Art Carr loves the GM 700-R4 overdrive automatic as much as the next guy. The problem is, the stock stuff tends to blow up when subjected to real power. That's why he's a huge supporter of the 200-4R overdrive automatic. Blessed by GM's Hydramatic Division with superior guts, it only takes a few well-chosen tweaks to make a 200-4R live behind as much as 1,000 hp. Got a 6-71 supercharged 468 Rat motor in your daily driver-like Robbie Whitlock's '66 Chevelle? Carr can build you a 200-4R that'll take the gaff. We stopped by Carr's California Performance Transmission and came away impressed by the 200-4R's clear advantage over competing four-speed automatics. First off, the 200-4R is an analog transmission. That means, unlike the 4L80E and its lesser "E" siblings, it isn't dependant on a computer to tell it what to do. This fact alone means the cost of a rebuildable core is much lower, a savings that quickly trickles down to your wallet.
While it is true that the 700-R4 is also analog and rebuildable cores are priced as low as the TH200-4R, it has a fatal flaw in the form of a weak input shaft and drum assembly. Its lightweight aluminum construction limits capacity to around 500 hp, less if the car is heavy.
The hassle is the drum is a very complex part and so far nobody has invested in the tooling required to manufacture a superior aftermarket replacement. On the other hand, the 200-4R is free of this inherent deal breakers. Oh sure, it's ripe for improvement, and this story outlines just a few of the steps Carr takes to bring one up to snuff. We'll show you that in a minute. But the 200-4R has other inherent advantages over the 700-R4. Let's make a list:
 Stock TH200-4Rs get a bad...  Stock TH200-4Rs get a bad rap in high-performance applications due to a weak intermediate drum assembly. On this cutaway, the pen points out the failure-prone undercut. Carr used Kenny Duttweiler's 10-second Buick GN as the test mule to research the problem. At first, he tried a welded bead to fill the area and eliminate the stress riser. It helped, but occasional breakage was still an issue. Carr then considered the metallurgy of the part, and after some trial and error, arrived at a proprietary annealing/heat-treatment process that triples its strength. Problem solved. |  The Second gear band (PN 12255)...  The Second gear band (PN 12255) is lined with CPT red friction material that improves drum stopping and holding power. By contrast, the stock band (top) has recesses in its apply surface that reduce contact area. |  The stator support is another...  The stator support is another 200-4R weak spot that's corrected by heat treating. The pen points out the worn splines on the stock support. The darkened splines on the stator support to the left have been heat-treated to prevent fatigue. Carr sells the heat-treated stator support separately (PN 12275) and says it's a must when installing a new torque converter. "Worn splines can catch the new converter's stator and cause a thrust load that's transferred into the engine and can wear out the crankshaft thrust bearing." |
*At 27 3/4 inches, it's the same length as a Powerglide or short-tail TH350, so swappers can reuse the driveshaft without modifications. By contrast, the 700-R4 measures 30 3/4 inches and generally requires a custom-length driveshaft.
*If you swap it for a 28 1/4-inch short-tail TH400, just change yokes and the original driveshaft fits.
*It shares the same 26 3/4 face-to-mount distance as the short-tail TH400, so it'll bolt right up to the TH400 transmission crossmember.
*The 700-R4's 3.06 First gear ratio is a little too much of a good thing for most applications. The 200-4R's 2.74:1 ratio makes more sense for V-8s, where low-end torque is in good supply.
*The overdrive ratio-0.70 for the 700-R4, 0.67 for the 200-4R-is virtually identical, but the 200-4R offers a better ratio spread (2.74, 1.57, 1:1, 0.67), which reduces rpm drops during gear changes. The 700-R4's ratios (3.06, 1.63, 1:1, 0.70) cause a drastic 46 percent rpm drop on the 1-2 upshift.
*GM designed the 700-R4 valvebody to prevent overdrive access at full-throttle to ensure survival. Not a good sign. The 200-4R is free of such nonsense and is ready for big-block overdrive blasting with only minor beefing.
*The TH200-4R case has a dual-bolt pattern that fits Chevy, as well as all BOP V-8 blocks. The 700-R4 case requires an adapter behind non-Chevy blocks.
By now it should be clear there's a pretty strong case-pun intended-for the 200-4R. Let's dig in and see how Carr makes it live with big power.
 The stock 200-4R input shaft...  The stock 200-4R input shaft is safe to about 550 hp. Shown here is the end of the shaft that fits into the overrun drum at the rear of the transmission. The pen points to a factory-machined undercut in the stock shaft. Again, it's a stress riser (potential fracture point) that also reduces the length of the splines. For maximum durability, Carr offers a replacement shaft (PN 12282, foreground) that's machined from superior 300M steel. Note how the splined surface is longer than stock for increased engagement into the drum and maximized load-transfer capacity. |  All factory-issue 200-4Rs...  All factory-issue 200-4Rs came with five direct-high clutch plates regardless of vehicle application. That's right, GM gave granny's Malibu grocery getter the same setup as an intercooled Grand National. For a significant increase in torque capacity, Carr juggles parts. Replacing the stock 0.080-thick steels with thinner Kolene-coated 0.076-thick steels and using 0.002-thinner-than-stock Red Eagle clutches results in an eight-pack and a 20 percent improvement in holding capacity. |  The stock overdrive clutch...  The stock overdrive clutch assembly uses three steels and two clutch plates. By removing 0.080 from the overdrive apply piston (pen points), Carr can add a third clutch plate for a 33 percent increase in torque capacity. Unlike a 700-R4, the 200-4R is not prevented by its valvebody program from running in Overdrive at wide-open throttle. The extra clutch capacity assures your 502 Rat motor won't overpower the clutch in triple-digit Cannonball Run mode. |