torque converter 101

[Sazman]

I have about decided I am going to rebuild the C6 in the 72 F250. I am reading up on the subject and need to know what you guys think about a new or rebuilt torque converter. In my little quest for information I see some claims of increased mileage with low stall TC's and I know absolutely nothing about this. This is going behind a stock 390 with an unknown number of miles on it, but seems to be reasonably healthy. I have an Edelbrock 4 barrel carb and headers on it, but is apparently stock otherwise. Whaddya think a good choice of a TC is and why? And while we're at it, any suggestions on where to get the aforementioned TC and C6 rebuild parts? Awaiting the communal wisdom, thanks

[averagef250]

Buy a standard stall speed converter from a local converter rebuilder or just reuse your present one. Low stall converters are great for turbodiesels, not great for a carbed gas engine. I like Transtar auto soft parts, NatPro is decent too. A shift kit should be part of your plan too, Transgo works well and has easy instructions.

Stay away from anything that says TCI on it.

[Sazman]

Thanks Dustin, how do I know my converter is good, is there a way to tell, or do you just reuse them till they are obviousy shot? I just want to do it right, but not unnecessarily, if you know what I mean.

[fordman]

one way to tell if your converter is good is if it drives ok now. if it doesnt go then testing it is probably out. mostly ifthe converter doesnt have a lip ground itno it from the front seal it is probably ok. the tq pushes fluid through the ssytem to help pressurize the fluid for the clutches to stick together and make the trans go. the front pump gives the tq more pressure to get this done.

[averagef250]

The TC has nothing to do with actuating the clutches, the front pump is the only thing in the transmission that generates pressure.

Lots of metal shavings in the pan that didn't come from anything in the rest of the tranny may indicate a bad converter as well as a gravel/banging sound from the tranny that isn't covered by anything else in the tranny.

If your tranny is still working check the stall speed of the converter you have by powerbraking the engine in the trannies strongest range (forward or reverse) with the brakes on and a tach hooked to the engine. I don't honestly know what your converter should stall to, but I'd imagine in the range of 1500-1800 RPM for a stockish 390. If it flares up much higher and the tranny isn't slipping you may need a converter.

I've reused many a non-lockup converter without a single issue.

[fordman]

th tc provides fluid via the front pump to move fluid through the trans to go into the clutches. no the clutches are not activated by the tc.

[fitzwell]

If you have the luxury of a local builder that does his own converters, discuss it with them. Seems as tho converters are a "black art"

[Banjo]

there are local automatic transmission rebuilders who would rebuild your transmission and sell you a remanufactured torque converter for likely around $500 or less. And, you could still remove and reinstall and hook up your own C-6. They call it a "bench build". Of course, since you're the one who installs it, they cannot guarantee it. Likely they'd do the complete remove and install for around a grand if you find the right guy. Or, that very same guy will also sell you a remanufactured torque converter (stock stall) for around $100.
Or, most junkyards will sell you an old automatic you wrestle out yourself with the torque converter for anywhere from 50-400 bucks, depending on their profit points. I like to buy from the junkyards where you could get tetanus and have to fight cows and dogs and carry buckets of tools and wear coveralls and mudboots. The kinda place where you basically pay by the pound.
I'm only throwing these out there if money were an issue or experience or the desire to gain experience, as I don't know which angle you're coming from on your busted transmission. I don't know how quick you need to use the truck, if you're working on concrete and inside (unlike I'm always stuck) or what. A C-6 is heavy and a fight. I've removed Powerglides, turbo 350s and C-4s and manual transmissions and it can get rough taking them in and out and most guys I've known who rebuild their own had to buy special tools and were also not successful the first few trys. But, I admit I have an abnormal fear of automatics, not of taking them in and out but working on them. And you have to consider a truck that will now want to wiggle and roll if not park braked and tires chocked.
Also, now might be a good time, while you hve the driveshaft out to get new ujoints installed? While the driveshaft is out, does the pumpkin leak any already? Or is this a good time to pull your pumpkin and reseal the differential, and if so, are you prepared with jacks to pull the axles? Just some other things that hit me while I'm typing. I just mention those things too, because I've learned from owning so many cars/trucks, things can get overlooked and it might be easiest to do several maintenance type things in one shot. Last time I had a driveshaft balanced and new ujoints installed I believe it was around 150, but that was for a engine seeing 6 grand regularly, so that likely higher that stock ujoints (likely extra balancing involved,I guess). Good luck, Banjo.

[Banjo]

another quick thought, is your truck long wheel base or short if long, might be time for the bearing in the middle of driveshaft. And, how much room to you have to work around dual exhaust (guessing) and do you have a sawzall or grinder or what to cut in case you have to hack at some exhaust tubing or something to remove your auto. just random thoughts, banjo.