Making the decision which high performance/ heavy duty transmission to purchase is confusing because there are so
many different claims by transmission builders. I will attempt to explain some of the different claims to make your
choice a little easier.
When I began working on automobiles 32 years ago at the age of 18 years I was taught that patience and quality parts
are the key to a repair that will give long service life. I learned this while building my first high performance
vehicle. I installed a 327 CID small block in a 1973 Vega GT wagon. I learned that high performance was a totality
of components working together to create the desired results. As a young apprentice I thought we just put the engine
in the car and drive. After several months performing modifications to the suspension, engine, transmission, cooling
system, sub frame and rear differential, I figured out high performance is not easy or cheap. I drove that Vega daily
for several years performing only routine maintenance. The point I am making is that if a transmission builder only
installs a "shift kit" and a few frictions it will not stand up to high performance abuse. The transmission must be
built installing the totality of high performance components that work together eliminating any weak links.
The 4L60 series transmission was designed by the GM as a medium duty transmission with a maximum engine torque rating
of 360 ft. lbs. from the factory. Experience has shown that over 360 ft. lbs. of torque the input shaft, input drum
or the sun shell usually fail. For the transmission to withstand over 360 ft. lbs. of torque these parts must be
reinforced or replaced with stronger units. At Trutech Transmissions all our transmissions rated over 450 HP have a
reinforced input drum and a heavy duty sun shell. In our later model units over 450 HP we custom fit the late model
reinforced 4L70E drums, which have a much improved input shaft. The new GM input shafts are made with a better alloy
and heat treated with electric induction. This method makes the shaft 57% harder the the older model standard 4L60E
shafts. These new shafts can withstand greater torque loads with reduced wear. At Trutech Transmissions we are
realistic; we understand that with modifications the maximum engine torque for our 700R4 or 4L60E transmission is
approximately 600 ft. lbs. of torque. This is why our top of the line performance 4L60E/700R4 transmission is rated
at 650 hp and 550 ftlbs of torque. Add the options of the 300 maraging steel output shaft and Raybestos Blue Plate
Frictions to raise the torque rating to 600 ftlbs. These are expensive parts, be leery of low priced transmissions
rated over 375 HP that do not have these modifications.
The planetary gear sets are very important in the high performance transmission. At Trutech we install new ACdelco 4
pinion planets in all our transmissions rated to 450hp. In our units rated over 450 HP we only install factory ACdelco
5 pinion heavy duty planetary sets with new ring gears. Period!!! No inspected, remanufactured or cheap aftermarket
Our Transmission all are built with brand new ACdelco pumps that are upgraded to use the stronger input shafts. In our
top of the line transmissions all the major parts are brand new with the exception of the valve body which has been
remanufactured by ACdelco usually with a new casting.
Only high performance frictions and steels are used in our performance transmissions. We have come to appreciate the
Raybestos Stage One and Alto Red Eagle frictions. Both of these frictions are comparable red frictions and perform well
in high performance applications. Our units used in vehicles close to the maximum horsepower rating get the Raybestos
Blue Plate frictions. The Raybestos Blue Plate frictions are a racing friction and can withstand the abuse. When it
comes to the band we only use the wide carbon band with a new ACdelco reverse input drum. To apply the band we use
the factory "corvette", Sonnax or Superior servos depending on application to create a stronger 2nd and 4th gear. The
friction clearance is tight but always within factory specification and we always use new waved plates in the clutch
packs that use them.
When building any transmission to give a long service life you must pay close attention when inspecting parts that are
to be reinstalled. The most overlooked part in the 4L60E transmission is the valve body. The valve body usually shows
little or no signs of wear on a visual inspection. In reality, in the 4L60E transmission valve body wear is the most
common cause of clutch failure. The aluminum casting is prone to wear from oscillating valves and bypasses fluid creating
low apply pressure to the clutch pistons. At Trutech Transmissions every valve body is completely remanufactured and
tested for leakage. We also install high performance accumulator and shift valves for better shift performance. We do
not install "quick fix TCC valves" or "shift kits" claiming to repair worn or damaged valve bodies. Only high quality
replacement parts that meet or exceed factory specifications are used in the remanufacturing process. The valve body
is also the single most expensive part in the transmission. If the transmission price is real low chances are the valve
body has not been replaced. Transmissions built with worn or "patched" valve bodies usually last just past the warranty
The 4L60E was designed to have a maximum rpm limit of 6000rpm from the factory. When you exceed this limit chances are
very good you will break the pump rotor. In our units over 450 HP we install a billet pump rotor that can withstand the
higher rpm range. The pump also receives other modifications necessary for high rpm operation. There are other problems
that occur when you turn a higher rpm. The main trouble is centrifugal apply of the 3-4 clutches. We make modifications
to prevent this problem.
There are numerous other parts that are upgraded or modified to meet the demands of High Performance applications. As
you can see it is impossible to build a cheap high performance transmission. When you spend thousands of dollars creating
horse power you need a transmission that can handle the power. We can build that transmission for you at Trutech
Transmissions. Every transmission is custom built for each application and custom calibrated to work in your vehicle.
We do not use "shift kits". Most shift kits are largely designed to block or modify accumulator operation to create a
hard shift feel. This does absolutely nothing to strengthen the transmission, in most cases it shortens transmission
life. Our transmissions are calibrated to increase operating performance for better clutch holding power. The shift
is crisp and firm. Our transmissions are built dependable and give a long service life.
Every transmission is assembled by an ASE Certified Master Technician.
Trutech Performance Transmission offers it's customers a free technical assistance email hot line. All questions will
be answered within 24 hours.