On 11/1/05, jon@dakota-truck.net <jon@dakota-truck.net> wrote:
> That statement probably requires some qualification. :-) Granted,
> Mopar has had some transmission problems over the years (who hasn't?)
> but don't forget, this is the same company which created 727s and 833s
> that can be bolted to the business end of a HEMI and stand up to daily
> abuse. The 727 in particular has attained legendary status due to its
> bulletproof reliability. That doesn't necessarily help Tom, unless
> he is willing to give up overdrive, but I just felt the need to add
> my $.02 lest your statement go unchallenged into the archives. :-)
> -Jon-
The overdrive unit is plenty strong, so it isn't the weak point in the
system. The weak point is in the fluid delivery system to the
overdrive. Basically the od unit is starved for fluid pretty much all
the time. This can be fixed by honing out the fluid transfer passage
in the center of the shaft (0.010 if I remember correctly, need to
find my notes) and honing out the holes in the shaft (0.004-0.005 if
memory recalls, again need my notes) then chamfering these holes.
This increases the fluid flow into the starved od unit without killing
the flow into the rest of the trans. Another reason the od unit dies
is heat. Lack of fluid flow, the fluid must go through the entire
length of the trans to reach the od unit (from front pump, into
valvebody, through the mid shaft, etc...), which all leads to hot
fluid reaching an already starved (hot) od unit. So increase the
fluid flow (honing process), increase fluid capacity (if possible, pan
clearence issues on a 4x4 if heavy offroading is done) and cool the
fluid as much as possible (maximum size tranny cooler) in order to
keep the od unit in good health.
If you want to tear into the trans yourself, it really isn't that
hard. The main things to remember are:
1) Cleanliness is Godliness when rebuilding an auto trans.
2) Patience. Rome wasn't built in a day and you shouldn't try to
rebuild the trans in an hour. It took me three days to rebuild my
42RE.
3) Make sure seals are properly installed. This is especially
important for the seals inside the drums. They apply pressure to the
clutch packs, which engage to create the gearing system. If the seal
is even slightly nicked there will be problems. Especially once you
consider the internal pressures can go over 300psi at times.
WiLieR
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