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Torque converter 727

Started by SilverFrost73, March 30, 2023, 11:48:55 AM

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SilverFrost73

After getting a quote from Hughes for a TQ converter for $1300 I thought it may be good to ask around to see what other brands people are using.
I dont have it in the budget to spend more then $700 on a converter.
My application is as follows
Plymouth Cuda
1969 727
440 stroked 512
Lunati Voodoo 703 cam
3:23 gear
With a 28-29" tall tire
The car will be used for cruising hwy/in town, car shows, with the occasional burnout.
I need a lock-up converter due to the 30min hwy drive to town.
What are you all using in your rides and what was the price range?
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Mr Cuda

Time for more information.
1969 727 cannot used a lockup converter. It's a whole different front pump assembly and valve body modification. Also not compatible with a 69 case.
So 3.23 with tall tires will give you a comfortable 2500 at 60.
A performance converter with a stall higher than 2400 ( factory high stall) will burn your transmission up by being in the flash range.
So power band of cam?
Consult an actual gear ratio tire chart as I'm shooting from the hip on rpm.

SilverFrost73

#2
Quote from: Mr Cuda on March 30, 2023, 12:42:03 PM
Time for more information.
1969 727 cannot used a lockup converter. It's a whole different front pump assembly and valve body modification. Also not compatible with a 69 case.
So 3.23 with tall tires will give you a comfortable 2500 at 60.
A performance converter with a stall higher than 2400 ( factory high stall) will burn your transmission up by being in the flash range.
So power band of cam?
Consult an actual gear ratio tire chart as I'm shooting from the hip on rpm.

The power range of the cam is 1800-6200
According to the Summit gear ratio tire chart the RPMs at 65mph would be 2519 RPMs with 3.23 rear gear and a 28" tire.
I said lockup because of my trans getting to hot on the hwy in a non-lockup situation and burning the trans up.
So do I need a completely different transmission now? I'm so confused about all this. :clueless:
If prayer isn't needed to accomplish your goals then you're not setting your goals high enough!
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Hard work beats talent when talent doesn't work hard!
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Mr Cuda

Working remote on your issues, it's hard. The first items are minimum cam speed  for cam life,  and the fact that strokers build big torque down low.
  Minimum Cam speed for flat tappet life is generally 2200
Engine speed of under 2400 will kill transmissions with factory high stall or performance converter.
So if your idle quality is good at 800 rpm, a mid stall or factory 12" low stall could be used.
Yes, there's always the issue of hard engagement into gear w/low stall converters,  but they are "locked up" or fully efficient at a lower rpm.
A converter that is stalling while driving is building more heat than the cooler can handle,  and a bigger cooler isn't the answer.
So what converter do you have?



Mr Cuda

Side question,  with a stroker,  and performance build , is your kickdown linkage correct? And adjusted properly?

SilverFrost73

What do you mean by factory high stall? Is that the stall rpm of a factory converter?
Right now the car has whatever came in it when I bought it 6yrs ago. I've been working on replacing body panels and the block is at the shop getting machined for the stroker build. I'm ready to start buying some other parts to get it on the road this summer. So in other otherwords I've never driven the car.

Hughes got back to me again and said they can build me a non billet converter for $824.56 but didn't recommend a non billet converter for the torque my motor would make. They said theres a chance of a lockup clutch failure due to distortion of the bottom cover.
If prayer isn't needed to accomplish your goals then you're not setting your goals high enough!
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Hard work beats talent when talent doesn't work hard!
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Mr Cuda

So you have never run the transmission to know if it will "burn up"?
RPM and automatics doesn't mean they will build excessive heat.
Almost all heat comes from the converter when it's "working".
Once at a speed above its stall point and at peak efficiency, it's heat output is limited.
(In a stock application)
You have special needs with the torque available,  and yes a lockup will be hard pressed to handle it.
  You need to work backwards from engine,  stall speed, gearing, cruising speed,  to make a decision.
Everyone has opinions on what you need.  I was assuming you were already driving,  with a problem.


7212Mopar

Recommend you call John at Cope Racing Transmission. I got the PTC torque converter and 727 trans from him a few years ago. Car runs great. But mine is a SB stroker to 416. It was dynoed at 528 ft-lb. The PTC I have is 11" 2800 stall. I am running 3.23 rear, 275/40/17, about 3000 RPM at 70 mph. I run a decent size trans cooler in front of the radiator and bypassed the radiator. Not a problem in CA.

I just looked at his website and he is no longer building complete transmission. But it does not hurt to call or email him with your questions. He was very helpful when I deal with him.
1973 Challenger Rallye, 416 AT
2012 Challenger SRT8 6 speed Yellow Jacket

SilverFrost73

Quote from: Mr Cuda on March 31, 2023, 03:17:59 PM
So you have never run the transmission to know if it will "burn up"?
RPM and automatics doesn't mean they will build excessive heat.
Almost all heat comes from the converter when it's "working".
Once at a speed above its stall point and at peak efficiency, it's heat output is limited.
(In a stock application)
You have special needs with the torque available,  and yes a lockup will be hard pressed to handle it.
  You need to work backwards from engine,  stall speed, gearing, cruising speed,  to make a decision.
Everyone has opinions on what you need.  I was assuming you were already driving,  with a problem.

Like I said I'm in the process of rebuilding the car. I started with the motor and now I'm working my way back from there. I'd never use a transmission that leaks and is caked with lord knows how many years of grease on it. Common sense tells me it won't last long and will "burn up".
If prayer isn't needed to accomplish your goals then you're not setting your goals high enough!
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Hard work beats talent when talent doesn't work hard!
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chargerdon

Some help here, please.   Are we saying that cruising RPM needs to be above the stall speed or excess heat will occur ?   Is this true with lockup torque converters as well ?   

I put an A518 tranny in my 408 stroker 74 Chally.   The camshaft is a flat tappet Lunati 703.   The torque convertor i put in with it came from a rebuild site in Ca and was only about $150-$200 (Torco) and is around 2400 RPM stall and a lockup.   I verified the stall speed by holding the brake on and bringing revs up until the tires started to spin and was right around 2300-2500 RPM depending on street surface.    With 3.23 gears and 14 inch wheels (25.1 tall) i can run down the highway at 60 mph and in 4th gear and lockup engaged, only be turning around 1700 RPM which is way below the stall speed.   IS THIS A PROBLEM... ?????  Note, i am just running a normal radiator cooling.   Heck, at 50 mph or below ill be down around 1500 RPM...and i have not noticed any problem...   In 3rd gear and lockup off it turns about 2800 at 60.

i do NOT have a temperature gauge on the transmission, however, after a 15 mile drive with speeds between mostly 50-55 and in 4th with lockup engaged whenever i could, i did one time as soon as i got home and engine running in Neutral, used a infrared temp gauge on the line going into the radiator and it read 240...   I thought that was good ??????

Bullitt-

  There's a little company in N. Alabama that I discovered a few years ago that has been providing torque converters for 50-years now, ACC Performance better known as Boss Hogg. At the time I bought mine they had a stellar reputation with better prices than most anyone.

https://bosshogtorqueconverters.com/?post_type=product&paged=26
I would chose the 54093 11" 2400-2800 stall (varies based on weight of car & power applied) or possibly 54053 11" 2800-3200 stall for a street driven car.
  AS I Understand it the higher the stall the more Heat will be generated.....

They will sell direct but as with many manufacturers their products are priced lower through re-sellers ..... I'm sure these folks drop shipped from ACC.
https://www.kmjperformance.com/search.html?q=TF-727+Torque+Converter
.                                               [glow=black,42,300]Doin It Southern Syle[/glow]       


Mr Cuda

@chargerdon, your factory 518 is working correctly and won't have any of the issues we are talking about. But since you are savvy enough to have a pyrometer, there is one more test you can do for us.
When a 518 goes into lockup the converter is no longer putting fluid through the cooler. That  combined with heat generated  by the overdrive will raise fluid temps.
Drive with od off and see if temps come down. The converter will still  lockup at 35-45 depending on what valve body upgrades you have done. I suspect they will be lower.

chargerdon

Ill do the temp checks again with od on and off and lockup on and off.    I use manual toggle switches to control shifting into OD and also to perform lockup.   No hydraulics here just two toggle switches.   

Mr Cuda

@chargerdon
You must have a 96 or newer trans. I've been playing with 95 and older from obd1 cars. There is no option to override lockup.
For my test, could you run lockup-od off?

Katfish

Quote from: Mr Cuda on April 01, 2023, 06:40:58 AM
@chargerdon, your factory 518 is working correctly and won't have any of the issues we are talking about. But since you are savvy enough to have a pyrometer, there is one more test you can do for us.
When a 518 goes into lockup the converter is no longer putting fluid through the cooler. That  combined with heat generated  by the overdrive will raise fluid temps.
Drive with od off and see if temps come down. The converter will still  lockup at 35-45 depending on what valve body upgrades you have done. I suspect they will be lower.

Never hrd this before, what does LU have to do with the transmission pump circulating fluid?
Its well known LU reduces temps because there's no longer any TC slippage.