4L60e replacement - year compatibility

[ASJT3]

Folks,

After years of faithful and thankless service, my 93 K1500 finally decided it didn’t want to go fast anymore. Displaying typical symptoms, in third gear engine just tachs up; I suspect 3-4 clutch packs are toast, tranny fluid was low and grey (smelled kinda burnt) when I checked.

Anyways, I toyed with rebuilding the tranny and I’m a handy guy, but that just seems overly complicated when I could probably swap out for a donor tranny in a day. Question is, what year group trucks are compatible with my 93 K1500, 350 with the 4L60e?

Thanks,

Alex

[Blue Bowtie]

Unless you get a known like-new "donor" unit, or if you get a "donor" with any questions whatsoever about its lineage, it may be worthwhile to go through it before making the swap.

The 4L60E is a fairly easy rebuild, and is reasonable, even with premium parts:

http://www.wwdsltd.com/4L60/4L60ERepairs.html

For your applicaton, only 1993 & 1994 units are direct drop-ins, and probably none of those are going to be low-mileage, pristine units.

[Blue Bowtie]

For further information:

1993 4L60Es were used in trucks only. Not available in F-Bodies, B-Bodies, or Y-Bodies.

1994 is fully interchangeable with 1993 4L60E with no modifications. Those years are a Non-PWM transmission, meaning that the converter lock up apply strategy is an digital arrangement. The trans has an 11-pin main electrical connector. There is a one-piece TCC control valve in the valve bodym and the early design 3-2 valve.

1995 is a stand-alone year for the 4L60E. It will not interchange with any other year. This is a PWM lockup transmission with an extra solenoid added to the valve body to control the pulsed lock up scheme of the torque converter clutch. The unit used a 12-pin main case electrical connector and required an extra wire in the transmission harness and different PCM to control the PWM circuit. The units have "PWM" cast in the front pump body. The front pump internal passages different to match new TCC strategy, along with a two-piece TCC control valve in valve body. It retained the early design 3-2 valve. A 1993-1994 PCM will not function with the pulsed TCC scheme and will tend to burn up the convertedr clutch and 3-4 clutches. The 1996 PCM is also not compatible with early 3-2 control solenoid.

1996/1997: The 3-2 downshift control was changed to a digital scheme. The TCC solenoid was changed to a 20-31Ω unit, from the previous 10-15Ω solenoid. The 3-2 control valve was changed to the second design valve. The easiest way to identify the valve is in that the second design valve will fall out as soon as the solenoid is removed. The first design has a separate port plug and circlip. The TCC solenoid remained 10-15Ω, which is the same as 1995. Most 1995-and up units will have "PWM" cast in the pump housing. The 1996/97 pump itself is the same as 1995, but it will not exchange with a 1995 unless the 3-2 solenoid is also changed. Also the 1994/95 PCM will not operate the 20-31Ω 3-2 solenoid and will generate a powertrain DTV, then force the transmission into "limp" mode.

[ASJT3]

Thanks Bowtie for the info. I've decided to go ahead and do the rebuild, and removed the transmission yesterday.

Do you or anyone else have a recommendation for a good rebuild kit? I've watched vids on transmissionbench.com and they sell rebuild kits for around $400, which while seems a little pricey although it appears to be a pretty comprehensive kit.

Thanks,
Alex

[Schurkey]

The 700 in my '88 has been rebuilt twice.

Both times, the planetaries were broken, as were the springs in the accumulators.

[ASJT3]

Originally Posted by Blue Bowtie

For further information:

1993 4L60Es were used in trucks only. Not available in F-Bodies, B-Bodies, or Y-Bodies.

1994 is fully interchangeable with 1993 4L60E with no modifications. Those years are a Non-PWM transmission, meaning that the converter lock up apply strategy is an digital arrangement. The trans has an 11-pin main electrical connector. There is a one-piece TCC control valve in the valve bodym and the early design 3-2 valve.

1995 is a stand-alone year for the 4L60E. It will not interchange with any other year. This is a PWM lockup transmission with an extra solenoid added to the valve body to control the pulsed lock up scheme of the torque converter clutch. The unit used a 12-pin main case electrical connector and required an extra wire in the transmission harness and different PCM to control the PWM circuit. The units have "PWM" cast in the front pump body. The front pump internal passages different to match new TCC strategy, along with a two-piece TCC control valve in valve body. It retained the early design 3-2 valve. A 1993-1994 PCM will not function with the pulsed TCC scheme and will tend to burn up the convertedr clutch and 3-4 clutches. The 1996 PCM is also not compatible with early 3-2 control solenoid.

1996/1997: The 3-2 downshift control was changed to a digital scheme. The TCC solenoid was changed to a 20-31Ω unit, from the previous 10-15Ω solenoid. The 3-2 control valve was changed to the second design valve. The easiest way to identify the valve is in that the second design valve will fall out as soon as the solenoid is removed. The first design has a separate port plug and circlip. The TCC solenoid remained 10-15Ω, which is the same as 1995. Most 1995-and up units will have "PWM" cast in the pump housing. The 1996/97 pump itself is the same as 1995, but it will not exchange with a 1995 unless the 3-2 solenoid is also changed. Also the 1994/95 PCM will not operate the 20-31Ω 3-2 solenoid and will generate a powertrain DTV, then force the transmission into "limp" mode.

Thanks for this info. Are the 98/99 transmissions same as 96/97?

[Schurkey]

Originally Posted by Blue Bowtie

1995 is a stand-alone year for the 4L60E. It will not interchange with any other year. This is a PWM lockup transmission with an extra solenoid added to the valve body to control the pulsed lock up scheme of the torque converter clutch.

My understanding--correct me if I'm wrong--is that the torque converter clutch friction material ALSO changed when they went to the Pulse-Width Modulated (PWM) control strategy. I believe they went to a Kevlar material that will withstand additional heat generated by the slow engagement of the PWM control of the converter clutch.

Short story--the PWM converter clutch slips a lot more, gets hot, needs high-temp friction material.

I don't know if there's a downside to using the Kevlar material in an On/Off converter clutch, but I'm pretty sure you can't use the older material/older torque converter in a PWM transmission.