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354mm Adaptor Bracket Installation Guide (R34 GTT, R33 GTST)

  1. Begin by removing your existing rotor and caliper and clean your hub face with a wire brush, brake cleaner and some sandpaper to remove any surface rust.
    * Do not skip this step as it is impertitive in preventing rotor runout!
  2. Behind the hub/knuckle is a hard-line bracket with an M8 bolt; remove this bolt and the bracket.
  3. Sort out your provided HFM.Parts bolt kit and Caliper Adaptor.
    You should have:
    2x 75mm Hex Head Bolt w/ 2x 28mm Support Spacer
    2x 50mm Hex Head Bolt w/ 2x 10mm Support Spacer
    4x 60mm Hex Bolts
    8x M14 Washers (used on all bolts)

    Plus, 2x HFM.Parts Caliper Adaptors P/N:
    1x R34354AKE-L & R34354AKE-R
    L = LHS and R = RHS
    *It is very important to be aware of the correct positioning of the bolts and spacers, please refer to the photos and video provided.
  4. Use LockTite 262 or equivalent for all bolts.
  1. Bolt the Adaptor to the inside of the knuckle and tighten by hand. Do not fully tighten this bolt yet!
  2. Using the 75mm Bolt and 28mm Spacer, mount the Adaptor, making sure the cut-out of the spacer is facing the caliper. This will help to align the Caliper’s top mounting hole to rest into the spacer’s cut-out. Then, tighten both the top and bottom bolts properly – but without using the torque wrench, as we will be removing the Caliper again. This will set the Support Spacer up to be torqued into place.
  3. Then, torque the Caliper Adaptor bolts at 58 – 62 ft-lbs, which will also lock the Support Spacer into place.
  4. Remove the Caliper and install the rotor, holding it in place using a lug nut.
  5. Re-install the Caliper and torque both bolts to 58 – 62 ft lbs.
  6. Make sure to re-install the M8 hard-line bracket bolt from behind the hub/knuckle. However, it is up to you if you would like to retain the Hard-line bracket, as it will serve no function.
  7. Lastly, check for clearance between the backing plate and the rotor. If there is any interference, bend the backing plate out of the way.
  8. Your OEM brake lines will be at full extension when using this adaptor/brake kit. We highly recommend using the HFM.Parts Front Hard Line Delete Braided Brake Lines (SKU: HFM-R34GT-HDDL), which can be added on when purchasing a brake kit.

Special Notes: In an attempt to create a lightweight rotor and considering the outer ring is the heaviest component, we’ve enlarged the aluminium centre hat as much as possible so that we could reduce the rotor surface. This means that the centre hat sits quite close to the caliper and during heavy track work has the potential to expand and skim the caliper.
To prevent any binding, we recommend either linishing a very small portion of the caliper or back-off the caliper bolts and pivot the caliper upwards, re-tighten the caliper bolts whilst holding this position. Then torque the bolts as above. This will hold the caliper slightly further away, preventing any interference.

Unsure? Contact help@hfm.parts