General Motors 4L60E Transmission shift quality upgrades
There's a ton of 4l60E shift kits on the
market out there and all kinds of
different results and costs. here we
will give you some simple and
inexpensive or just free upgrades you
can do to improve the shift
characteristics of your 4L60E
transmission. these are not "race car"
upgrades but ones that will work for
your truck or street hot rod type
vehicle.
AFL valve: make sure the AFL valve bore
in valve body is not worn or
repair/replace with Sonnax kit
77754-09K
Accumulators: You can make significant shift feel changes with the
accumulator springs and condition of the
pistons. Replace the plastic 1-2
and forward or line accumulator pistons
with
new aluminum ones, the plastic ones
enjoy cracking! replace the seals with
new, inspect inside bore of
used aluminum ones for wear from guide
pin and replace as necessary. (big
problems if worn)
Scotch Brite the piston bores in the
case with a light Scotch Brite. this
will give the new seal a better "bite".
Springs: the heavier or lighter the spring is in
the accumulator the firmer the shift
will be, for the line accumulator the
heavier the spring the firmer the
engagements into D and R will be
the result. (Spring
examples)
The 1-2 accumulator usually has 2
springs and is acceptable as is but you
can make better with lighter spring, if you turn over the
piston and spring assembly here you will
have very firm 1-2 shift, you can try
but may not like!
3-4 accumulator has very light spring
and you can put the huge spring out of
torqueflite 2nd and will be nice and
firm, or you can even block the
feed
hole and have same result, we've
wondered why they even have this
accumulator sometimes?
For Accumulator basic function see our
Accumulator bulletin.
Band servo: the size of the band servo
determines the quality or firmness of
the 1-2 shift,
there are 4 different size servos,
casting number on large piston for
"corvette" servo is: 8642093 and makes
for the firmest shift, you may not want
to use on 4 cyl. or diesel as will be
too harsh. This works great in trucks
and some even come with it from the
factory, you need to change both the
large piston and divider ring to update
your transmission. There are also
several aftermarket larger servos
available that work very nicely for hot
rods.
Get yourself the Kent Moore tool # J-33037 which checks band pin length. If
you need to change band pin the longest one available is GM # 8680501 and can be
ground down to adjust instead of buying several sizes. Do make sure the ground
end is smooth and round like original before you install so doesn't dig band
anchor thru.
Drill out the clutch feed holes in the
separator plate.
click here for
instructions. these are beginning
guidelines and you can adjust as you
feel fit.
Pressure regulator valve: inspect and
replace boost valve and sleeve if worn,
you can upgrade the regulator spring
with pressure boosting spring/valve
kits. we recommend the
Sonnax line pressure booster kits,
they come with new boost valve/sleeve
and upgraded pressure regulator spring.