I am considering a 3800 or LS4 swap. I have a built 2001 GTP transmission I want to use. For an LS4 swap, does anyone know if the LS4 pcm will control an older trans? Or another pcm that will work for this?
Im putting in a LS4/4T65ehd in my Diablo kit with Microsquirt running the LS4 and a TCM806 form: http://www.magnashift.com/m...ift_controllers.html to run the trans via paddle shifters. The guy over at Magnashift is a Fiero guy (check out his video) and all around great guy to do business with.
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07:43 PM
Jims88 Member
Posts: 268 From: Kalamazoo MI Registered: Jul 2011
I am considering a 3800 or LS4 swap. I have a built 2001 GTP transmission I want to use. For an LS4 swap, does anyone know if the LS4 pcm will control an older trans? Or another pcm that will work for this?
I don't know if the transmission your referring to has the starter mounted on transmission like the Ls4 requires, originally I had wanted to mount an older style 4t60e and use the existing throttle cables to control the throttle body and trans kick down, then Mega Squrit just the motor.
I dont konw if this helps but there were some good responses.
Only the LS4 4T65e-hd has the needed starter mount for the LS4. However, I am sure my bolt on LS4 starter mount could be adapted to an earlier 4T65 (or 4T60).
The trans I have does not have a starter mount. I wonder if the bellhousing with a starter mount can easily be swapped? That is if one can be found at a reasonable price. Or I could use an adapter like shown above.
Some of the GTP guys have used newer 4T65's with older pcm's by some rewiring at the trans connector. I assume that it could work the other way but I figured I would ask if anyone knew for sure. I would prefer to use a gm pcm with my swap due to the cost of a megasquirt.
What have you done to build up your transmission? That's the only reason that i can see for not using the transmission that comes with the LS4. Feel free to correct me. I was wrong once before.
What have you done to build up your transmission? That's the only reason that i can see for not using the transmission that comes with the LS4. Feel free to correct me. I was wrong once before.
Doing a DoD delete, and running the non-eletric 4t60-HD would really be the only reason. But then you have a somewhat weaker transmission based on the TH-125.
If you had a built non-LS4 4t65e-HD though, it would be very simple to swap the parts into the LS4 version of the trans (as it would almost certainly be cheaper to buy a whole used trans, than just the bell half of the case).
The trans I have does not have a starter mount. I wonder if the bellhousing with a starter mount can easily be swapped? That is if one can be found at a reasonable price. Or I could use an adapter like shown above.
Some of the GTP guys have used newer 4T65's with older pcm's by some rewiring at the trans connector. I assume that it could work the other way but I figured I would ask if anyone knew for sure. I would prefer to use a gm pcm with my swap due to the cost of a megasquirt.
Oh. Also, the LS4 doesn't use a PCM like the 3800 does. It has the ECM and TCM as separate modules. And the ECM and harness are different between the 05-06 LS4 engines, and the 07+ engines.
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11:47 AM
Darth Fiero Member
Posts: 5922 From: Waterloo, Indiana Registered: Oct 2002
You'll probably find a whole 4t65e from an LS4 cheaper and easier than you'll find just the bell side of the case.
Unfortunately this is not the case. I'm in the midst of another LS4 / 4T65-E Fiero swap and have found it almost impossible to locate a good 4T65-E trans that came off an LS4. There are tons of LS4 engines for sale just about everywhere you look, but very few 4T65-E's that go with them. I wasn't even able to find a rebuildable core trans for decent money.
You can buy a brand new bare 4T65-E case (LS4 specific) from GM for less than you can get a used core transmission for. The problem is all you get is bare case which means you'll still have to at least transfer parts from a complete 4T65-E to end up with a working trans. And if you are going to go thru all of this, you might as well have a professional rebuild done while you are at it. My customer is having Dave at www.tripleedgeperformance.com do his build.
-ryan
------------------ OVERKILL IS UNDERRATED Custom GM OBD1 & OBD2 Tuning | Engine Conversions & more | www.gmtuners.com
Unfortunately this is not the case. I'm in the midst of another LS4 / 4T65-E Fiero swap and have found it almost impossible to locate a good 4T65-E trans that came off an LS4. There are tons of LS4 engines for sale just about everywhere you look, but very few 4T65-E's that go with them. I wasn't even able to find a rebuildable core trans for decent money.
You can buy a brand new bare 4T65-E case (LS4 specific) from GM for less than you can get a used core transmission for.
For less than $500 shipped? Good deal then. A complete trans from GM is almost $2000.
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05:10 PM
PFF
System Bot
Darth Fiero Member
Posts: 5922 From: Waterloo, Indiana Registered: Oct 2002
For less than $500 shipped? Good deal then. A complete trans from GM is almost $2000.
A brand new bare case from GM (my cost) isn't as expensive as salvage yards are wanting for bad rebuildable LS4-specific 4T65-E cores - IF YOU CAN FIND THEM.
A complete new GM 4T65-E (for LS4 applications) is going to have the same problems and suffer from the same failures that the ones that came in the LS4 cars from the factory did. I wouldn't put a new GM trans in anything I build. I would rather have Dave at TEP do a performance build so we wouldn't have to worry about it.
Bringing this up again. Here is some info I found on the transmission connectors of the 4t65e. GTP guys have switched pins on the 2003+ trans and made them work. It looks to me that it might be possible to swap pins in this case too.
