When did they upgrade the 700R4? The tech articles on the sight say 87. A lot of the posts say 88. so when was it? I had an 83 Z28 with 56000 miles and the tranny felt pathetic compared to my 87 IROC with 150000 miles. I know there is a big power difference between the two but I feel as though if I put the 83 tranny in my 87 it would break.

Rich

 

My haynes manual says in 83 you could get 200c or 700-r4, in 84 and up all you got was the 700-r4. Just going buy what I read here.

 

It was for the 87 model year they made significant changes to the 700r4 transmission. Only small adjustments were needed for subsequent years onwards. The difference is pretty dramatic though between the versions, but this guy has said it better than I ever could

http://www.technicalevolution.com/700r4.htm


"There are basically 3 major versions of the 700r4. From '82 until '84 there was a small-input-shaft unit with the same spline as the 200c transmission. It took an RPM part# C-21 (gas) or C-37 (diesel) torque converter*. Make sure not to use the later torque converter. It will install just fine, but the vehicle will not move when you are finished! From '85 to '87 there was a large input shaft version, which has the same spline as a 350 trans. It takes an RPM part # C-40 (gas) and a C-39 (diesel) torque converter*. The early torque converter ('82-'84) will not install, so there is no danger of using the early torque converter on the large shaft. From '87 1/2 up, the large shaft is still used, but GM incorporated an auxilary valve body to cushion engagement into drive.

There are some interchange problems that arise. There have been many changes to the 700r4 trans since it's first production. Obviously, input shafts (and the drums that connect to them) are different. Reverse input drums come in three different varietys ('82-early '87, which has a square oil orifice, and a steel piston, '87-'92, which has a smaller round oil orifice, and an aluminum piston, and '93, which has an aluminum piston and a larger square orifice (similar to the early drum). Pump stator supports, and their respective pump halves have changed through the years. There are, as you may have guessed, small shaft, large shaft, and '87 1/2 up auxilary valve body versions. There is an early ('82 to '84) sprag assembly that has gold thrust washers, and uses the plastic washer between it and the front planet; And the later version of the sprag assembly, that has silver thrust washers and Does not use the plastic washer between it and the front planet....put a washer there and you will eliminate all thrust end-clearance, and the unit will fry (I told you, I have to learn everything the hard way....Oh well, at least this way, I never forget this detail!). Always replace the valve body separater plate with the same code stamped on the plate. Watch the checkball location. Different years take different locations. Prior to '87 1/2, there are (5) 1/4" check ***** in the case and (3) 1/4" check ***** in the valve body. Later years take (4) and in rare cases (5) in the case and (2) in the valve body and (1) in the auxilary valve body."

 

The 1987 still used the early valve body. In 1988 the late valve body was introduced and remained the same till the introduction of the 4L60E. In 1992 the viton input to output shaft seal was introduced to solve the rear planet burnup (which it did) and is still in use today (2002), and should be used in all applications for the above reason. 1988-1992 units are pretty much the same and are the ones that should be sought after for heavy duty/performance use.