Bolting the transmission into Project C4orce required a few alterations to the standard installation, necessitated by the LSx engine. The Tuned Port engine that had been residing in Project C4orce's engine bay was fitted with a 153-tooth flywheel, so the original bellhousing couldn't be used. In its place, we installed a traditional, old school, small-block bellhousing designed for a 168-tooth flywheel and mechanical throw-out bearing. These bellhousings are relatively easy to find and are reasonably priced.
However, since these bellhousings have been designed to work with mechanical clutch linkage, they have no provision for mounting a slave cylinder, which is required with a hydraulic throw-out bearing. That problem is easily resolved by installing McLeod part number 1363 and routing the hydraulic lines through the opening in the bellhousing that was formerly occupied by a clutch fork.
Pilot bearing location is another issue that must be addressed during installation of a transmission designed for a traditional small-block. Standard bearing location in an LSx crankshaft is farther forward than in a Gen I small-block, so if a traditional-style bellhousing is bolted to the rear of an LSx engine, the input shaft on a Gen I-compatible transmission isn't long enough to engage the pilot bearing. The remedy for this is to install GM pilot bearing number 12557583, which is designed to fit the larger diameter bore in the very end of an LSx crankshaft.
A third area of modification is the C-bridge section that contains the bolt holes through which the transmission tailhousing is connected. These have to be elongated approximately 1/4-inch to accommodate the LSx engine's bellhousing face position, which in our installation is slightly forward compared to that of the original engine.
Back in the day, a clutch...
Back in the day, a clutch fork stuck through the opening in the bellhousings side. The opening obviously provides plenty of room for the braided stainless line required to connect a hydraulic throwout bearing to a master cylinder. Don't squint too hard; the line wasn't connected when this photo was taken.
TKO transmissions incorporate...
TKO transmissions incorporate a conventional-style speedometer gear housing, so either mechanical or electronic speedometers can be connected. Transmission kits for C4s include the components necessary to provide proper input for the car's electronic speedometer.
McLeod's hydraulic throwout...
McLeod's hydraulic throwout bearing is a one-piece assembly that mounts in place of the TKO's bearing retainer; whereas the C4's original system incorporated an externally mounted slave cylinder.
Even though the TKO-600 doesn't...
Even though the TKO-600 doesn't have a big, ugly overdrive unit at the rear, we were a bit concerned about clearance between the transmission and the Random Technology 3-inch-diameter x pipe system. Before getting too far along in the installation, we put the transmission in place with a makeshift C-bridge adapter to make it easier to move things around if necessary. Fortunately, there were no clearance issues.