Brabham BT50 BMW Turbo

Model
Tamiya Brabham BT50 BMW Turbo model number 58031 released for sale in 1982 and available for sale until 1984.
Styrene body
F1 Competition Special chassis

Analysis of the model to be restored
Starting from the front going towards the rear, the analysis of the body reveals that

– the body itself is intact without any breakage
– the colouring corresponds to the official colouring,
– the stickers have been applied correctly
– the two wing mirrors are missing and
– the roll bar is missing.

Starting from the front going to the rear, analysis of the chassis reveals that

– the front steering system has fixing points made of zamak instead of white nylon,
– the front Diplo wheels are in very poor condition, they have taken the shape of a hexagon; they have been resting on the ground for too long,
– the servo guard with the special tie rods is missing, the Brabham servo guard is the same as the Super Champ model 58034 and is a much more efficient evolution of the previous version,
– black right side wing is broken,
– the FRP chassis is well put together, but with evident marks left by the surface where the car has travelled and span touching the ground and
– the motor mount is made of zamak instead of aluminium.

Given the excellent condition of the body, it makes sense to consider a non-conservative restoration with the replacement of damaged or incorrect parts with new ones.

Chassis restoration
Sequence of pictures showing new or restored parts replacing damaged ones:

– front and side bumpers for F1 chassis, set number SP-5085,
– nylon suspension arms, set number SP-5133,
– servo saver, set number SP-5155

– front wheels for F1 foam chassis version A, set number SP-5075;
– FRP chassis wheels for F1, set number SP-5124,
– RS540 motor carrier system with differential, set number SP-5103, and
– rear axle and spacers, set number SP-5009

All the small parts were treated with the ultrasonic washing machine for 25 minutes at 70°C. The most oxidised parts were treated for seven days with diesel, leaving them immersed.
The chassis was assembled with all new parts while retaining the rear wheels of the starter model, which are in excellent condition.

The electronic part is in excellent condition and consists of:

– servo holder plate, receiver and battery. It is made of metal and has been washed with hot water and dish soap to remove dirt that had accumulated,
– mechanical motor speed controller, complete with fuse and quick plug for the battery,
– steering servo complete with tie rod,
– servo for controlling the mechanical speed regulator complete with tie rod,
– antenna holder,
– 540 motor with black rear cap complete with pinion gear,
– 4 x AA batteries holder – stylus for the receiver complete with on-off switch and
– slotted screws and bolt to secure the parts on the plate

The following sequence of pictures shows the procedure for re-assembling the chassis:

– Screw the two nuts that join the electronics carrier plate with the chassis through two rubber vibration dampers.
– Install and adjust the steering rods, which are fitted with the metal ball joints set number SP-144 “special rod end set”; the length shown in the instructions is 60 mm on the left and 31 mm on the right.

Body restoration
List of materials required to build the rear-view mirrors:

– ABS bar with 5 mm square cross-section
– ABS tube with circular cross-section, 3 mm external diameter and 2 mm internal diameter
– ABS bar with a circular cross-section of 1 mm diameter
– various files,
– box cutter,
– hacksaw and
– pencil

The following sequence of pictures shows the procedure for constructing the two wing mirrors

– Cut a part twice as long as the single mirror from the square bar.
– Work this piece by rounding the sides and ends.
– Cut along the dotted line the bar to divide it into two equal parts and separate the right mirror from the left after obtaining the correct rounded profile. Only by machining the bar is an identical profile obtained for the two mirrors. The same result is not obtained by machining the two mirrors separately.
– Cut two small pieces about a 7 mm long from the 3 mm diameter tube. These will be the mirror arms.
– Join these brackets to the two mirrors using an acetone + ABS solution. Select the strongest ABS and Acetone solution from those available, the solution must not run, instead it must stay where it is placed.
– Using a brush, place a drop on the mirror at the point where the bracket attaches to the mirror.
– Press the support into its optimal position. The drop acts as a base and solidifies to seal the two parts well.
– Repeat the same operation with another mirror.
– Insert a piece of 1 mm diameter bar about 6 mm long inside the tube. This support will be used to install the mirror on the body. There are two holes (one on the left side and one on the right side) in the front of the cockpit to allow the rear view mirrors to be installed correctly.
– To hold the bar and tube firmly, brush some acetone on the bar before inserting it into the tube.

List of materials required to build the roll bar

– a strip of ABS measuring 2 x 10 x 80 mm,
– sandpaper and file, and
– hair dryer

The following sequence of pictures shows the procedure for constructing roll bars:

– Heat the ABS strip with a hair dryer.
– Fold the strip into a V shape. To obtain a suitable shape, place the hot strip on the handle of a brush and bend the bar. This gives the top a rounded shape.
– Reduce the size of the two short sides that are the base, first using scissors and then refine the size by working with 600, 1,000 and 1,200 grit sandpaper until the piece fits perfectly into the body.
– Work with 600, 1,000 and 1,200 grit sandpaper on the roll bar to obtain the side shape that is a scalene right-angled triangle (the three sides are all different sizes).

Paint the roll bar and the two rear view mirrors respectively with Grey X11 and White X2.
To simulate the mirror of the two wing mirrors, paint the rear side with Grey X11 to colour this part.
To glue the parts, apply a few drops of the glue that solidifies under UV light.

Restored model
Images showing the finished model.

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