DeAgostini AE86 Build Journal 04 — Issues 34–45: Engine Bay, Steering & Electrical System

Issues 34–45 were where the AE86 build started becoming noticeably more complicated.

The earlier stages were mostly about building individual mechanical assemblies. In this chapter, many of those parts begin coming together around the chassis. The engine bay takes shape, the retractable-headlight mechanism is installed, the steering system is added, the completed 4A-GEU engine finally goes into the car, and then the build moves into its first major stage of wiring and electrical testing.

This was also the point where I could no longer finish three or four issues in a day as easily as before. There were more parts to work around, more things that could be damaged accidentally, and some of the earlier assemblies now had to line up properly with each other.

I’m starting to understand why a real car is so expensive, lol.

This article follows the earlier chapters in the series:

• AE86 Build Journal — Project Introduction
• AE86 Build Journal 01 — Issues 1–13: Building the 4A-GEU Engine
• AE86 Build Journal 02 — Issues 14–22: Chassis and Suspension Work
• AE86 Build Journal 03 — Issues 23–33: Rear Axle, Exhaust & Fuel Tank

In This Build Journal

• Milestone 1: Building Up the Engine Bay — Issues 34–37
• Milestone 2: Retractable Headlights and Custom Wheels — Issues 38–40
• Milestone 3: Steering and Installing the 4A-GEU — Issue 41
• Milestone 4: Wiring, Circuit Board and Electrical Testing — Issues 42–45
• Overall Build Impressions
• The AE86 Is Starting to Come Alive

Milestone 1: Building Up the Engine Bay — Issues 34–37

Issues 34–37 move the build into the engine bay.

The bulkhead is installed first, followed by more of the surrounding engine-compartment details and the front fender apron.

At this point the build starts feeling quite different from the earlier chassis work. There are now more finished and painted surfaces around the work area, so handling the assembly becomes more important.

Issues 34–37 — Bulkhead and Engine-Bay Details

One thing that surprised me was the bulkhead.

At first, I thought it was a metal part. It looks substantial enough, but it is actually plastic.

That means some care is needed when fitting it to the floor pan. The floor pan has already become quite heavy by this stage, and its own weight could damage the plastic bulkhead if the assembly is handled or supported badly.

This is one of those moments where the size and weight of a 1/8-scale model begin to matter during the build itself.

As more details are added inside the engine bay, there are also fewer safe areas to hold the chassis.

When fitting the right front fender apron, I had to be careful not to knock the smaller engine-bay parts that were already installed. The painted surface of the apron also needs some protection while working around it.

Nothing particularly difficult happened during these four issues, but the build was definitely becoming more crowded.

Milestone 2: Retractable Headlights and Custom Wheels — Issues 38–40

The next stage adds the mechanism that will eventually operate the Trueno’s retractable headlights.

Fuel and brake tubes are also routed through the chassis, together with more engine-related wiring.

This is where a small decision from an earlier stage came back to make the work more troublesome.

Issue 38 — Headlight Mechanism Base and Tube Routing

Issue 38 installs the base for the retractable-headlight mechanism onto the chassis.

The fuel tube and brake tube are also routed during this stage, together with some of the engine-related wiring.

The biggest lesson here was actually related to the small cable holders that had been installed earlier.

I should have glued them.

The fuel and brake tubes have enough stiffness that they kept pushing some of the holders out while I was trying to route them. It turned a simple job into something that took much longer than necessary.

If I were doing this stage again, I would secure those holders before starting the tube routing.

Another difficulty is identification.

DeAgostini supplies the tubes in the same black colour, so once several of them are running around the chassis it becomes surprisingly easy to forget which tube is which.

Labelling them early saves a lot of checking later.

Issue 39 — Retractable-Headlight Mechanism

Issue 39 builds the mechanism that will operate the retractable headlights.

I was quite interested to finally see how the small motor and gear system would work.

During assembly, however, I found that one of the square protrusions on the retractable arm was slightly oversized. It may have been caused by the thickness of the black paint.

The gear would not fit onto it properly.

Rather than forcing the gear into place, I used a Tamiya diamond file to carefully remove some of the black paint from the protrusion.

Only a small amount needed to be removed.

Once the fit was corrected, the mechanism could be assembled normally.

This is another place where I would recommend test-fitting before applying force. The parts are small, and forcing the gear onto an oversized section could easily damage the mechanism.

Issue 40 — Front Fender Apron and RS Watanabe Wheels

Issue 40 installs the left front fender apron onto the engine compartment.

At this stage, I also changed from the original wheels to the optional RS Watanabe custom wheel set.

There is one important difference when fitting these wheels.

The washers used with the original wheels cannot be used with the custom wheel set. The four wheels are secured directly using the VM screws.

Do not overtighten them.

The wheels still need to rotate, so I tightened each screw only enough to hold the wheel securely while keeping the tyres free to turn.

With all four Watanabe wheels finally fitted, the chassis also started looking much closer to the version of the AE86 I had planned from the beginning.

Milestone 3: Steering and Installing the 4A-GEU — Issue 41

Issue 41 was the longest single issue for me up to this point.

It also had the most steps.

This issue builds the steering mechanism, replaces the earlier upper exhaust front pipe with a revised version, and finally installs the completed 4A-GEU engine into the engine compartment.

More importantly, this stage becomes a test of a lot of the work done earlier.

Issue 41 — Steering Mechanism and Engine Installation

The steering mechanism is assembled and attached to the chassis before the engine goes in.

The earlier upper exhaust front pipe is also removed and replaced with the revised part supplied at this stage.

Then comes the main job: fitting the completed 4A-GEU engine into the chassis.

I had already spent a lot of time building the engine separately, so finally seeing it sitting inside the engine bay was a major milestone.

But this installation also tells you whether the earlier work was done properly.

If some of the previous assemblies are not aligned correctly, the engine may not sit properly in the engine compartment.

The same applies to the steering system. If the centre rotary mechanism built earlier is not working or aligned correctly, the steering mechanism fitted here will not operate properly either.

So Issue 41 is not only about installing new parts. It also checks the accuracy of quite a lot of previous work.

Fortunately, everything came together.

After spending so many issues looking at the engine as a separate assembly, it was good to finally see it where it belongs.

Milestone 4: Wiring, Circuit Board and Electrical Testing — Issues 42–45

From Issue 42 onward, the character of the build changes again.

The mechanical assemblies are still there, but now a large part of the work becomes wire and hose routing.

This stage requires a different kind of patience.

A fitting problem is normally visible immediately. Wiring problems can be much less obvious, and troubleshooting them after everything is buried inside the car is something I definitely wanted to avoid.

Issue 42 — Engine-Bay Wiring and Hose Routing

Issue 42 mainly focuses on routing the wiring and hoses around the engine compartment.

The circuit board also appears at this stage — basically the heart of the AE86’s electrical gimmicks.

Before starting the routing, I spent some time identifying the different wires and hoses.

Once again, the colour does not help very much.

Many of them are black, and once several lines are running beside each other it becomes difficult to remember which one goes where.

I labelled each one before routing began.

That small amount of preparation made the later stages much easier.

Another build note from this stage: if any wiring or hose fitted in an earlier issue is too long and interferes with the assembly, it is better to trim or adjust it before the engine bay becomes even more crowded.

Issues 43–44 — Circuit Board and Main Wiring

Issue 43 mainly connects the electrical gimmick wiring to the printed circuit board.

Issue 44 then brings the circuit board, speaker and wiring into the chassis and routes the connections toward the different areas of the car.

There were more wires than I expected.

This stage took considerably longer than I thought it would.

The wiring runs toward both the front and rear of the chassis, including connections for the taillights, instrument panel, interior lighting and other electrical functions.

This is the kind of work where I prefer to slow down.

The wires, LEDs and soldered connections are quite fragile. Accidentally pulling a wire, damaging a solder joint or pinching a cable underneath a holder could create a problem that is very difficult to find later.

I kept all of the connections labelled and checked the routing carefully before securing them.

The main thing is not to rush just because the wiring looks repetitive.

Troubleshooting afterwards would be much more painful.

Issue 45 — Remote Controller and First Electrical Test

Issue 45 mainly builds the remote controller used to operate the Trueno’s electrical gimmicks.

The controller itself is not particularly complicated.

I did make one small change.

Because I planned to use the custom steering wheel in the finished AE86, the original steering wheel would become spare. I decided to use the AE86 steering wheel for the horn button on the remote controller instead.

It gives the controller a small connection to the actual car rather than leaving the original wheel unused.

More importantly, Issue 45 gave me a chance to test the electrical system.

I really did not want to continue building the car, bury all of those connections inside the chassis, and then discover much later that something did not work.

So I tested the electrical gimmicks before everything became harder to access.

In my own way, lol.

Fortunately, the system worked.

That was quite a relief after seeing how many wires were now running through the chassis.

Overall Build Impressions — Issues 34–45

Issues 34–45 changed the build quite significantly.

At the beginning of this chapter, the work was still mainly structural: building the engine bay, installing the fender aprons and adding the retractable-headlight mechanism.

By Issue 41, several major assemblies finally came together. The completed 4A-GEU engine was installed into the chassis, and the steering system began connecting the earlier mechanical work into something functional.

Then the wiring started.

That part required more concentration than I expected.

The individual connections are not especially complicated, but there are many of them, and the consequences of a mistake can appear much later in the build.

The main things I learned from this stage are:

• Support the heavy floor pan carefully when working around plastic parts such as the bulkhead.
• Protect painted engine-bay surfaces as the chassis becomes larger and harder to handle.
• Secure tube and cable holders properly before routing stiff tubing through them.
• Label similar-looking black tubes and wires before the engine bay becomes crowded.
• Test-fit moving parts rather than forcing them when paint or moulding tolerances make the fit too tight.
• Do not overtighten the wheel screws if the wheels still need to rotate.
• Engine installation is also an alignment check for assemblies completed much earlier.
• Route electrical wires carefully and make sure none are pinched beneath holders or surrounding parts.
• Test the electrical system while the wiring is still accessible.

The build had become slower by this point, but that was mainly because more earlier work was now starting to depend on everything else being correct.

It was no longer just a collection of separate assemblies.

The AE86 was beginning to work as one system.

The AE86 Is Starting to Come Alive

By the end of Issue 45, the engine is sitting in the chassis, the steering mechanism is in place, the retractable-headlight system has been installed, and the first major electrical connections have been tested.

This felt like an important transition in the project.

Up to this point, most of the build could still be understood by looking at individual mechanical parts. From here onward, more of the interior, electronics and operating features start coming together around the chassis.

There is still a long way to go, but the AE86 is starting to feel less like a collection of parts and more like a car.

Continue the AE86 Build

This article covers Issues 34–45 of the DeAgostini 1/8 Toyota Sprinter Trueno AE86.

For the earlier stages:

• Project Introduction — DeAgostini 1/8 Toyota Sprinter Trueno AE86 Build Project
• Build Journal 01 — Issues 1–13: 4A-GEU Engine
• Build Journal 02 — Issues 14–22: Chassis and Suspension Work
• Build Journal 03 — Issues 23–33: Rear Axle, Exhaust & Fuel Tank

Or visit the DeAgostini AE86 Build Project to follow the complete project, build journals, custom parts and full build service.