Swapping out a 7A-FE for a 3S-GTE? Check this out., Consolidating for ST users. Updates will happened to correct mistakes Options

[Soulend]

First off, this is more difficult than just swapping a GT 5S-FE to a 3S-GTE. The GT shares many components with the 3S-GTE engine. First of all, the major parts that will need to be replaced.
So, you thought you could save some money and just buy the engine and not the clip? Sorry to tell you but you will probably spend the same IF NOT MORE than just a clip. So BUY A CLIP.
I made that mistake and this list reflects that.
If you bought a clip you can salvage a lot of parts listed on here GOOD CHOICE!

Transmission:

The 7A Transmission will not mount up and you cannot use the GT-4 Transmission and ‘just cap the back.’ So you will have to get a Transmission of your choice. The GT one, is a probably the most common you’ll see. To save money, time, and effort people will generally use it. However you also have the choice of an MR-2 E-153 Transmission.

The E-153 comes with its own work as it doesn’t directly mount up like the GT transmission. I don't know all the details but, with the MR2 transmission you need the MR2 AND GT half shafts. You are basically replacing the inner heads of the GT axels because they won't work in the transmission, while the passenger MR2 axel is shorter and neither wont mate with wheel splines. The rear transmission mount and bracket can be used off of the GT-4 from what I have read, but I think there is a little more work to it.(see other Swap threads for more information).
But with that, the E-153 can hold the power way better than the GT transmission, as well you might have the chance to get LSD.
Now because you are getting a new transmission you’ll need a few more things.

Axels:

GT and ST Axels are of course, different. Everything on an ST is just smaller so nothing really likes to work. Now the GT Passenger axel uses a Carrier bearing to keep it in the transmission. So if your 3S didn’t come with the carrier bearing bracket. You’ll need to beg and plead to get one.
Here is a Guide on the Axels: http://www.diy.icydesigns.com/article/308/...:_Axle_Removal/

Engine mounts and Brackets:
Guess what, the ST has a different Passenger side mount. The other MOUNTS around the car are the same however; make sure you get Celica GT mount BRACKETS. These are severely different from the ST. since you are changing the engine change the mounts. Just order GT mounts and you should be golden.


Passenger side mount notes:
On the GT they actually have wielded bolts on the underside of the frame, but of course the ST doesn’t. so you are going to need a few washers, 2 nuts and 2 seriously long bolts. Then you are going to drill out the pre marked spots on the body of the engine. (two indented points on the frame) then two on the bottom. Then you need to run the bolts down through the frame and tighten that sucker up.


Shifter Cables:
Now if you are looking here and have an auto transmission, I don’t know if it works with the 3S-GTE (my guess? NO).
Other than that, you will need to replace your ST Shifter Cables for GT Cables. The positions of the cable ends are completely different on the transmission end. The shifter in the car can be used.
E-153: you CAN use the GT-4 cables.

Exhaust:
Of course this also has to be changed out. But that isn't a bad thing. At this point you can take the time to upgrade the exhaust to either 2.5" or 3" exhaust depending in preference. (if you have the money I highly suggest it.) if you go the route of 3" Berk Technology has an amazing 3" 2nd and 3rd gen downpipes. (Berk Tech). After the work and parts I spent around $500.
The possible bad. I have a 97, so I have OBDII. After everything was finished I had a full 3" system through the muffler with NO cat.
Not sure if this was because of my cities regs or what. I've heard people saying OBDII won't pass emissions so I don't know what is up with that.
While we are on the subject, I had my wire harness done by TWEAK'D performance, so that might have something to do with no codes being thrown. So check them out.

Radiator: (might be able to use Clip one)
HAS to be replaced. Not only will outlet be on the wrong side, the size is twice that of the ST. so cooler engine=happy engine. And with that the hoses have to be switched out as well.
You will also need a radiator thermostat. A GT one will do, and the plug is tapped up on the body so its plug and play after that.
Steering: (clip should have this)
On the ST the reservoir is attached to the pump on the back of the engine. Well you can guess what that means. You need to get the GT reservoir AND the hoses that run to the rack and pump.

AC: (might be able to use clip, but might want to replace them.)
The lines are not the same. The AC is bigger and pretty different as well. So you need to replace those.

Besides all of the other random parts you will need for the swap that even the GT's need, that should cover most of the work. I am always happy to take questions and help out where I can.

Kevin

This post has been edited by Soulend: Oct 10, 2013 - 2:47 AM