Lock up options

[raunch]

I know from all the information available here that there are several ways a 700r4 can be wired. What I haven't come across yet is anything about 2nd gear lock up. Reason I am wondering about it is that any direction I go from my place, there is a mountain pass along the way. If I am pulling my tent trailer (2500 lbs) I am often in 2nd gear before the climb is finished. As I understand it, lock up is critical for lubrication. So wouldn't I want a 2nd gear lock when the transmission is working hard?

Another option I want to learn more about the hydraulic lock up kit from Transgo. From the sticky it sounds like a reasonable option, as I want the least amount of electronics possible, but only if the hydraulic is more reliable and durable. Any experience with this option anybody?
Thanks.

[Edahall]

I also have an 82 Suburban that was upgraded with a transmission out of an 89. I am able to manually lock the torque converter with a switch in all gears except 1st. It enables all the power to get to the ground rather than be soaked up in the torque converter. With 3.08 gears, I shift into 2nd gear at speeds of 45 mph. Before the 89 transmission was installed, it had the original transmission that had a hydraulic lock up on it. I absolutely hated it because I had no control over the lock up. It would usually lock up at the wrong time causing the engine to lug.

[6.5TDTahoe]

Very early MPH lockup in 2nd gear was utilized in the very early 6.2 DSL /2wd 700-R4 trans. It was for city driving fuel economy & drivability. 15 MPH 2nd gear lock up.Other 1/2 shift calibration of 20/21 mph knocked off about 2/3mpg in city driving. IMO you folks need to concentrate the best bullet proof Reman torque converters available.Waiting for lockup till 40/50 MPH in third or over overdrive cost big time in MPG. The 700 is a very wide ratio trans(3.06 first & 1.68 second gear ratio is to get the truck moving with a light throttle during acceleration. I was a trans shop owner starting in the 70s & buying my first 6.2 in late 1981. Then became an ATS Turbo distributer/installer. Really enjoyed the challenge of the new to me, technolgies.

[Robyn]

I have been into many 700R4 trannies.
These "little" boxes are not bad if you throw enough money at them.

The converter clutch in these things are failry small simply because of the space available inside the converter.

Using second gear lockup is a BAD Plan as is low speed third lockup and "CHugging" around town.

The Lockup clutch was realy never meant to handle "PULLING" torque.
The clutch was designed to handle cruiseing power only to facilitate good highway mileage.

Set the lockup to come in at around 40-45 MPH in 4th gear only and the thing will live.

Now if you want to spend some serious $$$$$ on a custom built converter the scene can change greatly.

A well setup 700R can cost you a couple grand to build if you do all the bench work yourself.

There really is no halfway mark with a 700 if you want it to live and handle any power.

The bottom line is that the parts are way too small for what it is being asked to do. (stock form)

If the clutch packs are upgraded to a better quality and the 3-4 clutch pack is increased in the number of frictions and steels.

The 2-4 band upgraded, sunshell replaced with an improved design (Beast)
Low roller lock and the front sprag upgraded.
Input drum upgraded with the hardened ring around the shaft spline area.

2-4 servo upgraded
Front pump upgraded to 13 vane unit
Top notch shift kit installed

This along with a normal selection of bushings, thrust washers and such and the 700 is good to go.

The early 700's in trucks 81 or so had a small input shaft and they would break. (they are like swiss cheese with many passages and holes)

The best 700 to start with is the K case units of late 80's

These had a large K on the bell housing

The 87 trans is likely the best choice as it has all the valve spools so you can use a hydraulic lockup control kit.

This kit allows the tranny to run completely on its own without any electrical connections, adjustable shift points on the lockup are done by a selection of springs that come with the kit.


The 700 is not the best choice for a rig thats going to do much pulling.

The 700 can be outfitted to handle some serious chores but be prepared to spend some serious cash $$$


Missy

[raunch]

Well, here's another opinion to add to the mix.... I talked to the builder at another tranny shop and he recommended a non-locking converter, which they can build in-house, and beef it up some. He would make neccesary changes to pump to go along with no-lock converter.

Seems to me that so long as transmission will stay cool, that a no-lock conversion eliminates one more element that can go bad. Fuel milage may not be as good, but it would be better than what I am getting right know (15mpg avg) and I can drive a little faster at a lower rpm, thus improving overall drivability.

Just to reiterate my driving needs, I pull a 2500lb tent trailer or a 700lb snowmobile trailer. So long as the temps stay safe, and the tranny seems happy, I hope to pull the snowmobile trailer in OD cruising on the flats. Most of the miles I put on are pulling one of these two trailers. That being said I am about 20% unsure of the swap I am planning. But there is only 11,000 on the rebuild the 700r4(with some upgrades) and with parting out the donor rig, the swap will cost me very little. So unless, there is a bunch of metal on the magnet in the pan, I think I will move foward with the swap. I know the history of the transmission; it came from a friend and I know he never towed anything or has abused the transmission in any way.

For the swap I plan on adding a trans. temp gauge and hopefully an auxillary cooler.

[Robyn]

OH yesss

The practice of using a non lockup on the 700 is not bad.

The converter on the 700 is small inside anyway and when you add the clutch it takes away even more room for other needed parts (size)

As long as the cooler is sized to handle the extra heat of running OD without lockup your set.

The lockup is what really gives the 700 the edge on mileage, but there is a tradeoff.

Choices choices.

Those folks are giving you the straight stuff for sure.

You may want to ask if you can get a lockup converter with a heavier duty clutch (Kevlar or multiple disc type) Once you see what the lockup clutch on the 700 looks like you wil just walk away wondering how it ever works (stock stuff)


Missy

[raunch]

Funny you say that, because after I pulled the 700 from the donor rig, I was wondering how the [I]whole thing[I] would work. It looks awfully small, and then to imagine how small the parts inside it are and that all those little componets wll move a 6000lb rig? Pretty amazing really.

I'd like to say thanks to all for the great info. There is more to know and learn for sure, but this has made the process a little easier and much more smooth.

[Robyn]

You are very welcome.


Missy