What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

replacing my TH400 with a 700R4, am i crazy?

muddysub

muddysub

1 ton status
Staff member
Moderator
GMOTM Winner
Joined
Jun 23, 2001
Posts
11,158
Reaction score
3,076
Location
North Branch MN
as i'm figuring out a direction i'm going with the build up of my suburban, i'm finding myself really wanting OD. i'm wanting to do more of an expedition/camping rig than a crawler. it's a suburban, not a tube buggy. it'll be much more useful to me if it wouldn't kill my wallet to cruise down the highway a couple hundred miles. i'm just worried that a 7000+lb truck on 37s and occasional mud and rocks mixed with 75mph highway speeds is gonna kill a 700r4 in no time...

so am i crazy for even thinking about this and can a 700 be built to handle my truck?

sorry for the noob questions guys...
 
You'll like OD for a 4x4 cruiser/long trip vehicle.

Just run a good trans cooler and kick it out of OD when you tow with it and you should be fine.

I rebuilt a 700r4 in the 87 K20 4x4 I had with Kevlar clutches and Kolene steels, corvette servo, shift kit, etc, etc, and it was good up to a 500 hp motor.
 
x2 on the cooler. I have a TCI trans that I ran in my 81 sub K20 on 35's with a mild 454. It took quite a pounding. Ran down the road nice too. survived, and is now getting ready to take more abuse in my K5.
 
BTO is gonna do mine.... they can do a pretty bulletproof one.. it's all in how much coin ya wanna spend.. i expect my rmvb one with convertor will be $2500 or so.... I'll be running 38's and flogging it...
 
cost is definitely a factor.. i looked at monster transmission's site, reasonable prices, we'll see what happens with getting an engine first.
 
Heck I bought a 700r4 manual and the master overhaul kit with Kevlar clutches and Kolene steels, 3-4 clutch pack, Sun planetary gear, special sprags, corvette servo, shift kit, torque converter, etc, for like $600 - 700 and rebuilt it myself with the help of my brother.

When it was done, it was a hellacious tranny that worked awesome!
 
If you are that worried about it why not run a 4L80E, you won't need a new transfer case or adaptor, (maybe some minor machining on the adaptor). A 4L80E is a TH400 with an OD gear. About half the parts will interchange between the two. The only downfall is cost since you need a $500 controller, unless you find a controller from a 91 with a 4L80E. If you aren't runnnig much power a 700R4 can last a long time, but there is no doubt about it a 4L80E is much stronger.

This guy makes some pretty complete rebuilds (not half @$$) for a decent price.

http://www.jakesperformance.com/4L80E.html
 
Last edited:
folkenheath said:
If you are that worried about it why not run a 4L80E, you won't need a new transfer case or adaptor, (maybe some minor machining on the adaptor). A 4L80E is a TH400 with an OD gear. About half the parts will interchange between the two. The only downfall is cost since you need a $500 controller, unless you find a controller from a 91 with a 4L80E. If you aren't runnnig much power a 700R4 can last a long time, but there is no doubt about it a 4L80E is much stronger.

This guy makes some pretty complete rebuilds (not half @$$) for a decent price.

http://www.jakesperformance.com/4L80E.html
Click to expand...

That's crossed my mind a number of times. My DD pickup is a '99 with a vortech 5.7 and 4l80e in it, if I can find something else to drive I'd yank the engine and trans out of it.
 
muddysub said:
That's crossed my mind a number of times. My DD pickup is a '99 with a vortech 5.7 and 4l80e in it, if I can find something else to drive I'd yank the engine and trans out of it.
Click to expand...

Why not just find a used 4L80E on craigslist and leave your DD together. I bought one on there to rebuild for my car and when I took it apart it was like new inside. He said it worked fine but I was pleasantly surprised.

Or find a complete 6.0/4L80E w/ t-case used! If you are doing a whole engine swap might as well update. But I got to admit, the 6.0 doesnt seem to be as fuel efficient as the 5.3 if that's what you are looking for.

You want to hear something weird. All the newer cases have the 7 bolt holes for the bellhousing (additional top center one) for use with the LS engines and 8100s. Well, I have the newer case (2000 model). So when I unbolted my TH400 that I installed back in 1996, my 1969 350 truck block (it was a 4 bolt main I made a 388 out of back before it became more popular than the 350 itself) had the 7 bolt holes! I was surprised, I used it too since it was there. But I didn't know any older engines ever had the top middle bolt hole. The funny thing was, the trans came out of a van with a vortec 454, and the factory hadn't even used the 7th bolt hole in that transmission.
 
hmm, found a guy on CL locally with two 4l80e trannies, in need of a rebuild, for $250obo...
 
muddysub said:
hmm, found a guy on CL locally with two 4l80e trannies, in need of a rebuild, for $250obo...
Click to expand...

FYI, for any future testing purposes or emergencies, even completely unplugged with no electric or computer, a 4L80 will still have reverse and 2nd gear (no matter what forward gear you select it will be in 2nd).
 
folkenheath said:
FYI, for any future testing purposes or emergencies, even completely unplugged with no electric or computer, a 4L80 will still have reverse and 2nd gear (no matter what forward gear you select it will be in 2nd).
Click to expand...

a limp mode of sorts. cool.
 
Yeah it's also a good test if no computer is available. If reverse and 2nd work correctly, then that means the direct clutch, forward clutch, low band, and intermediate clutch work. Which means 1st and 3rd should work too with the proper electronics since they use the same functions just in different combinations. So the main unknowns are the OD clutch and the locking torque converter(and obviously the electronics).
 
Id like to swap my TH350 for a 700r4 one of these days too... Mines a daily driver, and that overdrive would be nice on the wallet.... Free up some paper to finish restoring... :D
 
I have heard a mix of opinions about Monster Transmission some good most bad. I read somewhere that the fine print about the warranty is crazy. Now about them 4L80s for 250.00 is that for both? I want to put a fully manual reverse valve body 4L80 in my Jimmy. I have never had good luck with a 700r4 and I have killed a few in my old street/strip truck. But you know how that goes 6 one way half a dozen the other way.
 
Chip Cross said:
I have heard a mix of opinions about Monster Transmission some good most bad. I read somewhere that the fine print about the warranty is crazy. Now about them 4L80s for 250.00 is that for both? I want to put a fully manual reverse valve body 4L80 in my Jimmy. I have never had good luck with a 700r4 and I have killed a few in my old street/strip truck. But you know how that goes 6 one way half a dozen the other way.
Click to expand...


that was each. then i saw he reposted them today as "make an offer" i'll call him this afternoon. in my personal experience, the 700 is my least favorite transmission, its the only GM automatic ive ever managed to kill. i'm gonna find out about those 4L80Es tomorrow and see what it'd cost to swap it.
 
Chip Cross said:
I have heard a mix of opinions about Monster Transmission some good most bad. I read somewhere that the fine print about the warranty is crazy. Now about them 4L80s for 250.00 is that for both? I want to put a fully manual reverse valve body 4L80 in my Jimmy. I have never had good luck with a 700r4 and I have killed a few in my old street/strip truck. But you know how that goes 6 one way half a dozen the other way.
Click to expand...

Do they make a reverse manual 4L80E valvebody? I've never seen one, but I haven't looked for one either? And you can make a 4L80E fully manual just by external wiring, no internal mods are necessary, unless you don't want to supply it with two wires (one for 12V+ and one for TCC ground control). Although a few internal mods would be good for strength.
 
Last edited:
Phoenix Transmission in Northeast Texas told me about a full manual reverse valve 4L80 they build I have never seen one but according to them yes.
 
You must log in or register to reply here.

Latest Posts

Top Bottom