two screws to the right. The one at the bottom stays.
After the two screws are removed the tach is just held in place by friction.
Pull it out.


Here is a side-by-side. Sorry about having the left one turned.
At this point it was about 1:30 and 95 degrees and I was suffering from heat stroke.
I have marked the areas that needed trimming.


Four areas need to be trimmed on the housing.
Be sure to put some tape or something inside the holes marked by the rectangle.
Otherwise light will bleed through into those cavities at night and you'll be able to read the idiot lights.
Tape 'em. The top one won't need tape. More on that later...


Some more areas on the gauge face that needed to be trimmed.




Then I had an idea... I didn't want to cut and splice my dash harness. These little clips held on to screws from the rear of the stock tach.
Too bad the Sunbird tach's feed screws won't allign with these clips.
So... I dropped in some #6-32 screws.


Then I added some nuts on the backside to hold them in.


This made it super easy to attach both tachs in tandem.


I went back out into the sun and hooked the wire harnesses back up to the cluster.
I started the car and had fun making the tach swing around by twisting the knob on the trimmer.
This was really cool and fun and I was sure that it wasn't going to work. But it did! WOOT!!!
Disconnect it all. Secure the trimmer where it won't be moved and back into the house I go.

I pulled the old tach back out and routed the wires in through an unused bulb socket.


This is where the wires fed through into the tach's area.


Besure to keep the wires away from the bulbs.


Then I started putting it all back together.


Unfortunately, I ran into a little snag. My ground post hit the back of the surround housing.


Nobody's gonna see it. So I drilled a couple holes with a stepper bit.


You can see the ground stud. It doesn't poke through all the way.
Looked good to me...


I put it all back in the car and it worked like a champ.
The boost gauge isn't working yet. The 3800SC II will be going in the car VERY soon.
Then I'll have to take out the center console. I'll run the green wire to the MAP sensor wire at that time.
I'll update this thread again when I do that.

[This message has been edited by 2002z28ssconv (edited 07-26-2010).]

definitly an awesome thread. im actualy s/c my 2.8 and trying to keep everything stock as can be i didnt want any extra gauges in my car . this is exactly what i was looking to do. and will say i think im going this route!!

Nice job, Chuck. It looks like a factory option.

I finally got it all buttoned up.
I connected the green wire from the back of the tachometer to the green wire that runs to the MAP sensor.
I cut the wire between the PCM (pin 25) and the MAP sensor (center wire).
I soldered and shrink wrapped the three wires back together.
Works like a charm.

I was giggling uncontrolably for a few minutes after I started it up the first time.

WOOT!

http://www.youtube.com/watch?v=eeb_2_SvkHY

Very nicely done Write-up. That will be quite helpful.

Nolan

Edit: A + for you!

[This message has been edited by Sourmug (edited 09-02-2010).]

cool

You did a great job! And the result looks Factory ! Thanks so much for sharing this with us! I learned a lot today !

Thanks, added to my favs for a future project...

+ for you!

Gotta find me a sunbird tach now

[This message has been edited by ALJR (edited 09-02-2010).]

Thanks for all the kind words and +'s.
This was a very fun project. Hopefully write up this will encourage others.

I think you'll need the hole there no matter what screw you use. Just having the wire terminal there makes it jam up a little getting the cluster in and out of the housing. It's pretty tight right there.

***EDIT***
I forgot to add that I slapped a piece of duct tape over the groove/slot that I cut in this picture. I made sure that the tape got pushed down into the groove so the tach would still slide into it.
Until I did this, the lights from behind the tach would bleed light into the areas behind the two bottom right side lenses. You can kinda see where I'm speaking of in the 2nd picture.

[This message has been edited by 2002z28ssconv (edited 09-02-2010).]

Was there not room to flip those 6-32 screws around and have the nuts on the inside? I assume you no longer use the stock tack clamp/spring contact points on the inside (the reason you ran the leads)?

You probably could do that. You'll have a hard time holding the nuts in place to get the screws threaded and then tightened down too.

Nice write up. I'll be doing this on my 88 soon. I have the tach, just need to install it.

------------------

88 Coupe: 2.0L Turbo 4 Cylinder
84 Indy #64: Restoration Project!

Nice Sears and Wesson!

Real nice writeup too! Wish those tachs weren't so hard to find.

Awesome write-up! This has inspired me to install my Sunbird tach even though my L67 swap isn't done yet.

Thank you. I actually picked up another complete cluster last month. I probably paid too much for it but like you said, you can't find them anymore. I'll be putting this one to use in another 88 3800, only this one will actually have a turbo. I don't know if the boost guage is that accurate or not but I don't really care.

If you need any help or have any questions just send a PM.