The purpose of this article is to show potential customers what all goes into a proper 200-4R rebuild and help out the enthusiast that wants to tackle the rebuild on their own. We have the kits, upgrade parts, and tech for you!
The 200-4R is an excellent unit for retrofits. It has a proven reputation in the TurboBuick community running well into the 9's successfully. It has been underrated by many since it's inception. Like other GM overdrives it had it's problems at first. Much of this was caused by the misunderstood TV cable and TV system. Some of the problems were caused by weak parts, whether by design or metallurgy. The aftermarket has taken care of every weakness in the 200-4R and it can be built to handle approximately 800 HP/lb-ft reliably.
At Jake's Performance we feel that in most applications where an OD is needed, the 200-4R is the unit of choice up to approximately 500-550 HP/TQ. After that level the cost effectiveness of using the 200-4R is somewhat prohibitive due to the cost of aftermarket components needed. We prefer the 4L80E in the big power applications however there are certain combos where the 200-4R is still a better choice. We can help you select the unit that fits your needs the best.
The 200-4R typically has the Uni-Case design that will fit all the GM engine bellhousing patterns. Buick, Olds, Pontiac, Cadillac, and even a Chevy.
This makes the 200-4R a very good choice for our Buick, Oldsmobile, and Pontiac customers. No need for a cheesy adapter plate, worrying about converter spacing and indexing, just bolt it up and go.
A completely stock 200-4R would usually be failure prone at a measly 300 HP, however some minor modifications, mostly hydraulic in nature, will make it reliable to 400 HP/TQ.
Above the 400 HP/TQ level we believe that an aftermarket forward drum with 4340 shaft installed is required for reliability, particularly in heavier cars. Please take note here, when you are shopping for a 200-4R, see if the vendor installs a "billet" forward drum or if they install an inferior "hardened drum" or just a stock drum.
We will show the issue with a stock or hardened drum for the stouter street cars later in the article.
We often see competitors rate their 200-4R's for 500 HP or even more and nothing listed about the forward drum. This is a $400+ component that a builder isn't going to dismiss on their build sheet.
Once this one major component is taken care of, a couple of other items internally need to be addressed. These are the sun shell and the stator tube.
The sun shell is a major rotating component. Early model 200-4R's were factory supplied with a shell that was known to strip the splines.
A new hardened sun shell should be installed on all builds. It's a relatively low cost component. Same scenario on the pump stator tube. It needs to be built with a heat treated stator tube.
Once these items are taken care of, a few modifications to the friction elements, attention to detail, and internally the trans doesn't need anything else to relaibly handle 550 HP/TQ.
The critical portion of the 200-4R, and the one that most builders cannot get right, is the hydraulics. They need the hydraulics properly setup. Servo size, clutch apply area, line pressure, line rise, and shift timing are very critical to making this unit live. Knowing this is what seperates the well respected 200-4R builders from the rest. Anybody can throw parts at it, we can make it live.
Now to the tech you've been waiting for.
Core Selection-The 200-4R had several updates over the years of production. There are also some cores more desirable thatn others.
The Turbo Buick cores with a BQ (1984-1985) and BRF (1986-1987) are some of the most desirable cores. Monte Carlo SS with CQ and CZ codes are desirable as well. Internally the hard parts are mostly the same year to year with newer years having the improved parts.
Some of the improvements include a hardened sun shell on later models, a torrington bearing replacing a failure prone plastic thrust washer in the rear planetary, as well as other improvements. The Turbo Buicks in 1986-1987 had the largest servo size.
Give us a call to discuss your project!
Output shaft and ring gear ready for assembly. Place the rear torrington bearing in place. You can support the output shaft in an old TH350 long tailhousing, a yoke welded to a bench or clamped in a vise.
Above is a factory upgrade on later model 200-4Rs. We recommend always replacing the failure prone plastic thrust washer with the later AC Delco torrington bearing on rebuilds. It is included with our rebuild kit.
Install the bearing as pictured. Then install the low sprag, and inner sprag race.
Rebuild the low support by installing new seals on the piston, install a new bushing, reinstall the piston, return spring washer, plate, and snap ring.
We also install a torrington bearing in this location on our Stage II 200-4Rs.
Install the rear planetary into the rear ring gear. It should have a 4 tang thrust washer on the back. This surrounds the torrington bearing you already placed in the output ring gear.
Now set the low support in the low sprag/rear planet.
Now install the sun gear/shell assembly into place. Take note, always use a hardened sun shell.
Now you can install the front sun gear, grooved side down and 3 tang torrington bearing on top of the sun gear.
Now you are ready for the front planetary.
Install the front planet using a spinning motion, then install the torrington as pictured. Now install the input ring gear as shown below.
After installing the input ring gear, install a new brass thrust washer, selective thrust, and then the snap ring.
You can now check the rear endplay with the rear section on the bench by measuring between the selective thrust washer and the snap ring. You are aiming for .005-.010" clearance.
GM 10 bolt pinion shims can be used between the front planet and the torrington bearing to set rear endplay.
Once endplay is correct, you can disassemble the rear section, and install it in the case.
First you need a method of supporting the rear section as you install it. We use a tool made for it shown here.
Next you set the output shaft, ring gear, carrier and low sprag assembly in the case.
Align the output ring gear parking lugs with the parking pawl.