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The gearbox conversion was finalized, and it was time to get the engine and gearbox back into the car.


The clutch and pressure plate were fitted....

Adapter plate bolted on...

Starter motor fitted...

Gearbox bolted on with a new clutch slave cylinder.....

Ready to go...

And in it went....

Sorting out the gearbox mounting turned out be incredibly easy. The manual gearbox is only 15mm longer than the auto box, which was easily taken up by the sliding splines in the propshaft. An adapter plate was made to extend the gearbox mounting bracket, which allowed the bracket to be bolted straight back into the original holes. The locating jig made just before the engine was removed now secured the propshaft in place and once the engine and gearbox was secured, the propshaft lined up perfectly with the gearbox coupling.

The gearbox flange was drilled and tapped before the engine was installed to accommodate the larger bolts used on the 6.3 coupling, and everything screwed into place.

The manual gearbox is tiny compared to the bulky auto box.


While the brake booster and master cylinder were away being overhauled, a manual clutch pedal assembly was sourced, which fitted perfectly in place. When the booster was returned, it was re-fitted along with the brake master cylinder and then the clutch master and slave cylinders were plumbed into place. A brake reservoir from a Mercedes-Benz Fintail was used for the hydraulic clutch system. It bled easily and worked well.

After a long search a used gear selector mechanism from a Mercedes-Benz 190E 2.3-16 was found in Germany.

The position of the gear selector was measured, and a hole was made to accommodate this. A mounting plate for the gear shifter was made from sheet steel and bolted into place.

The gearbox links were then connected to the gear selector. The rods needed a bit of bending and manipulation so that they didn't clash, and eventually all gears were able to be engaged.


A gear lever and adapter to turn onto the gear shift mechanism was turned from bight mild steel, as well as a gear knob from aluminium.

The propshaft was overhauled with a new centre bearing and universal joints, and then balanced.

The limited slip function on the diff in the racing car was not working, so this was swapped out with a functioning diff in a 6.3 parts car.

It was decided to restore the diff and rear suspension properly before refitting it into the race car, as had been done with the front subframe and suspension.

Getting the radiator in and out of a 6.3 is a tight job guaranteed to skin the knuckles. Seeing as there's a strong chance the radiator might have to come out quickly, the mounting principle was copied as on the W123/ 126 series cars.

The original engine fan and shroud would not be used but replaced by an electric fan mounted on the outside of the radiator, like on the original car.

The plan was to have an electric fan that would be triggered by a thermo switch mounted at the bottom of the radiator. There would also be a manual fan switch for the driver in case the thermo switch failed.


The radiator was sent in to be refurbished and modified to take a thermo switch. Mounting brackets were added to the outside of the header tank, as well as locating lugs at the bottom of the radiator.


The front valance of the race car was slotted at the top and brackets were made on the bottom valance into which the lugs of the radiator would be inserted. A standard set of radiator rubber buffers and clips was bought from the agents and secured the new arrangement tightly in place.

The diff and rear suspension were cleaned so that the restoration could begin.


A support cradle was made so that the diff could be re-fitted with minimal fuss using a trolley jack. Once this was made, the diff was stripped down and all the relevant parts were ordered.

Nylon bushes were turned to replace the rubber bushes on the front anti-roll bar connecting rods, and the anti-roll bar was fitted. The standard anti-roll bar was retained with the idea to do little changes at a time and then to assess what affect each change has on the handling when track testing.

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