Trutech Performance Transmission specializes in General Motors high performance transmissions. Our technicians have
years of transmission repair and performance modification experience. Trutech Performance Transmissions manufactures
and sells high performance GM transmissions and parts. To better serve our customers we offer free
technical assistance through email and phone. Our goal is sell a quality product and service. The General Motors 4L60/65/70 type
transmissions have been in service since 1982. The hydraulic control components have changed from a TV cable
operated system to the current electronic controlled system. The internal gear train has been updated but remains
relatively the same since 1982. This transmission is without question the most popular transmission used by
performance enthusiasts world wide. Over the past two decades this transmission has been upgraded to correct
dependability issues. at Trutech/procare Transmissions we implement and improve on these upgrades to create our performance
transmissions. This guide will answer questions most frequently ask to our technical personne.
Building a strong transmission starts with internal gear train. The weakest link in the 4L60 transmission gear train
is the sun gear shell. We recommend you upgrade this shell even if you are doing a simple stock overhaul. The sun
gear shell has a tendency to strip out or completely break off at the splinted area. The factory recognized a problem
with this shell and attempted to correct the issue by heat treating the splinted area of the shell and replacing the
thrust washer with a thrust bearing. As many factory technicians have discovered this did not work. The aftermarket
company SPX offers a replacement shell nicknamed "the beast". This shell has a much thicker splinted area and can be
used with either the thrust washer or the updated thrust bearing hub. The SPX "beast" shell is an excellent choice
for stock to moderately modified applications. Recently, the aftermarket company Sonnax put on the market an improved
beast type sun gear shell. Sonnax named this shell system "The Smart Shell". Sonnax determined that by controlling
the height of the low roller support inner race, reinforcing the the splined area of the beast type shell with a
precision steel collar and adding a thrust bearing between the low roller race and shell, the thrust load can be
directed away from the captive planet bearing and sun gear. This rerouted thrust load is directed to the rear
planet carrier protecting the more vunerable captive bearing and sun gear. This design also benefits by preventing
thrust load flexing which causes breakage at the splined area of the shell. We recommend this shell system in any
4L60 transmission application but especially in applications where engine torque can exceed 400 ft lbs.
The planetary gear carriers is the next area to be addressed in high performance build applications. The factory
4 pinion gear carriers can withstand up to 400 ft lbs of engine torque. General Motors now manufactures a 5 pinion
planetary set that can be retrofitted to the early 4L60E and 700R4 transmissions. The addition of the one extra
planet gear increases the torque handling capability. There are aftermarket 5 pinion planet carriers available but
we at Trutech/procare Transmissions do not recommend these carriers. It has been our experience a new factory 4 pinion
planet set is stronger than the aftermarket 5 pinion sets. The factory 5 pinion carriers are a drop in replacement
and can be used with the original ring gears. As standard repair practice, a new ring gear should be used with
a new planetary gear carrier. The factory 5 pinion input planetary carrier requires that you update the input
hub with the improved bearing type hub. This input hub and bearing are included as a set with the 5 pinion input
carrier from ACdelco.
In high torque or nitrous applications the factory input drum can fail. The failure usually occurs at the splined area
of the drum where it messes with the input shaft. Under high torque the drum gives way and breaks away from the shaft.
The aftermarket company Sonnax offers a reinforcement steel ring that is pressed over the overrun piston seal area
of the drum reinforcing this splined area. Sonnax includes a modified aluminum overrun piston to work with this
reinforcement ring. Sonnax also offers a reinforced drum kit for transmissions using 300mm converters. This kit
starts with a brand new reluctor type input shaft drum and strengthens it with thier reinforcement ring kit. These
factory reluctor type input shafts were improved by the factory and can withstand higher torque loads than the
original 300mm shafts. Sonnax includes a custom stator shaft to retrofit this drum to early 300mm converter
transmissions. Sonnax does not offer this drum kit for 298mm converter transmissions. If your engine torque
is higher than 400 ft lbs or you have installed a nitrous kit we recommend you use one of these two Sonnax
Our contact information.
Call 1-800-762-9846 Inside USA.
1-334-577-4400 Outside USA.
Thank you for for choosing Trutech/Procare Performance Transmission.