The Stovebolt Site Forums The Shop Area Engine Shop 700r4 or t350

I am getting ready to begin the search for a transmission and was wondering what everyone thought about these two. What are the advantages of choosing one over the other. I don't know very much about transmissions so any help would be appreciated. Thanks

This decision is a factor of several things.
1. What rear gear ratio will you be running?
2. How much HP will you be running?
3. What becomes available in your price range.

The rear gearing is the first priority in my opinion. If your gearing is 3.73 or numerically higher then the 700R4 is the way to go so you get good performance and good highway mileage. If your rear gear is 3.40 or numerically lower down to 2.41 the 350 will be fine for both with the optimum rear gearing of 3.08 for a balance between performance and mileage. This is what I found out when I had the same choice but there are probably others that have different advice. Do some research on the web regarding both trans. The 350 is cheaper to buy and repair. With my rear gearing I went with the TH350.
If you are building a high HP/torque engine you may want to consider the TH400. These are harder to find but are great transmissions.
Good luck.

Not an expert here, but I believe the TH700R4 has 5th gear overdrive for the highway while the TH350 will have the straight 4 gears in drive. Houston 54 is right on, but if you intend on putting on a lot of miles at highway speeds, you'll save rpms (equals gas dollars and engine wear) with the rare TH700R4.

Unless you are going to have huge horsepower, I would go with a 700R4. It is a 4 speed with the 4th gear being overdrive. It also has a lower 1st gear than the th350. With the 700, you get the benefit of a low (numerically high) first gear and the benefit of overdrive for highway use.
Just my $.02.

The 700 R4 has a couple of weak points, but if you're not going to abuse it, it will give you better gas mileage. It's got overdrive, and a lockup torque converter that eliminates the 10% slip that all converters have as a factor of the physics involved in being able to multiply torque. The overdrive clutch is pretty puny, but it can be replaced with the clutch drum intended for the Corvette which has bigger clutch plates, and more of them. If you're planning to tow anything, stay out of overdrive. The OD clutch cycling in and out every time a load goes on will wear it out, and also overheat the fluid. Use the biggest auxiliary transmission cooler you can fit if you go with the 700 trans.

350's are plentiful and cheap, and there's a lot of hotrod parts available for them if you plan to get radical with the power. The best choice for a high-performance package is the Turbo 400. it's a little heavier than the 350, but MUCH stronger. If you can figure out the wiring without going to a full computer hookup, the 4L80 is a 400 design with overdrive and a lockup converter, but it would be a bear to wire up!
Jerry

Thanks for all of your help. I am running a stock 350 engine with a rearend that has around 3.40 gears( I'm not sure of the exact number). I think that I am gonna go with the turbo 350 because the guy who is building the transmission said that he could provide the core and the rebuild for 360 dollars and that the performance would be just fine. My major concern is running at high RPMs when I get on the interstate because it is going to be a daily driver not a hot rod. So I guess gas mileage will be a concern also(when is it not these days). He also said that it could be a bit tricky getting everything hooked up where it would shift just right and I could run the risk of burning it up. I really have no idea what he is talking about there but I guess I've got to trust him. After all he is the professional not me. Thanks again for everyone's help. If someone who has a 64-66 chevy pickup with a 350/350 driveline could let me know how it is working for them I would greatly appreciate. Thanks again
Brady Eldridge

I have a 64 swb with 350/700r4 setup & couldn't be happier. Headers,4 barrel, HEI. 16+ honest mpg at the very least, drives great. Love the rpm drop when it hits OD! If you want to drive it daily, its the only way to go. Brian

Brady,
I personally have researched this and have found that if your truck came with the Turbo 400, the 700R4 would be the best option primarily because the dimensions are closer..please verify this.

BUT, if your truck came with the Turbo 350, then I strongly recommend the 200R4..it is a virtual bolt in, and you can utilize the original driveshaft.

Final note..I personally prefer the 200R4 and Turbo 350 over the other two because these transmissions have less internal rotating mass, thereby avoiding sacrificing HP as well as rev-ability. They are still quite strong for even the wildest street machines, and proven by numerous racers.
It is only for the extreme high torque applications and excessive hard use that I would recommend the T400 and 700R4.

i do not know what standard transmision dimensions are in comparision, if this is your atarting point.

If given the choice I would always choose the 200R4 over the T350 as mileage is quite a concern..engine life being secondary.

My '70 truck is really in need of the another gear(T350) and I am running a 3.07:1 rear gear.

So, I would urge you, especially with the gear you are running, to go with the 200R4.

I am not that familiar with a 200R4. Is that a common transmission? What years did they make it?

I am not sure if the 200R4 is still being manufactured new or not.

I did some research on the subject (200R4vs. 700R4)as to which would be the best swap for my truck and read some very good articles as well as several comparisions with all the transmissions.
But, after doing some search's, I can not seem to find them yet.

Here are a couple of links...

Dimensions
http://www.geocities.com/MotorCity/Track/7062/trans.html
http://www.hotrodssuperstore.com/trandim.html

...note the 200R4 dimensions to the T350.

Here is a pretty wild web site dedicated to the 200R4..scroll down to the bottom for the gear ratio comparisons...
http://www.200raptor.com/

If you are going to run the 200 plan on getting a few upgrades as they do not handle HP very good.The TH350 is a very good trans but again no od.The 700R4 is a great trans but a little more to rebuild.Just my $.02

Mike

take it from me (a guy who owns one), if you are gonna run 3.40 gears, don't use the 700 and if ya do, don't be surprised when your fuel milage sucks.
lugging down the road at 1800 rpm when the engine isn't designed for that rpm just eats gas...
got a 48 chevy coupe with a 350/700r4 and 3.25 gears....

picked up some 4.10's, that'll help;)

Oh really so I figured 1800 RPM would give you good gas mileage. Is that too low? So you would suggest the 350.

I recently faced the same decision...700R4 is attractive becuase of over drive and a certain level of reliability. If you're going to do a lot of towing then the 700R4 would'nt be a great choice. The TH 350 is a proven performance type trans but is limited in driveability and gas mileage. My decision was the TH400...it's as close to "bullet-proof" as you can find...with certain modern rebuild upgrades that are now available it is far and away the best street/performance trans available.
I've mated my 350/330HP with a rebuilt TH400(about $600. no core)and a 3.42 rear in a '52 Suburban... along with an Edelbrock 600cfm carb, I recently averaged over 22mpg on a 400 mile, relatively high speed trip (VA to NJ).
The trans performs well, runs cool, is a good towing trans and has an excellent reputation for reliability.

With what little time I have I was able to find a few other things on the "200-4R".

The original driveshaft is used along with the yoke off your T350, and the rear cross member will just need to be slid back about 5/8" (?) of an inch to utilize provisions (existing holes) intended for the T400 which most early GM vehicles have.

Thus, there is no drilling , no yoke swapping, no driveshaft cutting (required with the 700R4..you will only need to run wires for a lock up converter, i believe.

It is recommended to upgrade the earlier 200R4 for strength and longevity..but the later ones were apparently improved.
The following is an excerpt:

"But the 200-4R received many improvements over its life. At its peak it was used in the Buick Grand National. This was a turbocharged Regal that generated 255 net horsepower. At the time it was 10 more horsepower than the Corvette was available with (245hp). And the GNX version of the Big Bad Buick was for a short period of time... the fastest car made in America... with a 200-4R transmission".

Excerpt:
"There are a some pluses and minuses to choosing a 200-4R over the 700-R4. On the plus side, it is lighter and more efficient, so it should allow more power to get to the tires, and (as it was designed) provide a little better mileage in a low to moderate horsepower car. The 200-4R is within 1/8" of the length of the TH-350 and the Powerglide AND uses the same yoke as the TH-350. This means I would not have to shorten the driveshaft, or get another yoke".

T350 to 200-4R swap
http://www.442.com/oldsfaq/oft200.htm

Here is a very good article by Street&Custom RODDING titled "GM overdrive tranny's are superb, so why are they getting such a bad rap?".
It is in PDF format...
http://www.bowtieoverdrives.com/eprints/rc_eprint.pdf

Here are a few good reads...
http://www.442.com/oldsfaq/oftswp.htm
http://www.scott-lewis.com/archive/cars200209.html

I think I have supplied you with much that you will need to transpose, happy thinking.

That article seems to be incomplete, but have seen it in its full version..I will see if I can find it.

Thanks for all of your help and time vito. The articles are interesting.

brady, i've got a lot of cam in mine and it's just lugging at (legal) hiway speeds.

same setup with a 400 turbo (yeah, i've had to play with driveshafts) got better milage and was more fun to drive (with the 3.25 gears).
you'll need at least a 3.73 gear to be livable with a carb motor.
just like everybdy else has been telling ya, it depends on YOUR combination.

ain't gonna matter to me much anyway, it's goining in for a cage this winter and i'm gonna fit it for a 4 or 5 speed manual trans and do some draggin'

From a rebuilder's point of view, avoid that 200R4 like a bad case of hives! it's a modification of the Turbo 200 to include overdrive, and it's got all the 200's bad features, a very expensive variable-displacement pump, and a flimsy overdrive! There are a lot of stamped parts, and some pretty flaky hydraulic circuits. They're one of the worst transmissions to rebuild I've ever worked with!
Jerry

Another good point brought up is the cam.A cam with a good amout duration that comes on around 3000 rpm would not like the low rpm of say a combo of 3:23 gears and overdrive.the same motor with 3:73 to 4:10 with overdrive would love it.Pick what you are going to use the truck for most and select your cam,trans,and gears and you should have a great ride!Nothing kills a great motor faster than the wrong cam.

I personally am not familiar with the inner workings of the Powerglide, but down in southern california it was a VERY popular setup to run a powerglide behind a big block, because it was such a hot combination for the strip..especially for camero's.

Of course they were all upgraded, which is insignificant in cost, compared to a standard rebuild.

I had seen so many of these in so cal at that time, I even had several friends running this combination to be both on the edge and competitive. Never, have I seen nor heard anything negative as long as they were upgraded. In fact a closer friend had allowed me to drive his many times (396ci + T200), and these things were driven aggressively...no problems what-so-ever.

Down in socal the powerglide had quite the "little" following by those in-the-know.
I did not know that the 200-4R was based on the Powerglide..I must say it makes me much more comfortable with this tranny.