GM Tranny Bolt Patterns

[Steve Ochs]

Message text written by INTERNET:diy_efi at esl.eng.ohio-state.edu
>Anybody know if the 3.8L Buick FWD engine and the 2.8L/3.1L/3.4L Chevy FWD
> share the same bellhousing pattern? I thought so originally until I found
> out that the Quad 4 and the 2.8L are different. So maybe the Buick is
> different too.
><

Boy, gone from the digest for two days and I miss a lot!!!  I wish I could
have gotten into this discussion earlier. 

Here is the scoop:

Rear Wheel Drive -
There are two bolt patterns made, Chevy and BOP (Buick-Olds-Pontiac)
Some transmissions came in both, some in Chevy only.
The 700-R4/4L60/4L60-E came in Chevy ONLY until 1995 when the split case
became avaialble.  All BOP applications used the THM-200-R4, THM-200,
THM-250, or THM-350 until those trannys were discontinued (last was 200-R4
in 1990).  That is why 3800 was not available in Camaro/Firebird until
1995.  In order to be more flexible including outside customers, a 2-piece
case was designed for the 4L60-E.  The transmission housing is the same but
the bellhousing can be replaced with different versions (like a manual
tranny).
All Chevy truck engines mated to the 700-R4/4L60/4L60-E (including 2.8L
V-6, 4.3L V-6, & All V-8s) have the Chevy bolt pattern.  No adapters have
ever been used with the 700-R4 tranny.

Front Wheel Drive -
ALL transverse FWD Automatic trannys have the SAME bolt pattern EXCEPT for
the 4T80-E which is used exclusively on the Northstar V-8s.  There have
only been THREE FWD transverse transmissions made for all applications
other than Northstar

The first was the THM-125 which is now known as the 3T40 (3-speed
auutomatic).  

The second which is basically a beefed up O.D. version of the 3T40 is the
THM-440-T4which has evolved into the 4T60, the 4T60-E, and the 4T65-E.

The third is the newer 4T40-E which is a O.D. 3T40.

All of these models all have the same mounting bolt pattern.  I don't have
my manual near me but unless the engines were made with a different bolt
pattern, the Getrag should have the same pattern.  It is possible the
engines (such as the Quad 4) were made with a dual pattern, but the
Automatic version of the Quad 4 is the same as the V6s.

    The following is a list of GM FWD transmissions
and their applications:

    Model           Years       Current Application
---------------  ------------  ---------------------
THM125-C (3T40)  1979-2002     J (possibly to 2002)
4T40-E           1995-future   J,N,P-90
THM-440T4 (4T60) 1984-1990     None
4T60-E           1988-1999     W,U,H
4T65-E           1997-future   W,U,C,H,G
4T80-E           1992-2002     Northstar

     The following is a list of many of GM trannys over the years and their
torque capacities, etc.

                                |--------Maximum-------|
                                Engine  Gearbox  Gross    Torque     
Overall
     Transmission       Weight  Torque  Torque  Veh. Wt. Conv. Dia.  
Length
        Model           (lbs.)  (lb/ft) (lb/ft)  (lbs)    (inches)   
(inches)
     Rear Wheel Drive:
     TH-180C (3L30)     130/140   258     440     7716   9.6/10.24  
26.29/28.11
     TH-200-4R          157       330     550     6000     11.73     28.26
     TH-400 (3L80)      190       440     885    12000     12.20    
29.30/34.48
     TH-700-R4 (4L60)   167/184   350     650     8600   9.6/11.73  
29.77/30.64
     4L30-E             168/177   258     440     7716   9.6/10.24  
28.54/31.57
     4L60-E             160/176   350     612     8600   9.6/11.73  
29.77/30.64
     4L80-E             260       440     885    15000     12.20    
31.93/33.02

     Front Wheel Drive:
     TH-125C (3T40)     161       200     416     5100     9.64
     TH-440-T4 (4T60)   195       235     369     5181     9.64
     4T60-E             203       280     390     6400     9.64
     4T65-E             214       285     400     6400   9.64/10.16
     4T80-E             295       305     461     6800     10.43

     Here are some common tranmission gear ratios: 

     Transmission
        Model           First   Second   Third   Fourth   Reverse
     Rear Wheel Drive:
     TH-180C (3L30)     2.400   1.479    1.000     ---     2.000
     TH-200-4R          2.741   1.568    1.000    0.674    2.067
     TH-350             2.52    1.52     1.00      ---
     TH-400 (3L80)      2.482   1.482    1.000     ---     2.077
     TH-700-R4 (4L60)   3.059   1.625    1.000    0.696    2.294
     4L30-E             2.400   1.479    1.000    0.723    2.000
     4L30-E Optional    2.860   1.620    1.000    0.723    2.000
     4L60-E             3.059   1.625    1.000    0.696    2.294
     4L80-E             2.482   1.482    1.000    0.750    2.077

     Front Wheel Drive:
     TH-125C (3T40)     2.840   1.600    1.000     ---     2.067
     TH-440-T4 (4T60)   2.921   1.568    1.000    0.705    2.385
     4T60-E             2.921   1.568    1.000    0.705    2.385
     4T65-E             2.921   1.568    1.000    0.705    2.385
     4T80-E             2.960   1.626    1.000    0.681    2.130

Steve Ochs aka N8TYS- Mfg. Engineer - GM Powertrain - Parma Plant
Transmission Division (4T60/65-E) - Steve_Ochs at compuserve.com
The statements and opinions expressed here are NOT an official
statement of General Motors or the GM Powertrain Division

'97 Chevy Blazer LT 4x4 4.3L V6    '96 DCM Impala SS 5.7L V8 
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