HRPC come in.

[1low4x4]

I need reassurance that im about to make the right choice.

As you know I have a th400 in the C20. I want to make it more of a.daily driver and to do that I need to get the gas mileage up.

I have dropped off a 700r4 (early model judging by the pressure ports and lack of later markings shown in your sticky) at the best trans shop in town. The guy says ill need a new torque convertor and the lockup wiring kit, and hell go thru it and see what all needs to be done and call me. I am expecting to be told that it needs rebuilt and am planning on spending around $1500 but not sure.

Ive also read that a manual is better for heavy haul apps but I will be pulling just a light pontoon and maybe a lowboy. I can pull in third I suppose.

Question 1. I have read that 4.10s like I have will be good for the 700r4 and not strain it too much. Is this correct?

2. Im running like 3300-3500 rpms now at 70 mph, what can I expect with 4.10s and the 700r4? Will mileage improve enough for me to see a good return on gas money?

3. What are the weak links in this trans? When he calls and says he wants to rebuild it, should I ask for special parts? What about the converter? Stock or special?

Thanks for your help if you can answer any of this

 

[X-cabsquarebody]

I personally would not tow any thing with a 700r4. A 4l80e would be much better.

Over drive is worth the time and money, not only for fuel mileage, but saves wear and tear on the motor too.

Trans rebuild around here, with a converter is around $700 for over drive trans.

 

[bucket]

Rebuilding a 700r4 is a giant waste of money if you aren't having all the good parts put in it. Might as well just keep the money and buy gas.

I do light towing with a 700r4 (usually not over 5K, including trailer) and it's not ideal but it works. Run a big cooler and a trans temp gauge! My issue is gearing, but if I had proper gears for the application it would work better. I had it rebuilt with all kinds of improved parts in it, about the most you can do for a non-racing type application. I have 50-60K on it now and I expect it's nearing the end of it's life. It still works fine, but it's a half ton trans that has seen a lot of use hauling around a 3/4 ton Burb.

 

[1low4x4]

Well I have a trucool 40k cooler on now and I gave the guy my transmission gauge I want hooked up so I can rewd temps.

 

[Jims86]

OOOffff, especially with that early model 700! I would stick with the TH400 and change the rear gears to 3.73, or even closer to the overdrive RPMs would be 3.42....you may sacrafice some take off power though.

 

[1low4x4]

If a 700r4 is so weak why are they so popular? Everyone always said the same about a 4l60e but I never could break mine

 

[Jims86]

I have only heard very little about it, But I think there is a kit that allows you to put 4l65 internals in a 700r4...a 5 gear plantetary, with a beast sunshell. HR could elaborate more. I know the GM made planetary is the only one to go with, there are cheap chinese knockoffs on the market.

 

[bucket]

I have only heard very little about it, But I think there is a kit that allows you to put 4l65 internals in a 700r4...a 5 gear plantetary, with a beast sunshell. HR could elaborate more. I know the GM made planetary is the only one to go with, there are cheap chinese knockoffs on the market.

The beast sunshell and 5 gear planetary goes right in a 700r4 without a kit.

 

[bucket]

If a 700r4 is so weak why are they so popular? Everyone always said the same about a 4l60e but I never could break mine

Where are they popular? I hardly ever talk to anybody that actually likes them.

 

[Jims86]

The beast sunshell and 5 gear planetary goes right in a 700r4 without a kit.

Those are just parts in the kit that i am trying to remember...I could only remember those particular items standing out.

 

[MrMarty51]

I had My 700R4 crap on Me at Fernley Nevada.It was`nt because I pulled the guts out of it dragging a 22 foor class A motorhome across the eastern half of Montana and well into South Dakota or anything,well,maby that might have had "something" todo wit it.
I had that transmission rebuilt in Citrus Heights Cali,that was a hundred and twenty two thousand miles ago.
The shop uprated that transmission with any and all parts availeable at that time.
The problem they found with the transmission was that the previous rebuilder had not rebored the oil vein going to the overdrive sun/planetaire gears.
I since then have done a lot of pulling with this pickup,but,not in overdrive,I have changed the fluid twice,last,about twenty thousand miles ago and the fluid is still real nice.
One thing for sure to do is to have them install a drain plug in the pan so to make chanmging fluid/filter not such a messy job.

 

[HotRodPC]

OK, I found the thread. Sorry for the delay. Yeah, as you're being told, for towing, and being a 3/4 ton truck, scratch the 700r4 Idea. They are OK at best and are so common since they came OEM in the half ton OEM trucks. And notice I said OK, not good or excellent. Not a bad deal. They're not real strong, have issues, which can be worked on, but even at their best, they're not going to be bullet proof and you'd do damn good to get 50,000 miles out of one in that truck towing that light pontoon boat. John boat, yeah maybe, but it's not just the little bit of added weight. It's also the wind drag and the added friction of more wheels and dragging. The 4L80-E is the damn near bullet proof option. It's basically a Th400 with an OD built into it.

What hurts on the 4L80-E, is there is NO Old school model. It's computer controlled like a 4L60-E. Now you can have it built and use it like a Full Manual. Means, it's still an automatic, no clutch, but you will have to shift it 100% of the time. Even down shift it, up shift it and all. If you have it in 4th gear, then it will take off in 4th gear. NO AUTO FUNCTIONS AT ALL. It's basically a manual transmission without a clutch pedal. The stand alone computers to operate one are about $1000-$1500 depending on the unit you get.

 

[HotRodPC]

I had My 700R4 crap on Me at Fernley Nevada.It was`nt because I pulled the guts out of it dragging a 22 foor class A motorhome across the eastern half of Montana and well into South Dakota or anything,well,maby that might have had "something" todo wit it.
I had that transmission rebuilt in Citrus Heights Cali,that was a hundred and twenty two thousand miles ago.
The shop uprated that transmission with any and all parts availeable at that time.
The problem they found with the transmission was that the previous rebuilder had not rebored the oil vein going to the overdrive sun/planetaire gears.
I since then have done a lot of pulling with this pickup,but,not in overdrive,I have changed the fluid twice,last,about twenty thousand miles ago and the fluid is still real nice.
One thing for sure to do is to have them install a drain plug in the pan so to make chanmging fluid/filter not such a messy job.

There are a few good issues like this that I see occasionally, but not many. I do intend to build a 700r4 soon for one of my 4x4 trucks. I'll be putting all the upgradeds I can find in it, but even then I know it's not bulletproof. Small Shafts, and Vane Pumps for one, no matter what upgrades you put in it, those things won't change.

 

[towjoe]

I'd have to agree with jims86 on changing the rearend out to improve milage and engine rpm. A 700 might not be a bad choice if just driving your truck from point A to B. My newest tow vehicle has a 454 with a turbo 400 and 3:73 gears that seem about right. I also have a couple K30's that came that way from factory that work out well, with one towing a 48' trailer hauling 3 cars at a time alot. As stated the trick to any transmission is to not let them build heat.

 

[wildcatjason]

The stand alone computers to operate one are about $1000-$1500 depending on the unit you get.

You can get an optishift controller for the 4l80e for under 600.

http://www.usshift.com/index.shtml