Transmission Swap - Trans-ition

This original 1SC Z28 stripper currently retains a not-so-original 4L60E automatic transmission--and a slipping one at that. This just isn't going to work with my road and drag racing plans, so the slushbox has to go.

The 4L60E and the original 3.42 gears that came with the factory 6-speed in my car combine to produce only 60 mph in Overdrive at 2,000 rpm.

Joining me in this trans swap project is none other than GM High-Tech legal counsel and tech writer extraordinaire, Chris Werner. (Object seen in photo is calmer than it appears.)

I pull the Z into Chris' garage, disconnect the battery, and we lift it up.

I'd heard great things about the transmissions coming out of T56Rebuilds.com in Houston, Texas. After an in-depth discussion with owners Joe and Amber Huneycutt regarding my plans for the car, they recommended the 4A package...

...The 4A starts with a core transmission, and adds new 1-2, 3-4, 5/6, and Reverse sliders, a new mainshaft, carbon fiber synchros, 3/4 billet keys, a steel 3-4 fork, bronze fork pads for the 1-4 forks, a new bearing, and labor for only $1,950. Additionally, new 1-6 gears may be used, depending on how the core tranny's gears are.

Because I'll be asking a lot from this drivetrain in the upcoming months, I chose a clutch with some serious power capacity: Spec's 3+ kit. The 3+ is different from the regular 3 kit, due to the full-faced, carbon metallic friction, high torque sprung hub and disc assembly (Spec rates it at a huge 850 ft-lbs of torque). I also requested an aluminum flywheel and pressure plate, both lightweight components. These parts really make a difference in the drivetrain (the pressure plate is 7 lbs lighter than standard, and the flywheel is 11 lbs, or 46%, lighter!), and are especially great for road race and autocross duty. In addition, throwout and pilot bearings were included in this kit.

The thought of a flywheel coming loose and doing its best Texas Chainsaw Massacre impression on my feet isn't a pleasant one; to avoid this bloody end, I contacted McLeod about its SFI-approved bellhousing. This sucker is stout, and I'm gonna feel much better when it is bolted up.

Here's what we'll be working with: the major deviations from stock are the Loud Mouth exhaust, missing cats, and subframe connectors.

Let's do this thing: the trans pan's 16 13mm bolts are removed, and the fluid is drained.

A trans jack lifts up the rear so we can pull the torque arm's two bolts with a 13/16 socket. A breaker bar will be handy here--or so we think.

You have won this round, torque arm bolts.

With a pipe breaker extension, an impact socket, a 1/2-inch drive breaker bar, and a 13/16 closed end wrench, the two nuts are finally loosened. The bolts are pulled out the top of the torque arm.

The front torque arm mount is loosened with a 15mm ratcheting open end and 15mm wrench. A bolt goes all the way through, and the nut on the end holds the metal bracket that sandwiches the bushing in there.

Now the torque arm can be removed.

Four 11mm bolts come out at the rear axle yoke ...

And the driveshaft is pulled out.

The trans pan is replaced for jacking purposes, and the shifter cable is popped off.

The four outside 15mm bolts are removed from the auto trans crossmember, and the one trans bushing-to-crossmember bolt is removed from the center.

Here's a comparison of the automatic trans crossmember (top), and the manual trans crossmember sourced from F-body specialists, F-Body Motorsports (bottom). If you're looking for hard-to-find parts for your project, Roy Fender at FBM is your man--the M6 torque arm bracket/bushing, M6 crossmember, console shift plate and upper boot, and the clutch pedal switches and wiring were all obtained through F-Body Motorsports.

Now the seven trans-to-engine bolts are removed. We leave the two bottom bolts in for now, and attack the upper ones with a 13mm swivel socket and extensions. The trans wiring harness is disconnected from the VSS and the rear O2s (unused here). Chris attaches the chain to the trans and we get the trans dipstick bracket bolt out--the two trans fluid lines are disconnected with a 3/4 flare wrench.

Finally, the last two bottom trans bolts are removed, and we use a screwdriver on the built-in pry points to pull the trans off of the dowels.

The trans is dropped down--we found that the torque converter bolts were installed backwards, so we had to work hard to get them out before the trans was free. The stock mount was removed by pulling two bolts with a 15mm socket--this mount will be reused. Chris, always on the edge of fashion, proudly displays his new headgear.

Six 15mm bolts on the flexplate are removed with an impact wrench, and the flexplate is pulled off.