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4t80E trans swap

TwinV6GTP

TwinV6GTP

New member
I'd love to see all the info in one thread but compacted.

As for as fitment, all I need to know is block clearance, bolt patterns and also mods to the flexplate.
Basically how to make it work on a stand.

There is a very long thread about this I found and it mentions the bolt pattern is different and holes have to be drilled and tapped.
Block has to be grinded but where exactly ? Anything to save time and keep the twin engine Project progress. In return I will share my results and progress.

Then how to make it work on a K-frame.

This for the Twin Engine GTP's rear engine. Clearance front and back is not an issue.The rack and pinion is gone too.

What do I need electronically to make it shift right ?
Can I put it in safe mode like I can a 4T65E ? IE 2nd gear starts and manual shift to 3rd gear.
Or can it be set up with switches instead of ECU controlled shifts.
Which model had the tallest gear ratio ?

Axles: I read they fit the hubs but that you have to get a left side from an Aurora and the right side axle from an Eldorado to have the right lenghts ? (got that from Trannyman95's thread)

So any info from people who have worked with these trans would be helpful.
 


The only things you'll find on this are PontiacJeff, Dave aka Trannyman and James aka you know him.. IIRC there is only one bolt that needs to be worked, that's the rear bolt of the trans aka 5th bolt aka bitsh bolt aka .. that one. Then you need a bracket from tailshaft to engine and IIRC you might need the "other" oil filter adapter, not positive on that one though.
 
Thats sounds easy. I have no space issues. What about the shifting can i just shift it manually or using switches ?
 
I'm not one of the three guys. Sorry, don't know how the control happens beyond the little that I read up on. There is one thing that in the past had to be inverted because it was backwards to the programming for the 65E. Last I heard, Dave had some things figured out.
 
Dave had gmtuners.com ryan flash on some crap from tunercats that allows the trans to just work I guess.

If I can get an idea for where the addreses for those settings are I could build a 80e pcm.
 
My only problem is time and I'm missing the diagrams for the pinouts of these trans.
I need a quick solution. I have access to a super cheap 4t80E from an Aurora V8

I wonder if I could use the Aurora ECU and hook it up to power and essential sensors so it sees engine RPM and speed sensor signal and thinks it's running the 3.8 engine and disable the error codes.
 


Ok, I had a long talk with Dave at TEP and he had a lot of great info for me.
I will let him fill in the details of what he said to me.
But overall, the transmission swap seems very doable for my rear engine set up.

I think we're going for it.

I have experience with electronic switching and with Dave filling in the details I think we can do something good.
His main concern was the 2-3 shift but he was working with a very high miles trans. With some luck I can find a trans with a better shift.
If not we'll have wasted time but it's worth a shot.

In the meantime I may get good deals on the parts I need for a decent 4t65 build that can be used up front if the 4t80 trans swap works out.

I hear James turbocharged400 has experience with these as well maybe we can collaborate also !

Ben
 
If you dont want engine braking... you could just peg the shift pressure to max and operate the shift solenoids manually. Pabst blue racing did that in the last lemons race I went to with their 4t80 maxima swap.
 
In manual mode there is significant engine braking in 3rd gear which is where I need it most as the trans doesn't shift to 4th.
The carbon/ceramic brake pads take over so far no stress at all on the brake pads.

One thing I forgot to ask Dave is which axles do I need. I hear one axle needs to be from the Aurora and the other from the Eldorado ?
 
We located a 4t80E and a local U pull it yard which means cheap but not garanteed to be good.
It is a Caddilac Deville with the 4.6L Northstar.
I think 75$ for the trans. Car has between 110K and whatever. It has a sticker on the door written by hand 110K miles. in 2012
Drivers seat is in decent shape but looks 130K-150K in terms of wear, that's how I usually tell how much mileage a car really has lol.

What's good about this is I get the axles and everything else I need for the trans.
Not sure if those axles will work directly or not I hope so.
 
TwinV6GTP said:
In manual mode there is significant engine braking in 3rd gear which is where I need it most as the trans doesn't shift to 4th.
The carbon/ceramic brake pads take over so far no stress at all on the brake pads.

One thing I forgot to ask Dave is which axles do I need. I hear one axle needs to be from the Aurora and the other from the Eldorado ?
Click to expand...

I suppose if you left it in 3rd it will enable overrun in 3rd, which gives you engine breaking down to 50mph or so. Otherwise just throw the shift switches and call it a day.
 


darkhorizon said:
I suppose if you left it in 3rd it will enable overrun in 3rd, which gives you engine breaking down to 50mph or so. Otherwise just throw the shift switches and call it a day.
Click to expand...

Remember I have TWO engines. I was worried about braking but that was when I didn't have the trans in auto mode.
I have the power of two engines slowing me down :)

I have surprising braking power, I was shocked. I took the 1st exit at my track vs the 2nd exit for most cars in the MPH range I am in. And that was without effort. I think my braking power can handle 150mph no problem, then I'll have to think Parachute.
 
So I picked up that 4t80e.

I got most of the info I needed last night.
Found the diagrams for the pinouts and lots of info on the swap coming from Pontiac Jeff and also Dave at TEP.

Now I'm missing the grounding pattern on the shift solenoid for each gear as I have to built my own gear switching device. I'm not fond of paying 1000$ for a trans controller.
 
samymuda.jpg
 
TwinV6GTP said:
So I picked up that 4t80e.

I got most of the info I needed last night.
Found the diagrams for the pinouts and lots of info on the swap coming from Pontiac Jeff and also Dave at TEP.

Now I'm missing the grounding pattern on the shift solenoid for each gear as I have to built my own gear switching device. I'm not fond of paying 1000$ for a trans controller.
Click to expand...

Only advantage to the shift controller is running the pressure control solenoid really... Max that b!tch out.
 


darkhorizon said:
Only advantage to the shift controller is running the pressure control solenoid really... Max that b!tch out.
Click to expand...
I was planning on that. Run it disconnect and max pressure.

There is a shift kit for this trans. It seems to have notoriously lazy 2-3 shift and even a soft 1-2 shift. The kit addresses this but it's more involved and better done when doing an overhaul as far as I know.
 
Now I know why very few have done this swap. Wow.
It's moving quickly almost done with the new trans/motor mounts.
Have to cut the rear manifold as well and redo my turbo mid pipe and wastegate placement etc...
 
Turbocharged400sbc said:
yeah it's not super easy but then again neither is building a strong 65 E
Click to expand...
I was a little worried about frame rail clearance in the back. It's close but we have enough clearance.
I'm actually going to have much better mounts then stock. Not solid, but stiffer and with enough movement but not too much.
Had to calculate a few things to makes things equal on both sides.

I had to change a few things on my alignment rods as well (where the rack was) etc...

Pain in the rear but I hope it will shift well and hold the power. More worried about the soft shifts to be honest.
 
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