700r4 behind 6.2

[Gunfreak25]

I have been doing some reading on the 700r4 and how the lockup works. Seems there's a million questions and even more answers. But some things are still hazy to me.

All I want is automatic lock up in 3rd and 4th gear, with a brake pressure switch to disable lock when applying the brakes. I'm good with wiring and was going to install a switch in a series to disable lockup for steep hills.

It is a 1992 K case 700r4. Np231 doubled with Military transfer case (permanent 1.16 high), 6.17 axles and 40" tires. 95% of driving will be in 3rd gear around town, so lockup would be nice to maximize mileage.

[Robyn]

Hi there

This is a simple one to handle.

Use an 88 model year Valve body that has the spools/valves to run the lockup clutch.

Install the hydraulic control lockup Kit from Transgo ( Part number 700-LU)

This will give you complete hydraulic control of the lock up clutch.

Now, the tranny should have the lockup electrical control valve installed in the pump body, which will be wired through a few internal switches.

Remove the extra wires and run your solenoid to your 12V source through the brake switch and your toggle switch.

With the toggle switch set to pass current and your foot off the brake the solenoid will be powered, the hydraulics will handle the shift points and your good to go.

The kit can be tailored to do the lockup where you want it.

Missy

As long

[Gunfreak25]

Thanks for the information, Missy. I am getting the hang of this work of art! The hard part was obviously inventing the thing. Bet that took a lot of coffee.

After some talking with a professional 700r4 builder, I am going to just keep the lockup system stock, but with a toggle switch to disable it for towing/hills. Other than that it will be ON all the time.

On more question, does a stock 1992 700r4 have 3rd gear lockup? I know this is something few people want but due to the trucks low gearing and my intended application 75% of driving will be in 3rd gear. I would love to have lockup to further maximize around town mileage. Heat from cycling isn't an issue since I am running a 30,000lb rated cooler.

I know the early 700's had a 3rd gear lockup, but do the 92 models only have 4th lockup?

[convert2diesel]

All the 700 (4L60) trannies had lockup in both 3rd and 4th. Pressure is supplied from the 2nd gear circuit and will actually lockup in 2nd if both the power (through brake pedal) and the ground circuits (usually the ECM) are activated. Very early varients used a pressure switch on both the 3rd and 4th gear circuits, with a mechanical disconnect on the power side through both the brake pedal and a TPS. TCC solinoid has built in delay (about 1 or 2 seconds).

The switch on the dash is a good idea. Used it as the only method on my conversion. Takes some getting used to as you have to remember to turn it off when slowing down as the tranny refuses to go into 1st until the car has come to a complete stop. Pulling away from a rolling stop in 2nd with the TCC locked up leaves alot to be desired.:)

Bill

[Robyn]

Yesssss, 2-3-4 can all be setup to allow lockup.

Dont be tempted to use lockup in 2 though as the converter clutch really does not like being used that way.

The converter clutch was designed to be used in "Cruise mode" to save on fuel.

If you notice, that in stock configuration the clutch will drop out any time you apply much throttle at all.

Now if you install a special built convertor with a heavy duty kevlar clutch you can get away with much harder useage of the little beast.

The real issue with the 700R4/4L60/4L60E is that these are a small transmission. Not in the sense of outer dimensions, but as in the size and strength of the components such as clutch size, shaft size and such.

The input shaft is pressed into the aluminum clutch drum splines and can wobble out the splines and rip them out.

The sprags/roller locks are small and do break

The clutch packs are small with too few discs/steels even on the V8 versions.

The input shaft on the early boxes (before about 86-87) were smaller and with all the holes drilled in them made a termite nest look solid :eek:

The later units had two valve bodies, sadly the aluminum VB is a source of issues.

Keeping the oil very clean on one of these boxes is a MUST DO thing.

Auto trannies are always (YES ALWAYS) chewing up and making small amounts of metal particles. (They all do it)

This stuff comes from the converter and other wear points. When this stuff gets into an aluminum VB it can and does cause the steel hydraulic valves to stick and or score the aluminum bores.

What follows this is a constant source of trouble with missed shifts and other wierd crap.

The best prevention is to install a spin on oil filter (just like on your engine) in the return line from the cooler.

This will catch most all of the nasty crap thats being fed back to the tranny.

Hot oil from the converter first goes to the cooler, then back to the VB or is used as the lube oil supply then to the sump.

If you clean it first, life is "More Gooder" (Big grin)
Change the add on filter evry time you change the engine oil filter and add the needed oil to the box.

The older Boxes like the TH 400 had a cast iron VB and could handle pretty much anything you fed them.

Most all of the issues with the 700R/4L boxes is due to cost cutting by the manufacture. (Read this as CEEEEEEZZZZZZY)

These trannies have seen more service bulletins than you can shake a stick at.

Back in the late 80's early 90's a local shop I used to buy parts from had one shelf about 8 feet long lined end to end with service materials on the 700R. :eek:

When they are working right, they are OK, but even under the best conditions, they are what I call "A Busy Box" as they are almost always doing something.

The 4L60E is far better, in that the shifts are handled by the ECM as is the throttle pressure and other functions.

The oil pump went through a number of upgrades over the years too.

Several changes to the number of vanes in the rotor and other imporvements.

The Sunshell used to be a contant source of trouble as it would break at the splined hub (game over)

An aftermarket unit called the "BEAST" came along (game fixed)

Another good addition was an after market idea of adding a hardened steel sleave over the inside of the splined hub in the clutch drum.

This little goody stopped the aluminum hub from expanding due to stress on the splines from engine torque.

Another area was the planetary assemblies, JUNK the aftermarket came to the rescue again with some good parts.

Thrust washers were plastic and the aftermarket provides some good stuff.
Sprags and roller locks with more elements again to the rescue.

Reprograming kits from "Transgo" fixed the throttle pressure issues that plagued these trannies from the gitgo.

A change to the 2-4 band with some kevlar and a modified servo helped to keep the second and fourth band hanging in there.

The throttle pressure cable adjustment on the NON electronic boxes is an "absolutely mut be "right" thing.

Get the throttle pressure set wrong and the box will go away in a matter of a very very short time.

Push the adjustment button, slide the adjuster all the way toward the firewall then press the throttle to the mat and press it fairly firm.\\\

This sets the system.

The test is to run the vehicle on a flat level surface at a very light throttle, as soon as the 1-2 shift happens, Mat the throttle, the tranny should drop back to 1st. If it does, Job is right, if not, throttle pressure is not right.

The cable is not a "Kick down" but instead controls the oil presssure that applies clutches/band and such

When the rig is driven easy (light foot) the pressure required to apply and hold clutches is far less than when there is a lot of power placed on the system.

The wrong TV (throttle pressure) and the clutches FRY and in a hurry.

One thing thats been said over the years, is that the diesels will eat a 700R/4L60

Well what really happens (in most cases) is that the little diesels thrash the converter, then the resultant abundant supply of metal junk goes through the box and finishes the job.

The first failure is that the converter clutch goes away.
The clutch is a simple device that looks like a shallow (very) Pan that is splined to the input shaft and sits just behind the front cover of the converter (where you bolt it to the engine)

This clutch (pan) fits in very close proximity to the converter outer shell (seals the oil) and has two "Little" rings of paper clutch lining, one near the outer edge and one near the shaft.

When oil is diirected behind the clutch (pan) this forces the device to go forward and the lining then grabs the converter cover and locks the shaft to the engine in a solid fashion.

Now all this theory out of the way, the clutch lining goes away, then the clutch (pan) is free to spin and grind away on the inside of the converter housing, chewing up copious amounts of metal and sending it through the hyadraulic system.

Remember that aluminum Valve body we spoke of earlier, Yup its TOAST.


Yessssss all about the 700R4 and its bretheren.

Now another thing, the 700R and family have a very small converter (inside size) and due to the clutch, the Turbine, pump and stator are all smaller than would be nice.

This results in the converter making a BUTTLOAD of heat due to hydraulic slip.

Pulling a rig hard at highway speed without the converter locked can really heat these guys up.

The 30K cooler you spoke of is GREAT.

The only other thing you need is a Transgo "Dash TWO" shift kit.

Install the entire kit and set all the choices on KILL. (firmest shift)

The little beast will shift like a ton of bricks, but it will live.

If your like me and have store bought teeth, keep your mouth shut during the 1-2 shift under a heavy foot, or you will be looking for the choppers.:D

The 700R/4L60/4L60E can be upgraded into a fairly good "Little" tranny.

It just takes $$$$$$$$$$$$$$$$$$$$$$$$

About $2K will usually build you a pretty good gear box.

Doing all the benchwork and R&R myself, the last one I did cost me about $1000 for the goodies.

Have fun

Missy

[phantom309]

personally wouldn't waste my time on a 700r4 with that much torque needed behind it ,.i,d look around for the tps controlled wee computer from 93 6.5's with their mechanical pumps, (school buses naturally aspirated etc,.) and run a 4l80e
with aswitch for manual lockup,.
and if you really are in direct 95% of the time,. i would just stick with a t400,.
around town mileage difference between locked and unlocked will be minimal.
JMHO,..
Nick

[wdkingery]

personally wouldn't waste my time on a 700r4 with that much torque needed behind it ,.i,d look around for the tps controlled wee computer from 93 6.5's with their mechanical pumps, (school buses naturally aspirated etc,.) and run a 4l80e
with aswitch for manual lockup,.
and if you really are in direct 95% of the time,. i would just stick with a t400,.
around town mileage difference between locked and unlocked will be minimal.
JMHO,..
Nick

i would appreciate more info on that, as i have a 700r4 that is burnt, and i might can get a 1993 short bus with a n/a 6.2 in it.. so i would be converting from 600 to 4l60/80e whichever it is.

[illfarmboy]

I have a '91 'burb, 6.2L, 4WD with the 700R4. Trans was recently rebuilt and I am not happy with the firmness and consistency of the 2-3 & 3-4 shifts. Also reverse seems to take a couple seconds to "catch" and will clunk if I rush it along. I am wondering if the advice Robyn offered would help these issues-
"The 30K cooler you spoke of is GREAT.

The only other thing you need is a Transgo "Dash TWO" shift kit.

Install the entire kit and set all the choices on KILL. (firmest shift)

The little beast will shift like a ton of bricks, but it will live.

If your like me and have store bought teeth, keep your mouth shut during the 1-2 shift under a heavy foot, or you will be looking for the choppers.

The 700R/4L60/4L60E can be upgraded into a fairly good "Little" tranny."

Thanks for any feed back.

[Robyn]

The key to getting a favorable result is the overall health of the tranny to begin with.

If the tranny has issues with bady worn clutches and seals, that have hardened up to the point where they are not holding pressure well, then the addition of the kit will likely not fix it.

Pull the pan and carefully dump the oil.

Look over whats in the bottom of the pan, and if its relatively clean the kit will certainly help.

A thin layer of what looks like soot in the bottom is pretty normal, but if you find clumps of black flakey stuff and or metal particles, then the box needs to come apart and be freshened, and then add the kit.

The slow reverse, is this all the time or just when cold after sitting all night ????

Slow reverse after an all night sit is probably do to converter drain back and not serious.
If reverse is slow all the time, its likely an issue with the servo seals in the reverse input clutch.

The 2-3 shift is achieved by releasing the 2-4 band and applying the 3-4 clutch and in stock trim are notoriously soft.

The 3-4 shift is achieved by applying the 2-4 band while the 3-4 clutch is applied and again, this shift is a soft one in stock trim.

The 2-4 band is a weak link in these trannies, as are the 3-4 clutch pack.

The 2-4 servo (located on the RH side of the tranny behinf the round cover) has issues and needs to be upgraded to allow higher holding power on the band.

There is a valve upgrade thats also needed too, and the kit speaks of the choices available. I always use the valve that will allow for the firmest shift.

The bottom line is, the 700R4 is a small box (internal parts like clutches) and when these start to fail, the only fix is a rebuild.

Good luck

Missy

[illfarmboy]

THANK YOU! I appreciate the guidance, I called the company tech line and was directed to the SK700 jr kit along with a .471 TV boost valve, a intermediate & reverse boost valve and vb gasket, aux vb gasket, red & blue servo "O" rings.

Also would it be worth while to replace the stock servo with Corvette servo?

Any thoughts on the difference between the SK700 jr and the DASH TWO kit?

Also what would be a source for the VB gaskets? I called a GM dealer parts counter and they say the gaskets are discontinued.
Appreciate your replies and sharing your knowledge.

[93chevrolet6.2]

I have a 1993 chevy 6.2 with what I was told by the trans shop owner is a 4L60e. As of the last couple of weeks it has been shifting odd or kinda bogging down. Feels like the TC is locking up too soon and wanting to shift wayyy tooo early. I was told that is was most likely dust and to decide how much i wanted to spend to get it up and running again. I also have a 1985 with a 6.2 and most likely a 700 i think. It is only a 3spd with no OD. I really dont want to switch out to that trans if i dont have to. Made my 85 hard on fuel. I am not pulling or hauling heavy loads with the 93 so not sure what to do. Is there any sort of tests to ensure it is in fact the trans? I heard before of a ice test where a person puts a bag of ice on the IP and see if that is not the problem. The truck seems to run fine and shift good when cold like the first run of tge day but after the truck warms up some and the heat gauge rises it starts bucking and bogging? Could this be an IP issue when it heats up it dosent run properlybor was the tranny shop guy right after all??? Please help as this is my only transportation. Thanks

[DmaxMaverick]

Welcome aboard!

I think you need to get a 3rd opinion about your tranny (you're about to get the 2nd).
The "E" part of the 4LX0E is "electronic". Meaning, it's electronically controlled. It doesn't shift, or lock/unlock the TC without electronic intervention. Temperature sensors can affect how the computer "thinks" it should shift, so if there are problems with temperature sensing, you'll likely see issues with tranny operation. When cold (or perceived cold), the transmission will operated on a "default" program designed to simply operate, and will become more adaptive to the environment as the temps increase.

There are a couple tranny options for your 1993. If it's a 1/2 ton, non turbo, it's likely a 4L60E. If it has a factory turbo, it will be a 4L80E. The problem you are diagnosing will be similar for either.

The "chilling" of the injection pump will only help diagnose an IP that may be mechanically worn to the point it may need overhaul. This won't help diagnose a tranny issue. Just cool water works better than "a bag of ice", in case it comes to that. Store that idea for later reference.

The tranny in your '85 is, in all likelihood, a TH400. 3 forward speeds, no TC lockup. If the truck is a 3/4 ton or better, it's a safe bet. If it's a 1/2 ton, either the (700R4) is broken, or it's been replaced with a non-OEM tranny.