This thread is going to focus primarily on how to swap from an automatic transmission (4L60E) to a manual transmission (T-56) in NBS Chevy/GMC full-size pickups. I figured I'd do a write up on this since I get quite a few PM's on the subject. This swap is not as bad as it seems at first. If you know how to R & R a transmission, then you can do this swap. If you already have a 5spd manual in your truck then R & R’ing is all the swap basically is.
Parts Gathering
Transmission
Any T-56 transmission from an LS1 f-body (Z28/ SS/ T/A etc.) will bolt to your Gen III/IV small block. The years this corresponds to are 98-2002. There are quite a few pull outs for sale at ls1tech.com every week. Make sure you get one that is fairly complete with switches and sensors though. Prices range from well under $1000 to $2500 depending on the mileage and how built it is.
Clutch/Pressure Plate/Flywheel/Slave Cylinder
The clutch, pressure plate and flywheel all must come from the same vehicle as stated above. If you opt to purchase everything new then make sure they fit these vehicles. As for the slave cylinder, purchase one new! I went with a used one and learned the hard way when a slave fails. If you do purchase a new one, make sure is a 2001-newer version. GM redesigned them for this year and they’re a lot less prone to failure. The major difference I could see is the front seal material.
Pedal/Clutch Master Cylinder
The first obvious thing your A4 truck doesn’t have is an extra pedal. To add one, you can order the assembly from a stealership or go the junk yard route. I went the junk yard route and found a complete assembly from a 2004 with 11 miles on it. The good thing about the pedal assembly is that the master cylinder is a part of it. When you buy the pedal assembly, ask for the master cylinder too.
Cross member
I’ve been told that a factory 5 spd cross member will bolt in and work with the T-56. I wasn’t so lucky to experience this, as I have a 2000. Evidently in 2000 GM revised cross member designs, and I have the older style. The picture below shows the difference.
Misc.
A shifter for a T-56 will obviously be needed, and it doesn’t matter which one you go with, as long as it’s for 98-up f-body’s. The hydraulic clutch line gave me some fits though. If you can get one with the pedal/master assembly, go for it. I thought I could just pick one up a new one at the dealer, but they won’t sell you one without the master cylinder. I managed to find one from an f-body, but then had to have it lengthened considerably. A pilot bearing will be needed, and I recommend going with a roller version. They’re cheap and easily found at any auto parts store. Ask for one for your truck or again, a 98-up f-body. There are some miscellaneous fasteners you will probably need, but they’re nothing you can’t get at your local hardware store.
In my opinion the parts gathering was the hardest part. It was a pain to research and find everything since the junk yards in my area don’t stock newer “rare” vehicles and parts. I had to talk to quite a few junk yards from
www.car-parts.com from all over the country to get the best deals.
Installation
Some of the installation can be done without the truck being down. This was very important for me, because my truck is my daily driver and my A4 was on borrowed time. The pedal assembly can be installed without making the truck in-operable.
Pedal/Master cylinder assembly
1. Locate the precut rubber/insulation under the dash on the firewall. This is precut, so it can easily be removed in a nice circle simply by pulling on it and tearing it out. You should now be able to see/feel a nipple on the actual firewall.
2. The nipple from the previous step is a dimple when viewed from the engine compartment. It is there so you can center your drill bit/hole saw. A 2.5” hole needs to be drilled and centered on this dimple. The dimple may be hard to see due to dirt, but just feel around for it.
3. Under the dash, directly to the right of the hole you just drilled are two vertical holes (see above picture). This is where the pedal assembly mounts. I was disappointed to find that there was nothing to thread a bolt into in these holes, so I fab’d up a nut plate as shown.
I felt this would be far easier than running a bolt all the way through the firewall only to have it wind up behind the power brake booster. I advise not to use large sheet metal or lag screws either. These will pull out over time, especially with severe power shifting.
Transmission/Clutch/ Bellhousing
Everything here installs just like and f-body. Just bolt it all in, torque to spec, align the clutch and you’re good to go.
Crossmember
If you have a late 2000-up, you’re in luck, because a factory 5 spd crossmember will bolt right in and work. I have an early 2000, so I had to modify mine. Here’s the difference between mine and the factory 5spd:
I just cut the factory mount off and welded on a piece of 1” square tubing as shown.
Shifter
A hole for the shifter will obviously need to be cut. I found it easier to do this once everything is mounted and in place. Make sure you cover the opening of the transmission real well before cutting. Also if you have an EC you will need to trim the HVAC duct work that goes to the rear seats for the shifter to operate fully.
Driveshaft
I have an EC so I was able to just slide the carrier bearing back 3/8” and be fine, but if you have a RC if will need to be modified to safely operate.
Electrical/Tuning
I originally had a Nelson tune, so he was the one that actually went in and edited a lot of my transmission tables. My tune basically looks like a hybrid truck/f-body tune. If you don’t have this luxury, then the main things that need to be changed to get you going are the teeth count on the reluctor wheel for the speedometer and you need to delete all automatic transmission codes.
The back up lights will need to be re-wired too in order to work. To do this you need to cut a green and pink wire in the A4. There are two green wires, so you might get lucky and you might not.
These wires need to be lengthened and run over to the passenger side of the T56 and hooked into the backup light switch. The switch is located on the side of the main body of the transmission.
If you're making over 400rwhp/rwtq then I advise not to cheap out on a clutch. Get a dual disc setup or at least a Textralia OZ700. I learned the hard way that a SPEC stage 3 just won't survive daily driving conditions.
I will add things if I missed some, so feel free ask questions in this thread.
Official A4 to M6 (T-56) Thread!
