IronBox BMW E30 Dual-Caliper Adapters — Drum Trailing Arms

This IronBox adapter kit is designed exclusively for BMW E30 rear trailing arms originally equipped with drum brakes
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It converts the rear axle to a disc-brake layout and provides mounting points for two calipers on each side — one for the main braking circuit and one for a separate hydraulic handbrake circuit
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The conversion uses BMW E30 front brake discs and matching front calipers, with either vented or non-vented components
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Using a dedicated second pair of calipers keeps the hydraulic handbrake circuit separate from the main rear braking system
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The adapters are manufactured from steel, finished with powder coating, and supplied as a left- and right-side pair with the required mounting hardware
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Main features:
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• Dual-caliper rear conversion — provides mounting points for two brake calipers on each side
• Independent hydraulic handbrake circuit — keeps the handbrake separate from the main braking circuit
• Rear drum-to-disc conversion — designed specifically for BMW E30 drum-brake trailing arms
• Multiple brake configurations — compatible with matching vented or non-vented BMW E30 front discs and calipers
• Bolt-on installation — adapters are installed using the supplied mounting hardware
• Steel construction — suitable for drift, track, and performance builds
• Powder-coated finish — provides corrosion protection and a clean appearance
• Designed and manufactured in Ukraine by IronBox

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Compatibility
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Compatible with:
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• BMW 3 Series E30
• Rear trailing arms originally equipped with drum brakes only

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Not compatible with:
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• BMW E30 rear trailing arms originally equipped with disc brakes
• Other BMW trailing-arm configurations unless confirmed before ordering

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Compatibility is determined by the installed rear trailing arms and braking configuration, not only by the vehicle’s body style or engine
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Required parts — not included
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• BMW E30 front brake discs — vented or non-vented
• Matching BMW E30 front brake calipers for the selected disc type
• Hydraulic handbrake
• Brake lines, hoses, fittings, and brake fluid

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Brake discs and calipers must be used as a matching compatible set
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Kit includes
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• Left-side dual-caliper adapter — 1 pc
• Right-side dual-caliper adapter — 1 pc
• Installation hardware

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Important installation information
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This product changes the vehicle’s rear braking configuration
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Installation, caliper alignment, brake-line routing, bleeding, and final testing must be carried out by a qualified specialist
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Do not operate the vehicle until the complete braking system has been properly inspected and tested
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Any brake components that differ from the configurations listed above must be confirmed before ordering