DeAgostini AE86 Build Journal 02 — Issues 14–22: Chassis and Suspension Work

After completing the 4A-GEU engine in Issues 1–13, the DeAgostini 1/8 Toyota Sprinter Trueno AE86 build now moves into a very different stage.

Issues 14–22 focus on the right-front suspension, revised front tyres, front axle, front subframe and floor structure. The individual assemblies are no longer limited to components that can be held comfortably in one hand. By the end of this chapter, the floor panel is fully assembled and the overall size of the 1/8-scale chassis is becoming clear.

This stage is generally straightforward, with no major fitting problems found. However, the growing size and weight of the assembly introduce a new kind of challenge. Supporting the chassis properly, keeping the work surface clear and tightening a large number of screws without damaging the surrounding parts become increasingly important.

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

In This Build Journal

• Milestone 1: Completing the Front Suspension — Issues 14–17
• Milestone 2: Building the Front Axle and Subframe — Issue 18
• Milestone 3: Constructing the Floor Panel — Issues 19–22
• Overall Build Impressions
• The Floor Panel Is Fully Assembled

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Milestone 1: Completing the Front Suspension — Issues 14–17

The first part of this chapter completes the right side of the front suspension and introduces revised tyres with a more detailed tread pattern.

The radiator grille is also fitted to the front bumper, while additional wiring is added to the completed 4A-GEU engine.

Issue 14 — Right Front Suspension and Stabiliser

Issue 14 begins construction of the right-front suspension and installs the front stabiliser components.

The right lower arm, tie rod, stabiliser bar and supporting brackets are assembled into a compact suspension sub-assembly.

Main Parts Supplied

• Right front lower arm
• Front stabiliser bar
• Two strut bars
• Two strut-bar supports
• Two front stabiliser brackets
• Left and right strut-bar supports
• Right tie rod
• 2.0 × 10 mm screw
• AM screws
• AP screws

The assembly is straightforward, with no fitting problems found.

As with the earlier suspension work, it is worth checking the orientation of the bars and supports before tightening the screws. Several parts are visually similar, and confirming their position first avoids unnecessary disassembly.

Issue 15 — Radiator Grille, Right MacPherson Strut and Throttle Wiring

Issue 15 works across three different areas of the AE86.

The radiator grille is fitted to the front bumper, the right MacPherson strut is assembled, and the cold-start-injector lead is added to the 4A-GEU engine.

Main Parts Supplied

• Radiator grille
• Right MacPherson strut
• Washer
• Right knuckle arm
• Right strut upper mount
• Front coil spring
• Cold-start-injector lead
• Two code bands
• AM, CM and AP screws

No assembly problems were found.

With the right MacPherson strut completed, both sides of the front suspension are now ready to be integrated into the larger front-axle structure.

The radiator grille also makes the front bumper look noticeably more complete, while the additional throttle-related wiring adds another small layer of realism to the engine.

Issue 16 — Right Disc Brake and Revised Front Tyres

Issue 16 fits the right disc-brake assembly to the front axle prepared in Issue 15.

This issue also supplies two revised tyres. One is used for the new right-front wheel, while the other replaces the left-front tyre originally supplied and fitted in Issue 3.

Main Parts Supplied

• Two revised tyres
• Right brake-caliper components
• Right brake-disc dust cover
• Right brake-disc components
• AP screws
• TM screws
• AM screws

Comparing the Original and Revised Tyres

The revised tyre has a more detailed tread pattern and additional surface features, giving it a more realistic appearance than the earlier version.

The original left-front tyre from Issue 3 should therefore be removed and replaced with the revised version supplied here.

No fitting problems were found during the brake or tyre work.

Issue 17 — Right Front Wheel

Issue 17 assembles the right-front wheel using one of the revised tyres supplied with Issue 16.

Main Parts Supplied

• Outer rim
• Inner rim
• Rim cap
• Washer
• AM screws
• VM screw

The inner and outer rims are joined inside the tyre before the rim cap is fitted.

This is a simple assembly, but the tyre should sit evenly around the full circumference of the rim before the screws are tightened. Checking both sides helps prevent one edge of the tyre from sitting slightly proud.

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Milestone 2: Building the Front Axle and Subframe — Issue 18

Issue 18 brings the previously completed suspension, steering and front-axle parts together inside the front subframe.

This is the point where the project begins to shift from small independent assemblies into a substantial structural section of the car.

Issue 18 — Front Axle and Front Subframe

Issue 18 fits the front axle into the front subframe and connects the front suspension stabiliser and strut bars.

Main Parts Supplied

• Front subframe
• Steering-rack support
• Front-member lower section
• AM screws
• BM screws
• UM screws

The previously completed front-axle and suspension components are now positioned inside the subframe and secured at multiple points.

No major fitting problems were found, but the character of the build changes considerably here.

Compared with the engine and earlier suspension sub-assemblies, the completed front subframe is much larger. Its weight also begins to build quickly as the axle, suspension, steering and supporting pieces are combined.

The number of screws required increases as well. It is useful to tighten them gradually and alternate between mounting points rather than fully tightening one side first.

This gives you more opportunity to check alignment before the entire structure is locked into position.

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Milestone 3: Constructing the Floor Panel — Issues 19–22

Issues 19–22 attach the front subframe to the floor pan before adding the centre cover, floor crossmembers, rear floor panel and rear subframe.

By the end of Issue 22, the full floor-panel structure is assembled.

This is the strongest visual milestone in the chapter because the overall length and proportions of the future chassis can finally be seen.

Issue 19 — Front Subframe and Floor Pan

Issue 19 attaches the completed front subframe and front axle to the main floor pan.

Main Parts Supplied

• Floor pan
• Cord clamp
• AM screw
• AFM screws

The floor pan alone weighs approximately 626 g.

That figure gives an early indication of how heavy the completed 1/8-scale AE86 may eventually become once the engine, interior, body panels, electrical system and remaining mechanical assemblies are installed.

When viewed from underneath, the moulded structure resembles the floor section of a real monocoque body. It feels similar to looking up at the underside of a full-size car while it is raised on a workshop lift.

The structural ribs, channels and mounting areas are not simply a flat base. They help reinforce the impression that this is being constructed as a miniature vehicle rather than a conventional display model.

The front subframe is secured to this structure using several metal screws.

Because the assembly is already large, support the floor pan on a stable and clear surface before tightening. Avoid allowing the front suspension or steering parts to carry the weight of the structure.

Issue 20 — Centre Cover and Floor Crossmembers

Issue 20 adds the centre cover and floor crossmembers to the main floor pan.

Main Parts Supplied

• Centre cover
• Floor crossmember 1
• Floor crossmember 2
• Cord clamp
• AP screws
• AM screw
• CM screws

This is a straightforward stage with no fitting problems found.

The centre cover and crossmembers help strengthen the floor structure while also adding more of the underside detailing.

Issue 21 — Rear Floor Panel and Stabiliser-Bar Brackets

Issue 21 installs the rear floor panel and the two rear stabiliser-bar brackets onto the floor pan.

Cord clamps are also fitted to the upper side of the structure.

Main Parts Supplied

• Rear floor panel
• Two rear stabiliser-bar brackets
• Cord clamp 1
• Cord clamp 2
• AM screws
• CM screws
• AFM screws

Connecting the rear floor panel is one of the most visually significant moments in this stage.

Once the front and rear sections are joined, the full length of the chassis floor becomes apparent. It is now much easier to imagine the body, engine, interior and remaining components eventually being mounted onto this foundation.

The project is still some distance from completion, but the structure now occupies a substantial portion of the workbench.

Issue 22 — Rear Subframe and Lower Control-Arm Brackets

Issue 22 completes the floor-panel structure by installing the left and right rear-subframe sections together with the lower control-arm brackets for the rear axle.

Main Parts Supplied

• Left rear subframe
• Right rear subframe
• Two lower control-arm brackets
• AFM screws

The rear-subframe parts require a considerable number of screws, but no major fitting problems were found.

Tighten the screws gradually while checking that the adjoining sections remain properly seated. The assembly is now large enough that pressure applied at one end can move or flex another area if it is not fully supported.

With the rear subframe installed, the full floor panel is now assembled.

From Issue 23, the project moves into the propeller shaft, rear axle and rear-suspension components.

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Overall Build Impressions — Issues 14–22

Issues 14–22 mark a major change in the physical character of the AE86 build.

The earlier engine stages involved many small mechanical and cosmetic details. This chapter begins with similar suspension components but quickly expands into much larger structural assemblies.

The main observations from this stage are:

• The revised tyres supplied with Issue 16 have a more convincing tread pattern and replace the earlier front tyre from Issue 3.
• The right-front suspension and brake assemblies fit together without major problems.
• The completed front subframe becomes considerably larger and heavier than the earlier engine assembly.
• The floor pan alone weighs approximately 626 g.
• The monocoque floor detailing is convincing when viewed from underneath.
• The increasing size of the assembly requires a larger and clearer work area.
• Heavy structural sections should be fully supported rather than resting on delicate suspension components.
• Large numbers of screws are better tightened gradually and in stages.
• Alignment should be checked before every group of screws is fully secured.

The parts are predominantly metal in the main structural areas, which gives the assembly a solid feel. However, that strength does not mean the entire build can be handled casually.

Smaller brackets, suspension pieces and previously installed components remain exposed. As the weight increases, an accidental slip can place much more force on those delicate areas than during the earlier stages.

From Engine Assembly to Vehicle Structure

One of the most interesting changes in this chapter is the shift in perspective.

The completed 4A-GEU engine is an impressive standalone assembly, but it can still be viewed and handled as an individual component.

The floor structure is different.

Once the front subframe, floor pan and rear floor panel are joined, the project starts to look less like a collection of model parts and more like the foundation of an actual vehicle.

Looking at the underside of the monocoque floor section reinforces that feeling. The moulded channels, crossmembers, mounting points and subframes follow the logic of a real automotive structure.

That is where the scale of the DeAgostini AE86 becomes much easier to understand.

A More Physical Build Stage

The other noticeable difference is the physical effort involved.

Issues 18–22 require many screws to secure the axle, subframe, crossmembers and floor sections. By the end of the session, I could feel the strain in my hand from tightening so many screws.

A suitable electric precision screwdriver could be useful during these repetitive structural stages, provided it has:

• low and controllable torque;
• a suitable small Phillips bit;
• good trigger control;
• the ability to stop before overtightening.

Final tightening should still be done carefully by hand, especially around plastic threads, smaller brackets or areas where the screw resistance changes suddenly.

The goal is not simply to finish faster. It is to reduce repetitive strain without losing control over the assembly.

The Floor Panel Is Fully Assembled

From Issue 14 through Issue 22, the build has progressed from the right-front suspension into a complete floor-panel structure.

The front axle and suspension are now mounted inside the front subframe. That subframe is attached to the 626 g floor pan, which is connected to the centre structure, rear floor panel and rear subframe.

The completed floor panel finally gives a clear sense of the AE86’s overall chassis length.

From Issue 23 onward, the next stage will add the propeller shaft, rear axle and rear-suspension components.

The AE86 Build Journal continues.

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Related AE86 Build Journal Articles

Start here:
DeAgostini AE86 Build Journal — Project Introduction

Previous chapter:
DeAgostini AE86 Build Journal 01 — Issues 1–13: Building the 4A-GEU Engine