MR2 Turbo Gearbox Installation
Having Investigated and researched various options for the gearbox, the choice was between a couple of sequential race type gearboxes and the MR2 Turbo (Toyota E153 gearbox).
I decided to go with the Toyota gearbox as I didnt have the budget for the sequential box.
The Toyota E153 Gearbox is found in the MR2 Turbo, Camry V6 and in the Celica GT4. I chose the MR2 Turbo version as it has the gearbox cable change on the front, so makes the installation easier.
This gearbox has been proven to work with many high power engines and is considered to be one of the strongest transverse gearboxes available. It even comes with its own oil pump and spray bars in the gearbox and has connections for an oil cooler! The gearbox input shaft has a 1-1/4" spline, compared to the 5/8" spline on the Alfa box, which is am indication that the MR2 box is designed to handle higher power.
A suitable gearbox was sourced from ebay & the first job was to see if it would be possible to fit it to the engine and in the car.
I turned up a spigot to centre the box on the engine and putting the two together it looked like things should work ok.
Next I bolted 3 pieced of alloy plate 8mm thick to the engine and marked through from the gearbox holes, tapping the plate, so that the box could be bolted to it. The box was orientated so that the driveshaft flange would be clear of the sump and the block. There was only one position where this was possible give or take a couple of degrees.
Here it is is fitted to a spare block.
Next was to try the engine in the car....
The engine/MR2 box fitted in the engine bay ok, but in order fot the diff to clear the chassis I had to reposition the engine 25mm to the right and 8mm up.
This needed new mounts for the gearbox ........
I Was able to use the same tilton twin plate clutch that I had used previously, but had to get new clutch plates as the spline is a different size. It just required a new mounting boss / spacer to be made up as below.
Some machining was required on the toyota box to make clearance for two of the engine bolts and to clear the starter motor gear. Also some material had to be removed from the diff cover to give clearance for the plate.
The Toyota box has a different cross shaft to the alfa, so I was unable to use the sameengine mount/bearing carrier/oil filter mount. To solve this problem I tapped the engine block and fitted a threaded tube for the filter to screw onto and then fabricated a new engine mount / bearing carrier.
Here it is painted and finally installed in the car....
The gear change as I said is a cable change, to make things easy I used the gever and mechanism from the MR2 , mounted on my own brackets & had some custom cables made up for the operation..