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beamn7 · 03-02-2012, 04:38 PM

Having built a fair share of automatics, here are my 2 cents:
1. THM-700R4 (4L60) built right is a good trans and can last a long time behind a smallblock with up to 450hp and towing no more than 5K lbs OUT of OD.
2. There is no such thing as a 4L80. They all have the "E" at the end and are all electronically controlled. 4L80E is also known as THM-R2 (4 = # of gears. L = longitudinal drive. 80 = series. E = electronic) Example: THM-400 was renamed 3L80 in the late 80's early 90's. 4T60E would be an electronically controlled 4 speed front wheel drive (T= transverse) 60 series.
3. 4L80E is based off the THM400 with the overdrive portion being based off the THM2004R. (2004R is stronger than 700R4)

I'm a fan of both transmissions but for some serious hauling / HP and Torque handling, I'd go with the 4L80E OR a NV4500. Always keep in mind that saying from the old Fram ads: "Pay me now or pay me later"

03-02-2012, 04:38 PM	#27
beamn7 Registered User Join Date: Oct 2011 Location: Wildomar, CA Posts: 466	Re: Trans swap from T400 to Overdrive Having built a fair share of automatics, here are my 2 cents: 1. THM-700R4 (4L60) built right is a good trans and can last a long time behind a smallblock with up to 450hp and towing no more than 5K lbs OUT of OD. 2. There is no such thing as a 4L80. They all have the "E" at the end and are all electronically controlled. 4L80E is also known as THM-R2 (4 = # of gears. L = longitudinal drive. 80 = series. E = electronic) Example: THM-400 was renamed 3L80 in the late 80's early 90's. 4T60E would be an electronically controlled 4 speed front wheel drive (T= transverse) 60 series. 3. 4L80E is based off the THM400 with the overdrive portion being based off the THM2004R. (2004R is stronger than 700R4) I'm a fan of both transmissions but for some serious hauling / HP and Torque handling, I'd go with the 4L80E OR a NV4500. Always keep in mind that saying from the old Fram ads: "Pay me now or pay me later"