Sequential gearbox upgrade

Ross’ Mazda RX-3 street car has dipped into the 8-second zone previously, but in order to improve consistency and reliability, Ross has recently made the switch to a Samsonas 6-speed sequential gearbox. With no cutting of the factory trans tunnel, the box has been adapted using our new to market light weight billet CNC bell-housing which is manufactured in house.

This is based off one of our bellhousings and adapted to the Samsonas Gearbox. Starting with a steel block which weighed 169kg/372lb, the finished bellhousing weighs just 10 kg/22lb.

The same Promaz 13B bridge port rotary engine is still in place with power transmitted through a leaf spring rear end and small 26×8.5in drag slicks. This was the first time out testing the new gearbox combination and as expected the car performed flawlessly.

1972 Mazda RX-3 street car
Promaz 13B Bridge port rotary engine
Garrett GTX42R turbocharger
MicroTech LT16c EFI, E85 fuel
Full street exhaust system
Samsonas 6-speed sequential gearbox
Promaz CNC billet bellhousing
Leaf springs & Caltracs
26×8.5in drag slicks

Check out the awesome video below!