Although invisible to the eye, sometimes the biggest gains are the ones that seem plain and mundane. When most people think about a custom classic truck, they ponder flashy paint, wheel and tire combos, and custom body mods. But what good is all that exterior hoopla if the drivetrain underneath limits the truck to side-street commutes and freeway speeds that refute Sammy Hagar's "I Can't Drive 55" argument? Oftentimes, poor driveability can be directly linked to the transmission, which is why TCI Automotive designed a new 700-R4 tranny that is sure to kick things up a notch.
Whether you're simply trying to step up from a Powerglide, Turbo 350, Turbo 400, or just replacing a tired 700-R4, the new TCI 700-R4 transmission is an improvement above them all, in more than just one way. But for starters, we'll go with replacing a Powerglide, Turbo 350 or 400. Due to the fact that the 700-R4 transmission is equipped with four gears, including overdrive, gear ratios will be adjusted for better take-offs, and perhaps most importantly, highway cruising. In terms of taking off from a dead stop, the 700-R4 clocks in with a 3.07 first gear, as opposed to a 2.48 in a T400 or a 2.52 in a T350. The 700-R4's 3.07 gear is basically the equivalent of a 20 percent lower rearend gear, which directly results in better 60-foot times. As for cruising, a 700-R4 is equipped with a .67 overdrive that gives you a 33 percent higher rearend gear. To put it another way, if you have a 3.73 rear gear and a Turbo 400, the switch to a 700 gives you a low gear like a 4.11 and highway cruising like a 2.56 rear gear.
If all those crunched numbers and figures are flying across the top of your dome, then let's slow things down and put them into laymen's terms. Let's say your truck currently runs a Turbo 350 or 400 and it cruises down the freeway at 4,000 rpm. If you upgraded to a 700-R4, the .67 overdrive would drop that rpm figure to around 2,800 rpm at the same speed! As a result of the lower rpm, your truck would no longer scream and shake like an overcaffeinated Robin Williams goin' down the freeway. And as a result of that, you'd be able to hear the local radio station play the same seven songs over and over and your friends talk about the glory days back on the football field.
First things first. John began by removing the driveshaft and draining the trans. But before that, save yourself a potential headache down the road and measure the old tranny and the new TCI tranny to make sure their dimensions are the same. |
When it comes to removing the transmission, there are various things that need to be disconnected. John's starting point was the speedometer cable. |
Next, John slid the trans jack under the trans, then unbolted the trans mount from the trans crossmember and slid it back. |
The shift linkage is held to the linkage U-bracket on the transmission via a cotter pin. With the cotter pin removed, John slid the linkage out. |