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?

[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]

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!

[88 Dippy]

the bolt pattern is the same on all the of them if you get one that was in a vehicle with a chevy V8.

i have no idea what would be the best for mountain driving because i live in a preaty flat state sorry

[79gmcc15]

ok, If I was in your situation. I would call around and find out how much it would cost to re-build Your TH350 with HD parts. then find out how much it would cost to do the same with a TH400. as I see it, TH350s are Great with a stock SBC up to a 350 motor. with light to occasional medium hauling in stock format. if I was to get a motor that was not stock or was going to do towing or lots of hauling up the mountains, I would go with a TH400. But I would start out with the numbers first and see what my pocket book can handle and time frame *if you need your truck running next week, kind of thing*. and go from there. I think either trans would be fine for you. I've heard that the 700's cost A lot more to rebuild right. and the amount of money you would save on gas. it would take a while to recoup the difference of a 350/400 rebuild and a 700. JM2C

[dga93]

So I found a th350 for $70. I hope it works. Find out tonight.
I have been without my truck for over 2 months.
Anything I should do b4 I put it in? Or add while I'm putting it in?

[79gmcc15]

well if you can't have it checked before you put it in. at least have all the fluids changed and filter. its pretty easy to do. I am sure someone can add to that.

[Tx Firefighter]

Be sure and measure the lengths of your old TH350 and the new one to make sure they are the same length. There are 3 different length 350 trans.