Looking into putting a 700r in my project truck. I put one in my father in laws 51 ford because the one in it was smoked when he got it. The rebuilder told us not to worry about the lock up torque converter not locking in at high speeds. He gurantees his tranny. The guy at the local tranny shop said not locking in the torque converter will ruin the trans and need a dummy converter. Both professionals with opposite opinions. Whats the real story?
I am guessing one of them is wrong... Sorry I don't know for sure which one, but I assume since lots of TQs before the 700R4 didn't lock, that yours should work ok without locking. I want to think with a HD or supplemental cooler it has to work. Heat would be the killer, take out the heat, and everything should be cool. Sorry for the guess, but I saw this when I opened up the HAMB, Hello 39 All Ford it appears that you have not posted on our forums in several weeks, why not take a few moments to ask a question, help provide a solution or just engage in a conversation with another member in any one of our forums? , I think maybe it is time I contributed something, even if I am wrong...
A 700R4 will run a lot cooler with a lock-up convertor. I'm not going to say that you must run a lock-up convertor or that you will ruin a 700R4 if you don't. I will just tell you that it is very advisable to run a lock-up convertor if you can.
you will surely defeat the whole purpose of the overdrive trans if u dont hook it up,and from what i understand it will trash the tranny. even not getting the tv cable adjusted properly will destroy it .
You will smoke a 700R4 in just a few miles if the TV cable is not adjusted properly. You will not ruin a 700R4 if you do not run a lock-up convertor. That is why the sell 700R4 convertors with and without lock-up.
Does the year of the 700r matter? Whether originally its a carburated, tbi, or tpi? I know locked in it runs cooler and more efficient. I will definitely be running a cooler too. I am looking at a tbi 700.
They made 700R4's with a 27 spline and a 30 spline input shaft. You want a 700R4 with a 30 spline input shaft. If you have a 700R4 with a 27 spline input shaft, you basically have a paperweight. GM also made 3 cases: an "MD8" case, a "K" case and a case with no designation. You want at least an "MD8" case. The "K" case is the strongest and the case with no markings is another paperweight. Many (if not most) of your 2 wheel drive, V6 S-10 pickups have a "K" case 700R4. You can also find "MD8" case 700R4's in most heavy duty GM cars like the Buick Roadmonster Wagon, the Caprice Wagon and Fleet cars (ex. cop cars, taxi cabs etc.).
I got a 700r4 from a guy in Irvine CA that used to rebuild them for a living. Now he is retired and works occasionally out of his house to support his drag racing. The guy knows his stuff, no B.S. He stands by his stuff and his transmissions see way more HP than I make. With that being said... Ive got a completly rebuilt one of his with a few little mods. I have a lockup converter in mine. It makes all the difference on the highway as you are locked up and not slipping at all. The wiring under the pan is key. Mine is wired where there is 1 wire coming from the sensor. I have it hooked to a relay that has 1 wire that ties to my brake pedal light. When I press the brakes it completes the circuit and I unlock. Let off the brakes at highway speed and it locks back up. Real simple real easy. IMO, Id go lockup and get a kit for the unlock. Theres plenty out there that ive seen with some kits over 100 bucks. I got mine from him for like 25. Since someone mentioned TV cables, like the guys said above, check the TV cable! Thats a must too! For the TV cable Id google BowtieOverdrives, alot of info and parts
My in laws truck had the no designation that was smoked and we got a K case. Does the md8 case have any markings?
Yes! Like the "K" case, the "MD8" marking will be on the side of the bellhousing near the dipstick tube/tranny cooler lines.
Simply buy a "non locking" converter. They are the same price. That's what I've been running for three years. Approx 200rpm higher rpm on the hiway than a lock up converter with my gearing. Then you don't need to worry about any wiring or a switch.
I ran without the lock up feature and loved it. I purchased the convertor without the clutch. spend the money on the "bowtie overdrives" tv cable - spendy, but worth every penny.
Use a General Motors TV cable. I've seen many blown 700R4's with aftermarket cables. They're not "pretty" but do you want pretty or reliability.
I have a Bowtie OD kit for my SBC with 700 and it works fine. Cool kit and cable all in one package. Would buy again. I have a 10" 3000 with lockup and it is damn near like a 5 speed when it locks up. I have a B&M controller, not bad but I had to add a vacumn switch for hard throttle.
HUH?!?!? You're gonna have to explain this one. There's nothing that needs a controller and there's nothing that's vacuum operated on a 700R4.
Yes the year matters. The late 1985 to 1992 (last non-computer year, also called 4L60) can be run fine without lockup. I have a 91 in my coupe and run all gears without lockup. Of course it would be nice to lock up in OD and one of these days I will install a switch to do that, but meanwhile it will not hurt this model year.
I've seen some lockup wiring kits (controllers?) that included a vacuum switch to disable the lockup at full throttle. That's my best guess.
Yes, that's right. Under heavy throttle you don't want lockup, so a vacuum switch that disables lockup is used. Best bet is to get an adjustable vacuum switch so you can tweak it to your liking. Plus, with a high horsepower engine, you really don't want lockup at high power levels, because the lockup clutch, at least in stock converters, can be damaged and start to slip or chatter if you ask too much of them.
Okay, I haven't heard about a vacuum system for the lock-up. I only heard of a vacuum system to eliminate the electronics on a 4L60e. And you are correct about high horse engines and 700R4's. I always ran a Hughes Performance Lock-up convertor till I went over 500 horse. Now I'm running a 700R4 with a manual/reverse valve body and a custom convertor without lock-up.
Run the lock-up if doing any highway driving. There is no downside to locking. Here's a simple kit that gives you plenty of options. http://www.summitracing.com/parts/TCI-376600/ Or could do a more simple ebay $20 4th only lockup. And if you really wanted to go low buck, just use a toggle switch. Now if you are building a race only car, I would skip the overdrive altogether.
Here's my take If you've got the car in overdrive the rpm could very well be below the stall speed of the converter that means slipage. Slipage means extra heat . Ive seen to many overdrives lose the converter clutch and the trans isn't far behind.
Check with a good rebuilder about running without lockup in 4th gear, as far as I know you need the lockup to work unless the trans has been modded to not use it. Something about how the coolant is routed through the trans in 4th, without the lockup solenoid picked there may not be enough cooling. Non lockup transmissions are modded to bypass this issue. I bought the bowtie overdrive lockup kit, locks up the trans in 4th gear. Pricey but works great. A vacuum switch can help to keep from lugging the engine but I just downshift manually if I really need to on a big hill.
The B&M controller has a speedo driven transducer and a remote switch with a variable MPH lockup function and a switch to turn the lockup feature off, the added vacumn switch just makes sure under hard load(ie throttle) that the lockup is disengaged to prevent damage to the lockup clutches in the converter and damage to the trans as well as a "passing" feature. Simple enough and for a daily driver a great thing.
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