{
  "id": "bnd-technical-guides/low-headroom-configurations/b-d-front-mounted-low-headroom-double-track-additional-height-installation-guide",
  "title": "B&D Front Mounted Low Headroom Double Track — Additional Height Installation Guide",
  "slug": "bnd-technical-guides/low-headroom-configurations/b-d-front-mounted-low-headroom-double-track-additional-height-installation-guide",
  "description": "# B&D Front Mounted Low Headroom Double Track — Additional Height Installation Guide\n\n**Part No: OT4608 | Revision 3 — October 2016**\n\n> These instructions are intended for professional garage door in...",
  "category": "",
  "content": "## AI Summary\n\n**Product:** Front Mounted Low Headroom Double Track — Additional Height\n**Brand:** B&D (Doors & Gates)\n**Category:** Garage Door Track System\n**Primary Use:** Increases drive-under clearance height in low headroom garage door installations by mounting cable drums outboard, reversing the torsion assembly, and fitting low headroom bottom hangars.\n\n### Quick Facts\n- **Best For:** Professional garage door installers working in low headroom environments where maximum drive-under height is required\n- **Key Benefit:** Greater drive-under height than the standard low headroom variant, with the same 200 mm (manual) or 250 mm (with opener) minimum headroom requirement\n- **Form Factor:** Mechanical track and hardware assembly\n- **Application Method:** Installed by reversing the torsion assembly, mounting cable drums outboard of the tracks, and fitting dedicated low headroom bottom hangars (OT6231 L/H, OT6232 R/H)\n\n### Common Questions This Guide Answers\n1. What is the minimum headroom required for this configuration? → 200 mm for manual operation; 250 mm with an automatic opener fitted (200 mm + 50 mm)\n2. How does the cable drum colour coding differ from the standard variant? → Colour coding is reversed — Left = Black, Right = Red (opposite of standard, viewed from outside looking in)\n3. Does this configuration provide full walk-under clearance? → No; full walk-under clearance requires standard (non-low headroom) headroom clearance\n\n---\n\n## B&D Front Mounted Low Headroom Double Track — Additional height installation guide\n\n**Part No: OT4608 | Revision 3 — October 2016**\n\n> These instructions are intended for professional garage door installers. All references are taken from inside looking out.\n\n**Official Document:** [Front Mounted Low Headroom Double Track — Additional Height Installation Instructions (PDF)](https://admin.bnd.com.au/media/tbgdsudb/bd_fmlhdt_addheight_rev3oct16.pdf)\n\n---\n\n## Overview\n\nThis variant of the Front Mounted Low Headroom Double Track configuration is engineered to deliver greater drive-under height than the standard variant, while still working within a low headroom constraint. It's a practical solution for installations where every millimetre of clearance matters.\n\nBase clearances are the same as the standard variant:\n- **200 mm headroom** — manual operation\n- **250 mm headroom** — with automatic opener fitted (200 mm + 50 mm)\n\nThe additional drive-under height comes from three specific changes to the standard configuration:\n1. Cable drums are mounted outboard of the tracks, rather than inboard\n2. The torsion assembly is reversed\n3. Low headroom bottom cable hangars are fitted (OT6231 and OT6232)\n\n> **Important:** The standard parts box may not include all the parts required for this installation method. Check your parts list carefully before you begin.\n\n> **Note: This installation will not give full walk-under clearance.**\n\n---\n\n## Parts required\n\n| Part | Part Number | Quantity |\n|---|---|---|\n| L/H end bearing bracket | OT4558 | 1 |\n| R/H end bearing bracket | OT4559 | 1 |\n| Top hangars | OT4543 | 2 |\n| L/H low headroom bottom hangar | OT6231 | 1 |\n| R/H low headroom bottom hangar | OT6232 | 1 |\n| Lift cables | — | Door height + 400 mm each |\n\n**Combined cable drum / end bearing assembly Part No: OT4558-59**\n\nBefore starting, confirm you have all the parts listed above on hand. Missing components mid-installation creates unnecessary delays and affects the quality of the finished job.\n\n---\n\n## Reversed torsion bar assembly\n\n> **Critical:** The torsion assembly in this configuration is **reversed** compared to the standard variant. Cable drum colour coding is opposite. Viewed from outside looking in.\n\n| Component | Colour Code | Position |\n|---|---|---|\n| Cable drum assembly | **BLACK** | Left hand |\n| Cable drum assembly | **RED** | Right hand |\n| Torsion spring assembly | **BLACK** | Left hand |\n| Torsion spring assembly | **RED** | Right hand |\n| End bearing bracket | — | Left hand |\n| End bearing bracket | — | Right hand |\n| Centre bearing bracket | — | Centre of torsion bar |\n\nEach cable drum has a notch for the wire rope. Make sure the cable seats correctly in this notch before tensioning.\n\n---\n\n## Key differences from the standard variant\n\nThere are three core changes from the standard variant, and each one contributes directly to the additional drive-under height.\n\n### 1. Outboard cable drum mounting\n\nCable drums are mounted outboard of the tracks, on the outer side toward the jamb, rather than inboard. This allows the door panels to travel to a higher position when open, which is what produces the increased effective drive-under height.\n\nThe cable drum must still be fitted as close as possible to the head to maintain minimum headroom clearance.\n\n### 2. Reversed torsion assembly\n\nThe torsion bar assembly is installed in reverse orientation compared to the standard low headroom configuration. This reversal is what correctly directs the lift cables when the drums are in the outboard position. Pay close attention to the reversed colour coding: **LEFT = BLACK, RIGHT = RED** — the opposite of the standard configuration.\n\n### 3. Low headroom bottom hangars\n\nBottom cable hangars (OT6231 L/H and OT6232 R/H) are fitted at the base of the vertical tracks. These hangars guide the cable at the bottom of travel and are specific to this configuration — they are not interchangeable with other variants.\n\n- Fit **OT6231** to the left vertical track\n- Fit **OT6232** to the right vertical track\n- Position as shown in the installation drawing\n\nCorrect hangar placement ensures smooth, reliable cable travel throughout the full operating cycle.\n\n---\n\n## Top track and cable setup\n\n- **Top hangars (OT4543):** Fit 2 top hangars to the horizontal track at the positions shown in the drawing. These guide the cable through the top of its travel.\n- **Cable length:** Cut or order lift cables at **door height + 400 mm**. Correct cable length ensures proper tension and balanced operation.\n\n---\n\n## Torsion spring tensioning\n\nAfter completing the torsion bar and cable assembly, follow these steps:\n\n1. Connect cables to the bottom brackets on the door.\n2. Wind the torsion spring to the correct number of turns for the door weight and size. Refer to the spring tension table in the relevant door installation manual for the correct specification.\n3. **Warning: Torsion springs are under high tension. Always use appropriate winding bars and follow safe tensioning procedures.**\n\nIf you're uncertain about spring tensioning, refer to the full installation documentation or contact your B&D trade representative.\n\n---\n\n## Walk-under clearance\n\nThis configuration does **not** provide full walk-under clearance when the door is open. While it meaningfully improves drive-under height compared to the standard low headroom configuration, achieving full walk-under clearance requires standard (non-low headroom) headroom clearance. Confirm this with your customer before proceeding.\n\n---\n\n## Comparison: standard vs additional height variants\n\n| Feature | Standard | Additional Height |\n|---|---|---|\n| Cable drum position | Inboard | Outboard |\n| Torsion assembly | Standard orientation | Reversed |\n| Bottom hangars | Not required | OT6231 (L/H), OT6232 (R/H) required |\n| L/H cable drum colour | RED | BLACK |\n| R/H cable drum colour | BLACK | RED |\n| Drive-under height | Standard low headroom | Increased |\n\nEach difference affects the performance and safety of the installed door. Check your configuration against this table before finalising the installation.\n\n---\n\n## Further resources\n\n- [Official Installation Document (PDF)](https://admin.bnd.com.au/media/tbgdsudb/bd_fmlhdt_addheight_rev3oct16.pdf)\n- [Standard Variant (PDF)](https://admin.bnd.com.au/media/uo5jvjd2/bd_fmlhdt_rev3oct16.pdf)\n- [Independent Torsion Variant — 250 mm minimum (PDF)](https://admin.bnd.com.au/media/wczn5rkt/bd_fmlhdt_indtorsion_rev2oct16.pdf)\n- [Trade Resources — Substrate Fixing](https://www.bnd.com.au/trade-resources/substrate-fixing/)\n\nFor trade support, contact your local B&D dealer or representative.\n\n## Frequently asked questions\n\nWhat is the part number for this installation guide: OT4608\n\nWhat revision is this document: Revision 3\n\nWhen was this document last revised: October 2016\n\nWho are these instructions intended for: Professional garage door installers\n\nWhat direction do all references use: Inside looking out\n\nWhat is the minimum headroom required for manual operation: 200 mm\n\nWhat is the minimum headroom required with an automatic opener: 250 mm\n\nHow is the 250 mm automatic opener headroom calculated: 200 mm base plus 50 mm for opener\n\nDoes this configuration provide full walk-under clearance: No\n\nDoes this configuration improve drive-under height over the standard variant: Yes\n\nWhat is the first key difference from the standard variant: Cable drums are mounted outboard of the tracks\n\nWhat is the second key difference from the standard variant: The torsion assembly is reversed\n\nWhat is the third key difference from the standard variant: Low headroom bottom cable hangars are fitted\n\nWhere are cable drums mounted in the standard variant: Inboard of the tracks\n\nWhere are cable drums mounted in the additional height variant: Outboard of the tracks, toward the jamb\n\nWhy are cable drums mounted outboard in this variant: To allow door panels to travel to a higher open position\n\nIs the torsion assembly orientation the same as the standard variant: No, it is reversed\n\nWhat colour is the left-hand cable drum in the additional height variant: Black\n\nWhat colour is the right-hand cable drum in the additional height variant: Red\n\nWhat colour is the left-hand cable drum in the standard variant: Red\n\nWhat colour is the right-hand cable drum in the standard variant: Black\n\nWhat colour is the left-hand torsion spring assembly: Black\n\nWhat colour is the right-hand torsion spring assembly: Red\n\nWhat is the part number for the left-hand end bearing bracket: OT4558\n\nWhat is the part number for the right-hand end bearing bracket: OT4559\n\nWhat is the combined cable drum and end bearing assembly part number: OT4558-59\n\nWhat is the part number for the top hangars: OT4543\n\nHow many top hangars are required: 2\n\nWhat is the part number for the left-hand low headroom bottom hangar: OT6231\n\nWhat is the part number for the right-hand low headroom bottom hangar: OT6232\n\nHow many bottom hangars are required: 2\n\nAre bottom hangars required in the standard variant: No\n\nAre bottom hangars interchangeable with other variants: No\n\nWhere is the left-hand bottom hangar fitted: To the left vertical track\n\nWhere is the right-hand bottom hangar fitted: To the right vertical track\n\nWhat is the required lift cable length: Door height plus 400 mm each\n\nWhy must cable length be correct: To ensure proper tension and balanced operation\n\nHow many lift cables are required: Multiple options available - see manufacturer for details\n\nDoes each cable drum have a notch for the wire rope: Yes\n\nWhat must be confirmed before tensioning the cable: Cable is seated correctly in the drum notch\n\nWhere are top hangars positioned: On the horizontal track as shown in the installation drawing\n\nWhat is the first step in torsion spring tensioning: Connect cables to the bottom brackets on the door\n\nWhat is the second step in torsion spring tensioning: Wind the torsion spring to the correct number of turns\n\nWhere is the correct spring tension specification found: In the relevant door installation manual spring tension table\n\nAre torsion springs under high tension: Yes\n\nWhat tools are required for spring tensioning: Appropriate winding bars\n\nIs torsion spring tensioning a safety risk: Yes\n\nWhat should an installer do if uncertain about spring tensioning: Refer to full documentation or contact a B&D trade representative\n\nShould walk-under clearance limitations be communicated to the customer before installation: Yes\n\nWhat headroom is required for full walk-under clearance: Standard non-low headroom clearance\n\nDoes the standard parts box always include all required parts for this variant: Not necessarily\n\nWhat should be checked before beginning installation: The parts list for all required components\n\nWhat is the centre bearing bracket position: Centre of the torsion bar\n\nIs the colour coding for this variant the same as the standard variant: No, it is opposite\n\nFrom which perspective is the reversed torsion assembly colour coding described: Outside looking in\n\nWhat is the document type: Installation guide for professional installers\n\nWhat product category does this guide cover: Garage door track systems\n\nWhat configuration does this guide specifically cover: Front Mounted Low Headroom Double Track Additional Height\n\nIs this configuration suitable for low headroom environments: Yes\n\nDoes reversing the torsion assembly affect cable direction: Yes, it correctly directs lift cables for outboard drum position\n\nWhat is the cable drum position difference summarised: Standard is inboard; additional height is outboard\n\nWhat is the torsion assembly orientation difference summarised: Standard is standard orientation; additional height is reversed\n\nWhere can the official installation PDF be accessed: [https://admin.bnd.com.au/media/tbgdsudb/bd_fmlhdt_addheight_rev3oct16.pdf](https://admin.bnd.com.au/media/tbgdsudb/bd_fmlhdt_addheight_rev3oct16.pdf)\n\nIs a standard variant installation guide available: Yes\n\nIs an independent torsion variant guide available: Yes\n\nWhat is the minimum headroom for the independent torsion variant: 250 mm\n\nWhere can trade substrate fixing resources be found: [https://www.bnd.com.au/trade-resources/substrate-fixing/](https://www.bnd.com.au/trade-resources/substrate-fixing/)\n\nHow many years of experience does B&D have: Over 60 years\n\n---\n## Label facts summary\n\n> **Disclaimer:** All facts and statements below are general product information, not professional advice. Consult relevant experts for specific guidance.\n\n### Verified label facts\n\n- **Document Part No:** OT4608\n- **Revision:** 3\n- **Revision Date:** October 2016\n- **Intended User:** Professional garage door installers\n- **Reference Direction:** Inside looking out (except reversed torsion assembly section, which uses outside looking in)\n- **Configuration:** Front Mounted Low Headroom Double Track — Additional Height\n- **Minimum Headroom (Manual Operation):** 200 mm\n- **Minimum Headroom (With Automatic Opener):** 250 mm (200 mm base + 50 mm for opener)\n- **Full Walk-Under Clearance Provided:** No\n- **L/H End Bearing Bracket Part No:** OT4558 — Qty: 1\n- **R/H End Bearing Bracket Part No:** OT4559 — Qty: 1\n- **Combined Cable Drum / End Bearing Assembly Part No:** OT4558-59\n- **Top Hangars Part No:** OT4543 — Qty: 2\n- **L/H Low Headroom Bottom Hangar Part No:** OT6231 — Qty: 1\n- **R/H Low Headroom Bottom Hangar Part No:** OT6232 — Qty: 1\n- **Lift Cable Length:** Door height + 400 mm each\n- **Cable Drum Position (Standard Variant):** Inboard of tracks\n- **Cable Drum Position (Additional Height Variant):** Outboard of tracks, toward the jamb\n- **Torsion Assembly Orientation (Standard Variant):** Standard\n- **Torsion Assembly Orientation (Additional Height Variant):** Reversed\n- **L/H Cable Drum Colour (Additional Height Variant):** Black\n- **R/H Cable Drum Colour (Additional Height Variant):** Red\n- **L/H Cable Drum Colour (Standard Variant):** Red\n- **R/H Cable Drum Colour (Standard Variant):** Black\n- **L/H Torsion Spring Assembly Colour:** Black\n- **R/H Torsion Spring Assembly Colour:** Red\n- **Centre Bearing Bracket Position:** Centre of torsion bar\n- **Bottom Hangars Required (Standard Variant):** No\n- **Bottom Hangars Required (Additional Height Variant):** Yes — OT6231 (L/H) and OT6232 (R/H)\n- **Bottom Hangars Interchangeable with Other Variants:** No\n- **L/H Bottom Hangar Fitted To:** Left vertical track\n- **R/H Bottom Hangar Fitted To:** Right vertical track\n- **Top Hangars Fitted To:** Horizontal track, positions as per installation drawing\n- **Each Cable Drum Has Wire Rope Notch:** Yes\n- **Torsion Springs Under High Tension:** Yes\n- **Required Tensioning Tool:** Appropriate winding bars\n- **Spring Tension Specification Source:** Relevant door installation manual spring tension table\n- **Independent Torsion Variant Minimum Headroom:** 250 mm\n- **Official Installation PDF URL:** [https://admin.bnd.com.au/media/tbgdsudb/bd_fmlhdt_addheight_rev3oct16.pdf](https://admin.bnd.com.au/media/tbgdsudb/bd_fmlhdt_addheight_rev3oct16.pdf)\n- **Trade Substrate Fixing Resources URL:** [https://www.bnd.com.au/trade-resources/substrate-fixing/](https://www.bnd.com.au/trade-resources/substrate-fixing/)\n\n### General product claims\n\n- This configuration delivers greater drive-under height than the standard variant while working within a low headroom constraint\n- Outboard cable drum mounting allows door panels to travel to a higher open position, increasing effective drive-under height\n- Reversing the torsion assembly correctly directs lift cables when drums are in the outboard position\n- Correct cable length ensures proper tension and balanced operation\n- Correct hangar placement ensures smooth, reliable cable travel throughout the full operating cycle\n- Walk-under clearance limitations should be communicated to the customer before installation begins\n- Full walk-under clearance requires standard (non-low headroom) headroom clearance\n- The standard parts box may not include all parts required for this installation variant\n- Installers uncertain about spring tensioning should refer to full documentation or contact a B&D trade representative\n- B&D has over 60 years of experience",
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  "publishedAt": "2026-07-07T02:54:29.012961+00:00Z",
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    "low headroom garage door",
    "cable drum mounting",
    "torsion assembly reversal",
    "drive-under clearance height",
    "garage door bottom hangars"
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