Mazda MX5 Conversion Blog
25 August 2007: Engine and gearbox removal
This afternoon, a couple of friends popped round to lend me a hand with the formidable task of removing the engine and gearbox from the MX5. The new workshop's roof went on about a week ago - nice to finally have somewhere dedicated to work on the car.
First step today was to drain the fluids from the fuel tank, engine sump and gearbox. We underestimated the amount of fuel in the tank, the (first) bucket was a bit too small.. I won't make that mistake again!
So with a modest puddle of fuel on the floor and all the windows open for ventilation, we continued work. Intake and exhaust manifolds were removed, as well as the rest of the exhaust, muffler and various heat shield panels. Any remaining wiring harnesses and pipes connected to the engine were also removed. We took great pleasure in cutting a few stubborn cables and pipes, knowing we didn't have to put things back together later!
Before loosening the bolts attaching the engine to the gearbox and chassis, we rolled in the crane, hooked it up to the engine's lift points and raised it just enough to take the weight. We also set up jacks under the gearbox to support it once the engine came out.
The engine is attached to the bell housing with about 8 large bolts, and there's one bolt per side for the engine mounts. Some of them are *really* awkward to get to. We couldn't help joke about the possibility that Mazda engineers had deliberately made things this difficult just to thwart EV converters! With these removed, the engine was carefully wiggled/lifted out.
Removing the gearbox was fairly straight forward. The rear differential is coupled to the gearbox by an aluminium beam, plus the driveshaft of course. Four bolts attach the driveshaft to the differential, once removed the driveshaft drops down and slides off the spline on the gearbox output shaft. Four bolts hold the aluminium beam to the diff and gearbox, two at each end. Once removed, the gearbox was free of the car. To remove it, we borrowed the lift points off the engine, reattaching them to a couple of bolt holes in the gearbox and used the engine crane to carefully lift the gearbox out through the engine bay.
It's a relief to have all the heavy stuff out. There's a surprising amount of space down the transmission tunnel - it looks like I might be able to fit the motors right down back, directly coupled to the differential. This would allow me to have all the batteries up front without messing up the car's weight balance.. quite promising.
(1) Ready to get started - MX5 on stands in the new workshop
(2) Draining the fluids - fuel tank pictured
(3) Engine with intake and exhaust manifolds removed
(4) Removing engine bolts, with crane taking the weight
(5) Gearbox is supported with jacks for engine removal
(6) And out comes the engine!
(7) Crane holding the gearbox while tailshaft is disconnected
(8) Cheesy grin to celebrate the gearbox coming out
(9) Look at all that space!