This section exists
to help give back to the community by explaining some of the technical
challenges we've faced along with their solutions.
Overall Approach Recommendations
The DSM auto trans is a stout piece, but everything has its
limits and anything can be broken if you try hard enough. The
first limit is pressure application during shifts. Shifting
with any of the full-manual methods like our wiring or a standalone
shift box all fix this and have shifts occur at full line pressure.
When shifted at full line pressure, a stock trans will live
a decent life down into the 10's. A trans with a 5-friction
front clutch and translab shift kit with the pressures cranked
will live down into the high 8's or so. Anything quicker than
this starts needing pressures cranked up higher. I've run over
300psi without problems, although I don't recommend much over
200psi for any mixed street plus racing usage.
Trans Fluid - a high film strength fluid is
needed to keep the gears alive in these transmissions. It should
also have very good high temperature breakdown resistance. I've
had good luck with both John Deere Hy-Gard universal tractor
fluid and Redline Racing ATF.
Brakes - use an electric vacuum pump in a
racing application so you can stage the car consistently and
also hold the brakes. Braking capacity should not be increased
beyond this level as all you will do is then be able to easily
hold enough torque to break transmission gears on the line.
Launch Boost and RPM - limit launch rpm to
a level where a 'normal' tune coming up on the converter makes
about 5psi for a 2.3l or about 10psi for a 2.0l. The rpm where
this happens sets a really good start point for your launch
2-step. Anything above this is hard on the gears and will not
be quicker to the 60ft mark. Running too much torque on the
brakes is by far the most common cause of catastrophic transmission
failures I've seen. The rpm on the 2-step is the torque through
the trans and the initial hit off the line. Boost on the line
sets how well it recovers from about 5ft to about 20ft out.
Your boost on the line should be set by timing retard at the
2-step (anti-lag if you want to call it that). I'm usually running
about 12-14psi off the line for 1.2x 60' times with a 4700rpm
2-step. More converter information and tips are available here.
Drive Gears - inspect yours every 20 passes
or so in a high power setup. The gears should also be shot peened,
I have TRE do this. If you're in the low 1.3's or so, even more
frequent inspection intervals are a good idea. There is no excuse
not to inspect the center diff gear in an AWD car, it is just
6 bolts to pull the cover, drain the fluid, and remove and inspect
that center diff gear. The inboard side of the gear (diff housing
side) is where I've seen cracking start in every single failure.
Look at the roots of each gear tooth for cracks and replace
all three of the drive gears if you find any cracks. The center
diff gear or this corresponding gear in the FWD always cracks
first, but the rest are very soon to follow. If the drive gears
break, it tends to explode the case and make a gigantic, dangerous
mess.
Flexplate and Bolts
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