245mm Brake Kit Rev4.2 Installation

Thank you for purchasing the Mamba Motorsport 245mm Big Brake Kit. These installation instructions are for the Rev4.2 kit only and do not apply to any other brake kit.


This is a performance upgrade for MG Midgets and AH Sprites as a replacement for the original caliper and rotor. Make sure that the rest of the brake system, wheels, tyres and suspension are able to cope with the additional load. The kit should be installed by a competent mechanic or professional. Brakes are an essential safety item and incorrect fitting could have serious consequences.

Basic kit contents:

  • 2 x Wilwood 4 pot alloy radial calipers
  • 2 x alloy caliper mounting brakets
  • 2 x steel caliper offset plates
  • 2 x 245mm solid brake rotors
  • 8 x 3/8" x 1"1/4 bolt
  • 8 x 3/8" nyloc
  • 4 x 7/16" x 1"1/4 bolt 
  • 4 x M10 x 60mm bolt
  • 4 x M10 x 25mm bolt
  • 4 x 10mm x 8mm spacers 
  • 4 x Copper washers 
  • 2 x 1/8BSP Banjo 2
  • 4 x 7/16" plain washers

Optional Ackermann kit  - [opt 1]

Ackermann plus dropper kit - [opt 2]

Note on tracking:

Because the Ackermann kits includes a change to the steering geometry, the tracking will need to be reset after the kit is fitted. The car will not be driveable unless this is done. Spridgets are quite sensitive to front toe so we highly recommend getting the tracking done regularly anyway. On a track car set to a very small amount of toe-in such that under braking the force on the front suspension tends to force the wheels completely parallel. 

Torque settings: 

  • 3/8" - 33 ftlb 
  • 7/16" - 38 ftlb 
  • M10 - 43 ftlb 
  • Hubnut - 46 ftlb

Installation Steps:

  1. [opt 1 & 2] With tracking gauges or string lines take the initial tracking measurement and record it.
  2. Before removing the wheels, check for excessive play in the front wheel bearings.
  3. Clamp the front brake lines, remove the front wheels and calipers. Undo the banjo bolts from the calipers to leave the banjos attached to the flexi lines.
  4. Remove the hubs
  5. Unbolt the original rotors and clean any debris /corrosion from all the mating faces of the hub. If there was excess play in the front wheel bearings replace them now!
  6. [opt 1 & 2] Slacken the TRE lock nuts and wind them back 16mm, use a caliper to check and then mark the tierod and lock nut positions with a paint pen / tape.
  7. [opt 1 & 2] Disconnect the TREs from the steering arms and wind them to the lock nuts.
    Depending on the design of the TRE and rack, the thread may bottom, if that happens then measure the gap between the TRE and lock nut, remove the TRE and trim the tierod by the correct amount.
  8. [opt 1 & 2] Remove the steering arms.
  9. Give everything a really good clean and degrease. Regrease the kingpins while everything is out of the way.
  10. [opt1 & 2] Refit the steering arms:
    [opt 1} use 16mm spacers between the upright and the arm. Use the 2"3/4 bolts instead of the original bolts.
    [opt 2] use 8mm spacer and the dropper plate with the spacer on the upright. Reuse the original steering arm bolts to attach the spacer and plate to the upright, use the supplied 1"1/4 bolts and nylocs to secure the arm to the drop plate.
  11. [opt 1 & 2] Reattach the TREs.
  12. Read the wilwood instructions and advisory information provided.
  13. Loosely attach the offset plate to the caliper bracket with the 25mm M10 bolts.
  14. Fit the caliper to the plate with the m10 60mm bolts, m10 nylocs and 8mm spacers so the order is caliper, spacer, plate, nyloc. The nyloc will be captive with a face against the bracket.
  15. Tighten all the m10 bolts.
  16. Fit the pads. 
  17. Bolt the rotors to the hubs using 1"1/4 bolts with the nylocs on the inside of the bell.
  18. Refit the hub with the nut finger tight and turn the rotor to check for runout.
    If the rotor is not centered correctly; mark the 'high point', slacken the bolts slightly and use a soft-faced mallet to re-position the rotor before rechecking and tightening. 
  19. Torque the hub nut.
  20. Bolt the caliper bracket assembly to the upright with the 7/16" bolts so that the rotor is between the pads. Due to the age and variation in manufacture of the original uprights you may need to add a 7/16" shim washer between the upright and the bracket.
  21. Use the new banjo bolts and copper washers to attach the original flexi line. 
  22. Bleed the brakes.
  23. Degrease the rotors.
  24. Reattach the wheels.
  25. [opt 1 & 2] Check the tracking (after "bouncing" the car to settle the springs) and tighten the TRE locknuts.
  26. Bed the brakes in by performing 5-10 progressive braking stops from 45mph. During this period do not drag the brakes. Allow the rotors to cool whilst moving before parking the car. 
  27. Enjoy your awesome new stopping power!

If you have any problems call Rich or John and we'll be pleased to help you. If you want to set up the car properly with 4 wheel alignment and corner weighting you can bring it to our workshop in South Oxfordshire and we'll help you get it dialed in and apply a 10% discount as a thank you for running the brake kit.