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Working on migrating interior from a 1984 Trans Am to a 1990 Formula. The Formula came with the dash, but no steering wheel, hush panels, or plastic bezel pieces, etc. I was planning on using the new dash, since it has a 120MPH speedo and such (and I have two 700R4s, mechanical and electrical speedo). However, I discovered that my trim pieces from the 84 do not match the 90, as well as buttons for defrost, etc. Additionally the steering column harnesses are a little different. Well, more like the Formula is missing three harnesses that the Trans Am had. I plan to reuse the Engine harness from the 84 Trans Am also.
So at this point I'm looking at doing a complete dash swap from the Trans Am to the Formula. I'm a little concerned, though, because the wiring in the Trans Am is a nightmare. A P/O appears to have done quick a bit of tinkering.
After doing some searching, it appears that a dash swap isn't as easy as I thought it'd be. Does anyone have a recommendation or is there an option that I'm not seeing?
Complete swap is definitely the easiest , lots of incompatibilities from 84-90
But if you don't have a good harness to swap over, still going to gave to do lots of repair.
Might be easier to look for better replacement harnesses.
There appears to be a security system installed on the 84, which would explain the mess of wires under the dash. I found it when I pulled off the dash pad.
As far as I can tell, it's just a crap ton of screws and then pull the firewall plug, and it should slide out?
Well, I pulled both the dashes. Much easier than I thought it was. Grand total of like 12-16 screws\bolts including the steering column.
I'll have to pull the entire harness out of the 84 also - including speakers, tail lights, etc. They're run differently between the two models - both in the dash and in the car. The 84 has a power block that several things just plug into for 12v ignition power, while the 90 doesn't have it. Also, it'll just be easier to pull all of it and put it in the new car rather than dinking around trying to figure out what wires go to what.
I had both dashes pulled in about an hour and a half. I should've taken pictures so we could have an official write up on here somewhere.
Yep, not easy! You need a complete electrical diagram. Your ECM might not match with the new dash. Might have to custom the wiring somehow. Mine took me lots of thinking, customizing and trial&error. The end sensors could also be different between 1984 and 1990. Just be aware that those gauges were not built to last forever. The mechanical odometer is prone to fail after all those years. The mechanical gears just dry up and brake. Also, the RPM could be inaccurate. Mine was off by 400rpm past 4500rpm. The speedometer and RPM were bouncing around. The coolant gauge failed as well. I had replaced it with a used one from same year and it was off also. I came to the conclusion that after 23 years the components were just worn out, so I decided to custom restore the whole thing. The challenge was trying to keep an OEM look.
I just pulled everything from the donor car, wiring and all. I won't be using the ECU since its a non cc-carb, so i just need to figure out the TCC lockup and speedo issue at some point. Should be easy enough.
Hope all is well. I'm looking at a 1986 camaro z28 305 , 4bbl carb , 5 speed and the speedometer is stamped with Z28 on lower right on its face and goes to 140 mph. Is this original or a swap out. I haven't seen this on any others. I'm trying to locate a resource that would show me if this was an option that came with the car. Any help. Thank you. Speedometer question. Was this an option for 1986 z28?
Hey Dave thanks for the quick response. By any chance is there a website or a document that you can direct me to that would show an image of the original speedometer? DId it only go up to 85 MPH? On the 86 Z28 305 4bbl? Thanks again.
08-06-2015, 08:59 AM
