84 to 86 Duke retrofit

[dguy]

If you're not a fan of the 85+ wiring which connects the temperature gauge to the bulb test circuit instead of the idiot light, why not modify it now before everything gets in the way?

Paul McKibben's Fiero Sails site has (among other things) an excellent play-by-play to correct this.  Two simple changes are involved, one of which is the swapping of two wires from one connector on the back of the instrument pod to the other.

In retrospect I should have done the work on the interior side either before I re-installed the dash, or even earlier when I had the wiring harness on the bench.  It would have been tidier had I been able to bundle up the moved wires with the harness proper.   

[dguy]

Since it can't be re-installed until after the 86 shifter & cables go in, and given the number of cracks & stripped threads, I'm going to give the console skeleton a little TLC while it's out of the car.

I'm using a product called Plastex to repair many of the cracks & breaks, and plain ol' polyester body filler where threads have been stripped.  I've tried fiberglass resin in the past, and find that it's ultimately too brittle for this particular application.

Plastex takes a bit to get the hang of, and I'm not going to go in to it.  Suffice it to say that I've used it for a few other applications, and it out-performs most solvent-type plastic cements IMO.  It can be purchased locally through this link if you want to play with it.

To repair stripped threads, I simply seal over the back of a hole & fill it with body filler.  Once the filler sets, drill through it with a bit which is a hair smaller than the screw diameter, and the screw will tap its own threads when you fasten it in.

The area of the skeleton where the radio bolts up needed extra attention--most of the "pods" that screws were set in to had long ago broken away.  I made a form of sorts, filled the void, and will set the screws in it as described above.

The first photo below is the empty form, the second is the form partially filled with Plastex.  Plastex will run/creep a bit before it sets, which makes it easier to fill in some of the teeny tiny gaps.  Once the small gaps were filled, I filled the remainder of the form with body filler.

Once I finish messing with this thing and am ready to re-install it, I'll post a photo showing the completed work.

[dguy]

Yup, it's time for it to go.

There's little to it.  Drain the juices, disconnect everything which connects the drivetrain to the body, lift the body off the motor and roll it (the cradle) out of the way.

The male side of C500 is actually two pieces: one for the body (tail lights & whatnot), one for the engine.  The two pieces snap together with a couple of clips...  undo them.

Rather than trying to disconnect each & every electrical connection to the motor, just unplug the ECM harness at the ECM, and push the whole mess through the firewall.

[dguy]

Push the shifter cables through the firewall.  Disconnect the throttle cable at the throttle body.  Disconnect the dogbone, vacuum lines, coolant lines, fuel lines, slave cylinder, etc.  If it's a link between the engine & the body, remove it.   

Raise the car, and support the rear of the cradle with jackstands while you undo the rear cradle bolts.  Raise a toast to the former owner who applied gobs of anti-seize when they last had the cradle out.   

Remove the nuts from the front cradle mounts, but do not remove the bolts.

Attach an engine hoist to the engine, and lift.  Set a dolly under the cradle, and lower.  Attach the engine hoist to the dogbone mount or another suitable hard point, and lift just enough to unload the front cradle bolts so that you can slip them out.

Raise body, disconnect a few things that you forgot, raise body some more, roll out engine, put body back down on stands.  Done.   

31 hours and counting.

[dguy]

Now on to preparing the engine compartment for the 86 wiring & hose routing differences.  Not to mention some obligatory clean-up of the battery tray.  Believe it or not, there's a solid battery tray under all that surface rust.   

[dguy]

Save yourself some future frustration when removing the trunk light by tieing a cord to the pigtail before pulling it out.

[dguy]

Remove the tail light lenses, rear side marker lights, licence plate lights, and the rear fascia.  Undo all of the clips which secure the rear wiring harness to the rear clip & whanot, and drop it on the floor in a big tangled mess near the LR wheel well.

Use something other than brute force when dealing with the clips which attach the wires for each tail light socket to the rear clip (shown below), as the grab-and-yank method has about a 50/50 chance of either tearing the clip out, or cracking the rear clip.

[dguy]

Now it's time for a magic trick.  Free the wiring harness from the car, without removing the rear clip.   

Remove the trim strip & the inner sail panel shown in the first photo below.  Underneath the strip you'll find that the wiring harness is stuck down with 20 years of dirt & foam tape where it passes through to the wheel well.

Your first instinct may be to try to pull what little harness is left in the engine compartment through the gap between the frame rail & the clip.  Your instincts are wrong.     The sockets for the tail light relays & the male side of C500 won't make it through there.

Instead, remove all of the light bulbs from the tail light sockets, and bring the whole thing up through the gap.  Everything fits through that space without doing anything destructive, regardless of how it may look initially.

[dguy]

Installing the 86 rear harness is reasonably straight-forward.  By removing the trim piece & inner sail panel from the passenger side, you gain just enough room to push the C500 connector up from below.  I had to deform (or if you prefer, squish) the connector's shroud a bit, so I wouldn't advise doing this when it's cold & plastic is brittle.

[dguy]

Don't forget to create a ground point for the harness inside the RR wheel well.  A few minutes with a drill, wire brush, and a self-tapping screw is all it needs.

[dguy]

Route the harness across the rear of the car, through the LR wheel well, back up through the clip/frame gap, and finally back through to the trunk.

If you're uncertain of the condition of the harness for any reason, it couldn't hurt to power everything up at this point.  I was lucky, and all i had to do was clean up a bunch of corrosion on the side marker & licence plate light sockets.

BTW to test the back-up lights without a transmission, install a jumper between the two pins of the "unused" connector at the main wiring harness where it passes near where the shifter mounts.  All 85+ harnesses are set up for either a reverse light switch at the shifter, or at the transmission.

[dguy]

Re-install the rear fascia, tail light lenses, inner sail panels, etc. at your leisure.

Finish cleaning up the battery tray area, and install the C500 support bracket that you remembered to save from the donor car.  If you're welding-impaired like me, a rivet gun or self-tapping bolts work nicely.

[dguy]

No cruise control to worry about here, so the bracket for the 84's cruise servo goes on vacation and the brackets which hold the relocated fuel vapour cannister & a few other things move in to the neighbourhood.

There are a variety of ways to ensure that you position the brackets correctly.  Careful notes & measurements made before removing the donor pieces, paper templates, you name it.

Note that this step is not required, as the location for the 84 fuel vapour cannister does not interfere with installing yet another Duke in the engine bay.  But what the heck... I'm moving everything else, so why not move this too?   


That's all for this update...  40 hours in to it at this point.

[dguy]

On to preparing the firewall...

As with relocating the charcoal canister, much of this depends upon just how detailed you want to get in the conversion.  Assuming that you want to mimic the bracketry & loom routing of the 86, read on.  Otherwise skip to the next post below. 

The three brackets highlighted in the first photo below can be removed.  After that, it's a repeat of the process used to relocate the charcoal canister.  Using templates, measurements, or "eyeballing it", fasten the mounting brackets you saved from the donor car's firewall to the 84.  As most of them are used to retain wiring looms it isn't necessary to get them precisely positioned--there is sufficient slack in the harness for things to be off a bit here & there.  The second photo shows the brackets riveted in place.  Some of them needed a bit of clean-up, hence the grey primer in some places.

[dguy]

The 86 4cyl fuel lines are slightly different from the 84.  The line for the charcoal canister ends in a different location, and the return line from the throttle body has a slight difference as well.

If you're not going to the trouble of relocating the charcoal canister you can probably get away without changing the fuel lines, but don't quote me on that.  I didn't check to see if the fittings or positioning of the 84 lines will work with the 86 motor.   

Securing the 86 fuel lines will require a small amount of creativity, as the locating holes for the mounting brackets which are normally on the LH frame rail aren't present in the 84.