TruTech Performance Transmission
How To Build A High Performance 700R4 4L60E
Gear Train Modifications
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 techinical assistance through email and phone. Our goal is sell a quailty 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 dependablity issues. At Trutech Transmissions we implement and improve on these upgrades to create our performance transmissions. This guide will answer questions most frequently ask to our technical personnel.
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 splined area. The factory recognized a problem with this shell and attempted to correct the issue by heat treating the splined 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 splined 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 are 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 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 meshes 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 kits.
There are many modifications that can be done to improve this transmission. Our series of guides will address these different areas to be modified. Trutech Performance Transmissions sells a complete line of General Motors performance transmission parts including the parts mentioned in this guide. You can view these guides in our EBAY store pages. Our contact information and technical assistance email address is in our store information. Visit our website.