TB1 - Technical Bulletin 1

Subframe Mounts

  • The Holden HQ-HZ subframe mounts to the monocoque body using 10 rubber mounts.
    Two mounts support the sub frame at the front near the radiator position, four in the middle by the firewall, and two down each side of the car near the sills.
    Eight of these mounting positions are retained, the two front mounts are not utilised.

    PTFE subframe mount replacing the rubber original

    The mounts are usually found to be distorted during disassembly of the vehicle.
    The mounts can be reused, but the position of the subframe in relation to the centre section affects the position of the nose mounting and other body components.

    A certain amount of movement of the subframe would naturally occur when the original vehicle was driven which reduced road vibrations and harshness. This poses no problem with the original vehicle as that is what it was design to do, but this is not ideal when a major body component, the nose, is mounted off it.

    It is recommended that solid mounts replace the rubber mounts to aid body alignment and reduce subframe flexing in extreme driving situations.

    The recommended material is PTFE as this provides some degree of vibration dampening with a non-deforming material which aids body alignment.

    The dimensions of the mounts previously used are shown in the line drawings below.

PTFE mount for HQ subframe
PTFE HQ subframe mount showing both parts
Note the champher on the top edge of this mount. It is required for the 4 mounts used in the subframe side channels to allow clearance for the top corner radius.
PTFE HQ subframe mount body dimensions
Mount Body Key
D1: 2.25", D3: 0.75", D4: 1.375" (1 3/8)
H1: 1.00", H4: 0.25"
PTFE HQ subframe mount cap dimensions
Mount Cap Key
D2: 1.75", D3: 0.75", D4: 1.375 (1 3/8 clearance)
H2: 0.375" (3/8), H3: 0.1875" (3/16)