DeAgostini AE86 Build Journal 03 — Issues 23–33: Rear Axle, Exhaust & Fuel Tank

After completing the front chassis and suspension work in Build Journal 02, this stage moves towards the rear half of the DeAgostini 1/8 Toyota Sprinter Trueno AE86.

Issues 23–33 cover the propeller shaft, rear axle and suspension, exhaust system, rear brakes, remaining standard wheels and fuel tank. This is also where several separate assemblies finally begin coming together on the large floor panel.

Most of the individual parts are not particularly difficult to assemble. The challenge comes when those assemblies have to be aligned and installed together — especially once the floor panel becomes larger, heavier and more awkward to handle.

This stage also introduces one of the first electrical-related parts of the build: the battery box hidden inside the fuel tank.

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

In This Build Journal

• Milestone 1: Propeller Shaft and Rear Axle Assembly — Issues 23–27
• Milestone 2: Exhaust System and Rear Suspension Integration — Issues 28–29
• Milestone 3: Rear Wheels, Brakes and Fuel Tank — Issues 30–33
• Custom Part: RS Watanabe Wheel Set
• What I Learned from Issues 23–33

Milestone 1: Propeller Shaft and Rear Axle Assembly — Issues 23–27

The first part of this stage connects the drivetrain towards the rear of the chassis and gradually builds up the complete rear axle assembly.

Individually, most of these components are quite straightforward. The more difficult part comes later, when the propeller shaft, differential, rear axle and suspension components all need to meet the mounting points on the increasingly large floor panel.

Issue 23 — Propeller Shaft

Issue 23 assembles the propeller shaft, including the front and rear shaft sections, centre support bearing, joint yoke and spiders.

Compared with some of the chassis work in the previous journal, this was a straightforward build and I did not encounter any particular fitting problem.

Issue 24 — Beginning the Rear Axle

Issue 24 begins the rear axle assembly. The upper control arms and their housings are assembled first, together with the upper control arm brackets and preparation of the rear brake tube.

This is one of those stages where a little preparation makes the later assembly much easier.

Build Note — Pre-tap the Control Arm Parts

I recommend pre-tapping the screw holes in the upper control arm housings and brackets before assembling the upper control arms.

The screws need to pass through quite accurately. If a screw starts slightly angled, it becomes difficult to line it up with the hole on the opposite side.

Pre-tapping first makes it much easier to check that the screw is entering straight before the actual parts are assembled.

Issues 25–26 — Completing the Rear Axle and Suspension Components

Issue 25 adds the lower control arms and rear stabiliser bar to the floor panel, together with preparation of the rear shock absorber brackets.

This part of the build was straightforward and I did not encounter any specific problem.

Issue 26 continues with the lower rear axle housing, rear shock absorbers, springs and related brackets.

The upper rear shock absorbers are fitted to the floor panel, while the left and right shock absorber brackets are attached to the lower rear axle housing before the upper and lower axle housings are combined.

At this point, the rear axle is beginning to look like a complete working assembly rather than a collection of individual suspension parts.

Issue 27 — Installing the Rear Axle onto the Floor Panel

Issue 27 brings the work from the previous issues together.

The differential components and propeller shaft are connected to the rear axle first, followed by installation of the completed axle onto the floor panel.

The individual assembly steps are not especially complicated, but fitting the complete rear axle to the floor panel took considerably longer than I expected.

The tricky part is alignment.

Both upper control arm brackets need to meet their mounting points while the rear axle itself also has to sit in the correct position. By now the floor panel is large and heavy, so I also had to be careful not to damage parts that were already installed while trying to line everything up.

This was probably the first point in this stage where the physical size of a 1/8 scale model became part of the assembly challenge.

Build Note — Support the Chassis

Once the chassis becomes this large, supporting the floor panel properly becomes increasingly important.

Trying to hold the whole assembly with one hand while aligning suspension parts with the other is not ideal. A stable support makes the work safer and gives much better control over the alignment.

Milestone 2: Exhaust System and Rear Suspension Integration — Issues 28–29

Issues 28 and 29 may cover only two magazines, but there are considerably more processes involved than the issue count suggests.

Before the exhaust can be installed, the rear brake pipe needs to be routed and secured, several brackets and insulators need to be fitted, and the rear suspension still has to remain accessible.

Issue 28 — Preparing the Exhaust System

Issue 28 prepares the front sections of the exhaust system.

The front exhaust pipes, insulator, exhaust bracket and piping holders are assembled first. These parts are then carried forward into Issue 29, where they connect with the rear exhaust pipe and mufflers.

Issue 29 — Exhaust Pipe, Mufflers and Rear Suspension

Issue 29 installs the exhaust pipe and mufflers beneath the floor panel while also completing more of the rear suspension installation.

There are several smaller jobs before the exhaust itself can go in. The rear brake pipe has to be routed and secured with piping holders, and the front insulator and exhaust-pipe brackets also need to be fitted.

Then comes the more awkward part.

The exhaust pipe passes underneath the rear axle, so the axle has to be lifted while the exhaust is carefully rotated through at an angle.

The silver finish on the exhaust is exposed during this process, so I took extra care not to scratch it while manoeuvring it past the axle.

Build Note — Use a Vise as a Chassis Support

The floor panel is already quite heavy and bulky by this stage.

I used a vise to support the chassis vertically rather than trying to hold everything by hand. This gave me a clear side view of the rear axle and made attaching the shock absorbers considerably easier.

The vise is not being used to clamp the model tightly. It is simply acting as a stable support.

Once everything is installed, check that the rear axle can still move up and down freely. That movement is a useful final check that nothing has been tightened or positioned incorrectly.

Milestone 3: Rear Wheels, Brakes and Fuel Tank — Issues 30–33

With the rear axle and exhaust installed, the final part of this journal fills in the remaining rear running gear and underside components.

Issues 30–33 complete the original rear wheels, install the rear brake system and add the fuel tank underneath the chassis.

Issues 30 and 32 — Completing the Standard Wheels

Issue 30 assembles the left rear standard wheel, while Issue 32 completes the right rear wheel.

Both are straightforward wheel builds using the tyre, inner and outer rims and related hardware, and I did not encounter any particular fitting problems.

With these two issues completed, all four original AE86 wheels are now assembled.

However, they will not remain on this build. I already have the RS Watanabe Custom Wheel Set planned for the finished AE86, so the original wheels will eventually be replaced.

Issue 31 — Rear Brake System

Issue 31 assembles the rear brake discs, calipers and dust covers.

The completed rear brake discs are then fitted onto the rear axle. This was another straightforward stage without any particular assembly problem.

Issue 33 — Fuel Tank and Battery Box

Issue 33 installs the fuel tank underneath the rear of the chassis.

The interesting part is what is hidden inside it.

The upper and lower fuel-tank halves contain the battery box and cover, allowing the model's battery compartment to be disguised as part of the real car's fuel tank.

After spending so much of this stage dealing with mechanical parts, this is also the first small hint of the electrical system that will become increasingly important later in the build.

I like this solution. Instead of attaching an obvious battery compartment underneath the car, DeAgostini hides it inside a component that is already supposed to be there.

A clever idea.

Custom Part: RS Watanabe Wheel Set

Alongside Issues 23–33, I also assembled AE86 Custom Part Set 3 — the RS Watanabe Custom Wheel Set.

The set includes four rims, tyres, rim caps and the required screws. These will replace the standard wheels supplied through the regular issues.

I assembled all four wheels together before fitting them to the car later.

Check the Tyre Direction Before Installation

The custom tyres are directional.

Each tyre needs to be installed so that its rotation direction matches the forward movement of the car.

When viewed from the outside, the left and right tread patterns can appear mirrored, so it is worth checking the direction carefully before mounting the wheels to the chassis.

What I Learned from Issues 23–33

This part of the AE86 build was less about complicated individual components and more about bringing several systems together.

The propeller shaft, differential, rear axle, suspension, brake piping and exhaust all occupy the same area underneath the chassis. Once these assemblies begin interacting with one another, alignment and the order of installation become more important than simply following one isolated step at a time.

Three things stood out for me during this stage:

1. Pre-tap parts when alignment matters.
   The upper control arm housings are much easier to assemble when the screw path has already been checked.
2. Support the chassis instead of fighting its weight.
   As the 1/8 floor panel gets heavier, a stable support makes underside work much easier and reduces the risk of damaging previously installed parts.
3. Check movement after assembly.
   Once the rear axle and shock absorbers are installed, make sure the axle can still move freely before continuing.

The model is starting to feel very different from the early engine build now. Individual assemblies are no longer sitting separately on the workbench — they are becoming part of one increasingly large AE86 chassis.

And with the fuel tank now hiding the battery box underneath the car, the build is beginning its transition from purely mechanical assembly towards the electrical gimmicks that come later.

Continue the AE86 Build

This article covers Issues 23–33 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

Or visit the DeAgostini AE86 Build Project to follow the complete project, current progress, practical notes, custom parts and build service.