200-4R Installation
Time to overdrive your T/A
I have just purchased a 200-R4 to install in my T/A and will be outlining my install here.
Important facts.
Flywheel holes for will need to be enlarged for the new metric bolts. NOT! My flywheel did not need this.
Trans mount bolt hole spacing is different. Most replacement mounts are slotted to fit both.
Output shaft is 27 spline just like the Turbo 350.
Turbo 400 uses 32 spline.
The transmission is the same length as the turbo 350, but the trans mount is on the very
end of the transmission so the cross member will need to be moved back about 5".
Trans cooler line fittings are the same thread, but will need to be relocated.
A bracket will need to be fabricated for the TV cable.
You will need an overdrive shifter I have found two choices the Shifterworks kit and the B&M Megashifter.
The Shifterworks kit is a very nice kit that includes everything you need to update your shifter
and the linkages you need for the shifter to transmission mounting.
Here is the B&M Megashifter console version that will work with a 200-R4.
| A | B | C | D | E | ||
| Trans | Length | Length | Length | Spacing | Width | Spline |
| Type | Overall | Bell/H to Tail/H | Bell/H to Mount | Mount Bolts | At Bell/H | Count |
| ST-300 | 27 11/16" | 20 7/16" | 20 1/8" | 3 3/4" | 19 1/8" | 27 |
| TH400 | 28 1/2" | 24 5/16" | 26 13/16" | 4 1/4" | 19 3/8" | 32* |
| TH200-4R | 27 3/4" | integral T/S | 26 13/16" | 3 3/4" | 19 3/8" | 27 |
| TH700-R4 | 30 13/16"** | 23 7/16" | 22 5/16" | 3 3/4" | 19 5/16" | 27 |
| * Some 27 | ||||||
| ** Vette 29 3/4 |
Check out High Performance Pontiac April '98 for the start of a six part series on how to install an overdrive.
GM Automatic Transmission Overhaul.
Links for Trans parts etc.
Gear Ratios and how to rebuild your 200 R-4
GN T-Type web site. Info on the 200R-4
A good article on putting a 200 R-4 in a GS.