Torque converter question

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bighammer

bighammer

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Will a high stall converter affect the performance of the tranny, other than from a dead stop? I understand how important they are in a performance build for getting the 'jump' off the line, but is that where the advantage ends? Or do they affect shifting as well?

I'm guessing a shift improver kit is the best way to slam gears, and that a TC won't have much affect at all on performance, once the car has gotten off the line(?)

Still a newbie learning this stuff, thanks for your thoughts.
 
In simple terms: A torque converter is designed to slip to an rpm as delegated by the internals of the converter. At which point when said rpm is reached, the converter "hooks" thus launching the car. Now a higher stall rating allows an engine to wind up to its optimum power band before engaging. Soooo....say you put a high stall converter in a daily driver...the converter will slip to a degree until the converters stall rating is reached. So if you putt to work at 40 mph, and 2000 rpm. But you have a converter that stalls at 3k. It will be slipping the entire time. More heat is created...never good. So you lose some drivability. A long, low rpm highway cruise could cook the trans. But most converters when properly matched to the car and cam can be very streetable.

Now for more long winded nonsense :)

A shift kit eliminates the smooth shifts and slams gear to gear with faster shifts because the clutches in the trans slip less. A converter with a higher stall wont effect shifting other than the engine will wind up to the higher rpm before surging forward.

Lastly, a stock converter is almost always leaving performance on the table with a cam swap. Dont let the high stall and my jargon above talk you out of a new converter. They are cheap, and I recommend one with almost any cam swap. TCI, ATI, or even B&M can recommend a suitable converter to get you drivability with some snap.

Hope this helps some. Good luck
 
Limited off the shelf converters for the 904 though, usually they are made to spec of the engine as johnnymac says, iv used a TCI 11'' breakaway on a street car, and it was good, but it was only ok on the strip.
depending what you want from your car and engine combo, and if its a daily driver, look at a TC with 1000 or so over stock like the Breakaway
 
A quality high stall convertor will drive normal until you matt your foot to the floor.
 
roccodart440 said:
A quality high stall convertor will drive normal until you matt your foot to the floor.
Click to expand...

+1. Also heat buildup mostly happens when you're at the light with the foot on the brake and you've got your RPM's up. You won't see a lot of heat buildup just cruising around with a high stall converter as long as you have a decent trans cooler.
 
Talk to one of the QUALITY converter builders for your needs. Your choice of converter will depend on a whole lot on what you've got under the hood, rear axle ratio and tire size, and what is the overall use of your car,race, street, cruiser or. When you select your camshaft they will give you a basic idea of what stall converter will work best with your selection of cam.

A stall that works in one persons car and application may not be ideal for you. Choose wisely and don't let money be your only guide to your purchase. Some of the lower priced converters aren't made by the name that's on the box. They can be made by outside sources. Avoid used high stalls, a waste of your time and money as you never know how its been used or what the condition of it is like inside. A nice paint job means nothing. One swap meet I was at there was a used high stall converter that was being advertised as a 3000+ stall converter for a TH350 trans. It was one that was made by the company I worked for and still had our part number on it: 35-12ss, which was a basic TH350 converter which was designed to give about 300-500 over stock stall depending on your engine. A stock TH350 converter stalls at around 1400 RPM.
 
Its the feel too. Nothing like a good converter. It's worth the extra $200, call PTC.
 
Yrs ago high stall converters were not very efficient and slipped a lot and if you buy a spragueless race converter it may drive like that but most common day high stall converters slip very little on light acceleration and the only time they build a lot of heat is when your dogging on them. A high stall converter will soften the shift so IT WILL affect shift feel to a degree. The looser the converter the softer the shift will be. I'm not talking a huge difference but a noticeable difference nonetheless

roccodart440 said:
A quality high stall convertor will drive normal until you matt your foot to the floor.
Click to expand...

Correct. I replaced a 2000 stall MP converter with a 3000 PTC converter and I noticed no difference driving under light throttle. I have a temp gauge on it and it never builds any more heat than the old 2k converter except when I dog on it.

I also agree with everyone that suggests not buying an off the shelf converter. Spend the extra to have it built for YOUR car and you'll get maximum performance and enjoyment out of it
 
dumb question but what happens in a transbrake application when the stall speed is c lose to the launch speed? Does it work the same as dumping a clutch? What is the reason for running a high stall in a t-brake car? say you launch at 5k on a 5k verter. why not just use a lower stall and maybe larger case say 10" or 11" vs. a 7" or 8"?
 
MidTexCuda said:
dumb question but what happens in a transbrake application when the stall speed is c lose to the launch speed? Does it work the same as dumping a clutch? What is the reason for running a high stall in a t-brake car? say you launch at 5k on a 5k verter. why not just use a lower stall and maybe larger case say 10" or 11" vs. a 7" or 8"?
Click to expand...

Your reference to the stall speed being close to the launch speed is a non issue. Using a high stall converter gets the rpm up in the engines power band so it takes off harder. The trans brake acts similar to dumping the clutch but also has the advantage of holding the car in place (a t-brake locks the trans in drive and reverse at the same time) on the starting line and letting go of a button is a quicker reaction than letting off the brake and flooring the accelerator.

If you use a lower stall converter you engine will not be in it's power band on take off so the car will be slower. You cannot get a 11" converter to stall at 5k. Doubt anyone could get a 10" to stall that high. Also keep in mind the mass your spinning with a 11 or 12" clutch vs. a 7 or 8. That mass may help the launch (if the stall speed were the same) but it sucks up HP

Think of it like this. Say your driving a stick shift car and you stop and rev it to 2500 rpm and dump the clutch then you stop again and rev it to 4500 and dump the clutch. Which rpm is it going to take off harder at? The 4500 of course. This assumes you have traction available to take off at a 4500 drop

Hope that helps
 
I know how a t brake works I was just curious why a person needs a big stall on a t brake car. I had a 5k verter in my car and left on the break at 4500 to 4800 never tried to launch higher that my stall...may have been doing it wrong.... but in my case why couldn't I have used a 3500 and left at 4500? Does the verter affect the engines ability to reach that rpm if the verter is locked?
 
MidTexCuda said:
I know how a t brake works I was just curious why a person needs a big stall on a t brake car. I had a 5k verter in my car and left on the break at 4500 to 4800 never tried to launch higher that my stall...may have been doing it wrong.... but in my case why couldn't I have used a 3500 and left at 4500? Does the verter affect the engines ability to reach that rpm if the verter is locked?
Click to expand...

The stall speed is the maximum speed in which you can rev the engine before the car moves. You cannot get an engine to rev to 4500 (before the car moves) with a 3500 stall converter. To sum it up, you cannot launch higher than the stall speed

BTW: the converter never really locks unless it's a lockup converter.
 
stroked340 said:
And stay away from tci nothing but crap!!!
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Why is that? I have a new one in the box ready to go in, why whould you say they are crap? what was your experience with them. which part number did you have? application etc? I have their Street fighter 142200 unit. Supposed to be 3400-3500 behind the motor i have.
 
Fisher said:
Why is that? I have a new one in the box ready to go in, why whould you say they are crap? what was your experience with them. which part number did you have? application etc? I have their Street fighter 142200 unit. Supposed to be 3400-3500 behind the motor i have.
Click to expand...

A lot of guys have had problems with TCI stuff. I wouldn't chance using them myself because of all the bad rap I've read on the Mopar boards. Go to the top of the transmission page and you'll see a stickey on TCI transmissions
 
fishy68 said:
A lot of guys have had problems with TCI stuff. I wouldn't chance using them myself because of all the bad rap I've read on the Mopar boards. Go to the top of the transmission page and you'll see a stickey on TCI transmissions
Click to expand...

Put me on that list. I bought a street fighter convertor and when it arrived it was a stock convertor re-painted with the weights knocked off of it. I don't even think it stalled much past 2,000 rpm. Dragged the engine down at idle. Junk. Even got boxed up to soon ad there was paint on the packing paper.
 
Yeah i spoke to a parts vendor tonight who said TCI was bought out by Comp cams and has changed everything. he went there for a site visit and was very impressed with what he saw. He said their warranty rate is less than 3% And not one return this year, and he sells a ton of TCI products. So thats a great sign.
 
TCI, B&M are all junk off the shelf converters. We wont install them in our shop, even if they are customer supplied.
I too am one for PTC.. great converters.

Every one I have ordered for customers cars has worked perfect. I just installed a 9.5" converter in my cuda. Changed the car dramatically.

Btw, shift kits make the transmission shift more firm, not HARD. Big difference. Transgo is all we use.
 
Fisher said:
Yeah i spoke to a parts vendor tonight who said TCI was bought out by Comp cams and has changed everything. he went there for a site visit and was very impressed with what he saw. He said their warranty rate is less than 3% And not one return this year, and he sells a ton of TCI products. So thats a great sign.
Click to expand...

Even if they were bought out, which might help with QC. They are still off the shelf convertors, not built for your application.
 
I was at the Mopar Mega event at Maple Grove, Pa., last year. TCI was there and I spoke to Mr. Beatty the owner. Remember, this is an all Mopar event. He all but said that torqueflites were junk and blow up a lot. He didn't seem interested in helping. I spoke to Cris Munroe of tci-racing trans in Keene N.H. yesterday. Chris' father, Carl, wrote the book on 727's. Together with Rick Allison of A&A Racing Trans know all there is to know about torqueflites. Talk to these people BEFORE you buy. We are here to help./
 
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