Midget Steel Pedal Box V2.20

Congratulations on your purchase of the Mamba Motorsport Steel Pedal Box V2.20.

Key features:

Trunnion-type balance adjustment gives the best control and initial braking.

Integrated residual pressure valves (RPV) reduce pad knock-off.

Compact design for easy pipe routing and under bonnet layout.

True spherical bearing cylinders for linear response.

Integrated adjustable clutch stop.

Important Notes:

These pedal boxes are for track / motorsport use only.

Installation must be done by a competent professional. Incorrect installation or use of a braking component can cause serious injury or death.

Inspect all components prior to each use to ensure safe operation.

Test the initial installation in a closed environment and at progressive speed before use in competition.

The pedal box uses shorter travel cylinders than the original so it is important to maintain the complete hydraulics system and adjust the rear drums frequently.

If you have paid for a pre-built pedal box then still read the assembly instructions as they will enable you to understand, adjust and maintain it correctly.

Assembly Instructions

Following the correct order will make the assembly much easier!

Diagram 1

Where the instructions reference left and right these are looking from the front of the vehicle bonnet towards the pedal box – see diagram 1.

Unpack the box and make sure all components are included, contact Mamba Motorsport immediately if anything is missing. Occasionally we update products so do make sure that the product version matches the instructions version. All versions of the instructions are available at mambamotorsport.co.uk.
Remove both trunnions from the balance bar. Slide the balance bar into the housing from the left with the longer thread to the left. The bearing should be an interference fit into the housing and may require a gentle tap to insert. If the bearing fit is too tight then it will bind causing the adjuster to be hard to rotate, sometimes a light sanding may be required to the inside of the housing to relieve the clearance. The balance bar should rotate smoothly by hand.
Screw the right-hand master cylinder trunnion onto the balance bar.
Screw the left-hand master cylinder trunnion onto the balance bar. Make sure the 2 trunnions are evenly spaced to each side with a total separation of 60mm +/-1.0mm
Push the 30mm rigid tube onto the reservoir spigots.
Assemble the brake reservoir supports by inserting the m6 nut and button heads through the top holes and screw the two halves together clamping the reservoir mounting tab between the two. Don't tighten – the reservoir needs to be able to align. Screw the two bottom sections together with the self-tapping screws from the left so that the head is fully countersunk.
Assemble the clutch master cylinder by removing the lock nut and sliding the clutch stop inner and outer onto the shaft making sure that the cup side of the outer is toward the cylinder and the grub screw faces the top. Add the 8mm washer, the lock nut and the spherical bearing rod end. Insert approx. 12mm of thread into the rod end but do not do up the lock nut.
Insert the 62mm M8 rod from the right into the clutch master mounting bracket with the slotted end to the right. Optionally use two m8 nuts as a jam nut to spin the rod through the parts. Assemble in the following order (right to left), bracket, nyloc, plain nut, spherical bearing in master cylinder (ports face upwards!), plain nut, nyloc, bracket. Wind the rod through until the left end is flush with the outside of the bracket. On the right side put a single nut on the outside of the bracket and tighten the inner nyloc against it to lock the rod in position. Tighten the two inner nuts against the spherical bearing in the cylinder and finally wind the left nyloc until it contacts the left bracket.
Insert the m6 nut and m6 buttonhead into the trunnion retainer bracket. Put the two halves of the trunnion retainer bracket around the brake balance brace so that the legs wrap the bearing and the locator lug fits into the cutout on the brace. Do up the bolt. Don't overtighten, this is a plastic component and only needs to be done up. The holes are deliberately tight to make sure the bolt will not loosen during use.
Screw the front master cylinder into the lefthand bias trunnion and the rear into the right. Flip all the cylinders up away from the baseplate.
Insert the bearing spacer tubes into the oilite bushes of the pedal arms with a little thick grease or assembly lube – do not use oil. The bushings are oil impregnated so will self-lubricate during use.
Feed the long, threaded rod into the right-hand side of the pivot brackets and spin on M8 plain nuts, the pedals and washers to achieve the following assembly (right to left) : bracket, nut, 12mm washer, pedal, nut, bracket, nut, bracket, 12mm washer, pedal, bracket, nut, bracket. Ensure that the 12mm washers are seated on the 12mm spacer tubes rather than the threaded rod. Adjust the nuts so that the rod ends are flush with the outside of the brackets and the clutch pedal in centred between the righthand side brackets then tighten the nuts to clamp the spacer tubes. There should be some end play in the bearings to allow for heat expansion. M12 shim washers can be used to adjust the play if required. If you do use additional washers make sure they are placed on the right of the pedal arms as that experiences the thrust force during normal usage.
Thread a nyloc 15mm onto one end of the 100mm threaded rod and feed it through from the left of the front master cylinder spherical bearing so that it is assembled in the following order (left to right): nyloc, front mc, 8mm washer, 22mm spacer tube, brake pedal, 22mm spacer tube, rear mc, 8mm washer, nyloc. Tighten the nylocs against each other to clamp everything together.
Insert the 30mm bolt through the clutch pedal from the right: pedal,8mm washer, clutch rod end, M8 nyloc. Tighten.
Adjust the pushrod lengths of the master cylinders such that full travel on the cylinder occurs just before the pedal arm contacts the frame. Tighten the locknuts.
If this is a completely new build then attach the braided clutch (-4) line's banjo to the clutch now using the provided banjo bolt. If its in the car already from a previous install then wait to install the clutch reservoir until after the line has been attached.
Screw the clutch feed elbows into the master cylinders. The brake ones require a single copper washer. The clutch uses a copper washer below the M10 spacer washer. Tighten using the nut then reposition the elbow to face away from the pedals.
Attach the braided brake lines to the RPVs noting the direction of flow and tighten. Use the banjo bolts to attach the lines to the cylinders. The banjos should point away from the cylinder bodies before tightening. Note: 2psi for discs (front) and 10psi for drums (rear). Position the braided lines to loop through 180deg and between the brake masters before crossing over and clipping the RPVs onto the top of the trunnion retainer bracket. Feed the cable tie through the slot under in the bracket and loop around the rpvs to secure them in place. Note the bracket is designed to tension the cable tie by springing outwards so hold the two sides together firmly while doing up the tie. Trim off the excess tie.
Push the tube for the fill into the elbow for each brake reservoir making sure that the reservoir mount fits around the fill port on the master cylinder. Tighten the 6mm bolt to fix the reservoir into place – Do not overtighten.
If the clutch line is attached, push the clutch reservoir tube into the elbow and then assemble the reservoir mount in-situ so the reservoir mounts away from the pedals.
Slide the fire gasket over the pedals against the underside of the base plate.
Fit the pedal pads using the M5 countersunk screws. Use the centre set of pad holes and the 2nd and 4th holes from the top of the pad with the full height of the pad covering the pedal arm flange. Do not over tighten.

Installation

Before starting installation of a new pedal box inspect all the brake lines and replace any corroded or damaged lines. Calipers and cylinders must be in good working order – the new pedal box will allow the use of high pressure braking at high speed and will cause more stress on the existing components than they will have had before.

Remove the old pedal box. Retain the bolts and carefully move the pipes out of the way. Clean the area and the bolts and washers. Replace any bolts as required. Do NOT use M6 bolts and nuts inside the footwell, if the original captive nuts are stripped replace them properly before installation. Corrosion due to brake fluid is a common occurrence in this area so make good and prep so that the new pedal box has a secure mounting.
Poke the bolts through the base plate and the fire gasket. The holes in the gasket will retain the bolts and keep the gasket pulled up to the plate during fitment.
Place the pedal box directly onto the old mounting points and loosely fit all bolts before tightening down. Sometimes where repairs have been carried out in the past the bolt holes may require slotting with a file to align fully.
Reroute the brake hardlines to the RPVs – be careful to make sure the lines are to the correct RPV - 2PSI (black) for front and 10PSI(red) for rear. In most instances the existing lines can be used by cutting the old fitting from the end and using the supplied hardline fittings and a flaring tool. Older lines may have work hardened and should be replaced with new hard lines. Do not run long flexi lines.
We recommend the use of a single -4 braided line directly from the clutch banjo to the slave cylinder. We also recommend running a Mamba race spec 7/8" slave cylinder for best clutch performance. Install the clutch line to the banjo bolt and tighten. Follow the assembly instructions from (20) and (6) above to mount the clutch reservoir.
Make sure the balance bar is centred and the pedals are moving freely without contacting the frame or bulkhead. Adjust the pushrod lengths as necessary – keep the brake balance bar parallel. Nip the locknuts, they will need to be adjusted during commissioning.
Fill the reservoirs with high quality DOT4 brake fluid and crack the bleed nipples on all calipers and slaves. Allow the master cylinders to gravity bleed for an hour to wet the seals and prime the masters. Close all the bleed screws.
Top up the reservoirs and vacuum bleed the rear brakes followed by the front following the instructions of the vacuum bleed kit.
Bleed the clutch slave. Note: It is easier to bleed the clutch slave without it attached to the gearbox or using a remote bleed adapter. Midget clutches are notoriously difficult to bleed manually on the car so don't rush this step. If you are using a non-Mamba 7/8" slave you may find it impossible to bleed as the cup seals on modern repro units often let air past the seals.
Make sure any spilled hydraulic fluid is washed down with water and cleaned up – it is corrosive and will damage paint and parts.

Adjustment - Brakes

Having bled the system and achieved a firm pedal, adjust the rear drums to make sure there is no excessive slack (with the wheels off the floor turn the square adjuster until the wheel cannot be turned by hand then back off ¼ turn.
Press firmly on the pedal. It should not creep or feel spongey, if it does then bleed again.
With the pedal firmly pressed, the balance bar should be parallel to the pedal pivot. If it isn't then undo the lock nuts and adjust the length of the pushrods by winding them in or out of the trunnions to achieve parallel. This is most easily done with 2 people. Tighten the lock nuts.

Adjustment – Clutch stop

Test that the clutch disengages by slowly depressing the clutch while someone turns the rear wheel. Most race clutches must have the cutch stop set to stop them over-stroking. Refer to the clutch suppliers information about the required travel.
To set the stop, undo the grub screw so that the inner can slide inside the outer. Extend the inner and outer to 22mm total length and push it back so that the inner is against the washer behind the locknut of the rod end.
Depress the clutch pedal until the required maximum travel is achieved and then gently release it. The adjuster will now be set to the correct length and the grub screw can be nipped up. Note: the inner sleeve is designed to protect the push rod so don't overtighten.
If the stroke needs to be adjusted in future, repeat the process but turn the inner sleeve round a bit as the grub screw will create an indentation in the old position and pull the adjustment back to that. Replacement stops (and all other parts) can be purchased from Mamba Motorsport. Call or email for support.

Adjustment – Brake Balance

Whether using the remote adjuster or manually adjusting between sessions, the adjustment principle is the same. Turning the balance bar moves the trunnions changing the relative pressure applied to the front or rear circuit. To move the balance forward turn anti-clockwise. Up to 5 turns of adjustment are available but work in small steps to avoid unexpected locking. When a good dry setting has been achieved it is good practice to repeat the balance bar position adjustment to set it parallel during use.

Enjoy your new pedal box. If you need any help, advice or parts please contact us and we'll be pleased to help.

- The Mamba Team