TOMEI Main Stud & Crank Cap Ladder Kits | 4A-GE / 4A-GZE (1983-87 Corolla / 1984-89 MR2)

TOMEI 4AG Main Stud & Crank Cap Ladder Kits

For 1983–1987 Toyota Corolla AE86 and 1984–1989 Toyota MR2 AW11 (MK1) 4A-GE / 4A-GZE 16V engine builds

Overview

TOMEI 4AG main studs and crank-cap ladders reinforce the lower end of Toyota 4A-GE and 4A-GZE 16V engines used in AE86 Corolla and MK1 AW11 MR2 applications. The main studs improve main-cap clamping consistency, while the ladder pieces increase support across the crank-cap area for high-RPM and performance engine builds.

Choose the five-piece ladder set, the main-stud set, or the complete matched package with both systems.

Key Features

• Designed for Toyota 4A-GE / 4A-GZE 16V bottom-end reinforcement
• 8740 chromoly main-stud construction
• M10 × P1.25 main-stud thread specification
• Ten main studs, ten nuts, and ten washers in main-stud-equipped configurations
• Five special heat-treated crank-cap ladders in ladder-equipped configurations
• Supports more consistent main-cap clamping and increased crank-cap rigidity
• Available as ladder-only, main-stud-only, or complete matched configurations

Bottom-End Reinforcement

High engine speed and increased cylinder load place additional stress on the crankshaft, main bearings, main caps, and fasteners. The stud-style fastener system provides a more consistent clamping arrangement at the main caps, while the ladder system adds structural support across the crank-cap area to help control deflection under demanding engine operation.

The complete configuration combines both upgrades for builds where main-cap clamping and crank-cap rigidity are being addressed together.

Vehicle Fitment

Toyota Corolla AE86

• 1983–1987 Trueno (JDM) — 4A-GE 16V
• 1983–1987 Levin (JDM) — 4A-GE 16V
• 1985–1987 GT-S (U.S.-Market) — 4A-GE 16V
• 1984–1987 SR5 (U.S.-Market) — 4A-GE / 4A-GZE 16V engine swap

Toyota MR2 (AW11 / MK1)

• 1984–1989 JDM — 4A-GE 16V
• 1985–1989 U.S.-Market — 4A-GE 16V
• 1986–1989 JDM Supercharged — 4A-GZE 16V
• 1988–1989 U.S.-Market Supercharged — 4A-GZE 16V

Fitment Notes

• Fitment is determined by the installed 4A-GE / 4A-GZE 16V engine configuration.
• The factory AE86 SR5 4A-C engine is excluded; SR5 fitment requires a properly configured 4A-GE or 4A-GZE 16V engine swap.
• Crank-cap ladders cannot be used with the factory main-cap bolts. Use the TOMEI main studs or another properly sized fastener setup that provides adequate engagement.
• Main-bearing clearance and crankshaft rotation must be verified during final assembly after the reinforced fasteners are torqued.
• With ladder-equipped configurations, verify No. 5 ladder, oil-pan, and baffle clearance; modification may be required if interference is present.
• Clean and inspect the engine-block threads and follow the supplied tightening, lubricant, and thread-treatment procedures.
• Professional engine assembly is recommended.

Product Specifications

Brand: TOMEI
Product Type: Bottom-End Reinforcement
Engine Family: Toyota 4AG 16V
Main Stud Material: 8740 Chromoly
Main Stud Thread: M10 × P1.25
Main Stud Quantity: 10
Crank Cap Ladder Quantity: 5
Ladder Construction: Special Heat-Treated FC Material
Primary Purpose: Main-Cap Clamping & Crank-Cap Reinforcement

Which Configuration Should You Choose?

Crank Cap Ladder Set – 5 Ladders

Choose this option if the engine already has a compatible main-stud setup and only needs the TOMEI crank-cap reinforcement. The factory main-cap bolts cannot be used with the ladders.

Main Stud Set

Choose this option if upgraded 8740 chromoly main studs are needed but additional crank-cap ladder reinforcement is not. This configuration focuses on improved main-cap clamping without adding the ladder system.

Complete Main Stud + Crank Cap Ladder Set

Choose the complete package for a bottom-end build that needs both upgrades together. It includes the matching TOMEI main studs and all five crank-cap ladders, providing the complete TOMEI bottom-end reinforcement configuration.

Starting from scratch? The complete set is the most straightforward choice when both main-cap clamping and crank-cap reinforcement are desired. If compatible main studs are already installed, the ladder-only configuration may be the more appropriate option.

Alternative Main Stud Option

For builders who only need upgraded main fasteners and do not need the TOMEI ladder system, the ARP 8740 Chromoly 4A-GE Main Stud Kit is a main-stud-only alternative for compatible 4A-GE 16V builds. Choose the TOMEI complete configuration when both the main studs and crank-cap ladder reinforcement are desired.

Available Configurations

Crank Cap Ladder Set – 5 Ladders

• (5) TOMEI crank-cap ladders
• Main studs are not included
• Requires TOMEI main studs or another properly sized fastener setup; factory main-cap bolts cannot be used
• Package: 15 × 14 × 6 cm; 0.8 kg

Main Stud Set

• (10) 8740 chromoly main studs
• (10) nuts
• (10) washers
• M10 × P1.25 stud thread
• Package: 15 × 14 × 6 cm; 1.55 kg

Complete Main Stud + Crank Cap Ladder Set

• (5) crank-cap ladders
• (10) main studs
• (10) nuts
• (10) washers
• Complete matched bottom-end reinforcement package
• Package: 17 × 29 × 8 cm; 1.0 kg