In order to make it clear the long-tube headers, Gearstar removed 1 1/2 inches of metal off of the dust cover ear on the transmission case. While this procedure was performed on a lathe, a die grinder will work just as well. Surprisingly, this was the only grinding necessary on the case to get it to fit.
Made from flexible steel-braided hose, Gearstar’s custom trans dipstick eliminated the need to bend and wrestle with rigid tube when routing it through the chassis. Longer and larger in diameter than the stock piece, it doubles as a filler tube as well. An adjustable bracket enabled Gearstar to mount it on the cowl, although other locations will work as well.
The only cutting required was a 4-inch section of metal on the driver side of the trans tunnel just ahead of the crossmember. This provides clearance for the wiring harness bolt head. With the trans mocked into place, Gearstar technicians marked the area with a Sharpie, then cut and removed the metal section with a cutoff wheel. Since the metal flap isn’t a structural member, it has no adverse affects on chassis stiffness.
True to the car’s sleeker appearance, Gearstar removed the stock shift lever and mounted a B&M Pro Stick shifter inside the factory center console.
The B&M shift cable and trans brake line were routed through a factory hole located on the trans tunnel right above the crossmember mount. To get rid of some slack, the cables were angled rearward by attaching them to the fuel line with zip ties, then routed back forward on a gradual bend.
Should a transmission ever overheat, it’s designed to puke fluid out of the breather tube to relieve internal pressure. The factory tube is only three- to four inches long, and dumps fluid right on the case. To avoid a potential mess, Gearstar extended the tube all the way to the tailshaft housing.
Not only is the slip yoke used on the 4L85E significantly larger than that of the 4L60E, it features 32 splines instead of 27. Gearstar matched the yoke up with beefy 1350 U-joints. The upgraded yoke assembly can be welded onto any driveshaft during the shortening process.
With the popularity of the TH400 swap, many manufacturers offer torque converters that fit the LS1’s bolt pattern. This isn’t necessary with the 4L85E, as it was designed for LS-series motors from the get go. From this view, it’s clear where the dust cover area of the trans case will smack into the passenger-side header if it isn’t ground down. While it’s possible to dimple the Number 7 primary, the potential for impeding exhaust flow isn’t worth the risk.