So, over the last couple of weeks, I did manage to find some time to work on the 5.3 swap project. As I have said in earlier posts, I am planning to use an early 700R4 transmission instead of the 4L60E that was behind it originally. There are several reasons for this, but mainly because the stock trans was a 4x4 application and I wasn't ready to tackle a computer controlled engine and a computer controlled transmission. One thing at a time...right?
When GM brought out the LS platform of engines, they decided to change the flexplates and torque converters slightly. This is really no big deal, you just have to know what you are looking at. The easiest change to spot is the torque converter bolt pattern. The newer transmissions have a slightly larger bolt pattern than the older ones do. To address this, most people just file out the holes and make them egg-shaped.
However, if you find an early 5.3 flexplate, both bolt patterns are there. I have to say that was a very pleasant surprise...
The other main change is that the 5.3 torque converters have a long snout to fit into the back of the crank. The older ones do not and you will have to run some type of spacer/adapter. I got mine from Summit Racing here.... Hughes Flexplate Adapter...part number HUP-HP3795. It slips right in the back of the crank and is now ready for the 700R4...
To get the 700R4 ready so you do not have to run a computer, there is a little bit of re-wiring that needs to be done. Other that having an overdrive, the main benefit of the 700R4 is that it has a lock up converter. The wires that run under the filter go to the solenoid that controls the lock up and the three connectors are for the pressure switches that originally sent the signals to the controller. The switch with the yellow terminals is for the 4/3 downshift so that the converter will disengage lockup while downshifting. The switch with a single wire is plumbed in the pressure port of 4th gear and this really is the only one that we are concerned with.
When the transmission shifts into overdrive (4th gear), we want it to then lock up the converter. So, when there is pressure, the switch will make contact and ground itself to the valve body. You can take one of the solniold wires and run it to this switch. The other wire, you will have to run a constant 12 volts to. This by far is the simplest way of doing this...you can make it much more complicated by tying back into the brake switch and a vacuum switch but this method works great. Here is a really good link that explains this in great detail:
700R4 Lockup Wiring Made Simple
Now comes the fun part...the engine harness. When you look at the bundle of wires originally coming from the ECU, just know that about half of them are not needed and will eventually be pulled out. More on this to come....I promise. It is not as bad as it initially looks.
