{
  "classification": "Manufacturer replacement-interface comparison plus conditional supplier-photo gear envelope; not fitted-unit identification.",
  "manufacturer_source": "https://shop.quaife.co.uk/wp-content/uploads/2014/03/QDF5K.pdf",
  "manufacturer_product": "https://shop.quaife.co.uk/shop/atb-differentials/atb-differential-aseries-qdf5k/",
  "manufacturer_drawing_sha256": "d53566bac802f4988d79131f1c59b9cbb7beae12b46aa3da5c6005f5f30472ac",
  "examined": "QDF5K R.W.D. differential data sheet, issue01 dated17.5.05, visually read. Used In: Austin Healey Sprite / M.G. Midget. Quaife product page asks application confirmation using drawing. This is an aftermarket ATB interface, not a stock open-cage/internal drawing.",
  "manufacturer_dimensions_mm": {
    "D1_crown_bolt_pcd": 109.5,
    "bolt_count": 6,
    "through_hole_diameter": 10.0,
    "D2_crown_spigot_diameter": 95.2,
    "D3_bearing_journal_diameter": 35.0,
    "L1_bearing_shoulder_distance": 101.6,
    "L2_journal_projection": 18.8,
    "L2A_journal_projection": 18.8,
    "L3_overall_journal_length": 139.2,
    "L4_shoulder_to_crown_face": 20.6,
    "D4_bore": 25.4
  },
  "listed_spline_context": {
    "teeth": 10,
    "pitch": "1 NOM.",
    "use": "Documentary only; no spline geometry, fitted count or engagement inferred."
  },
  "supplier_photo": "https://rimmerbros.com/ItemImages/Large/BTA1223.jpg",
  "supplier_product": "https://rimmerbros.com/Item--i-BTA1223",
  "supplier_photo_sha256": "7c5917dcc9be20fa5e0c638a11a0a08e12dc28de93202707e9aac9380ea415ef",
  "conditional_crown_photo": {
    "six_hole_centers_source_pixels": [
      [
        213.25,
        154.0
      ],
      [
        271.5,
        188.5
      ],
      [
        265.75,
        254.75
      ],
      [
        189.25,
        287.0
      ],
      [
        127.0,
        246.0
      ],
      [
        142.5,
        179.25
      ]
    ],
    "conditional_hole_pcd_mm": 109.5,
    "homography_plane_mm_to_source_pixels": [
      [
        1.4316630494061764,
        -0.46824132872241714,
        202.17366602553358
      ],
      [
        0.1183848477638588,
        0.9340224563261992,
        215.93697258610595
      ],
      [
        0.00010770592971028334,
        -0.0012790046396243743,
        1.0
      ]
    ],
    "hole_reprojection_pixels": [
      0.3489395381315439,
      0.4694162681962808,
      0.5823563337314519,
      0.609186459839932,
      0.513256752715165,
      0.36581444623912124
    ],
    "outer_tooth_boundary_pixels": [
      [
        199,
        126
      ],
      [
        270,
        142
      ],
      [
        315,
        195
      ],
      [
        312,
        263
      ],
      [
        255,
        315
      ],
      [
        185,
        330
      ],
      [
        113,
        300
      ],
      [
        84,
        240
      ],
      [
        109,
        170
      ]
    ],
    "conditional_outline_diameters_mm": [
      164.0476771259135,
      163.77893971585527,
      166.39431072504965,
      172.06148500807362,
      168.39000073715496,
      168.05627530751207,
      164.17169361731536,
      161.41019523814418,
      161.3460832016429
    ],
    "conditional_median_outer_diameter_mm": 164.17169361731536,
    "selected_envelope_outer_diameter_mm": 165
  },
  "photo_hypothesis": "The BTA1223 supplier-photo six-hole flange is provisionally calibrated with the109.5mm QDF5K comparison circle. That transfer is conditional on matching interfaces, not a compatibility approval. Hole picks fit a plane homography; tooth tips lie at varying depths and are not coplanar with the flange. The161\u2013172mm outline spread and164.2mm median support a rounded165mm reference only, not a dimensional tolerance. No gear teeth or fitted ratio are selected.",
  "applied_reference_frame": {
    "nominal_shoulders_x_abs_mm": 50.8,
    "journal_end_x_abs_mm": 69.6,
    "crown_mount_face_x_mm": 30.2,
    "selected_positive_x_crown_side": "Inherited construction handedness, not verified fitted orientation.",
    "display_packing_mm": 0.1,
    "bearing_envelope_inner_outer_x_abs_mm": [
      50.9,
      67.9
    ],
    "cap_center_x_abs_mm": 59.4,
    "independent_bearing_envelope_mm": [
      35,
      72,
      17
    ]
  },
  "estimated_geometry": {
    "central_cage_outer_inner_radius_mm": [
      45,
      32
    ],
    "central_cage_x_mm": [
      -25.2,
      25.2
    ],
    "end_wall_gauge_mm": 4,
    "collar_outer_radii_mm": [
      35,
      24
    ],
    "crown_mount_flange_radius_mm": 62.5,
    "crown_mount_flange_gauge_mm": 5,
    "spigot_display_projection_mm": 2,
    "spigot_bore_clearance_radius_mm": 0.2,
    "gear_web_radius_mm": 72,
    "gear_bevel_outer_radii_mm": [
      77.5,
      82.5
    ],
    "gear_axial_extent_mm": 13,
    "front_saddle_open_arm_boundary_z_mm": 60
  },
  "limits": "The35x72x17mm SKF bearing remains an independent envelope, not an approved2K5943/fitted cross-reference. Manufacturer nominal shoulders and journals remain separate from the unselected0.1mm display packing and actual preload. All open-cage architecture, windows, end walls, collar shoulders, spigot projection, web/bevel sections, cap/stud map and front saddle/arm boundaries remain estimates. No Quaife helical mechanism is transplanted into the stock-reference cage. Front saddles belong to the carrier casting but their arms stop at an omission boundary; connection to the exterior carrier remains unverified. Old side-gear cylinders remain optional unfit boundaries rather than being moved to the new cage. Old260mm crown-wheel geometry is retained as an optional historical comparison. No actual axle/gearset identity, ratio, hypoid offset, loaded bearing fit, tooth contact, spline fit, torque, sealing, operating clearance or verified release/removal path."
}