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rfmaster · 07-04-2007, 12:47 AM

Ehman

If you are planning to stick with carburetor on your '77 stepside I would steer away 4L60E and PCM which is required to control this transmission. Factory PCMs appeared around 1992 and were fully deployed by 1996 as mandated by federal OBD-II requirements. From what I was able to find out factory OBD-II PCM are impossible to hack since feds mandated that all operational parameters stored inside the PCM to be encrypted. This was done to prevent EFI hackers from reverse engineering and modifying ECM-PCM code to do the things that we want to do as it was done with previous C3 and P4 generation of engine control computers (ECM).

To control 4L60E a GM Controller, #12497316 is required (or after market). Carbureted engines will also require installation of a Throttle Postion Sensor (TPS). When I was considering converting from 3 to 4 speed automatic a reworked TH700R-4 was a clear winner based on cost since it was cheaper to upgrade my $250 core (swap meet) with later transmission core parts vs. going to after market controller and 4L60E route.

On the other hand, 4L60 was produced from 1990-1992 which is a renamed version of 700R4 which was produced during 1980s. My truck was equipped with long tail shaft (9”) TH-350 (30-11/16”)which is nearly identical in length to a standard 700R4 (30-¾”). Hence, no driveshaft work was required to complete this swap other than moving cross member and drilling new mounting holes. If you chose to go 700R4 route try to avoid pre 1986 transmissions – these used weak internal parts and are prone to early demise. Early 700R4 can be updated with later parts, but it is extra money.
The 4L60 (700R4) uses a throttle valve (TV) cable for shifts while the 4L60E uses the PCM to control shifts. Correct setting of TV cable with 700R4 or 4L60 is critical – if done incorrectly it may destroy transmission very quickly. Check Bowtie Overdrives.com for more information and parts. If you plan to use lock up converter (TCC) there are several low cost wiring kits available (TCI, Painless, B&M, or DIY).

The 4L60e derives its designation from its specifications: 4-speeds, Longitudinally positioned, 6000 lbs. GVW, Electronically controlled, although the transmission sees factory service in trucks up to 8600 lbs. So, sell your 4L60E and get beefed up 700R4 (4L60) for a straight forward swap.

Picture is the prop shaft view of my 700R4 install.

07-04-2007, 12:47 AM	#10
rfmaster Registered User Join Date: Oct 2003 Location: OC CA Posts: 1,374	Re: 4l60e question Ehman If you are planning to stick with carburetor on your '77 stepside I would steer away 4L60E and PCM which is required to control this transmission. Factory PCMs appeared around 1992 and were fully deployed by 1996 as mandated by federal OBD-II requirements. From what I was able to find out factory OBD-II PCM are impossible to hack since feds mandated that all operational parameters stored inside the PCM to be encrypted. This was done to prevent EFI hackers from reverse engineering and modifying ECM-PCM code to do the things that we want to do as it was done with previous C3 and P4 generation of engine control computers (ECM). To control 4L60E a GM Controller, #12497316 is required (or after market). Carbureted engines will also require installation of a Throttle Postion Sensor (TPS). When I was considering converting from 3 to 4 speed automatic a reworked TH700R-4 was a clear winner based on cost since it was cheaper to upgrade my $250 core (swap meet) with later transmission core parts vs. going to after market controller and 4L60E route. On the other hand, 4L60 was produced from 1990-1992 which is a renamed version of 700R4 which was produced during 1980s. My truck was equipped with long tail shaft (9”) TH-350 (30-11/16”)which is nearly identical in length to a standard 700R4 (30-¾”). Hence, no driveshaft work was required to complete this swap other than moving cross member and drilling new mounting holes. If you chose to go 700R4 route try to avoid pre 1986 transmissions – these used weak internal parts and are prone to early demise. Early 700R4 can be updated with later parts, but it is extra money. The 4L60 (700R4) uses a throttle valve (TV) cable for shifts while the 4L60E uses the PCM to control shifts. Correct setting of TV cable with 700R4 or 4L60 is critical – if done incorrectly it may destroy transmission very quickly. Check Bowtie Overdrives.com for more information and parts. If you plan to use lock up converter (TCC) there are several low cost wiring kits available (TCI, Painless, B&M, or DIY). The 4L60e derives its designation from its specifications: 4-speeds, Longitudinally positioned, 6000 lbs. GVW, Electronically controlled, although the transmission sees factory service in trucks up to 8600 lbs. So, sell your 4L60E and get beefed up 700R4 (4L60) for a straight forward swap. Picture is the prop shaft view of my 700R4 install. Attached Images __________________ "The Beast" 1975 Chevrolet C20 longbed 350/700R4! with 3inch body lift Dual Flowmasters Super 40's! TBI retrofit completed (2007-07-29) New 383CID (+030) 08-304-8 9.5:1CR x36,005 (2012-12-17)