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Old 09-24-2011, 11:30 PM
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How much torque can a 700R4 handle?

I've had 3 "built" 700R4's in various vehs. and they worked great but I know they have their limits. I've been in the process of building a '32 Ford Victoria ...for way too many years now. I had a 331" sbc/700R4 but wanted something different. Sold the Chevy and trans and now I'm building a fairly warm 507" Cadillac/400 turbo.

The rear is a VERY heavy duty Currie 9" with a 31 spline 4 pinion posi, 3.50 ratio. The dynosim (I know it's iffy) on this engine parts combo shows 504 hp and 634 lbs.ft. torque....who really knows how much but the stock big Cads are major stump pullers.

The car is a f/glass body with steel fenders but still should only weigh about 2800 lbs. I'm not going to beat this thing to death but I will get on it occasionally...so my question is, can a 700R4 be built to withstand this kind of torque on a "every once in a while" basis without breaking the bank.....or the trans?

The original 400 turbo is brand new rebuilt, new pump, frictions, steels and if you could run a lockup conv. in a 400 I would just stay with it but as far as I know that won't work. I do remember an article where one guy had figured out a lockup for the 400 but I can't recall where. I have a line on the 700R4 trans. adapter so thats not a problem. Also, since I don't need any kind of a high stall converter can a low stall (1200-1300) unit be built and modified to try and eliminate as much slippage as possible while cruising...or is it going to slip anyway. Thanks for any info....Dave
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Old 09-25-2011, 01:44 AM
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I have heard people talk on ThirdGen.Org about how a 700r4 can handle 700 horsepower built (hear say), i couldnt really tell you how much torque, but im sure if it can handle 700 hp, it should handle up the same amount of torque cause the torque comes first. But this is not a fact, just an observation, maybe someone else could cure our curiosity bc ik they handle 350 HP stock.
O and by the way nice build!
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Old 09-25-2011, 06:01 PM
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Not sure of an exact number, but I have 700's running mid 10's in 3500# cars and 4L60E's (same in strength) running as quick as 9'7 in a 3600# car

Frank
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Old 09-26-2011, 07:25 AM
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If you are going with big power and high vehicle weight step up to the 4l80e/4l85e, it is pretty much a th 400 with an overdrive.

peace
Hog
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Old 09-26-2011, 08:23 AM
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Search for "switch pitch" converter info for th400.
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Old 09-26-2011, 08:39 AM
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Please remember its not horsepower that breaks them; its torque.
I would avoid a manual valvebody and transbrake for longevity's sake. If you have a small tire car with a mild suspension, it will help the trans live a lot longer (blow the tires off before the trans grenades). This trans should be okay if properly prepared, but I don't think it will last 50,000miles.

Also, make sure you align everything properly (some adapters aren't the most accurate).
Please run a driveshaft safety loop; its peanuts compared to new legs
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Old 09-26-2011, 09:00 AM
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Quote:
Originally Posted by Hogg
If you are going with big power and high vehicle weight step up to the 4l80e/4l85e, it is pretty much a th 400 with an overdrive.

peace
Hog
The '80E might be a good swap option for a cruiser, but not a drag car. We usually saw customers run 2-3 tenths slower in the quarter mile when we did the swap on a few 4th gen F-Bodies. The '80E is huge, and eats alot of horsepower, in addition the the extra weight. I have 4400# Impala SS's running in the 9's with '60E's. In the past 5 years, I've done alot of swaps back to 60E's for customers who thought they needed a 400. A 700/4L60E can be built to take over 800 HP.

If anyone ever questions how much a 700/4L60E will take, here's 3 of mine... All 3 are over 3 years old. 2 are 10 second cars...The other is in the 9's




Frank
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Old 09-26-2011, 10:05 AM
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As a GM tech, years ago we were told GM trannies were numbered according to the torque they were rated at. 350 = 350 lbs/ft, 400 and 700 the same. This changed when the started the T and L designations for Transverse (FWD) and Longitudinal (RWD) and I don't know the formula for those.
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Old 09-26-2011, 10:25 AM
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this is very useful, i plan on putting a 402 big block infront of a 700r4. I gotta admit these overdrives save $$ at the pump
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Old 09-26-2011, 03:24 PM
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My Car was built with a 700R4 in mind, and mid-build I went with more horsepower, so I was very concerned about it living. I called Hughes Transmission to get their take on the subject-

Me: Will a 700R4 live behind a 540 Big Block Chevy in a street-driven Hot Rod?

Hughes Transmissions: Yes, but if you put in a 4L80E you will only put it in once-

That was all I needed to hear, so I am working now to finish up the install-is it big? Yes! Is it heavy? Yes! Will I sleep at night knowing I can do that big, hairy burnout at the Car Show and not embarrass myself (well, more than usual) with a broken Car (if I DO a burnout)? Yes!

I am having to make a new Transmission Hump (removeable this time), and it hangs a little lower than I'd like, but I know it's strong-

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Old 09-26-2011, 08:15 PM
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Not sure how accurate this is >> http://www.442.com/oldsfaq/oftrn.htm...n%20Comparison

327Nut you should ask how much it will cost to make a 700R4/4L60 reliable behind that much TQ. I'm sure it take a few $$, Billet Input Shaft, Reinforced Drum etc..
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Old 09-26-2011, 08:33 PM
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Quote:
Originally Posted by SSedan64
Not sure how accurate this is >> http://www.442.com/oldsfaq/oftrn.htm...n%20Comparison

327Nut you should ask how much it will cost to make a 700R4/4L60 reliable behind that much TQ. I'm sure it take a few $$, Billet Input Shaft, Reinforced Drum etc..
9 second capable 700 can be had for $1400...
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Old 09-27-2011, 12:45 AM
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Frank,
That's a very reasonable price.
Has anyone stepped up yet with a better/stronger Input Drum?

Todd
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Old 09-27-2011, 09:20 AM
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Todd, The 700/4L60E input drum durability is a very interesting subject. If you find a broken input drum, what actually causes it to break? In reality, it has nothing to do with engine HP or torque. Input drum failure has actually been traced back to the torque converter choice. In MOST applications where I've seen input drum failure is because a customer has installed a multi disc converter. The more violent the lock-up apply, the more stress it puts on the input shaft and drum. The real question is, why would anyone need a multi disc converter? You're certainly NEVER going to lock the converter at WOT, but these converters were built for just that purpose. The chassis dyno helped the myth that a vehicle will be quicker in the quarter mile if you lock the converter on the top end. People based this on the fact that if you lock the converter on a dyno, you make more HP. The reason this doesn't transfer over to a quarter mile run is because when you lock the converter, it usually pulls the engine RPM's down below peak horsepower range. There are exceptions to this rule, such as a turbo V-6 Grand National. This is one of the advantages of actually being a racer as well as a transmission builder. We like to test all these theories...lol
I'm not saying that multi disc converters are all bad, but a converter should NEVER be locked at WOT.
There are places that offer "hardened" input drums and shafts. Most machine the area of the drum where the over-run piston rides and install a steel sleeve. In theory, this is supposed to give the splines more support. Then, what you get is a drum that breaks the whole center out, if a customers locks the converter at WOT. Congratulations, you just put a Band Aid on a bullet wound...LOL The big drawback to sleeved drums is, you can't use the steel input piston set with molded seals. I use the steel pistons in all my race applications because the aluminum forward pistons are notorious for cracking when the pressure is raised. This was a common problem on early 4L60E's in F-Bodies, Vettes, and Impala SS's. GM eventually went to steel pistons in 1997. I've also seen aluminum pistons break in 700's, although not as common. All the cars in the pictures above have stock input drums, and as long as I educate my customers, I don't have any drum failures.
I hope you've enjoyed this session of TRANSMISSION 101...

Frank
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Old 09-27-2011, 10:20 AM
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Quote:
Originally Posted by 10scnd70
The '80E might be a good swap option for a cruiser, but not a drag car. We usually saw customers run 2-3 tenths slower in the quarter mile when we did the swap on a few 4th gen F-Bodies. The '80E is huge, and eats alot of horsepower, in addition the the extra weight. I have 4400# Impala SS's running in the 9's with '60E's. In the past 5 years, I've done alot of swaps back to 60E's for customers who thought they needed a 400. A 700/4L60E can be built to take over 800 HP.

If anyone ever questions how much a 700/4L60E will take, here's 3 of mine... All 3 are over 3 years old. 2 are 10 second cars...The other is in the 9's




Frank
Nice cars, do you daily or even occasionally drive these cars?

The OP was looking into low stall TC's, so I assumed he is looking for cruising capability.

I have never had good luck with built 60e's, seems as though stock 60e's with DCLF V6 4.3's and shiftkits are more durable, but I think thats the lack of skillset on the trans builders part.

A good trans builder is worth theri weight in gold. A good trans is so much more than throwing in good parts.

peace
Hog
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