torque converters

[jimbo01]

I have to agree on the tech article idea. The only thing I would ask for is to have it broke down to where everyone could make use of the information. This may be easier said then done. About the only thing I have understood with all my reading so far is, a stock set up will run cooler but my passenger may be required to get out and push start me if I get caught up at a light, and if I go to a larger then stock converter the power will be put to the ground but at a price. The fluid may run so hot that I may be rebuilding transmissions every season or replacing the tranny fluid as often as I can afford to try and minimize damage if I can't get the heat down. I'm a little skeptical on the heat sinks ability to cool the fluid.

I'm also inclined to think that from all the experience and number of years and with all the T's that have been built, there would have to be someone that could almost pin point what size converter that would work the best. I understand that each cars set up is going to be different and affect the final results. But then again, there are only so many combinations that are being used.

So if my stock TC stall speed is 1400-1600 rpms, and from what I've read I should be using something that's 200-500 over stock. Then I look over everything that has been written here on the site or available on the internet and it always leads me to blow everything I've read way out of proportion or take me right back into that same brick wall. I really hope that I'm not over complicating this. Once again I'm just looking ahead at a future project. I can start to think this out now and make some plans or do it at the last moment and ask the kid behind the parts counter that would be more then willing to help me with what he had learned in high school shop class and help empty my wallet along the way only to find out that I can't return the part he sold me.

 

[donsrods]

My Son is running a 3000 stall B and M Holeshot in his T bucket behind a 306 Ford with an X303 cam and lots of internal work. It launches like gangbusters and when I am following him and he pulls away from a traffic light I have to push my 27 fairly hard to keep up, and I'm running a 331 stroker with aluminum heads, etc and a stick shift. That convertor puts his motor in the rpm range where the cam needs it to be. When I drive his T you can feel it pushing you in the back when you just give it any gas at all.

My other Son has a 468 Olds in his rpu and we originally had a 2400 stall convertor in it but just switched to a 3000 Holeshot because he had to bump it into neutral at ligthts and it was not all it could be when he got on it. He's also running a pretty stiff cam and it just wasn't taking advantage of it with the too tight convertor. I've seen some T buckets even running 3500 stall convertors and the owners say they love how they perform.

Don

 

[benT]

I'm running a TCI "2800" stall in my C4 that has been rebuilt and hot-rodded by a local tranny shop. The engine is a mild-warm 302 SBF with aftermarket heads and a decent Comp cam. Its OK, but I still need the brakes at stoplights. If I were to replace it, I'd use a "3000" stall.

 

[ellis8500]

Too much analysis here. Let's keep it simple. All auto trans have a torque converter. There is no such thing as a stall convertor. Lets say you have a TC designed for a pickup truck. Engine idle is 600, TC stall is 1200. 1st gear is 2.83, diff is 3.55. In gears alone you have a 10:1 torque multiplier. The engine RPM is not that far lower than TC stall. Even though the TC is slipping, it is still transmitting engine torque to the drive train; let's say 50%. If egine idle torque is 40 ft-lb then you will have 200 ft-lbs at the rear axle. Braking force will have to hold that 200 ft-lbs. Now if you have a higher stall TC, at idle the amount of torque transferred at idle will be lower, let's sy 10%. Now your braking force will only have to hold 40 ft-lbs. The numbers for torque and slip % transfer at examples. I do not know the real values. However, it illustrates the effect of how TC stall RPM affects baking force. When you have it right, a vehicle should just creep along at engine idle and brake pedal pressure should be very light to hold a full stop in a street car. Racing setups are entirely different. High pedal pressure at a stop doesn't matter much when you don't plan to be stopped very often. But for normal street driving your setup ought to be as much like a factory car as possible. The last statement is my opinion. Hope this helps.

 

[Chief-T]

I had a TH350C in a 1980 Chev travel van. It blew up at 35000 miles and I had it replaced with a standard TH350 as per the service dept recommendation. They told me they had mucho problems with the lockups. I didn't notice any difference in my van.

 

[409T]

I have a ~ 2400 - 2600 rpm stall converter behind my 409 in a 2200 lb. T. I wish I had 3000 rpm stall converter.

 

[donsrods]

Just a little update that might help someone make a decision. Last night we got my Son's rpu running and the 3000 stall convertor is perfect for it. It is so much better than the old 2400 in all ways. It doesn't lurch when pulled into gear, comes to a stop easier as the convertor isn't pulling the car, and it hauls butt so much better. The rpms are now able to get into the range taking off where the cam is doing it's thing. The car even hooks up better when you get on it maybe because the tighter convertor was locking up too tight right off the line.

I would recommend one in this range after seeing it used in two of our cars.

Don

 

[Mr T Bucket]

Don, what kind of gears are your boys running in their rods?

 

[donsrods]

Don, what kind of gears are your boys running in their rods?

Dan is running 4.11's in his rpu and Don is running 2.79's in his bucket. I offered to buy him some lower gears as a Christmas gift but he really likes the highway gears he has now. I'm running 4.30's in mine and love them around town, not so much on the highway as I crank 3000 at 60 mph.

Don

 

[T-Test]

Don, you know you can get out of the way of a fast approching tractor/trailer, if you don't spin the tires in high gear! LOL

 

[Mr T Bucket]

Thanks, Don. I've got a 4.11 setup right now.

In my effort to do this only once, and because everyone you talk to says this stall or this brand and not that one, etc., I emailed TCI and Coan about what they would recommend with what I have. Coan got back with me today and nothing from TCI yet, but I know it can take some time for a response. Tried calling B&M yesterday. First time the call got routed to Flowmaster's tech line, second time, got a busy signal. If I end up paying $500 or $500+ for a converter, it will most likely be the only try I get. Thinking about which company gives me a bigger headache than the stall question. My unofficial internet search and mental tally has TCI with a slight edge over B&M with regards to quality and Coan came up a fair amount with nobody unhappy with their products. (that I could find). Figured I'd also call one guy I know of at a local older trans shop to get his take on everything too. I had thought about going with a cheaper converter (B&M $260-ish) just to see if a particular stall would be good. Just don't want to buy a $500 unit and then find out one with 500 more (or less) rpm would be better and have to cough up the dough as well as yank the body, etc. to swap them out. Like I said, if I go the expensive (but better built) way, it will most likely be a one shot deal.

To be fair, I am getting pretty excited about getting this thing fired up in the next couple of months. Just hope everything works reasonably well together.

 

[Keeper]

Just to add some more wood to the fire.

My wife's buddy owns a transmission shop, when I got to talking to him about TC he recommended a stock Buick GN (d5) converter, stalls around 2400. Its a lock up converter and cheaper then the TCI/B&M counterparts. I paid $200 for mine brand new out the door and that is Canadian Money.

For the miles I put on mine this year its great. Though I need to swap out the 2.88's for some 3.56's in the next couple of months.

 

[donsrods]

A lot of people have had luck with TCI, I guess, but we didn't. My Son bought a C4 and their convertor for his T bucket. It ran for a little while and one night it was like it was in neutral so I towed him home with my T. We pulled the trans out and called TCI. They said if we paid the freight both ways they would repair them and send them back. I wasn't real happy about that as the shipping each way was $ 125 but we had no choice.

They called a while after getting it and said the convertor welds broke internally and it took out the transmission due to debris. I tried to get them to pay for at least the shipping back since it was almost new and it was their fault...........no dice. Luckily, Summit Racing, who we bought them from originally, kicked in $75 to help defray some of the costs. That left a sour taste in our mouth so we now go to B & M or Jackson Racing for our transmissions.

Don

 

[Keeper]

Yeah that would have left me with a bad taste as well. Did they at least fix the transmission?

 

[Lee_in_KC]

My TCI story...

I have had a grand total of one TCI transmission, so this is by no means a condemnation of the company or their entire product line, however...

I bought a Super Streetfighter TH350 for my T-bucket while it was under construction. I needed the tranny to set up the chassis. I knew that the tranny came with a 90-day warranty, but I didn't realize it ran from date of purchase, not the "in-service" date. I finished the T about 6 months after I bought the tranny and began driving. Within about 500 miles of tame street driving the tranny began making an curious noise that a local performance tranny shop diagnosed (just from the sound) as the drive shell rubbing against the case. They said the most likely cause would be improper assembly, a missing or under-sized shim, and/or a skewed bushing. At that point in time, the tranny was not making any noticeable metal. They said I could continue to drive it to see if it would clearance itself, but if it started making a lot of metal, bring it back.

Thinking it was still under warranty, I called TCI. They informed me of the 90-day-from-purchase policy. They said I could ship them the tranny at my cost and they would disassemble it to see what the problem was. They said if it was their fault, they would repair it for the cost of the parts. I asked if I coud take it to a local shop that they would accept and have it done locally. They said no, it had to go to the TCI facility in Mississippi. So it would cost me $350 round-trip for shipping plus whatever they decided to charge me to fix it based on their own evaluation of whether they screwed up or not, with no limit.

The noise just kept getting worse and the tranny started making pretty serious metal, so I took it to a local race tranny guy that is highly respected in the hot rod community here. He grabbed the output shaft and twisted back and forth a couple of times and said, "sprag race." He blew it apart and found the supposedly hardened intermediate sprag race was "brinelled." He said he had heard that TCI got a bad batch of "hardened" sprag races, but was not acknowledging it publicly. He called TCI to get a replacement and they just blew him off (he is a TCI vendor!). He completely rebuilt that tranny with all new race parts for $350... same cost of just shipping the tranny to TCI.

Now mine is one experience out of what must be many thousands. However, I personally know two other people who had TCI trannies fail very early on. In one case, even though the tranny was out of warranty, TCI repaired it at no charge (owner had to pay freight both ways). In the other case, according to my acquaintence, TCI took the same position as they did with me... send it to them and they would decide whether they would absorb any cost.

I will never buy another TCI product.

 

[sstock]

Good enough for me Lee. Thanks for sharing your experience.

 

[donsrods]

Yeah that would have left me with a bad taste as well. Did they at least fix the transmission?

Yeah, Keeper, they did fix it and sent a new tc with it and so far it is working ok. My experience mirrors the one Lee in KC had and up until the time they tore it down we didn't know if they were going to fix it at their expense or not, but luckily they admitted their tc failed. I bitched and said in that case they should pay the shipping but they flat out refused. By contrast, we had a front pump break off the tang on a Jackson Racing th350 and they offered to fix it free, even though we probably broke it installing it. We couldn't do that to them and paid a local shop to replace it.

Like Lee I will never buy another TCI product.

Don

 

[Screaming Metal]

Well, I have to agree with Don, if they put a bad product, they should've prepaid the shipping. Quality on some of this stuff is going right out the window!

 

[RPM]

My advice is to deal with local shops for engines and transmissions. Converters are a crap shoot, buy one and roll the dice and hope it works. Back in the drag race days, you never knew what you would get in the way of a converter. We seemed to have the best luck with TCI, but that was 25-30 years ago.

 

[Mr T Bucket]

Lee, I was pretty sure I remembered you having problems with your trans. I'd been planning on doing it anyway, but after reading the last couple of responses, I called a local trans guy that's been around a while to get his take on the matter. His experience doesn't favor B&M and he recommended either TCI or Hughes, more so on Hughes. I mentioned Coan and he said they were good too, but a little higher than others.

I suppose it's like Ford or Chevy or Dodge. All of us have had good luck with one, and bad luck with another.