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  Borg Warner Second Design ST-10 4-Speed Info 

History  Based on fact, rumors, internet stories, and my vague memory
The history of the ST-10 transmission begins with the Borg Warner T-85 3-speed which was the basis for the Borg Warner T-10 4-speed first used by GM in 1957. Various versions of the T-10 were used for AMC, GM and Ford. For a detailed history of the T-10 see classicar.com

The "second design" ST-10 replaced the old T-10 and Muncie. GM started replacing Muncie transmissions with the ST-10 starting around January-April 1974 depending on the assembly plant. Design work was done by a Mr. Johnson at the Borg-Warner Muncie, Indiana plant. Borg-Warner and GM Chevrolet Division each had separate unrelated transmission plants in Muncie.

GM versions have a 26 spline input shaft and most had a 32 spline TH400 output shaft (TH350 27 spline output shaft in 1982) and a 1" countershaft diameter.
 

Ford AS1-T10 Short output shaft
Ford AS2-T10 Long output shaft
GM AS3-T10 For Corvette, F, and A bodies
AMC AS4-T10 Long input shaft
Aftermarket for GM AS9-T10 "Power Brute" with iron case and nickel gears
Borg-Warner also sold a version of this transmission through speed shops under the "Power Brute" name. It had a 904 nodular iron case and 9310 Nickel alloy gears. The gears can be identified by a small dimple drilled into the side of each gear. Most of these version were designed primarily for drag racing and had a very low first gear. The theory at the time was to use the low first gear to launch a car quickly.

Nearly all versions used in production vehicles from 1974-1979 had the 903 aluminum case. Sometime around late-1979 through 1981 versions were offered in GM cars with the 904 nodular iron case. The change apparently came due to increased warranty claims from stretching problems with the aluminum case caused by the higher internal loading from the 3.42 first gear ratio. These also had an iron midplate for added strength.

A 4+3 overdrive version by Doug Nash Engineering was used in the 1984-1988 Corvette.

I believe Borg-Warner sold the ST-10 design to Rockland Standard Gear in the 1980's. It was then purchased by Richmond Gear which continues to produce the ST-10 as an aftermarket transmission.

Parts Sources
Richmond Gear Now manufactures the ST10   TexRacing Racing transmissions and parts
Gearzone Rebuilding service and rebuild kits   Old Man Engineering Racing transmissions and parts
Kajun Enterprises Rebuilding service, parts and rebuild kits      
Rebuild Info

ST10man.pdf 

Service Instructions, 12 pages, 1.2MB pdf
Service Tip: Examine the blocking ring and its corresponding gear and check for proper clearance between gear and ring. You want at least 0.50-inch. The two parts should face evenly without wobbling. Use another blocking ring if your doesn't seat firmly.

Date  Codes The following information is for GM applications starting in 1974

  • Codes are stamped on the driver's side of the case just to the rear for the side cover.

  • Note the difference between a STAMPED number and a CAST numbers.

  • For a quick reference, the next to last digit identifies the year.

Position >>

1st

2nd 3rd and/or
4th 		4th or 5th  Last digit
Meaning >> Warner Gear Division Month
"I" was skipped 		Day of Month 
1 or 2 digits 		Year
Next to last digit 		Production Shift

Codes >>

W

A = January

1 thru 31

4 = 1974 1

B = February   6 = 1976 2
C = March   5 = 1975 3
D = April   7 = 1977  
E = May   8 = 1978  
F = June   9 = 1979  
G = July   0 = 1980  
H = August   1 = 1981  
J = September   2 = 1982  
K = October   3 = 1983  
L = November   4 = 1984  
M = December      

Example: WB2472 = Warner Gear, B =February,  24, 1977, 2nd shift

VIN Stamp

  • If the transmission was originally installed in a car a partial VIN will probably be stamped on the case.

  • VIN information can be researched on the Internet.

  • The partial VIN is usually stamped on the passenger-side boss shown in the photo below.

  • The VIN can be on top of the boss, on the side or both.

  • The VIN is sometimes on the drivers side next to the date code per the factory print above. This is usually the case with Corvette transmissions.

  • Not all plant codes were used in all years.

  • New models were usually introduced in late-summer fall and model production usually ran from approximately August. thru the following August. This means a car/transmission built in late 1976 is for a 1977 model year car. The stamped VIN will match the model year of the car.

Example: 1BN100005 = Chevy, 1981, Norwood, 5th vehicle

Character Position: 1 2 3 4-9

 Division

Year Plant Production No.
1 Chevrolet 0 1970 A Lakewood, NJ Q Detroit, MI 2 Moraine, OH 1982 up

Usually starting with 100001 but may start with other numbers depending on vehicle type and plant. For example, Corvette may start with 500001

2 Pontiac 1 1971 B Baltimore, MD R Arlington, TX 2 Ste. Therese, PQ
3 Oldsmobile 2 1972 C Southgate, CA S St. Louis, MO 3 Detroit, MI
4 Buick 3 1973 D Doraville, GA T Tarrytown, NY 3 St. Eustache, PQ 1982 up
5 GMC Truck 4 1974 E Linden, NJ U Lordstown, OH 4 Scarborough, ON
5 1979-up GM Export 5 1975 F Flint (Chev), MI V Pontiac (GMC), MI 4 Orion, MI 1982 up
6 Cadillac 6 1976 G Framingham, MA W Willow Run, MI 5 Memphis, TN to 1975
7 GM of Canada 7 1977 H Flint (Buick), MI X Fairfax, KS 5 London, ON 1979 up
8 GM Export 8 1978 J Janesville, WI Y Wilmington, DE 5 Bowling Green, KY 1981 up
9 GM Export 9 1979 K Leeds, MO Z Fremont, CA  6 Oklahoma City, OK
0 GM Export A 1980 L Van Nuys, CA 0 Pontiac (GMC), MI 7 Lordstown, OH
C Chevrolet Light Truck B 1981 M Lansing, MI 1 Oshawa, ON to 1977 8 Shreveport, LA
T GMC Light Truck C 1982 N Norwood, OH 1 Oshawa, ON or London, ON for 1978 truck 8 Fujisawa, Japan
T 1979-up GMC Caballero D 1983 P Pontiac, MI 1 Oshawa, ON 1979 up 9 Detroit, MI

The transmission below is for a 1981 Trans Am with the iron case, iron midplate and 3.42 1st gear.

Applications (a work in progress, please feel free to contribute)

  • There is a 2 letter  application code for GM transmissions used in production.This was likely a paint stamp that quickly wore off.

  • Application codes are found in the GM master parts catalog.

  • All 2nd design tailshaft housings are aluminum.

  • Warranty issues caused GM to use an iron case and midplate starting around mid-1979 for some engines

  • Not all 79-up vehicles got the iron case and/or midplate, usually Trans Ams and Z-28s.

  • All Input shafts are 1 1/8 " dia 26 spline.

  • All output shafts are 32 spline.

  • F = F-body = Camaro, Firebird

  • A = A-body = Chevelle, Laguna, LeMans, Grand Am

Code Make/Model/Eng Dates 1st 2nd 3rd 4th Rev Ratio
Code 		Input
Grooves 		Case mtl./ casting # Midplate Notes Production
  Chevrolet A 350/454, F 350 Z28/M21 3/74+ 2.64 1.75 1.34 1.00 2.55 W 3 Alu. 903 Alu.   3,336
  Chevrolet A 350/454, F 350 Z28/M20 3/74+ 2.43 1.61 1.23 1.00 2.55 S 2 Alu. 903 Alu.   7,003
  Chevrolet F 350 Z28/M21 3/77? 2.64 1.75 1.34 1.00 2.55 W 3 Alu. 903 Alu.   5,114
  Chevrolet F 350 Z28/M21 78 2.64 1.75 1.34 1.00 2.55 W 3 Alu. 903 Alu.   15,118
 RX ? Chevrolet F 350 Z28/M21 79 2.64 1.75 1.34 1.00 2.55 W 3 Alu. 903 Alu. Metric speedo bolt? 18,987
 TC? Chevrolet F 350 Z28/MM4 80 3.42 2.28 1.46 1.00 3.51 Z 0 or 6 Alu. 903 or Nod. Iron 904 Alu. Metric speedo bolt? 10,780?
  Chevrolet F 350 LM1/MM4
Canada only 		81 3.42 2.28 1.46 1.00 3.51 Z 0 or 6 Alu. 903 or Nod. Iron 904 Alu. Metric speedo bolt? ?
  Chevrolet F 305 LG4/MM4 81 3.42 2.28 1.46 1.00 3.51 Z 0 or 6 Alu. 903 or Nod. Iron 904 Alu. Metric speedo bolt? 10,780
  Chevrolet F 305 LG4/MM4 82 3.42 2.28 1.46 1.00 3.51 Z 6 Alu. 903 Alu. TH350 output est.8,000
  Chevrolet F 305 LU5/MM4 mid-82 2.88 1.91 1.33 1.00 2.78 Y 5? Alu. 903 Alu. TH350 output est.2,000
  Corvette 350, 454 M21 3/74+ 2.64 1.75 1.34 1.00 2.55 W 3 Alu. 903 Alu.   <3,494
  Corvette 350 L82/M21 75 2.64 1.75 1.34 1.00 2.55 W 3 Alu. 903 Alu.   1,057
ZT Corvette 350 L82/M21 76 2.43 1.61 1.23 1.00 2.35 S 2 Alu. 903 Alu.   2,088
  Corvette 350 L82/M20 77 2.64 1.75 1.34 1.00 2.55 W 3 Alu. 903 Alu.   2,060
ZT Corvette 350 L82/M21 77 2.43 1.61 1.23 1.00 2.35 S 2 Alu. 903 Alu.  
  Corvette 350 L82/M20 78 2.64 1.75 1.34 1.00 2.55 W 3 Alu. 903 Alu.   3,385
ZT Corvette 350 L82/M21 78 2.43 1.61 1.23 1.00 2.35 S 2 Alu. 903 Alu.  
  Corvette 350 L82/MM4 79 2.64 1.75 1.34 1.00 2.55 W 3 Alu. 903 Alu.   4,062
ZT Corvette 350 L82/MM4 79 2.43 1.61 1.23 1.00 2.35 S 2 Alu. 903 Alu.  
  Corvette 350 MM4 80 2.88 1.91 1.33 1.00 2.78 Y 5? Alu. 903 Alu.   5,726
  Corvette 350 MM4 81 2.88 1.91 1.33 1.00 2.78 Y 5? Alu. 903 Alu.   5,757
  Corvette 350 MM4 84 2.88 1.91 1.33 1.00 2.78 Y 5? Alu. 903 Alu. Doug Nash OD 6,443
  Corvette 350 MM4 85 2.88 1.91 1.33 1.00 2.78 Y 5? Alu. 903 Alu. Doug Nash OD 9,576
  Corvette 350 MM4 86 2.88 1.91 1.33 1.00 2.78 Y 5? Alu. 903 Alu. Doug Nash OD 6,835
  Corvette 350 MM4 87 2.88 1.91 1.33 1.00 2.78 Y 5? Alu. 903 Alu. Doug Nash OD 4,229
  Corvette 350 MM4 88 2.88 1.91 1.33 1.00 2.78 Y 5? Alu. 903 Alu. Doug Nash OD 4,282
HW Pontiac A 400, F 400,455 3/74+ 2.43 1.61 1.23 1.00 2.35 S 2 Alu. 903 Alu. It appears the manual had the wrong ratios <2,000
HW Pontiac F 400, F 455 75 2.43 1.61 1.23 1.00 2.35 S 2 Alu. 903 Alu. It appears the manual had the wrong ratios 6,997
ZT Pontiac F 400, F 455 4/75+? 2.43 1.61 1.23 1.00 2.35 S 2 Alu. 903 Alu.   >10,000
ZT Pontiac F 400, 455 76 2.43 1.61 1.23 1.00 2.35 S 2 Alu. 903 Alu.   12,952
ZT Pontiac F 400 L78 77 2.43 1.61 1.23 1.00 2.35 S 2 Alu. 903 Alu.   13.137
ZT Pontiac F 400 L78 78 2.43 1.61 1.23 1.00 2.35 S 2 Alu. 903 Alu.   13,502
UF Pontiac F 301 L37 79 2.43 1.61 1.23 1.00 2.35 S 2 Alu. 903 Alu. Metric speedo bolt? 3,333
UH Pontiac F 400 L78 79 2.43 1.61 1.23 1.00 2.35 S 2 Alu. 903 Alu. Metric speedo bolt? 8,690
ZD Pontiac F 400 L78, 301 L37 4/79+?       1.00       Alu. 903 or Nod. Iron 904 ? Metric speedo bolt?  
DC or FN? Pontiac F 305 LG4 81 3.42 2.28 1.46 1.00 3.51 Z 0 or 6 Alu. 903 or Nod. Iron 904 Alu. Metric speedo bolt? 7,058
? Pontiac F 305 LG4/MM4 82 3.42 2.28 1.46 1.00 3.51 Z 0 or 6 Alu. 903 or Nod. Iron 904 Alu. TH350 output  
BW-AS9-T10V BW Aftermarket 74-81? 2.23 1.77 1.35 1.00 2.35 V 2 Nod. Iron 904 Alu. Nickel Gears  
BW-AS9-T10P BW Aftermarket 74-81? 2.43 1.76 1.47 1.00 2.35 P 2 Nod. Iron 904 Alu. Nickel Gears  
BW-AS9-T10S BW Aftermarket 74-81? 2.43 1.61 1.23 1.00 2.35 S 2 Nod. Iron 904 Alu. Nickel Gears  
BW-AS9-T10Q BW Aftermarket 74-81? 2.43 1.46 1.18 1.00 2.35 Q 2 Nod. Iron 904 Alu. Nickel Gears  
BW-AS9-T10T BW Aftermarket 74-81? 2.43 1.61 1.03 1.00 2.35 T 2 Nod. Iron 904 Alu. Nickel Gears  
BW-AS9-T10X BW Aftermarket 74-81? 2.64 1.61 1.23 1.00 2.55 X 3 Nod. Iron 904 Alu. Nickel Gears  
BW-AS9-T10W BW Aftermarket 74-81? 2.64 1.75 1.33 1.00 2.55 W 3 Nod. Iron 904 Alu. Nickel Gears  
BW-AS9-T10Y BW Aftermarket 74-81? 2.88 1.74 1.33 1.00 2.78 Y 4 Nod. Iron 904 Alu. Nickel Gears  
BW-AS9-T10CC BW Aftermarket 74-81? 2.88 1.91 1.33 1.00 2.78 CC 5? Nod. Iron 904 Alu. Nickel Gears  
BW-AS9-T10Z BW Aftermarket 74-81? 3.42 2.28 1.46 1.00 3.51 Z 6 Nod. Iron 904 Alu. Nickel Gears  
BW-AS9-T10U BW Aftermarket 74-81? 3.44 2.28 1.46 1.00 3.51 U ? Nod. Iron 904 Alu. Nickel Gears  
BW-AS9-T10AA BW Aftermarket 74-81? 3.29 1.72 1.00 1.00 3.51 AA ? Nod. Iron 904 Alu. Nickel Gears  
BW-AS9-T10BB BW Aftermarket 74-81? 4.17 2.28 1.46 1.00 3.51 BB ? Nod. Iron 904 Alu. Nickel Gears  
1304000070 Richmond Gear 85-up 2.43 1.61 1.23 1.00 2.35 S 2 Alu. 903 Alu. 375 Ft. Lbs  
1304000069 Richmond Gear 85-up 2.64 1.75 1.34 1.00 2.55 W 3 Alu. 903 Alu. 325 Ft. Lbs  
7021090 Richmond Gear 85-up 2.64 1.61 1.23 1.00 2.55 X 3 Alu. 903 Alu. 325 Ft. Lbs   
1304000072 Richmond Gear 85-up 2.88 1.91 1.33 1.00 2.78 CC 5? Alu. 903 Alu. 300 Ft. Lbs  
1304000062 Richmond Gear 85-up 2.88 1.74 1.33 1.00 2.78 Y  5? Alu. 903 Alu. 300 Ft. Lbs.  
1304000071 Richmond Gear 85-up 3.42 2.28 1.46 1.00 3.51 Z  6 Alu. 903 Alu. 286 Ft. Lbs.  

ST-10 Ratio Chart
Used By

Codes

 I/O
Splines		 Grooves

1st

2nd

3rd

4th

Rev.

 Cluster
In-3-2-1		 Input

1st

 2nd

3rd

 Rev. spur
BW

V

 26/32 2

2.23

1.77

1.35

1.00

2.35?

              
R

 

   2

2.41

1.47

1.19

1.00

2.35

 27-28-21-16 21 30 24 26   1.29
R

 

   2

2.41

1.61

1.03

1.00

2.35

 27-25-20-16 21 30 25 20   1.29
 

EE

   2

2.43

1.34

1.13

1.00

2.35

 27-24-22-18 21 34 23 21   1.29
BW, R, GM

S

 26/32 2

2.43

1.61

1.23

1.00

2.35

 27-23-20-18 21 34 25 22   1.29
BW, AMC

P

 26/32 2

2.43

1.76

1.47

1.00

2.35

     34   24    
BW, R

X

 26/32 3

2.64

1.61

1.23

1.00

2.55

 28-26-20-18?
28-24-21-18?		 20 34 24 21   1.40
BW, R, GM

W

 26/32 3

2.64

1.75

1.34

1.00

2.55

 28-23-20-18 20 34 25 22 39 1.40
BW, GM

T

 26/32 3

2.64

2.10

1.46

1.00

2.71

   21 34 25 20    
GM, BW, R

EE

 26/32 4 or 5

2.88

1.74

1.22

1.00

2.78

 29-25-21-18 19 34 24 20   1.53
GM, BW, R

Y

 26/32 4 or 5

2.88

1.74

1.33

1.00

2.78

 29-24-20-18
29-24-21-18		 19 34 24     1.53
GM, BW, R

CC

 26/32 4 or 5

2.88

1.91

1.33

1.00

2.78

 29-24-20-18 19 34 25 21   1.53
BW, R

AA

 26/32  

3.29

1.72

1.00

1.00

 

              
BW, R

OD

    

3.42

1.23

0.94

         30        
BW, R

L

 26/32 0 or 6

3.42

2.28

1.46

1.00

3.33

 31-25-20-18 17 34 25 20   1.82
GM

U

 26/32 0 or 6

3.42

2.28

1.46

1.00

3.33

 31-25-20-16 17 30 25 20   1.82
BW, R, GM

Z

 26/32 0 or 6

3.42

2.28

1.46

1.00

3.51

 31-25-20-16 17 30 25 20    
 

BB

    

4.17

2.28

1.46

1.00

3.51