Archive for February, 2010

Operation 1993 Subaru Legacy: Phase I

Posted in Auto Articles with tags , , on February 12, 2010 by consortiumoffools

So I finally bought an AWD turbo car, a 1993 Subaru Legacy Turbo.  It came with an automatic transmission and a 2.2 liter oil-leaking turbo motor.  First order of business is converting the car to 5-speed manual.  Some automotive experts (mainly drag racing enthusiasts) claim that turbo motors are better supported by an automatic transmission.  The idea is that the engine remains at high RPMs during the quick shifts and thus the turbo continues to spin quickly.  If the turbo spins quickly, more power is actively made.  This idea sounds great if the car’s intended use is straight line racing, but my build is purposefully for small track road racing and auto cross.  I’m opting for the manual transmission because of the predictability and control a 5-speed offers.  The manual transmission allows the vehicle operator to select the appropriate gearing for approaching road situations, such as a turn or another vehicle.

I bought a junkyard 5-speed for $100.  Within the first 30 days (the warranty period) I cracked open the case to inspect the contents.  I inspected the gears for unusual chipping or lashing.  I also verified that each syncro lined up properly and that the tines were not chipped or otherwise destroyed.

After I was finished inspecting, I put gasket material (RTV) on each side of the case and slapped them together.  I popped a few bolts in the case to ensure it stayed together while I connected end case. The end case contains the center differential and output shaft.  After a few failed attempts I realized that all of the pieces of the transmission have to be put back together before tightening down the bolts to spec.  Many clearances inside transmissions are very small, so everything has to be orderly reassembled and tightened down.  When I finished lining everything up and connecting the case, I still had to bolt up the gear selector itself through the rectangular service door:

There’s one black bolt that didn’t seem to seat, but certainly was the right bolt.  And as soon as I tightened down the end of the transmission on in a star pattern, the output shaft’s bearings seated perfectly.  The output shaft is in the foreground on the left, the bolt on the gear selector is on the right and the center differential is in the background:

Above view of the same thing:
The end of the transmission back on:

Now the transmission is complete and ready to go.  I have also already purchased the other necessary parts for the conversion including the clutch master and slave cylinders, pedal assembly, clutch, flywheel, manual transmission mounts, throw-out bearing, fork, and starter.

Next installment:  porting and polishing 2.5l SOHC heads!

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