Hey Guys -

I'm looking to do a rip and replace of my TH400. I dropped the pan last weekend and noticed a large piece of metal in the bottom of the pan. I don't know much about automatics, but it almost reminded me of a piston ring - like it was holding something in place. Anyway the trans seems to shift fine and doesn't slip, so I'm guessing it's the beginning of the end :-( I guess nows as good a time as any to replace with a 4 speed overdrive automatic, and am trying to figure out which one to go with. I've seen several posts who favor the 700r4 and others that say go with the 200r. I've heard people say the 700r4 is a HP "stealer", but I can't see how it would be any worse then the TH400???

My set-up is the following:

70 Chevelle Convertible 461 BBC, 850 mechanical secondary Demon carb, approx engine HP 490 / 480 ft. lbs trq. Cam specs - .553/.571 244/254 @.050 duration. Power range = 3000-6500. Current set-up is a TH400 with a 10" 3500 stall converter. Gear ratio - 12 bolt 3.90 with a 28: tire.

Questions:

1.) What trans would be best for my set-up?
2.) Which converter would be best? Most of the trans manufacturers are trying to talk me into a lower stall then what I have now. Like 2500???
3.) Is the gear ratio too low for a 700r4?
4.) Should I do a lock-up or nonlock-up?
5.) Who has the best trans kits on the market (price and quality being the deciding factors)?

Appreciate any help / guidance you can give!

Thanks!

I love my new 700R4. It was built locally by a very knowledgeable guy who led me in the right direction to make it survive behind a healthy 496/600hp motor...changed the whole characteristics of my car for the better. a bit of a hassle to install but worth every minute. am using a corvette style tc ($100) that has a 2075 stall > works perfect and the cam I run is much more aggressive than your listing (comp xs290s)...go for it >>>

Hey Heckler,

Thanks for the response. So your converter is working fine at that stall? Seems like it would be a little low compared to what is required?

What is it about the 700r4 that has changed the car? Launch better? Seem like it has picked up some better ET numbers? I would think that with a 3.06 first gear, it would come out of the hole like an angry ape...

Would really like to get some more specifics on what has changed for the better on your set-up as well as what made it a hassle to install.

Thanks!

I'm also looking into a new auto... I have a TH350 and I'm looking for an overdrive. The 1st gear for a 200-4R is a bit better than the 350 but not as quick as the 700 r4... The overdrive gear is almost the same. I think you'd LOVE the 700.

Hey Guys,

I was wondering if anyone has seen some serious fall-off on the 700r4 going from 1st to 2nd? It looks like it's a serious fall-off from a 3.06 first to a 1.63 2nd?? Just trying to understand what, if anything, I would be sacrificing going from a TH400.

Thoughts?

John

sacrafices and gains from leaving the ol 3speed to the over drive trans. If you could get to a 4l60 that would even be better, lots of beating of the trans tunnel though, and you would have to purchase a stand alone computer system, much more expensive, however the 700 is nearly the same but no TV cable use/adjusting on the newer trans.

Rebuild the 400. The strength can't be touched by a 700.

To get the 700R4 to live behind a big block the 700 will have to be very well built. I would suggest the following TCI parts.
371100P2 this kit will contain the super street fighter 700R4 rated at 650 hp and tq, breakaway torque converter 2600-2800 stall, filler tube, universal TV cable, universal cooler and 1 case of fluid.
If you would like the kit to have a higher stall converter use part number 371100P1, it will have all the above parts the only difference is the converter is will have the street fighter converter, stall will be around 3400.
Thanks
662-224-8972 ext 333

I love my 700r4 with my 350 engine ,but it will be even better with better rear gears. I currently have 308 gears but I should be ordering some gears from biggearhead soon.

Impression I wasunder is the 3.06 first gear of the 700 is too much and you will have tractin problems even further than you may have now behind a BB motor. The 200 from what I have read has something like a 2.72 first gear sot here isnt as much of a gap between first and second and not as much chance of traction problems. In addition the 200 was behind the Buick Grand natinals and lives well in 10 second cars when built properly. Now I maye catch heat for this but I dont care who builds it...in a BBC euqiped car with any torque and get driven hard...Ive never seen a 700 last long. If I was you if you could get a newer style 4L80E which is the same ratios as a 400 with overdrive thats my first choice or Better yet...rubuld the TH400 and put a gear vendors unit in. Yes its costly but if you want what is best I think the later 2 suggestions are gonna be most durable

I will throw in my 2 cents. I pulled my built turbo 400 and put in the 700R4. I have a 383 cu 442 HP 455 tq racing engine with 3:73 rear. I had it built with all the good corvette servos and goodies and had a custom TCI 2800 lock up stall put in. I think your gears will be perfect for the 700R4 because I can do 60 MPH with my lock up engaged and only be at 2000 RPM which I feel is too low for my high RPM racing engine. I will say that the overdrive is awesome......

I went with the 200 4R over the 700 R4. My motor is a 540 putting out about 700 hp and 655 torque. When I was doing my research I talked to several transmission builders and they pretty much all said that the 700 R4 is harder to build to handle big block power than the 200 4R. The 700 R4 is a steep first gear at 3.06 and the change between 1st and 2nd seemed like a big jump. The 200 4R gears are 2.74, 1.57, 1.00, and .67.

Now all that said, I live about 1.5 hours from you and have a perfectly good TH 400 sitting in my garage with a B&M shift kit in it. It was behind a 396 with the under hood blower that was putting out about 500 HP. If you want it I will give it to you and it will buy you some time until you decide what to do for the OD transmission. All you need to do is come and get it. Let me know.

Mark

I'm for the 200 here also.

I know guys SAY they get a 700 to live behind 500 hp/500 t, but I also read where even so, one doesn't hold up all that well over time.

Years ago, I contacted the real Art Carr and he said no problem building a 200 to take 800 hp. But that it would be pricey.

And I'm going to have to do something when my about 550 hp/580 t, 496 eat's my oem M-20 if I don't die before I get it on the road?

pdq67