rehirsch8

See new pictures of the swap in the post below. I've also added the connector part numbers and circuit numbers.

For the past several months I've been purchasing all of the parts needed to swap from a stock A4 with 2.73 diff to a M12 (Z06) transmission and 3.42 differential. I decided to swap transmissions versus replacing the car for several reasons. My car has low miles, one of the last 2004s built, and I've put a lot of time into the existing mods. I also love the Medium Spiral Grey Metallic color.

When I started the project I couldn't find a lot of information on the topic so I thought I would write it up so others could learn what I did and ask questions.

I worked with Doug Rippie Motorsports. They had never done the swap before but they do great work and were willing to work with me. bought all the parts and worked out all of the electrical and computer changes. Yesterday the car started and ran through all the gears on the first try and no codes!

Here are the parts I decided to use:

- 2003 M12 Transmission rebuilt and hardened by Rockland Standard Gear - purchased from CorrvetteRecycling.com
- New 3 rib 3.42 differential from GMPartsHouse
- 2003 Torque Tube with new couplers and bearings from RPM
- New bell housing GM PartsHouse
- Used bell housing access cover - ebay
- Z06 Manual transmission wiring harness - ebay
- LS7 Clutch and Flywheel - GM PartsHouse (GMPH)
- New OEM Slave cylinder GMPH
- New GM Master Cylinder - GMPH (used seal and reservoir)
- Reservoir bracket for firewall - Vettenutes.net
- Tickshift Master Cylinder - Tick Performance
- Tickshift remote bleeder - Tick Performance
- Z06 Shift Arm - Vettenuts.net
- Torque Tube Shift box - Vettenuts.com
- Shift box rubber gasket - CorvettesRecylcing
- MGW Shifter - MGW
- Shift boot - CorvetteEssentials
- Shift boot retaining ring - ebay
- Manual brake pedal - CorvetteRecycling
- New C6 Clutch pedal - GMPH (C5 bracket had to be modified)
- Pedal bushings, spacers and bolts - Vettenuts.com
- Clutch pedal bracket - VetteNuts.net
- Clutch bracket 3 bolt bar - Vettenuts.net
- Clutch start switch - vettenuts.net
- Cruise control clutch switch - vettenuts.com
- Clutch start switch wire connector with leads PN#12102690 - Amazon.com
- Cruise control clutch switch wire connector with leads PN#12126463- GMPH
- ECS transmission brace - West Coast Corvettes
- Redline fluids -DRM

The swap of the mechanical components is relatively straight forward if you've worked on automatics and manuals before. Where it gets tricky is with the electrical and PCM changes.

There are two approaches for the wiring. One is to replace both the transmission harness and dash harness. This works fine but it's very difficult to replace the dash harness unless you have the full dash apart for another reason. There are only 4 wires that are missing if you just replace the transmission harness. The second option is to just replace the transmission harness and directly wire the other four wires for the clutch. This is what I did.

For the clutch start switch the two wires run to the old wiring from the park/neutral switch from the old A4 wiring. The cruise control wiring requires one wire to go to ignition power in the dash and the other wire needs to run to position 35 of connector one on the PCM. This pin is not used on an A4. I have all the wiring details if you need them and posted a similar write up on this a few weeks ago. One thing that helped us out is that I bought the connectors with the wiring leads so we just had to splice the wires. I have the part numbers if you need them. They are a pain to figure out because the 2004 service manuals don't have the right numbers. Luckily the connectors are the same on C6s and the numbers are correct.

The computer programing is straight forward. when all the electrical is done you can actually start the car and test the gears using the old program. Because the clutch start and park/neutral use the same two wires, the PCM will start the car with the A4 program. Expect codes and the PCM will lockout reverse because those wires are used for something else on the A4. You can test that you get ignition start and you can test all 6 forward gears.Good luck with the transmission swap. I'm about to do the exact same swap in a few weeks. Here are a few important tips that I have learned as I prepare for the swap.

In the tunnel for the torque tube there are extra metal clips for holding the A4 shift cable. You need to bend them out of the way or they will interfere with the MN6 torque tube and shifter arm

Ignition Start wiring - When you disconnect the A4 transmission wiring you will disconnect the Transmission Range Switch Connector on the side of the transmission. You can use the Yellow Pin 1 (Circuit 269) and Purple Pin 12 (Circuit 1606) wires to run into the clutch switch on the bottom of the clutch bracket.

Cruise Wiring - The cruise wiring is a bit tougher going into the PCM. The voltage can come off of any pink Ign 1 (Circuit 339) wire for the transmission. There are several splice packs with that wire. The second wire needs to run into pin 35 (Circuit 48) on the PCM Connector 1.

There is an additional wire on the PCM that needs to be wired in for the Theft Deterent system but I don't have the exact details on that one right now.

We used a Tech 2 to reprogram the PCM. HP Tuners will work as well. The trick is to get the OS ID number for the PCM code for your vehicle. I used HP Tuners to find the OS ID. Once I had this ID I went out to the HP Tuner site and downloaded several stock transmission tunes for manual transmissions and found one with my same OS ID. Most of the OS IDs are the same each year so this is not hard. Once I new I had the same OS ID for a manual car, I wrote the VIN number down. The PCM code for that VIN number was loaded into the Tech 2 and into my car. Once done, the car is configured as an LS1/M6 setup. I use HP Tuners to eliminate skip shift and any other tuning adjustments.

Alternatively, I could have bought two more credits in HP tuners for the manual transmission code and had HP Tuners reload the code. Since HP Tuners locks itself to the PCM serial number and not the VIN or OS ID, it really doesn't care if I reload the tune with the Tech 2. I feel rewriting with the tech 2 is cleaner than using a third party tool.

I was really surprised that we didn't run into more problems along the way. DRM was excellent to work with and they took pictures along the way. We are going to run through the gears on their dyno on Monday. Unfortunately in Minnesota it's below zero and lots of snow on the ground so I won't be driving it for a while. I used a flatbed to have the car delivered and will have them return it home next week. They did a great job strapping it down.

That's all there is! This has been a fun project and very rewarding for me. I'm happy to answer any questions. My write up covers many of the questions I struggled to find answers to. All of the vendors I listed above have been extremely helpful and sometimes patient with me.

Here are some pictures of the swap.

On the way to DRM. The snow in Minnesota is taller than my car!


Here is the old automatic brake pedal and shifter



This is the A4 coming out of the tunnel



Removed the instrument panel for easier access to the pedals and wiring



Rear suspension



Here's the new LS7 clutch and flywheel



The new M12, differential and torque tube going in



New pedals installed and clutch wiring

Blow Torch

Darn, that's a lot of money and time to spend to make the car slower

Just kidding Bob That's a popular mod and I hope you have a ball rowing the gears

upsta8NY

Rehirch8.Your exact reasons to do the swap are my exact reasons.Congrats on the swap and would you mind if i pm'd you about some swap questions.Btw i love our car colors.

realvc

Congrats. on the trans. swap. I really enjoy my 6 spd and know you will too. Way to go.

rehirsch8

PM me anytime. I'm happy to help.

crainholio

Must be quite a lifestyle.

84REDCROSSFIRE

WOW
I would never go threw the hassle of changing all that, much easier to get another newer vette w/M6. As long as your happy, thats all that counts.

brrymnvette

Congrats on the swap. I did the same swap almost 10 years ago and had a hell of a time, b/c no one would help with the wiring. Had to figure it out mostly all on my own.

Evilash

Awesome. Sound like a lot of work but with the trans harness just a few wire mods and mostly a clutch job. I am hoping to do mine this year.

Vetteman Jack

Nice writeup. Thanks for taking the time to do this.

Bluefire

I don't care who you are, that's just funny.

Congrats to the OP! Excellent Job.

Gene Culley

Hello Bob. I can certainly see why you did the change. I really like your car. Your write-up and all is really good and helpful. Thank you for your business. Sheesh, I really wonder what something like this costs!

rehirsch8

I had been wanting to do this type of project for a long time so I knew what I was getting into in terms of cost. I also elected, as Gene knows, to buy many of the parts such as the differential, bell housing, pedal, electrical connectors all new from the factory. I could have saved a lot of money waiting and buying used.

I also got burned on several parts. I bought a bell housing that had been cracked and re-welded, a torque tube that had a bearing spun in the housing, etc...

There are other small parts that really get you like that darn shift boot retaining ring.

I also got lucky. I bought a used M12 transmission and found out after I bought it the unit had just been hardened by Rockland Standard Gear.

The labor is about $3,000 if you don't do it yourself (if you give them my write up that will save you any additional R&D they need to work out). I have about $5,000 into the hardware. I also have a lot of A4 parts that are in mint condition along with a bunch of PMs asking me to sell the parts.

I could have saved a ton of money not buying the Tick master cylinder and remote, MGW shifter, ECS brace, etc...

If I didn't change out the transmission I was planning to upgrade to 3.42 gears and a higher stall torque converter anyway (although that would have been much cheaper).

DRM let me try the car on their Dyno Monday night. After shifting through all the gears and listening to the engine rev, I forgot how much it cost.

Evilash

I'll have to remember to print this write up. Thanks for the info.

I was assuming $5k all together also. But, my car already has a new 3.42 and I picked up the wiring, pedals with brackets and switches, stock master and res, stock Z06 shifter with unbroken boot and a 22,000 Z06 trans and TT for $1,300.
I still need a clutch and flywheel so maybe under $4k is reasonable? I have a slightly used YankSS3200 and 40k mile auto drivetrain I could sell afterwards.

rehirsch8

It sounds like your almost there.

You can get a new LS7 clutch reasonably. The flywheel is heavier which has pro and cons based on how you will use the car.

While you are doing the swap I would at least get the remote bleeder. You will also need the slave cylinder as well.

While you have the TT out, open it up and make sure the bearing is not spun in the housing and that the couplers look okay. With only 22K on it that should be ok.

Do you have the shift control box that sits on the torque tube? If you don't have it yet, get a Z06 style. It doesn't have the rubber mounts to give you a more solid shifter feel.

I think if you do your research online you can get some good deals on quality parts.

Gr8Wht

Very nice write-up!

Evilash

Yep, got the box and shifter shaft and everything.

Was planning to take apart and service the TT and replace the couplers.

My car is cammed so I'm thinking of going with a lighter flywheel package since it's a little dead off idle.

I was planning on getting the Tick MC but the stock one was part of the package.

Gene Culley

Thanks for the information Bob! It seems as if you did it right and that is the only way to do something!