72 K5 Blazer 700r4 upgrade

[bassackwards]

Yes the lock up is for economy, but it will kill the trans if you run it unlocked at lower engine speeds. And @shady if you don't believe me that they won't lock in other gears, come out here and I will show you on 3 different trucks. My '70 and '72 will lock them in 2nd, 3rd and 4th. Because I have them on toggle switches. The 4th gear switch in the transmission is easy to bypass and some already have switches to lock in 3rd, it depends on the year of the valve body. My '90 will lock in 3rd on its own. Both the current trans will do it and the previous one did it before the doubler. The '90 never had a vacuum switch for the lock up because the ECM took care of it. That truck now no longer has the factory ECM because I put the Edelbrock Proflo on. No ECM trans controls.

I question how many 700R4 transmissions have you guys been into or owned?
Have you ever seen one torn down after it got burned up? Were you ever personally involved in building one of these, let alone several? How many miles have you put on a truck with a 700? I know that you don't known my history and what I have done or witnessed, but don't start your post by calling me a liar.
Try going back to the 80's and 90's when these non electronic transmissions came out.

GM designed them to only lock up in 4th gear at light throttle cruising speed and even then the ECM will unlock it with a significant throttle position change. They never lock up in stoplight to stoplight driving unless you have long stretches where you can cruise in overdrive, we don't. We barely get to cruise on the interstate at 3 am.

Yours only lock up because you chose to bypass the engineers who determined when lockup was needed after millions of dollars and thousands of hours invested on R&D. Tow/Haul mode causes the converter to never lock up, even at cruising speed.

 

[6872xtc]

GM designed them to only lock up in 4th gear at light throttle cruising speed and even then the ECM will unlock it with a significant throttle position change. They never lock up in stoplight to stoplight driving unless you have long stretches where you can cruise in overdrive, we don't. We barely get to cruise on the interstate at 3 am.

Yours only lock up because you chose to bypass the engineers who determined when lockup was needed after millions of dollars and thousands of hours invested on R&D. Tow/Haul mode causes the converter to never lock up, even at cruising speed.

Where is the tow haul button on a 700R4? Show me one.
Not all years of these transmissions had the identical wiring and switches.
Yes, I know that the ECM will unlock it with throttle input. It reads the TPS and MAP sensor. I have experienced this.
I have plenty of areas where the converter lock between stop lights. Stoplights out west aren't 150 yards apart. You have to pay attention to catch it.
You haven't told me, have you torn down a 1990 700R4 in the year 1995? It wasn't modified.. I was in a Chevy dealer with my buddy helping him do just that.

 

[imiceman44]

I don't know when the change happened if it was the second generation 89 and up or the 4l60e, but I remember the lockup working on 3rd and 4th.
I know my 97 s15 Jimmy does.
My Honda does it on 2nd 3rd and 4th

 

[bassackwards]

Where is the tow haul button on a 700R4? Show me one.
Not all years of these transmissions had the identical wiring and switches.
Yes, I know that the ECM will unlock it with throttle input. It reads the TPS and MAP sensor. I have experienced this.
I have plenty of areas where the converter lock between stop lights. Stoplights out west aren't 150 yards apart. You have to pay attention to catch it.
You haven't told me, have you torn down a 1990 700R4 in the year 1995? It wasn't modified.. I was in a Chevy dealer with my buddy helping him do just that.

Interesting, GM renamed the 700R4 to 4L60 in 1990.

The 4l60E is basically the same trans with upgraded electronics and yes they have a tow/haul mode and use the exact same torque converter, rebuild kit, even fluid, filter, gaskets.

Not sure what you are trying to prove, the high paid engineers decided that lock up is not needed under all situations except gentle cruising, even then just in order to boost federally mandated fuel economy standards.

You can even purchase a non lockup converter for a 700r4 now

 

[bassackwards]

I don't know when the change happened if it was the second generation 89 and up or the 4l60e, but I remember the lockup working on 3rd and 4th.
I know my 97 s15 Jimmy does.
My Honda does it on 2nd 3rd and 4th

It is now easy to control with the PCM and everything being electronic so that allows more flexibility with engineering

 

[6872xtc]

Interesting, GM renamed the 700R4 to 4L60 in 1990.

The 4l60E is basically the same trans with upgraded electronics and yes they have a tow/haul mode and use the exact same torque converter, rebuild kit, even fluid, filter, gaskets.

Not sure what you are trying to prove, the high paid engineers decided that lock up is not needed under all situations except gentle cruising, even then just in order to boost federally mandated fuel economy standards.

You can even purchase a non lockup converter for a 700r4 now

What changed in the transmission in 1990 with the name change? The addition of the "E" as in 4L60E, showed when it went to electronic control. These have a completely electronic control of the valve body. They will not interchange with the 700R4 or the 4L60. The name change to 4L60 was also to help combat the bad reputation of the 700R4 from the early 80's models which were the reason that the aftermarket came out with retrofit kits to go back to a TH350. So what 700R4 or 4L60 has a tow/haul button? That makes it an electronic transmission.
And under low engine load is when you aren't on the throttle very much, so this is when it is possible to be below the stall speed of the converter. When did I ever say that they would lock the converter under heavy throttle and normal transmission operation? ( normal oil temperatures)
The whole purpose to this thread was putting a NON-ELECTRONIC 700R4 into a non-stock application. If he was interested in electronic, he would have asked more about the LS3/4L80E combo that he mentioned.

I don't believe that I posted that running without a converter locked up will kill the transmission as fast as not having the TV cable properly adjusted, it just can shorten trans life a fair amount.
And the non lock up converter that the aftermarket makes is for a modified application, correct?

 

[6872xtc]

@PompUOP I am sorry that we may have derailed your thread.
I was trying to give you the best input that I have from installing a non-electronic overdrive transmission into your '72. And tell you what I know about helping the durability of the end result.
But I am going to be interested in how you proceed, and if you try a lower stall speed converter in the 350 trans. or go with a swap.

 

[bassackwards]

What changed in the transmission in 1990 with the name change? The addition of the "E" as in 4L60E, showed when it went to electronic control. These have a completely electronic control of the valve body. They will not interchange with the 700R4 or the 4L60. The name change to 4L60 was also to help combat the bad reputation of the 700R4 from the early 80's models which were the reason that the aftermarket came out with retrofit kits to go back to a TH350. So what 700R4 or 4L60 has a tow/haul button? That makes it an electronic transmission.
And under low engine load is when you aren't on the throttle very much, so this is when it is possible to be below the stall speed of the converter. When did I ever say that they would lock the converter under heavy throttle and normal transmission operation? ( normal oil temperatures)
The whole purpose to this thread was putting a NON-ELECTRONIC 700R4 into a non-stock application. If he was interested in electronic, he would have asked more about the LS3/4L80E combo that he mentioned.

I don't believe that I posted that running without a converter locked up will kill the transmission as fast as not having the TV cable properly adjusted, it just can shorten trans life a fair amount.
And the non lock up converter that the aftermarket makes is for a modified application, correct?

You posted that it will "kill it". Your exact words were "kill it", and that is not true

OP, yes you can run it without a functioning tcc for a very long time

 

[6872xtc]

You posted that it will "kill it". Your exact words were "kill it", and that is not true

OP, yes you can run it without a functioning tcc for a very long time

In the long run, yes it will. I believe that you can easily find out what excess heat will do to an automatic transmission. It all depends on the overall installation and operating conditions as to how much heat is generated. If you always miss the conditions which would have the converter below stall speed and unlocked, then it won't be a problem. Without knowing his driving habits, terrain and the other factors in the drivetrain of the truck, the safer way is to warn of conditions which can generate more heat and eventually lead to transmission failure. (dead transmission)

 

[TuckerK5]

All of you guys are way more knowledgeable than me so I have nothing to offer on this transmission debate.

I think that if it were my truck I’d be thinking less stall converter and possibly a gearing change.

By the sound of that engine / camshaft it might need to turn 2000 or so to keep from lugging at highway speed.

My truck turned 1500 at 60 with 3.73 on 33 with OD. Changed the gearing to 4.56 and now it turns 2000@60. It doesn’t lug now and the fuel economy almost doubled. All of my driving is small two lane roads cruising 60 or less.

 

[Blue85]

A high stall and no lock-up is a recipe for overheating the trans. Sure a stock rig can run in 3rd on the street without L/U, but big cam and big stall implies it will rev and slip speed x torque =heat. The 700 doesn't flow much oil to the cooler in 4th gear.

 

[tenderfoot]

Dats a hell of a nice rig.

 

[6.2Blazer]

The 350 was bored .30 over to my knowledge, but I have no idea how much more power that provides.

Kinda' of off topic but just have to comment on the above because most people don't understand this. First of all it is bore 0.030" which is a huge difference from 0.300"! Pretty sure if you tried to bore a 350 over by 0.300" you would be into the water jackets. Second, you bore an engine 0.030" over during a rebuild to clean up the cylinders.......nothing more, nothing less. All other things equal you do not get any real power by boring the cylinders out this much. You are talking the difference between 350 and 355 cubic inches, or 1.4%. If you started with a healthy 300 HP engine you would jump up to a whopping 304 HP after boring the cylinders. That's a lot of time and expense (tearing down the engine, taking it to a machine shop for boring, buying new pistons, reassembly) for 4 HP.

 

[imiceman44]

Kinda' of off topic but just have to comment on the above because most people don't understand this. First of all it is bore 0.030" which is a huge difference from 0.300"! Pretty sure if you tried to bore a 350 over by 0.300" you would be into the water jackets. Second, you bore an engine 0.030" over during a rebuild to clean up the cylinders.......nothing more, nothing less. All other things equal you do not get any real power by boring the cylinders out this much. You are talking the difference between 350 and 355 cubic inches, or 1.4%. If you started with a healthy 300 HP engine you would jump up to a whopping 304 HP after boring the cylinders. That's a lot of time and expense (tearing down the engine, taking it to a machine shop for boring, buying new pistons, reassembly) for 4 HP.

Yeah I usually say 30 over and that's 30 thousandths off which is the way I learned to say it 30 thousandths =0.030"

 

[TuckerK5]

It’s the np205. I figured there would be more to the upgrade, however I know it has been done on a handful of Blazers I’ve seen for sale. I’ve read some posts about getting the TV cable adjustment correct and risk of burning up the transmission. I’d like to get educated on the whole project so I don’t have any surprises. I’ll search the forums, too.

Right now, the TH350 in it has a 3200 stall convertor which I do not care for. Backing it into my storage with a 2” lip to the floor has me gunning it... imagine that!

Going back to this, I think you need to evaluate what your current RPM's are at the cruising speed you will be driving the most and decide where you want to get to. I assume your reason for wanting the OD transmission is to lower your RPMs at cruising speed? A torque converter change might be all you need if it is currently stalling at cruising speed.

After going back and looking at your video it looks like you could get by with a lot less stall converter.

What are the gears and tire size?

 

[6.2Blazer]

Going back to the topic of the lock up torque converter function and burning up the 700r4, from my experience it seems related. Between my dad and myself we have literally put almost a million miles on 700r4/4L60/4L60E transmissions in many different vehicles ranging from 2.8L V-6 S-10's to diesel powered K5's. My dad averaged 70k miles a year on his work vehicle and usually kept it around 2 years. He had about every combination of Chevy truck or SUV out there over the years. Every vehicle either of us had was over 100k miles. We've only ever had two transmissions fail. One was run low on fluid because it had a leak, and the second was found to have damaged TCC lock up wiring harness. The one with the damaged TCC lock up wiring failed at about 40,000 miles and obviously got extremely hot. It was replaced with a GM reman trans, and was running fine when we got rid of it with somewhere around 150k on the clock.

 

[Blue85]

I tested it with a 2000RPM stall converter and large tube/fin cooler, with the temp gauge on the transmission outlet line. 70MPH on the freeway with TCC unlocked the temperatures climbed quickly beyond what I was comfortable with. TCC locked, temp would stay at 120 degrees. In 3rd gear, unlocked would warm the tranny, but everything was reasonable. I want to say this was with 4.10 gears and 35" tires, but don't remember for sure. Granted, most temp gauges measure the pan, but why would you want to require massive cooling to get rid of heat that you don't have to make? Just more lost fuel. While you could probably get away with an unlocked stock (or diesel) converter, a 3000RPM stall unlocked could cook the transmission on the first outing.

It's a common perception that constant shifting overheats a trans. Sure it puts more wear on the clutches and some extra heat, but that slip is less than 1 second. The majority of the heat from an automatic transmission is from the (unlocked) torque converter. When you're running loads that keep it near the shift point, you're also at loads that tend to unlock the TCC.

 

[imiceman44]

I tested it with a 2000RPM stall converter and large tube/fin cooler, with the temp gauge on the transmission outlet line. 70MPH on the freeway with TCC unlocked the temperatures climbed quickly beyond what I was comfortable with. TCC locked, temp would stay at 120 degrees. In 3rd gear, unlocked would warm the tranny, but everything was reasonable. I want to say this was with 4.10 gears and 35" tires, but don't remember for sure. Granted, most temp gauges measure the pan, but why would you want to require massive cooling to get rid of heat that you don't have to make? Just more lost fuel. While you could probably get away with an unlocked stock (or diesel) converter, a 3000RPM stall unlocked could cook the transmission on the first outing.

It's a common perception that constant shifting overheats a trans. Sure it puts more wear on the clutches and some extra heat, but that slip is less than 1 second. The majority of the heat from an automatic transmission is from the (unlocked) torque converter. When you're running loads that keep it near the shift point, you're also at loads that tend to unlock the TCC.

One reason for me wanting a different option to control my 4l80e I am putting in the suburban is the lockup control.
It comes with a 454 tbi and full harness and ecm so it should be fine stock configuration, but I believe I could get better performance if I tailor it to my driving style, I just can't justify paying more than what I paid for it to get the fancy ones.
TC lockup is the most important thing that should have been from the beginning of automatic transmission history and it finally is here and I don't see why anyone would not want or care for it.

 

[Blue85]

TC lockup is the most important thing that should have been from the beginning of automatic transmission history and it finally is here and I don't see why anyone would not want or care for it.

Automatic ~1940, torque converter ~1950, lockup ~1980, so we've had lockup about as long now as we didn't.

 

[imiceman44]

Automatic ~1940, torque converter ~1950, lockup ~1980, so we've had lockup about as long now as we didn't.