When we dropped our fire-breathing 400-cube SBC into good ol' Project Exit 98 (which you can read about in the September 2011 issue or at www.superchevy.com), we felt going into the deal that the stock TH200-4R was not the best choice to handle the 480 lb-ft of torque our shiny new Dart motor produced. A quick call to the folks at Monster Transmission and Performance in Brooksville, Florida, confirmed this suspicion.
"GM never designed the 200-4R to go into anything with more than 300 or so horsepower," says Achilles Thomas, president of Monster. "That's why you don't see them in trucks; they can't handle the associated torque."
Our solution was to swap in a TH700-R4. Both the 200 and 700 were early '80s overdrive incarnations of General Motors Turbo-Hydramatic automatic transmissions that first appeared in 1964 model year Cadillacs. While there are a significant number of similarities between the two, the 700-R4 is a stronger transmission, featuring a 30-spline input shaft as opposed to the 27-spline one found in the 200. The lock-up circuits in a 700 are different as well. Most importantly, the planetary in the 700 is much stronger than the one found in the 200, making it a popular choice for muscle car restorations like lil' ol' 98 here.
Of course, here at Super Chevy we're not just going to drop in any old junkyard 700-R4. Quite the contrary. Since we're already pushing close to 500 lb-ft on this motor, we opted for Monster's SS Mega Monster 700-R4. Designed for vehicles powered by engines producing up to 650 horsepower (600 torque), the Mega Monster is perfect for our application, and with a price tag of $1,695.95 it's also a great deal. For the lowdown on what makes this trans so well suited to our combo, check out the sidebar at the end of the story. Now, on to the install. j
Building a Monster
Before our 700-R4 SS Mega Monster transmission ever got anywhere near Exit 98, it first had to be completely rebuilt. But the guys at Monster Transmission do way more than just rebuild the trans. Actually, "rebuild" is somewhat of a misnomer for what they do. Complete upgrade would be a better description. The 700-R4 that's in our Monte is ideal for vehicles powered by engines producing up to 650 hp and 600 lb-ft of torque (without nitrous), using pump gasoline. The 700-R4 has a 3.06 ratio in First gear, which is 20-percent lower than most automatic transmissions. The 30-percent overdrive will give a 30- to 40-percent increase in gas mileage on the road when compared to a three-speed transmission. Equipped with a Manual/Automatic valve body, most units allow you to manually shift the vehicle into each gear change or, by placing it in the Drive position, remain fully automatic. Of course, in order to have complete control of the rpm shift timing, you must upgrade to a full manual valvebody. When you select the normal Drive position, the transmission retains its firm, automatic shifts for the ease of driving you look for in an automatic transmission.
There are almost too many upgrades to list in one sidebar, but some of the more major ones include the swapping in of stronger five-pinion front and rear planetary gearsets, an updated accumulator, a new high-flow filter, new 29-element, heavy-duty forward input sprag, and a new high-performance aluminum servo. Monster also modifies the sunshell drive gear to increase rear planetary lubrication and the input sun gear to increase forward planetary lubrication. In fact, the guys at Monster focus a lot of attention on lubrication during their rebuilds. Better lubrication equals lower operating temperatures and better overall performance.
Finally, they perform dozens of system checks throughout the build, not just when the trans is completed. Before any trans goes out the door of Monster's shops, it gets dyno'd and road-tested, a hallmark to their dedication to quality control. We're looking forward to beating the snot out of Exit 98 when we get to the track.