4L80e transmission swap

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4L80e transmission swap

Postby critter » Fri Jan 01, 2010 8:50 pm

Some of you might have thought I'd dropped off the face of the earth the past few days. I've been a busy fellow. I've begun the process of swapping my TH400 transmission for the electronic 4L80e overdrive transmission. I've been taking pictures so here's a build thread for you.

The first thing I'd like to say is that this is in no way a bolt it in and go operation. There is going to be some fabrication involved and I suspect Bryan and I will have to do some creative thinking before it's done. I'd also like to thank my brother in law and our club sponsor, Bryan Blocker of Blocker's Performance and Restoration, for helping me with this project. (Like he had a choice, he's family after all. LOL.)

The first order of business is to remove the old TH400. Bryan Blocker and I have done this so many times that it takes less than 30 minutes with us working together.

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The next step is removing the flex plate. It has to come off to mount the transmission adapter plate since the modern electronic transmission do not have a BOP bolt pattern. This aluminum Reactor flexplate I was using won't work with the new setup due to its thickness so it will be replaced with an stock flexplate.

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Since we're using an adapter plate to mount the transmission the old locating dowels have to be removed and new, longer dowels installed. The part number is Moroso 37932. The first dowel come out with vice grips and a twist. The second one wouldn't come out despite the use of heavy explosives. I ended up drilling it to get it out.

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With the new dowels in place the adapter plate from TCI bolted right in, no problems at all. That part is TCI 230001. Be sure to read the instruction on which way the plate faces and how to measure the pull on the transmission. You MUST use the supplied washers.

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The next item was to drill a hole in the transmission tunnel to route the wiring harness. The main connector has a 1 5/8 inch diameter so the hole has to be that big. The wires coming through include the main connector, the transmission input speed sensor (TISS), the transmission output speed sensor (TOSS), the throttle position sensor (TPS) and a ground wire that needs a direct connection to the (-) pole of the battery. I'm bringing all this through the tunnel as I'm placing the transmission control unit (TCU) under the center console.

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The throttle position sensor seen here is critical to this install. It helps the transmission control unit to determine where shift points should be and when to lock up the over drive. I fabricated a bracked on the rear of my Quadrajet mount and set it up to use a pull wire via the throttle linkage on the driver's side of the carburetor.

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Here's the stock flex plate installed along with a Trans Dapt torque converter pilot bushing we were led to believe we needed. Maybe some other folks do need it. We did not. When we bolted up the transmission with it in place it jammed the converter snout so tightly we couldn't turn the converter by hand. We pulled it all apart, threw the damned thing aside and it all came togther like a dream. For those who might need it, Summit Racing sells it and the part number is TD-055.

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You might be able to pull this swap off in the home garage but at my age, it ain't happening. The use of a lift and the transmission jack are the only thing that makes this job doable. Again, a big thank you to BPR.

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The complaints against the 4L80e is that it's huge, heavy and sucks up horsepower like a black hole. In a side by side photo you can see that the 80e is much larger. We didn't weigh them but others have and the 80e outweighs the TH400 next to it by 45 pounds, sans converter. Most of those complaining of the weight will admit that the bulk of the xtra weight is in the stock converter, a huge, heavy duty piece for towing and big trucks. I'm using a small, performance converter so the actual weight gain for me is going to be very close to that 45 pound mark. As for huge, cut off the two transfer "ears" on each side of the case and it will fit your F-body's tunnel with no modifications.

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Here's a shot of the transmission going in with the smaller, performance converter in place. I sourced that through Jake Shoemake out of Sanger, Texas. He has a strong following with the Buick performance guys and a lot of experience with 4L80e builds.

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Remember my admonition to read the instructions on the TCI transmission adapter? It includes using these hardened washers when you bolt down the converter. You have to measure the pull back from the transmission towards the flex plate. If it's less than 1/8 inch you'll be OK. Oh, don't forget you'll need metric torque converter bolts. They are 10mm x 1.5 thread.

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This next shot is a little hard to see but I'm trying to show you the -6AN fittings I'm using for cooler lines and the flexible cooler lines. You can use hard lines but the bigger transmission makes it a VERY tight fit in there. I found that using the 3/8 NPT to -6AN fittings made routing this stuff a lot easier.

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With the transmission bolted in, converter on and cooler lines routed we moved to the electrical connections. It's all plug and play here. They're all weather pack connections and can only go on one way.

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Now we get into the fun part. No one builds a cross member for this swap It's fabrication time. With the cross member from my TH400 flipped around backwards it appears we can reuse it with some cutting and welding. I grabbed a grease pencil and started some sketching.

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No matter what we did on the cross member, that mounting tab has to be on the other side so I used a cut off wheel to lop it off. This is where we stop for now. The drive shaft shop had not returned our cut down drive shaft yet. Without it we can't set the pinion angle and determine the exact mount location. And for those who are already asking, the drive shaft had to be shortened by 3.25 inches. Also, the TH400 yoke with its 32 spline count will work with the 2 wheel drive version output shaft on the 4L80e.

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To be continued...
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Re: 4L80e transmission swap

Postby 77TA » Sat Jan 02, 2010 11:28 am

Looking good !!!

Had many of the same problems when I put my TKO in with bellhousings and crossmembers etc... It is worth the headache when it is done if you care about driving the car on the hwy long distance.
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Re: 4L80e transmission swap

Postby gotcha » Sat Jan 02, 2010 7:01 pm

Chris....I had to register just to reply to this post. That picture taking is really hard work. Good thing you got Bryan to pose as the model, pretending to do the work.

Seriously....really nice work and a great swap. You guys are better than me. Anytime I pull a transmission, change a cable, or touch a trans, there are puddles of red fluid on the floor.

I don't see any so you must be doing something right.

Looking forward to seeing all the Great Pontiac club members at the show next weekend.

See you there

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Re: 4L80e transmission swap

Postby critter » Sat Jan 02, 2010 7:16 pm

:mrgreen::mrgreen::mrgreen::mrgreen:

Just so you'll know, we cleaned 'em up as we went. I made some puddles but Bryan insists that we keep the shop clean and don't hurt ourselves. I think he's trying to avoid liability with having a non-employee falling in a puddle of tranny fluid if you know what I mean. :grin::grin::grin:

Bryan is darned good at what he does. I'm not just saying that because he's family. I give him a lot of grief but he's been messing with cars as long as I've known him and he really seems to care. He jumps me all the time about the details and telling me that's the difference between a car done right and just another car.

I'm looking forward to next week. We have a "special" wardrobe planned for Saturday that should put a smile on most folks faces.
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Re: 4L80e transmission swap

Postby caramaro » Sat Jan 02, 2010 9:43 pm

yeah all that work pushing that button on that camera must have worn you out!Bless your heart!
RIP 2002 COLLECTORS EDITION TRANS AM,may your screaming chickens fly far above...
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Re: 4L80e transmission swap

Postby critter » Sat Jan 02, 2010 10:26 pm

Don't you have a car to fix or something? Besides, he's just a model. He makes me do all the work and he hogs the glory. :mrgreen::mrgreen::mrgreen::mrgreen::mrgreen::mrgreen::mrgreen:
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Re: 4L80e transmission swap

Postby FrankieRider2 » Mon Jan 04, 2010 12:39 am

Gotta say that is one handsome dude in those safety glasses.... :lol:

Interesting post, even though an idiot like me would never attempt something so technical even with professional assistance.
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Re: 4L80e transmission swap

Postby critter » Mon Jan 04, 2010 9:07 am

Handsome? Are we looking at the same pictures? :grin:

Hope the drive shaft makes it back today.
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Re: 4L80e transmission swap

Postby critter » Sat Jan 09, 2010 9:42 am

The good news is that the drive shaft is ready. The bad news is that I won't have time to fool with it again until next week some time. I sure need to be stupid rich so I can do anything I want when I want. :roll::roll::wilting:wilting8):lol:
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Re: 4L80e transmission swap

Postby 77TA » Sat Jan 09, 2010 11:28 pm

Tough living out here in the real world of the common working man aint it.... frustrating but making do does teach patience I guess...

I am a very patient person...it goes with out saying...
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Re: 4L80e transmission swap

Postby critter » Mon Jan 11, 2010 10:04 pm

We talked today. Since the drive shaft is back we need to have the car with the weight on the wheels and still have room under the car to set pinion angle. We could have done this with some boards and jack stands but I saw some stuff on Detroit Speed and Engineering's site of stands constructed of cross hatched 2X4 lumber. After doing some research I see where these are commonly used by a lot of shops. I asked Bryan to hang on while a build some for his shop. I'll show how I do it as I go in this build thread.
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Re: 4L80e transmission swap

Postby critter » Wed Jan 13, 2010 10:14 am

I've finally found time to continue. Last night's project was building the wheel stands so I can get the weight of the car on the suspension and still get under it to set the pinion angle.

I started by taking big boards and making little boards out of them. I was cutting 12 and 14 inch lengths.

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To build the base I used 2 of the 14 inch length boards and three of the 12 inch length. After the base is built, just cross hatch with 2 of each as you build it up.

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The key to strength is glue. The screws are just to hold them together while the glue drys. I used Liquid Nails and 2.5 inch wood screws to put them together.

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And these are the finished product. You could build these in sections and make them stackable to achieve various heights.

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Re: 4L80e transmission swap

Postby critter » Mon Jan 18, 2010 2:39 pm

It was back to the shop on Saturday. Before I get into the progress, I'll mention to you folks that I'm leaving out some minor stuff, like finding a new throttle return spring because the factory one interfered with my TPS setup and building some brackets to help route the cooling lines. Minor stuff like that is part of any project like this.

I started by connecting the shifter cable. I'm using the ShiftWorks kit to convert the stock, factory TA shifter. I found that the kit does not work worth a dang with what people call the factory "rally" shifter that came in some of these cars. For those who don't know what I'm talking about, these shifters allowed you to push the shifter to the right and forward against a stop for each gear. This was considered "sporty" back in the day, allowing you to aggressively shift the car through the gears manually.

The Shiftworks kit replaces the stock detent plate to allow for the extra gear. What I discovered was that my rally shifter had 2 ears that needed to slide back under the detent plate when used in the non-rally mode. With the new plate they would simply jam and would bind rendering the shifter useless. I found a non-rally shifter to use and the kit is working now.

Back to the cable. The key to this working correctly, according to the instructions, is that the amount of cable, measured from the cable attaching bracket to the center of the pin that attaches to the transmission gear selector be 5 7/8 inches. That's where we set it and the car did seem to shift through the gears properly. We'll see if it needs tweaking later.

For now, I'm ignoring the linkage and brackets for the neutral safety switch. I'm looking at a mechanical solution for that based on modifying the linkage that came with the transmission. It's out of a 93 Suburban, I'm told. If that doesn't work, I may have to look into some type of microswitch setup.

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Next up was determining the proper transmission height/pinion angle so we could finish modifying the crossmember. The drive shaft fit like a glove. We had measured a 1-2 degree pinion angle prior to starting this project so placed the angle finder at the same spot we measured from initially.

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Then we dropped the car down onto the stands I'd made. Once the weight of the car is on the wheels, bounce it a few times to settle the suspension and then check the angle. We then slid a floor jack under the back of the transmission and found right position for the proper pinion angle. We marked it so we could raise the car in the air again to finish the fab work.

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Back under the car we used our guide marks...

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...when Bryan whacked the excess out of the way with a cut off wheel.

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Now we have the tab where we want it. Next up is welding it in place. Bryan and I are not welders so we stopped here. Once the guy who knows how to weld gets it done we'll be ready to put in some fluid, hook up a laptop and see what happens.

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Re: 4L80e transmission swap

Postby Vanmor » Wed Jan 27, 2010 6:52 am

Chris,

You guys make that swap look easy. I'd hate to lay under the car and do that though.

That transmission is a monster. Looks like it will handle that big 455. I'm so ignorant when it comes to the modern transmissions. I like that better than the overdrive unit on the tail of the Turbo400.

The pictures are awesome. Looks like a magazine article.

Can't wait to see how it works.
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Re: 4L80e transmission swap

Postby critter » Wed Jan 27, 2010 10:26 am

Thanks for the kind words. I'm still working on it. Right now I can't get it to move. It acts like it's low on fluid but we know that's not the case. I've had advice from the techs at TCI and Twist Machines (they supplied the paddle shifters I intend to install later). My problem is that it's in Brians shop and I have to drive 40 minutes to get there. If I can ever get it drivable, it will come back home and I can finish up stuff like electronic gauges, paddle shifters, etc.

Stand by for updates. Gotta work on it and not write about it for now.
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Re: 4L80e transmission swap

Postby critter » Wed Jan 27, 2010 9:46 pm

I ran it tonight. I also data logged it.

Watching the real time display it seemed everything was normal. The TPS was responding, the RPMs looked normal and it appeared to understand what gear it was in.

Reverse works but the forward gears just seem to not want to move under load as if the stall on the converter is WAY up there. Looking at the data logs I can see where it shifted all the way into OD but the logs show a lot of transmission slippage. It is a used transmission and I took the seller's word for it being solid. Looks like I might have been burned. Bryan says we need to get the gauges on it and I agree. If the ice storm doesn't stop me I'll be back there tomorrow night.
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Re: 4L80e transmission swap

Postby 77TA » Thu Jan 28, 2010 9:17 pm

Man I tell ya if its a bad tranny I swear I'll never buy a used one. It seems like there are lot of low lifes out there selling transmissions! Maybe it will be something that can be fixed without too much expense anyway.
Good luck with it.
I was talking to Jack and the GN boys about transmission rebuilders and they are all kinda uncertain and hesitant to recommended someone so it seems for some reason getting a good transmission is tough all around... makes me want to get a book and learn how to build trannies. Then you probably need a bunch of special tools too.
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Re: 4L80e transmission swap

Postby critter » Sun Jan 31, 2010 6:29 pm

So here's where I stand as of today.

TCI had looked at the data logs and asked that I recalibrate the base profile in the TCU. I went back through the wizard and created a new data log that I'll send to them. Unfortunately, with the ice and snow we have on the ground, all I was able to do was run the car in the shop, moving it back and forth. If anyone else has experience in reading these and wants to peek, let me know and I'll be happy to send it along.

The results were no different. The car seem fine in reverse but all the forward gears seem to slip. I then used the voltmeter to confirm the TPS was working. It is. We then hooked up a pressure gauge.

In reverse we had between 85-90psi at idle. It would increase with throttle increase.

In all forward gears it was 50psi and didn't budge with throttle position unless we stabbed the throttle. When we touched 3000 rpm or more it would suddenly spike the pressure over 100psi. I couldn't hold it there because I was still in the shop and I wasn't taking chances. It didn't actually feel like it was pulling against the brakes, I was just scared it might suddenly grab. I wish we hadn't had any snow, I could have put it on the parking lot and tried.

So I'm asking for opinions again. Is this electrical or mechanical. I'm open to going into the pan if need be. After that, it may be time to yank it and head for the tranmission shop.
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Re: 4L80e transmission swap

Postby Vanmor » Tue Feb 02, 2010 1:51 pm

Chris,

I am no transmission expert by a long shot. I am going on a hunch that the Torque Coverter is suspect. It looks awfully small in the pictures. The fact that you get pressure spikes at 3000 rpm make me suspect the TC even more. Thing is, i have no idea what the pressure readings are supposed to be. Do you have a stock TC to try ?

The ice and snow is clearing out, so maybe you have had time to test outside by now.
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Re: 4L80e transmission swap

Postby critter » Tue Feb 02, 2010 2:38 pm

Yes, but it works normally in reverse. Torque converters don't know what gear you're in so if it was slipping it should do so equally in reverse.

Two guys who build transmissions for a living Jake Shoemaker and Cliff Ruggles, both feel we have an internal seal issue allowing it to bleed off pressure in the forward gears. Bryan isn't saying that's not true but insists we go into the pan before pulling it out of the car. I'm going in tonight after work to see what we can see.
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