whats the difference?

[dga93]

what is the difference between...?
700r4
t350
t400

[78 Chevyrado]

th350 is the light duty 3 speed automatic
th400 is the heavy duty 3 speed automatic
th700r4 is the light duty 4 speed Overdrive automatic

[badblu97]

but doesnt the turbo 400 have overdrive?

[rockn30809]

Originally Posted by badblu97

but doesnt the turbo 400 have overdrive?

Turbo 400 is 3spd, no overdrive.

[SBTork]

Originally Posted by badblu97

but doesnt the turbo 400 have overdrive?

in the later years gm made a 4L80, basically a TH400 with overdrive.

[heavychevy79]

At the risk of starting a transmission debate, I will say you should avoid the "heavy duty" TH400, and run away
(like a little girl from a frog weilding boy) from the overdrive 700-R4 because in original condition (not rebuilt w/heavy duty parts) they are both flawed and not very dependable. That's my past exp with them anyway.

[dga93]

Is the 700R4 better if rebuilt? and about how much you think is it to rebuild?
And is it better on gas because it has more gears?

[LONGHAIR]

There are some variations in gear ratios even in the 3 speeds, but they are minimal. The TH400 takes a little more power to operate, so it is not the best choice for a lower powered engine, but I have never heard of anyone having reliability issues with them.
There are more choices in the Over-Drive automatics though.
4L60-E and the heavier duty 4L60-E HD have the lower first gears like the 700-r4. The 4L80-E has a higher first gear, more like the 3 speeds.

Is the 700R4 better if rebuilt? and about how much you think is it to rebuild?
And is it better on gas because it has more gears?

Yes, as long as it is being done with the intent of improvment. A completely stock rebuild won't really gain you much.
Cost is very relative. It depends upon your area.
Yes, as long as you are geared correctly for the tire size you have, (and your intended road speed) the overdrive should gain you a noticable amount of mileage increase.

[powerdriver 1958]

The only thing that i have heard about 400s that is the least bit bad has been some of the 4X4 guys knocking reverse out of them.And the two complaints came from from trucks that had (38s on one and 39.5s on the other)

[dga93]

I live on a hill and i drive up the Appalachian Mountains everyday. All i want is a transmission that i know will last and not die on the mountains.


I'm still learning about cars. So i don't know much.

[factory2wdblazer's]

i love the 700r4.. i have a 90 700r4 in my blazer best automatic transmission avialible i think. over-drive transmission with the lock up converter, only up grade the transmission has is a corvette servo, the transmission shift's perfect. i beleave the 700r4 is way better then the turbo 350 & turbo 400..........just my 2 cent's..........700r4's/4l60's do not suck, take the time to hook them up right and they will treat you right.......stock build or not.......

[Manbearpig]

TH350 ratio's:
1st: 2.52 |2nd: 1.52 |3rd: 1.00 |R: 1.93

TH400 ratio's:
1st: 2.48 |2nd: 1.48 |3rd: 1.00 |R: 2.00

700r4 ratio's:
1st: 3.06 |2nd: 1.62 |3rd: 1.00 |4th: 0.70 |R: 2.29

[Manbearpig]

Originally Posted by factory2wdblazer's

i love the 700r4.. i have a 90 700r4 in my blazer best automatic transmission avialible i think. over-drive transmission with the lock up converter, only up grade the transmission has is a corvette servo, the transmission shift's perfect. i beleave the 700r4 is way better then the turbo 350 & turbo 400..........just my 2 cent's..........700r4's/4l60's do not suck, take the time to hook them up right and they will treat you right.......stock build or not.......

That was funny.

[heavychevy79]

Hey wtf is that thing? I can't even see what it is, maybe NASA has a screen big enough to see that but I sure don't.

[trenchwarfare]

Originally Posted by heavychevy79

Hey wtf is that thing? I can't even see what it is, maybe NASA has a screen big enough to see that but I sure don't.

It actually pissed me off. Why? I don't know.

[heavychevy79]

Originally Posted by trenchwarfare

It actually pissed me off. Why? I don't know.

What did? huh? Oh yeah the big thing...

[Manbearpig]

I would change it to a smaller one but I can't edit it.

[heavychevy79]

Originally Posted by Manbearpig

I would change it to a smaller one but I can't edit it.

That thing is gonna give someone a seizure and n2trux is gonna be pissed.

[LONGHAIR]

Resized that huge thing into something much more "friendly". THat is 10% of the original size.....LOL

[78 Chevyrado]

Basically as far as reliability goes IMO none of the automatics are strong enough for me. I've broken them all in stock form..... with stock power engines.... I will say though for me the th400 lasted way longer than the others before needing work. They all do better after a quality rebuild and whatever updates/improvements have come out since it was last rebuilt. Think Upgrades....

[Captkaos]

When the 700R4's first came out in these truck 27 years ago 1982, they did have issues. In 6 years (1987/88) all those that had issues were upgraded. If you have a 1982-1986 truck with an original 700R4 transmission that is still alive you aren't going to have any problems with it as it has probably been replaced already.

You can build one to handle a LOT of power, but if you start with a 1988 trans it already has all the good upgrades in them. Keep in mind most of the hard parts from a current 4L60E will go in a 700R4 (4L60) as they are the same transmission just one has a electronic valve body.

[heavychevy79]

Originally Posted by Captkaos

When the 700R4's first came out in these truck 27 years ago 1982, they did have issues. In 6 years (1987/88) all those that had issues were upgraded. If you have a 1982-1986 truck with an original 700R4 transmission that is still alive you aren't going to have any problems with it as it has probably been replaced already.

You can build one to handle a LOT of power, but if you start with a 1988 trans it already has all the good upgrades in them. Keep in mind most of the hard parts from a current 4L60E will go in a 700R4 (4L60) as they are the same transmission just one has a electronic valve body.

Yeah they are great if they are pro built with stronger parts, I was thinkin he
was looking to buy a stock truck, but I guess he should give us more details about what he's looking at and what he has to spend.

[dga93]

Do the 3 have all different bolt patterns?
and does it matter on the year of the motor in the truck?

[88 Dippy]

my truck has a 700r4 out of a 84 (same with the 208 t-case) both seem to work fine i love the over drive with the 4.10's i can only imagine the milage suck it would have with a 3 speed auto or any tranny with a 1:1 only


i have noticed that you can not feel it shift when just cruising this kind of bugs me a bit because i can not tell if it is slipping or what? i plan on getting the vette servo and a shift kit (the fluid is nice and pink though)

[dga93]

O.k. So i have a 1978 c10 with a 350 and a dead slipping th350..
I don't have much to spend but i can save my money.
I drive up a lot of mountains and highway driving is most of it.
I want to know what would be my best way to go?
And if the bolt pattern is the same thru all transmissions?
I know so far if i get a 700r4 i would have to shorten the drive shaft but that's all i know.
HELP!