47/48RE Single Disc Converter

Goerend designs and manufactures torque converter components from start to finish using eight in-house CNC machines. This ensures accurate dimensions that will work with your transmission. This also means you're communicating directly to the manufacturer, which is very rare in this industry, and allows for your questions to be answered quickly and accurately. Goerend builds billet front covers and clutch pistons from steel forgings, greatly reducing any chance of porosity. Goerend stators are designed to rotate better when going into coupling mode, as well as assist torque multiplication. Our stators are guaranteed to never break and create a venturi effect to help torque multiplication. The patented internal design of Goerend torque converters insures that the torque converter clutch will lock up on the computer and valve body’s signal. No more feathering the throttle to get the converter clutch to lock up. Our knowledge, equipment, and patented converter components allow us to build the converter to match your needs, no matter if you use it as a daily driver or a dedicated race truck. Click here for an explanation on single and multi-disc converters.

Features:

• Designed and manufactured in-house
• TIG welded, furnace brazed, and silicon bronze reinforced turbine
• Proprietary high-performance multi-disc lockup clutches
• K-factor and torque ratio tested on in-house dynamometer
• Below 0.005 blueprinted runout tolerances
• Dual Torrington bearing stator design
• Multi-bolt pattern billet front cover
• Blueprinted internal clearances
• Fully pressurized and leak tested
• Patented fluid flow deflector
• Computerized robotic welding
• Billet lockup assemby piston
• 4140 hardened turbine hub
• 4140 flanged impeller hub
• Accuratly designed pilot
• Computerized balancing
• Lugged stator races
• Billet stator cap

Frequently Asked Questions:

How does a torque converter work?

Let’s start with two wall fans facing each other. If we turn one fan on, it now becomes the drive fan. The wind from the drive fan will make the other fan turn, although. The fan that is not turned on is known as the driven fan. In the case of a torque converter, the drive fan is bolted to the engine and the driven fan being is connected to the input shaft of the transmission. In addition, oil is used to transmit the energy between the two fans, as opposed to air in the example scenario.

When stationary, such as at a stop sign, with the transmission in gear and the engine at idle, the drive fan is spinning so slow that it can't transfer enough oil to the driven fan to make it turn. As the engine speed is increased, the drive fan blows more oil at the driven fan, which allows the driven fan to be turned move the vehicle. This important concept is commonly referred to as fluid coupling.

The drive fan will always turn a little faster than the driven fan, just like the wall fans. If you were to stick a feather into the driven fan blades, it would slow the driven fan down, but not the drive fan. In a real application this is just like pulling a heavier trailer, the straw in the driven fan is essentially adding a load.

How does lockup work?

Once the truck is up to speed, there is a mechanism called a lockup clutch, that will lock the fans together. In actuality, the driven fan is locked to the front cover of the torque converter, which is bolted to the engine. When this occurs, the drive fan and driven fan turn at the same RPM, with no loss of power in the fluid coupling. When the drive and driven fan are not locked together, heat is generated in the converter. The greater the load and RPM difference, the greater the heat generated. This heat is essentially lost power, which results in a lower transmission life, performance and fuel economy. The loss of energy in this process can be calculated. Suppose we have a converter where the drive fan, known as the impeller, is turning 2,500 RPM and the driven fan, known as the turbine, is turning 1,800 RPM. The efficiency of this converter, at this speed, is 72% (1,800 ÷ 2,500 = 0.72). The efficiency is constantly varying, depending on the RPM of the converter, the power input to the converter and the output load, or towed weight. When the converter clutch locks the fans together, the engine rpm will drop 700 RPM.

If we use a converter that is more efficient, such as a low-stall converter, we will be able to achieve a higher efficiency rate. For example, an 88% efficiency rate could mean that the impeller would be turning 2,500 RPM and the turbine would be turning 2,200 RPM. When the converter clutch locks the turbine to the front cover, we would only see a drop of 300 RPM, as opposed to 700 RPM. A lower RPM drop is substantially easier on the converter’s clutch lining and will reduce glazing. In addition, because the fluid coupling of the converter is more efficient, more power, less heat and better fuel economy are delivered before the converter locks up.

How does stall speed work?

To explain stall speed, let’s start with a true full stall. If the transmission were in drive, and the brakes were held down so the vehicle will not move, and the throttle was held wide open, the torque converter will stall the engine at a certain RPM. When stalled, the engine will not be able to spin any faster unless the vehicle is allowed to move. This is a true full stall. Do not test for true stall, it can damage shafts and overheat the torque converter. We have specialized equipment which we use to perform this test.  

The next stall speed is generally called break away stall speed. If a vehicle is stopped on a hill and held in position using light throttle as opposed to brakes, then we are almost at the break away stall speed. If the engine RPM required to hold the vehicle was 1,100 RPM and an increase to 1,125 RPM started to move the vehicle, then the break away stall speed would be 1,125 RPM.

The last stall speed is generally referred to as flash stall speed. The flash stall speed takes effect under hard acceleration. From a standing start, if you were to floor the throttle, the engine would start to accelerate quickly and then pause at an RPM as it starts to pull the truck. If the engine went from idle to 1,500 RPM in 1.5 seconds when floored, and then took another three seconds to get from 1,500 to 1,700 RPM, this would mean the flash stall speed was 1,500 RPM. When we lower the stall, we want to lower the break away speed as well as the flash stall speed. This will make the engine work at a lower RPM for a given road speed and will increase fuel mileage in most cases. Once up to speed, the computer will command the lock up clutch on, and the turbine will lock to the front cover of the converter. At this point, the impeller, turbine and engine are turning the same speed which means all engine power will be delivered to the transmission and back to the wheels.

What determines stall speed?

The two major things that determine the stall speed are the engine torque and the torque converter. Here are a few different ways to think about it:

Let's say you're on an exercise bike that uses a fan as the load. The smaller the fan, the faster you can pedal. The larger the fan, the harder it is to pedal. With the larger fan , your maximun RPM will be slower. With a smaller fan, you may be able to pedal at 200 RPM and no faster, that means your stall speed is 200 RPM. With the large fan, you may only be able to pedal at 50 RPM. The larger fan stalled you at 50 RPM with the same person on the bike. Two different fans, two different stall speeds.

Now a professional athlete hops on the exercise bike. With the big fan, they may be able to pedal 100 RPM, as opposed to your 50 RPM. To compare this to the engine and converter, you have to remember that the converter is nothing more than two fans consisting of the impeller and turbine. The impeller connected to the engine and the turbine is connected to the transmission. The impeller blows oil at the turbine. When the impeller blows enough oil at the turbine, the turbine will start to rotate and the vehicle will start to move. If you install a converter with larger fans, the stall RPM will be lower. With smaller fans, the stall RPM will be higher, and if you add horsepower to the engine, just like the athlete, the stall RPM increases.

Now lets talk about air. A person on the bike can pedal harder at sea level than on the top of a mountain because they can breathe better. The closer to sea level, the more oxygen in the air. The air will be more dense, so will the engine. The engine is nothing more than an air pump that uses fuel. The fuel must burn, expand, and push the piston down. You must have oxygen to burn the fuel. The higher the elevation, the less oxygen we have, so the less fuel we are able to inject. Less fuel means lower power into the converter and therefore a lower stall speed. Normally, the higher the elevation, the higher the stall speed that is needed. The engine turbocharger also can make a huge difference. Like the converter, The turbo is also a set of fans, the drive fan is located in the exhaust of the engine and the exhaust flow makes this fan spin. The driven fan of the turbo is connected to the drive fan and sits in the intake side of the engine and forces oxygen into the engine so more fuel can be burned to get more power. When you have a turbo with larger fans, it takes longer to spool up and start to blow more oxygen into the engine. If it takes longer to spin up, it will take longer to get the oxygen into the cylinders to burn the fuel. This is called turbo lag.

Are the impellers and turbines furnace brazed?

Allison 1000 impellers and turbines are furnace brazed from the factory. 68RFE impellers are also furnace brazed from the factory, however the 47RH, 47RE and 48RE turbines are not brazed from the factory. These parts are all brazed in a large oven and when they vary in size and thickness, this can lead to over-baking smaller and thinner parts which results in warpage. We MIG weld the fins on any turbine or impeller that has not been factory brazed and we never use any warped parts. If the fin angle must be changed on an impeller or turbine, we weld the fin in that position. It does take more time to do this but if you move a blade, it must be secured so it does not bend back to the original position or break.

Make:

• Dodge

Transmission:

• Chrysler 47RH
• Chrysler 47RE
• Chrysler 48RE

Notice:

• To receive the full core deposit back, the core returned to Goerend Transmission must be an unmodified core of the same model of the purchased converter. (Year, Type, Etc.) No part of the core may be rusty/damaged in any way, or you may receive partial to no credit towards your core deposit. When a usable core has been received, the core charge will be refunded to your original form of payment. Call for any questions on what cores are accepted. Click here for additional core return information.
• The warranty is specifically limited to the torque converter purchased from Goerend. The warranty applies to any potential manufacturing defect inside the torque converter. The warranty doesn't not cover any outside influences on the torque converter. The warranty is not included on converters with stock stators. The warranty does not include loss of time, use, towing, installation, freight or per diem damages. Warranty does not cover broken shafts, stripped bolts, rust or overheating. To transfer warranty, invoice must be provided to Goerend. The warranty is only valid through Goerend. Warranties are void if cores are not returned within 45 days of receiving the converter.