turbo 400 vs 700r..pro's/con's

[ChevyDude]

My 71' SWB driver currently has 3 on the tree. I am collecting all the necessary parts to change over to AT. The engine is a 350 that runs very smooth and is perfect for an everyday driver. Question is do I put a turbo 400 in or a 700r AT??? Can someone that knows AT's tell me what the differences between the two? If it were your truck what would you put in? Just because I'm "old school" I'm leaning towards the th400, but don't want to not consider the 700r if it is the better way to go. Thanks!

[Super Chevy]

stock for stock the TH400 is stronger, the TH700r4 has a .76 over drive and also a 3.06 first gear ratio. with a corvette servo and some beefy internals the 700r4 will handle all the power you could throw at it, but the TH400 is bullet proof pretty much.

[Bowtie67]

I have run both transmissions in different conversions, TH400 in a 62 C10 with a 350 and a 67 C10 with a 700r4 with a 350. The OD with normal Standard type rears with gear ratios of 3.73 or lower are almost a must for gas milage, especially on the highway. If you have a modified engine and want to run on the strip the 400 would be a better option. both transmissions are good units the later the better for the 700's because of the initial problems. I have one built buy TCI and have had it for 4years and I will never go back to a 3spd auto and my motor is built up and I am not easy on my vehicles. As fas as instalation goes, they are almost identicle with the exception of bolt holes for cross member and possible driveshaft, I use the standard automatic column shift in my 67. JMO

[lukecp]

A TH350 would be the cheapest auto tranny option.....a TH400 is much stronger, but the TH350 is fine for a stock or mild engine.

[67dragtruck]

I have run about every GM trans out there with the exception of the newer electronic OD's which I would be drooling at the mouth to have.

I can tell you this. I tried to drive on the power tour last year without an overdrive and it was terrible. Now I have put a 700R4 in mine and it is so much more enjoyable. You can truly have the best of both worlds with the low 1st gear and the overdrive. Just don't go too deep with the rear gears. I haven't taken my 4.30's out of mine yet and 1st gear is about worthless. I have 33" rear tires and even with the 4.30's cruising 80-85 mph is no problem. I am going to swap the rear gear and it will really be awesome. I have a friend with a shop that installs them and even with 3.08's the low 1st gear gives good take off and still cruises on the highway. Unless you are pushing well over 500HP, I would go with the 700. I had to take all the nitrous off of mine because I knew that I would destroy the 700. But to be honest, I did test it a few times and as long as you didn't shift it on the nitrous it still lived just fine. I hit it quite a few times in high gear and it held and pulled like crazy. The only thing that I have found to be a pain in the butt is getting the TV cable adjusted properly. I'm using the Lokar one and if anyone wants to offer me some help with adjusting it, I'm all ears.

Sorry for the long winded answer, just wanted to help as much as I could.

Tom

[71Rat]

to be honest with you a 350 can handle any power u want to put in front of it, just the 400 will handle more towing and off-roading better...... the 400 allows the heat to disapate some more then a 350. as for the 700, i just built one for my truck. you can buy upgraded kits for them and now since gm just came out with a 4L65E you can get hardend parts. I would strongly recomend a 700R4 foir anything, i know people running then at the track without problems. they just make sure it doesn't go into 4 gear. The main killer of 700's and most transmissions is heat, make sure you ahve a nice trans cooler on it. people complain about 700's dieing soo quickly and the main causes of it are from heat and improper kick down cable adjustment. Best of luck with your choice.

Rat

[Cat Fuzz]

I have a stock TH400 behind a 327 that came from another vehicle. It's starting to get a bit squishy. If I had the money, I would, for sure, go with the 700r4 just for the overdrive. I just about killed my motor on a 600 mile trip last summer trying to keep up with the rest of the group. 3300 RPM's at 70mph pulling a trailer was not a good thing to do. Also, didn't help that it my motor has an oil leak I've been putting off fixing.


Anyway, if it were me, 700r4 for sure.

[FirstGen]

700r4 are all over ebay for 500-600 plus core charge, not bad!!!

[Perchjerker]

My bro had a stock 700r4 in a deisel 85 Blazer. Took out the deisel and put in a 454 out of an RV. Motor was probably around 400 hp but was a TORQUE MONSTER. He destryed the tranny in 2 weeks, so, instead of getting the 400 out of the RV, he lets a street/strip tranny shop in Shreveport talk him into a Corvette stylr setup for his 700r4. Wouldn't you know it, 1 month later he blows the damn thing again (along with 2 rear ends). Shop refused to help him since it was past the 30 day warranty. A lot of bucks down the tube!
I love this story- we used to get in that Blazer and walk Z-28 Cameros in a full size blazer. He would put it in 4 wheel drive and white smoke all 4 33" Super Swampers!! HAHAHA
Just had to share this-wish I had pics!

[Bowtie67]

67 dragtruck have you gotten the proper hardware from Edelbrock for this MPFI, I know Holley released a proper cable setup later on to fix the same problem, This is another reason why I am going to the stealram, Stock TPI brackets work with the stock TV Cable.

[skid]

You might want to check out www.700r4.com. They seem to have the TV cables problems worked out

[robby]

Me being a cheap skate I would put in a 350, you would never know if you had a 400 or a 350 when you are driving. If I had money and or no kids in the house I would put in the 700.

[miket]

In my opinion the difference is strictly money.

It won't cost that much for a bullet proof T400 that will take a serious beating.

However to get 700R4 in that range. it's gonna cost you some more cash. However you get overdrive.


It really depends on the motor and what you will be doing with the truck.

[FirstGen]

Daily driver with less than 350 hp go with the 700r4 I say!

[rn2fine]

Love my 700R4. I am getting 15 mpg in my 72 carbureted Burb. It has paid for itself already in saved gas money.

[67dragtruck]

Originally posted by Bowtie67
67 dragtruck have you gotten the proper hardware from Edelbrock for this MPFI, I know Holley released a proper cable setup later on to fix the same problem, This is another reason why I am going to the stealram, Stock TPI brackets work with the stock TV Cable.

I was unaware that they offered anything. I had modified the bracketry that I used with a carb.

Tom