700R4 questions

PrdsOffroadnJT

PrdsOffroadnJT

Well-Known Member
Joined
Feb 17, 2006
Location
Monroe
Can a 700R4 out of a Z28 be used in a 4x4 application. I don't know if maybe it needs a diff. tailshaft or what. Also, I've heard the 700R4 is quite a bit weaker than a Th350 or Th400. How could I beef one up and approx. what would it cost? Thanks. Tyler

P.S. This is to go behind a SBC and mated to a NP205. Thanks.
 
YEs, changing the tail shaft will work in a 4wd. I think you would need an adapter for the 205. Pros being you get a lower first gear, and an OD for the hwy. Is weaker, but have heard of some beefing that can be done. If the lower first gear is what you seek, some shops take the first gear from a 700r4 and put it into a T350. 350 is a lot cheaper to have built.
 
I don't see how a 700R4 is any "weaker" than a TH350, since it's the same trans, with an OD unit.

If you put some decent gearing behind it and don't rely on the torque convertor to make up for it, it should work with you just fine. It was behind a SBC in the Z28, too.. :)
 
A 700 IS weaker than a th400 but is not weaker than a th350.
They are essentially identical except for another gear added up top (overdrive) and a lower 1st.

The rebuild kits is marginally more expensive and depending on which unit you purchase the front pump is actually cheaper than a th350.

many shops will rip you a new one, because some folks assume OD means more work...yeah one extra friction disk set to soak and slide in.

I am a big fan of the 700 for a street driven rig. For trail only its a toss up.

To build a 700 to stand up to big meat and skinny pedal you need to upgrade the front pump to at least a 10 vane(after 87) front pump there is also an aftermarket 12 vane but the last time I built one I couldn't find one of these, they may not be around, but I haven't even tried google, so maybe available.

Also the 2nd servo is notoriously weak, the Vette version was substantially stronger and thats what I run in my Blazer, again there are aftermarket options.

Finally there are a few tweaks that can be done to the valve body to help fluid flow, and these things HATE heat. I run an external cooler and Mercon V fluid, and have had good success.

cost you are looking at 150-250 plus labor. I think the local going rate on a bench job (you R&R) is ~$400...but if you are mechanically inclined and get your hands on a shop manual, you can easily rebuild it yourself, trust me there is no magic genie inside an auto tranny like so many people think. Time, patience and a clean shop bench are all you really need to do the job..
 
As far as I know there are no 700 variations (other than tailshaft) between models except the post 87s and the vette versions
 
ShyHiK5 said:
As far as I know there are no 700 variations (other than tailshaft) between models except the post 87s and the vette versions
Click to expand...
x2

ones built or rebuilt after 87 are the best. The diesels they went behind (6.2, NA 6.5) had less then 200 hp, and didn't need to be 'beefed up'
newer higher output diesels would've had 4l80e, a electronic HD verion of the old 700R4

If you are buying an adapterkit for a particular tcase that comes with a output shaft, a 2wd trans will work just fine, but it has to be pulled apart to install the shaft.

the first trans rebuild i did was on a 700r4, and that truck still runs and drives with it as far as I know. cost ~ $150 for rebuild kit, and another $100 for a new torque conv. if you drop of a pulled tranny, i wouldn't pay more than $500, unless there are damaged hard parts.
 
Thanks everyone! I'll be running 5.13's with 38's to start with, then larger tires. I was looking into an overdrive tranny for any of the street use the K5 would see. Thanks. Tyler
 
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