Tremec TKO 600 Transmission - Clutched And Dangerous Part 2

From the bottom side of the car, Jarvis marked and drilled the spot on the patch panel where the shifter needed to poke through. It was then enlarged with a 3-inch hole saw. The hole should be cut as small as possible, as it will allow less heat and road noise to enter the cabin. With all the welding and cutting of the patch panel complete, the area was painted inside and outside the car to prevent corrosion.

Back underneath the car, it was time to wire up the trans, which was pleasantly simple. The Hurst kit includes a speedometer cable that connects to the factory gauge with plug-and-play simplicity. The same goes for the reverse lights, but as with most cars that have seen 40-plus years on the road, the factory connectors on Project Olds were severely thrashed, so Jarvis hardwired them in instead. To prevent bumping the starter with the trans in gear, we hooked up a neutral safety switch as well. The Hurst setup includes fittings that screw into the starter terminals, which are then spliced into the NSS.

Hurst offers both hydraulic and mechanical clutch linkages for Chevelles. Granted, the Cutlass shares the same A-body platform as the Chevelle, but since there was still the possibility that some variation exists between the Olds and Chevy, we ordered up a reproduction linkage assembly from The Parts Place (PN MT4614T). The kit includes a Z-bar and bracket, brake and clutch pedals, a clutch pushrod, a clutch fork, a clutch fork ball and pushrod, return springs, and ball studs. The Z-bar is an old-fashioned yet effective linkage system whose center shaft mounts between the driver side framerail, right behind the lower control arm, and the engine block. Via actuator pushrods, one lever connects to the clutch pedal, and the other lever attaches to the clutch fork. As the driver steps on the clutch pedal, the Z-bar shaft rotates around the ball studs, and transfers motion to the clutch fork to disengage the pressure plate.

Accessing the pedal box area can be a pain, as it requires dropping the steering column. Fortunately, bolting up the pedals is less challenging. The big automatic brake pedal in our Cutlass was attached with a tube that ran through the pivot point, which was then locked down with a pin. The manual trans clutch/brake pedal assembly mounts in a similar fashion to the stock location. The only difference is that the clutch pedal pivot slides inside the pivot tube of the brake pedal.

On most GM muscle cars, the Z-bar mounting bracket attaches to the outside of the driver- side framerail. To access the framerail, Jarvis cut a hole through the driver-side front wheelwell. The Z-bar kit includes a template to help position the mounting bracket properly. Ideally, the Z-bar should be situated as parallel to the ground, and perpendicular to the motor as possible to ensure easy clutch disengagement.

One ball stud attaches to the bracket that's welded to the framerail, while the other screws into a threaded boss on the block. The ends of the Z-bar shaft slip onto the studs and rotate around them. The threaded boss on the block is very difficult to access inside the car, so it was screwed in before the motor was installed.

Most GM muscle cars equipped with automatic transmissions from the factory also had a hole in the floorboard to accommodate the clutch pedal pushrod, but it was covered by a block-off plate. Removing it can be difficult since it's hidden beneath the brake booster, but it eliminates the need to drill a hole yourself. The pedal kit includes a rubber boot that bolts in place of the block-off plate using the stock screws. With the pedals in position, the clutch actuator pushrod was attached from the pedal to the Z-bar, and then the master cylinder pushrod was connected to the brake pedal. Next, the clutch fork pushrod and springs were attached to the Z-bar and clutch fork.

As the linkage assembly begins pulling on the clutch fork, it pivots on an adjustable ball stud, which in turn releases the,throwout bearing on the pressure plate. Exactly how the ball stud is adjusted determines where in the pedal's range of travel the clutch engages. Many drag racers prefer a clutch pedal that engages right off the floor for quick launches and reaction times. Road racers, on the other hand, often prefer the pedal to engage as high up the travel range as possible for brisk shifts and reduced clutch rattle. Since Project Olds certainly isn't a drag car, Jarvis opted for the latter option by lengthening the adjuster stud until the clutch fork began contacting the throwout bearing, then backed it off a few turns. After the clutch's break-in period, the linkage should be adjusted again to take up any slack.

Included in the Hurst swap kit is a custom driveshaft from Inland Empire Driveline. After sending in the necessary measurements, it sent us a 3-inch steel driveshaft to mate up with our TKO 600 and 1350-series rearend yoke. Although an aluminum shaft would probably work just fine, Jarvis prefers steel units in A-bodies since their wheelbase is so long.

While test-fitting the driveshaft, it's good practice to check for sufficient runout. The sweet spot is roughly an inch, which prevents both the slip yoke from smashing into the trans as the suspension compresses, and ensures adequate spline engagement.

With the pedals in place, the steering column was re-installed. Obviously, the granny column shifter is of little use now, so it was tossed in the trash.

After installing the clutch linkage and patch panel, the final step was buttoning up the interior. The only modification necessary was cutting a small hole in the carpet for the shifter. If retaining the bench seats, one caveat is that the shifter needs to be positioned as far forward as possible. Fortunately, the TKO 600 has multiple shifter mounting locations. Furthermore, for those who have bucket seats and a factory center console, Hurst also offers an offset shifter to position it perfectly in the stock hole.

Project Olds is just about finished, and by the time you read this, the fuel system, exhaust, and cooling system will already be completed. One of the last items to be bolted up before firing up the 461 was an MSD 6AL2 ignition box, which we mounted underdash for quick and easy rev-limit adjustments.