Mating 700R4 to NP 205.

[Forced Overtime]

Looking to mate a 700R4 tranny to a NP 205... While researching I found that Chevrolet put in this transfer in all of its four wheel drive vehicles in 1980..... Any ideas if the 700r4 would mate to a np 205 from any vehicle of this year or do I have to look for a specific vehicle model due to bolt patern or other details?

[Samco Fab]

No info on the married adaptors, but if you had the wheelbase, you could run a 2wd trans and a 205 divorced T case from a Dodge. I saw that in a full size Ford prerunner.

In some cases it can make your driveline setup better, like if you normally would run a carrier bearing and 2 driveshafts, you just put one driveshaft in front of the t case. It also would make your front drive line longer. It can make for easier tranny changes and moves that 150 lb beast of a t case further back in the chassis.

[scottm]

First you need the factory center piece for a th350 to np205. They came in the 1/2 ton automatic trucks with part time 4x4 (np205) from I think 70-75. Then get the Advance adapters 700r4 - np205 kit that comes with a new trans output shaft. You build up the tranny with the new shaft and then it bolts right up to the 205 through the center piece. I bought one probably 10 years ago for a 76 blazer with a muncie 465 and np205. Make sure you modify the trans to limit kickdown out of OD, because trucks with big tires run deep in the throttle with od. I forget what its called, but it prevents it from downshifting all the time when running on the hiway in od.

[Stephen]

We carry the adapter and conversion shaft, you might look us up, I do this literally every day.
Watch your front driveshaft attachment, the flat flange for the GM 3R CV joint won't clear the trans pan. This was stock on 205's from about 78-up. Earlier versions used a 1310 CV yoke that does clear the pan. Yokes won't swap on all the shafts but the shafts generally swap easily. You should check the condition of the drivesleeve, they wear and break eventually. Also, make sure your axle gears are deep enough since the 700 has a big overdrive ratio. You'll want 4.56's or so with a 35" tire. I ran a 700/205 for several years and have some experience with that combo.

The suggestion for the full throttle kickdown is good. There are a lot of games to play in the trans to make them hold up so spend some time researching that part. Another favorite part for me is a torque convertor lockup switch. B&M makes one that lets you turn the convertor off until 4th gear which is nice. You want the clutch locked when cruising and not shifting in and out since they're tiny clutches.

[sickrick]

Never ever under any circumstance put money into a 700r4 trans. They are junk have always been junk and even if you spend a fortune on rebuilding it you will still own expensive junk.

Give up the overdrive and use a th400 or use the 4l80e.

The 700r4 is a turd, and everyone knows you soulnd't try to polish a turd.

[johnnyweb]

i have the a 205transfer case with the center support from a t350. i will sell the unit for $300.00 +shipping. pm me if you are interested. yes 700r4 does not have the best rap. but it depends on what you will be doing with the vehicle?

[scottm]

Rick everything I own is a polished up turd! Isnt the 700r4 as strong as the th350? The 350 can be pretty good, so how much worse could the 700r be? One from an 86 or 87 camaro is supposedly good.

[sickrick]

No the 700r4 is not as strong' or more importantly more reliable then th350.

The biggest difference is that the turbo 350 is only a few hundred dollars to rebuild and the 700r4 is a few thousand.

I worked with a guy who had 5 transmissions in the same stock diesel suburban. Each time he spent more money on more upgrades to keep it from happening again. This truck was never taken off road and never hauled anything heavier then a snowmobile trailer.
This is just one of several horror stories I know about first hand relating to the 700r4.

I can't see putting money into something that was fatally flawed from the day it left the factory.

I'am sure your 700r4 works fine in a camaro. But put it in a truck and try to pull a load or go wheeling with it and it just will not last.

The th400 or 4l80e used from the junkyard is better than a $3000+ 700r4.

[Stephen]

Shop around on the 700, they had some problems but can be built to work. I've had several in my K5 since it was new, the 1st and 2nd were dealer replacements before my parents bought the truck (it's an 82 they bought in 83 when the PO couldn't keep 700's in it). The 3rd my Dad put together with some early B&M parts and it ran another 200K miles till I broke the convertor clutch with a fresh 383. We built another for it at that point and ran it for another 100K or so with the last of it's life being pounded with a big block and 42" tires. The current version has been behind a 504 for a full season with no problems.
I briefly ran a Art Carr trans and cannot say enough BAD things about the trans and the way they took care of the problems. I have nothing good to say about the Art Carr trans company.
The 700 isn't the only trans choice but if you need the overdrive, it's a good lighter duty choice over a 4L80, just do your homework.

[toddz]

I briefly ran a Art Carr trans and cannot say enough BAD things about the trans and the way they took care of the problems. I have nothing good to say about the Art Carr trans company.

Sounds like another version of the same story with that outfit.....too bad Art's name is still attached with it. I had a similar experience with them and a C4 they built for me back in '98.

I'm currently close to getting the 700 up and going in my Bronco.

Todd Z.

[scottm]

No the 700r4 is not as strong' or more importantly more reliable then th350.

The biggest difference is that the turbo 350 is only a few hundred dollars to rebuild and the 700r4 is a few thousand.

I worked with a guy who had 5 transmissions in the same stock diesel suburban. Each time he spent more money on more upgrades to keep it from happening again. This truck was never taken off road and never hauled anything heavier then a snowmobile trailer.
This is just one of several horror stories I know about first hand relating to the 700r4.

I can't see putting money into something that was fatally flawed from the day it left the factory.

I'am sure your 700r4 works fine in a camaro. But put it in a truck and try to pull a load or go wheeling with it and it just will not last.

The th400 or 4l80e used from the junkyard is better than a $3000+ 700r4.

Rick, what do you think of the 4L60? Is that one equal to the durability of the 350?

[sickrick]

Scottm,
Its better then the 700r4, I expect the 4l60 is about as reliable as the th350 but far more money and more complicated.

My guess is that most people looking for overdrive want to lower their rpms for highway driving.

I think it makes more sense to start with a better (cheaper, more reliable) 3sp auto trans (th400-c6) and lower the first gear and run a little higher rearend gear then you would with a overdrive trans. The result will be reduced rpms at highway speeds and a little larger gap between gears but the first gear will be about the same.

[Stephen]

At this point, the 4L60/700 architecture has more design time on it that the TH350 and it's been much more intensive than the development the 350 saw. The current 4 speed technology is very good. It is more expensive and there's the problem of finding someone to build/apply it to our individual vehicles. That can be VERY frustrating, I talk to guys every day with various trans stories and the 700 is loved or hated. I've been there myself a couple of times.
The hard thing to decide is if you need it or not. Many guys pay lots of extra money for a deeper 1st gear and the overdrive but put it in a vehicle that only sees the highway for a few thousand miles a year. At that point it better not be about economics but more about having just what you want since a 3 speed could do the same job for a lot less money.
In some cases, the 4 speed is the right tool. It's easy to run a 4.56 or deeper gear in a truck with 35's and have good high speed highway rpms and awesome offroad gearing for any use. I've been in plenty of trucks with 4.56's and 35's with no overdrive and it makes long trips really long.

So I'd have to say I agree with sickrick on the 3 speed being good for most recreational use, but I know the 700 trannies can be built right so if it's the right tool, use it.

By the way, I'm one of the guys with a overdrive trans in a truck that would work just as good or better with a TH400. In my case, the original plan was to use the truck on the road a lot more and it didn't work out that way. Lots of projects work that way but maybe some can learn from this.

[sickrick]

Stephen,
You seem to know quite a bit about the 700r4; how much money do you need to spend (parts and labor) to get a 700r4 to suvive 400hp in a heavy prerunner type vehicle (4500 lbs)?

I noticed you had a 700r4 behind a big block and said it lasted quite a long time; I think me and you have totally different driving style.

[Stephen]

I don't know that much about them, I know a lot of people that have used them with different levels of success in different applications. At this point, I don't even know how much is into my 700 because it's been kind of a work in progress but I doubt you could get something similar put together for much less than $2500-$3K. From what I know, a lot of what I have now is just factory 4L65 parts so a guy with a late model trans might have a good head start. Keep in mind that the physical size of the important parts in the 700/4L60 is similar to a TH350, they seem to have very similar power handling ability. Neither is a TH400.

I make no claims to how what I have or have had would hold up in hard desert use, but you bring up another important variable, how do you drive it? Is your (not you specifically but in general) definition of prerunning beating the truck like it's a racer or are you out there to check out the course and take care of the equipment that has to take you home? There's nothing wrong with either one but you have to know the strong points of you vehicle and drive around them or be broken a lot.

If it has to be super tough and you still want the overdrive, build a 4L80. They cost a lot too, we have one in a truck being assembled here that was a good deal at around $2K to rebuild and put the manual VB in our core. The question is how bad do you need overdrive? It could take 50K miles to make the trans pay for itself, are you going to put 50K miles on the truck? If it's a serious toy, that'll take a LONG time. If it's a daily use vehicle, it sure makes sense. How much is it worth to have the lower axle gears and still hear yourself over the motor at 75 mph on the asphalt?

The point I'm throwing out is the cost, power handling ability and gear ratios of your trans have to match up to what you're doing with it and the 700 platform is not a guaranteed bomb.

i think i just threw out a lot more truck philosophy than anyone asked for...

[Brutpwr]

I ran the first Tony Rossi Racing built 700R4/203 transfercase combo back in the 80's when Advance Adapters first came out with the adapter. Tony did not even have to charge me for the adapter as maybe he was working with Advance Adapters on this but I'm not sure--all I know is it was free and shortly after I got mine the adapter was $600+ as I recall. This was all behind a supercharged 355 small block in a tow rig. At the time B&M, Art Carr, TCI etc did not offer any mods for the 700R4 so I went with Toni as he came highly recommended. As I recall he was doing all the work for the LA PD, Highway Patrol and/or Sheriff depts and they would send him cars regularly as they could not keep them in the patrol cars reliably so he modded them and they would live. But I could not keep them alive with my heavier more powerful combo. The longest I could keep one in my truck was 13000 miles! Everytime I broke or damaged the trans I would send the tranny back and Tony would take apart the trans figure out what went wrong and would either all ready have a fix for it or figure it out. I had a early style case so you will want to start with an 88 or even later case as most of the mods I had to have done will be factory upgrades etc. He would send me a rebuilt tranny for mainly the cost of parts. I remember even getting the trans back from his son after Toni passed away and they only charged me like $565 and this included truck shipping
and a new lower than stock stall custom converter! Anyway I now run larger tires and a 4.10 gear and while an overdrive is quieter and a bit more economical I like the rock solid reliability of the Turbo 400. I also feel the 400 has much better shift/downshift characteristics and shift feel that the 700R4. I have used up to a 2500 hundred RPM stall lockup converter with the 700R4 and one of the things I did not like was that the converter would unlock at full throttle and I would loose power thru converter slippage especially when towing heavy loads. There is a Corvette mod of some sort but I was recommended not to use it for heavy towing but this was some 15 to 20 years back so maybe you can use it now if the coverter clutch slippage problem is solved. I think the best tranny combo would be a Turbo 400 with a gear vendors underdrive with appropriate rear end gearing or a 4L80E if you must have an overdrive and can't fit a gear vendors in your rig.

Jason:)