700R4/4L60 Valve Body Overview

When is comes to this area of this line of transmissions, it is real difficult to nail it down. i have literally three different manuals open on my desk here and a catalog of footnotes i have gathered from builds i have done and advise i have gotten. so at best, this is an overview to give you an idea what to expect.

there are two major groups of valve bodies on this line of transmissions. what most people call a type 1:which is 1982-early 1987, and type 2: which is mid 87-92……often called an auxillary valve body tranny.  they are both a cast iron valve body similar to the older th350’s and 400’s.  there are 13 valve passages in the body. one being your manual valve, another being your TV, or throttle valve(which controls shift point like a vacuum modulator), and one passage believe it or not is is usually rendered useless on most transmissions for non-electric TCC engagement. there are then 3 primary shift valve passages for your main shift points. the 1-2,2-3, and 3-4 shift valves. these three valves receive oil signal from your governor and TV valve to trigger shift at the appropriate pressure signal. this leaves 7 more valve passages. these valves control downshift and accumulator characteristics and work in conjuction with the other 5 or 6 valves.

basically, during a standard rebuild, most people clean out the valve body with solvent then use a small screwdriver to make sure the springs on all the valves are not broken and the valves move freely. if there was a problem with the quality of shift at all with your transmission, you should buy the shift kit and follow the instructions. i have found that the primary source of wear in these things is the spacer plate/accumulator and not the valve body specifically. all of these trannys are prone for spacer plate wear to the point the check balls get stuck in the spacer plate. the accumulator also comes apart and beats the shit outta the plate as well.

Type 1 trannys use a fairly common midplate from what i can gather, differences being between diesel and gas models. most had 6 check balls in the case-one of em being larger than the other 5  for the TV exhaust port, and one for the accumulator housing.  there were also usually 3 check balls in the valve body on the opposite side of the spacer plate making a total of  8 check ball locations.

here you can see ach the type 1 installed on a unit. the upper left hand corner is you accumulator housing. this housing holds the 1-2 accumulator. below this accumulator under the mid plate is also your 3-4 accumulator piston. most early type set ups use a piston with a teflon seal. later type 2 set ups often used a different style piston with a rubber seal(which is considered more desirable and can be interchanged). the accumulator springs are also color coded for different tensions and shift characteristics. my transtar book list 7-9 different colors/springs here. from what i can gather black springs are thought to be the weakest and white the stiffest. the stiffer the spring the more aggressive the shift. red color being above average and blue color being just under that.  often these springs will have damage or be busted. also note that next to the accumulator is a flat plate…..similar to what a non-lockup th350 has to the front of the valve body. this is the location of the auxillary valve body on type 2 valve bodies.

type 2 valve bodies, also called auxillary valve bodies, are slightly more complex than the older trannys. the valve body is similar to the type one but is different. interchanging early and late model valve bodies is NOT recommended. also between 87 and 92/early 93 there were literally dozens of different style mid plates. there is even an interchange chart in the later model ATSG manual that at a glance…….seems like about 50 different plates! also the check ball locations change. the one later model i did for myself omitted two check balls over the type 1 i did. valve body gaskets are also different between the two valve bodies. TAKE NOTE OF WHICH GASKETS YOU HAVE DURING DISASSEMBLY! most kits come with 4-6 different gaskets. make sure you get the right ones or you will be in deep shit. gaskets are usually marked “C” for the case side of the mid plate and “V” for the valve body side, or lower valve body gasket.  one set will have a hollow pie wedge out of a spot on the edge representing the “V”, whereas the other type gasket will have a more distict “V” shape. which one goes where? well, take note during disassembly.

the Type 2 auxillary valve bodyt is located here, and has a tube that runs to the top of it from the front of the transmission. it bolts on in place of the rear cover plate location. GM started having trouble with a harsh engagement when shifting into drive or overdrive on some 700R4 models, which over a period of time not only irritated the customer but tore up the forward clutch of the transmission. so, in mid to late 87 they added this in place of the plate you saw earlier. basically it’s only job is to cushion engagement from neutral or park, especially at high idle which most fuel injected cars seem to do for a short period of time after start up. these are prone to having the center pin of the accumulator. there is also a check ball location beneath it. do not put it in the wrong port as there is an orificed plug next to the check ball location.

now i said earlier that there was a valve that is pretty much a dead slug in there. GM actually has a valve set up for hydraulic engagement of the TCC in place of the TCC solenoid and computer controlled engagement. most transmissions never got it and the factory installed two aluminum plugs in the passage to render them useless. sometime in 1989 they quit casting the bore in the valve body, but up until then you could remove the two aluminum slugs and put in the hydraulic valve set up for hydraulic TCC engagement. Companies like Superior make a kit to retrofit this valve into your transmissions so you can do away with the electrical lock-up all together. i have never done one of these, so please don’t ask me what is involved. i do believe the part number though is a K017, and is currently around 100 bucks if you shop around.

For performance, it seems GM had many parts that were corvette specific. so upgrading several parts in your 700R4 with corvette calibrated components seems to be a going theme. the TV valve in this case may not allow an upshift to 4th gear past 3/4 to full throttle. here you can get a different “corvette” sleeve for the TV valve in the valve body to correct this.

well, this is the last i am writing on these trannys for a while- my brain is fried now i need a cup of coffee!

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