Parts compatibility between '84 and later models (Page 1/2)
FiatBen JUL 27, 09:58 AM
I recently have purchased an '85 and an '86 SE (I4 and V6 respectively). My local u-pull-it yard just got in an '84 (which is the first they've had in years). I don't know yet what all I need to revive the two sitting in my driveway, but looking at pulling what I can off the one they have. I know some changes were made after the '84 year model, but was wondering if there was a list or, or some very knowledgeable people who could tell me, what parts are NOT compatible between the '84s and the '85-'87s. Any help at all is much appreciated. Neither of mine has ran in 7-8 years but I intend to make them both road-worthy again.

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rbell2915 JUL 27, 11:00 AM
I've never had an 84, only an 86 and 88, but here's a link for wiring diagrams and service information that may be useful to you. You can do some digging in there and compare specifics depending on whatever you need.

Charm.li
Patrick JUL 27, 11:24 AM

quote
Originally posted by FiatBen:

I know some changes were made after the '84 year model, but was wondering if there was a list or, or some very knowledgeable people who could tell me, what parts are NOT compatible between the '84s and the '85-'87s.



Ben, try narrowing down for us what you're after. Engine/drivetrain, suspension, body panels, interior pieces, etc.

[This message has been edited by Patrick (edited 07-27-2025).]

82-T/A [At Work] JUL 27, 03:48 PM

quote
Originally posted by FiatBen:

I recently have purchased an '85 and an '86 SE (I4 and V6 respectively). My local u-pull-it yard just got in an '84 (which is the first they've had in years). I don't know yet what all I need to revive the two sitting in my driveway, but looking at pulling what I can off the one they have. I know some changes were made after the '84 year model, but was wondering if there was a list or, or some very knowledgeable people who could tell me, what parts are NOT compatible between the '84s and the '85-'87s. Any help at all is much appreciated. Neither of mine has ran in 7-8 years but I intend to make them both road-worthy again.





Ok, for your 1985 Fiero 2m4... almost everything from the 1984 will FIT and work on your 1985. The only real differences are:
- Wiring harness is a little different.
- Gauge cluster is a little different (volts vs oil pressure)
- The fan is a 2-speed in the 84, versus you single speed, plus two coolant fan-switches for the 84.
- The front control arms are a little different... will still fit your 85, but reduce your steering radius slightly
- All the buttons in the 1984 are black, versus the buttons in your 85 which are gray.
- 1984 comes with a couple of options your 85 might not have, but not much.
- A/C lines are different in the engine bay, including the heat shield that protects the A/C lines.


For the 1986 Fiero... all the body panels and interior panels from the 84 will fit your 86. Obviously though, since the 1984 is a 4cyl, and the 1986 is a V6, none of the engine compartment stuff is the same.
Dennis LaGrua JUL 27, 04:50 PM
Ben: If neither car has not been run in 7-8 years you may have to drop the gas tank to remove the varnish or at the minimum drain it. Member 82-TA has given you the remainder of good info like all body panels and glass fitting both Fieros. One thing that is different are the quarter windows. The 84's use glass while the later models use cheap plastic,

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olejoedad JUL 27, 07:52 PM
Front fenders mount differently to the front bulkhead and the doorskins are slightly different.

Electrically they are very dissimilar.

Front control arms are slightly different in the steering stop area.

[This message has been edited by olejoedad (edited 07-27-2025).]

FiatBen JUL 28, 07:43 PM

quote
Originally posted by olejoedad:

Front fenders mount differently to the front bulkhead and the doorskins are slightly different.




Well, that is one of my issues. The '85 has a damaged front PS fender. I was hoping to pull one off the '84. Do you know if it can be easily made to work? Also, I'm trying to get the damaged fender off, but it looks like I need to remove the lower side trim to get to the last 10mm bolt. Any suggestions? It looks like that is riveted in, so am I going to have to drill those out?


82-T/A [At Work] JUL 28, 07:46 PM

quote
Originally posted by FiatBen:


Well, that is one of my issues. The '85 has a damaged front PS fender. I was hoping to pull one off the '84. Do you know if it can be easily made to work? Also, I'm trying to get the damaged fender off, but it looks like I need to remove the lower side trim to get to the last 10mm bolt. Any suggestions? It looks like that is riveted in, so am I going to have to drill those out?





Yes, you can take the panel from the 84 and put it on your 85 or 86. They are nearly identical, just the holes in a couple of the more inconspicuous places are slightly different... not at all a problem.
FiatBen JUL 28, 08:00 PM

quote
Originally posted by Patrick:

Ben, try narrowing down for us what you're after. Engine/drivetrain, suspension, body panels, interior pieces, etc.




I have only just begun to dig into both cars so at this point I have no idea what all I might need. I have a damaged front PS fender on one, a non-working parking brake, a missing front hood pull handle, and I'm sure a lot more things along these lines. Not so concerned about engines as much as suspension, steering, body, interior. I just thought the list of things that got changed in the '85 model year would be fairly short compared to what was kept.
Patrick JUL 28, 08:11 PM

quote
Originally posted by FiatBen:

I'm trying to get the damaged fender off, but it looks like I need to remove the lower side trim to get to the last 10mm bolt. Any suggestions? It looks like that is riveted in, so am I going to have to drill those out?



I've drilled those large plastic rivets out, and then just used regular (appropriately sized) metal bolts as replacement fasteners.