A727 Stroker Combo

[El.Padrino]

I am pretty sure this topic has been covered somewhere here but couldn’t find the answers to my questions.

So far, I am building a 496 stroker based on a ‘69 383 for my ‘68 Coronet. Not decided on cam yet.
Goal is to hit the 500hp mark not much more.
Street use only! Burnouts, redlight races, that’s it. No slicks, no strip.
Dana rearend, 3.54 gears powerlock.

A727 trans, casting number says it is a ‘69 Hemi 727.

Do I need to beef up the trans? As my ongoing restoration already eats high $$$ I have to cut down on the costs but don’t want to pull the trans after a season bc it failed.

My mods I was thinking of is a deep aluminum oil pan, a Transgo TF-2 shift kit and a new torque converter. Do not want to go to deep into the trans internals if possible. Is that good enough for my intentions?

What size torque converter and stall is your recommendation?

thanks!

 

[PurpleBeeper]

I think you will be just fine like that. Personally, I would use a transmission cooler (the "little radiator" type) instead of deeper aluminum transmission pan...or maybe do both?

 

[1967coronet440]

Like said above run both cooler and deep al pan. Converter/stall can’t be chosen until after you know your cam specs. Ask someone like @PRHeads to spec a cam for you

 

[moparcrazy]

Personally, I would sell that hemi trans for around $2000.~$2500. then buy a truck trans for around $250. and use my profits to help build a badass trans. I have a used torque convertor for sale, $300. stall's @ 3000 rpm? used it for two years, has maybe 1000 miles. (regarding your cam call Comp Cams they'll help you select your cam)

 

[Lefty71]

Obviously the higher the horsepower, the farther you are getting from what was originally expected from the transmission in its original state. Also, keep in mind that with 3.54 gears, you are asking for more from that trans than some of the drag and street-strip cars with higher ratios when you are thrashing it. Its a heavy car too. I personally would beef up the internals as well, and I like the idea of selling a collectible trans as others have said, to get what you need, which is good hard cash to make a cheap heavy duty one. You will definitely need a cooler to go along with the converter. HTH, Lefty71

 

[Dipstick]

Personally, I would sell that hemi trans for around $2000.~$2500. then buy a truck trans for around $250. and use my profits to help build a badass trans.

Excellent idea.

 

[dvw]

Excellent idea.

Sell it, I'd do it in a heart beat. The Hemi specific band is COSTLY. Any standard non lock up 727 will suffice. Needs a 4 plate front drum. 3.8 lever, good Borg Warner frictions, Deep truck pan, good cooler. Either a valve body kit as mentioned with the proper kick down linkage or a Turbo Action Rev manual. Use an early small pin servo with 2 springs. Or a late large pin servo with the inner spring removed (shim solid by using 2 output thrust washers). 15 springs in the front clutch, .060"-.075" clearance. .025" rear clutch clearance. This will get it done. No need for 4 pin planets, billet servos, ect.
This set-up will easily live in a 10.50 strip only car. Very little more to upgrade to a unit that will live behind a 9.0 car. All these parts are available here.

https://www.transpartsonline.com/TRANS_PARTS_FILE/tpcat.php?TransPartsOnline=727&TransPartsType=727

Doug

 

[El.Padrino]

I appreciate all your answers. You guys always help me here!

I agree with you selling the trans for good money would be the best option. Unfortunately, I doubt selling it easily here in Europe as it would be in the US.
So I will keep the trans and rather treat it well.

What I gathered from all your comments above this is a must:

-TF2 shift kit
-trans cooler
-deep oil pan

Sell it, I'd do it in a heart beat. The Hemi specific band is COSTLY. Any standard non lock up 727 will suffice. Needs a 4 plate front drum. 3.8 lever, good Borg Warner frictions, Deep truck pan, good cooler. Either a valve body kit as mentioned with the proper kick down linkage or a Turbo Action Rev manual. Use an early small pin servo with 2 springs. Or a late large pin servo with the inner spring removed (shim solid by using 2 output thrust washers). 15 springs in the front clutch, .060"-.075" clearance. .025" rear clutch clearance. This will get it done. No need for 4 pin planets, billet servos, ect.
This set-up will easily live in a 10.50 strip only car. Very little more to upgrade to a unit that will live behind a 9.0 car. All these parts are available here.

https://www.transpartsonline.com/TRANS_PARTS_FILE/tpcat.php?TransPartsOnline=727&TransPartsType=727

Doug

@dvw do you think that this is necessary when keeping my hemi 727 too? My horsepower is mild but high torque numbers could kill it. Keep in mind it is a street car ONLY.

Whats your thoughts of upgrade the front band to a Kevlar and the rear.
Maybe change the clutches to Alto Red? But then I am deep into disassembling, really want to keep things simple and do only what necessary.

From what I’ve read the servos are considered to be a weak point too but probably could be changed easily in the process of changing the bands..but like I said it is a street car..

I want to go with the Bouchillon Performance kickdown linkage.

 

[dvw]

I appreciate all your answers. You guys always help me here!





@dvw do you think that this is necessary when keeping my hemi 727 too? My horsepower is mild but high torque numbers could kill it. Keep in mind it is a street car ONLY.

Whats your thoughts of upgrade the front band to a Kevlar and the rear.
Maybe change the clutches to Alto Red? But then I am deep into disassembling, really want to keep things simple and do only what necessary.

From what I’ve read the servos are considered to be a weak point too but probably could be changed easily in the process of changing the bands..but like I said it is a street car..

I want to go with the Bouchillon Performance kickdown linkage.

The Hemi will already have a high ratio lever, check and see. Nothing the matter with Altos. I use them in the racecar. Do NOT use a Kevlar band. Red lined only. I've never broke a servo in over 25 years of trans builds. A real Hemi trans will have a double wrap 2.5" KD band, 5 friction front drum, 4 pin planets. All HD stuff, but heavy. Stopping the heavy Hemi drum on the 1/2 shift, then reaccelerating it on the 2/3 shift. The biggest issue will be finding a Hemi band. I don't even change out the rear band unless its damaged. Only controls 1st gear braking and reverse. Grab the TF2 kit and deep pan and go.
Doug

 

[Hemirunner]

The Hemi will already have a high ratio lever, check and see. Nothing the matter with Altos. I use them in the racecar. Do NOT use a Kevlar band. Red lined only. I've never broke a servo in over 25 years of trans builds. A real Hemi trans will have a double wrap 2.5" KD band, 5 friction front drum, 4 pin planets. All HD stuff, but heavy. Stopping the heavy Hemi drum on the 1/2 shift, then reaccelerating it on the 2/3 shift. The biggest issue will be finding a Hemi band. I don't even change out the rear band unless its damaged. Only controls 1st gear braking and reverse. Grab the TF2 kit and deep pan and go.
Doug

Doug,
What is the reason for recommending against the Kevlar band?

 

[dvw]

Doug,
What is the reason for recommending against the Kevlar band?

Kevlar is not as good at grabbing rotating parts. Holds well if applied in a stationary position, IE rear band. However the rear band is lightly loaded unless in a snow plow truck type application. NEVER use with an aluminum drum, it'll tear up the drum.
Doug

 

[Hemirunner]

Kevlar is not as good at grabbing rotating parts. Holds well if applied in a stationary position, IE rear band. However the rear band is lightly loaded unless in a snow plow truck type application. NEVER use with an aluminum drum, it'll tear up the drum.
Doug

What are your thoughts on the carbon fiber bands?

 

[dvw]

What are your thoughts on the carbon fiber bands?

Never used one. I can say the red band in my 900hp racecar has 414 passes on it. In the next week or so I'll pull it for inspection. At 2017 inspection (344 passes) it looked new.
Doug

 

[MoparLeo]

https://www.hotrod.com/articles/15-tips-improve-727-torqueflite-trans/#

 

[El.Padrino]

The Hemi will already have a high ratio lever, check and see. Nothing the matter with Altos. I use them in the racecar. Do NOT use a Kevlar band. Red lined only. I've never broke a servo in over 25 years of trans builds. A real Hemi trans will have a double wrap 2.5" KD band, 5 friction front drum, 4 pin planets. All HD stuff, but heavy. Stopping the heavy Hemi drum on the 1/2 shift, then reaccelerating it on the 2/3 shift. The biggest issue will be finding a Hemi band. I don't even change out the rear band unless its damaged. Only controls 1st gear braking and reverse. Grab the TF2 kit and deep pan and go.
Doug

Today I removed the pan again to assure the lever ratio again. The number is a bit hidden but pretty sure it looks like a 5.0 ratio stamped. How a Hemi 727 is supposed to be.

Will check the bands when disassembling further for the TF2 kit. What‘s the best way to check the bands and/or remove them?

Aren‘t any aftermarket 2.5“ hemi bands available eg maybe from A&A transmissions? What about the rear band?

If you never had a servo failure in 25+ years I will keep mine untouched!

 

[dvw]

https://www.hotrod.com/articles/15-tips-improve-727-torqueflite-trans/#
"The speed and force of the front band engagement can be manipulated via changes in the First/intermediate band apply lever. As seen here, levers with 2.5, 2.9, 3.2, 3.8, 4.2, and 5.0:1 ratios (bottom to top) are available. The higher the ratio, the quicker the band stops the drum to engage Drive."

This is incorrect. The higher the ratio , the slower the band applies. Think about it. If the ratio is 5.0-1, the servo moves 5 times as far as the band apply end of the lever. 2.5-1 is only 2.5 times. Obviously it takes the servo longer to travel double the distance. A 5.0 lever multiplies the clamping force on the band greater than a 2.5. As far as planetary's strength he is correct. However I've only ever see 2 planetary bearings fail in almost 30 years. Never seen a planetary gear fail.
Doug

 

[dvw]

5.0 is what I would expect with the Hemi stuff. Leave it in there. No need for a new rear band unless it's burned, worn to metal, which I doubt. A&A or Cope may have a Hemi band . It'll probably be an exchange. I haven't bought one in years. If the KD band in the trans is not blackened or worn it may be reusable. You could also just run a standard drum and band if the cost gets out of hand. Then sell the Hemi drum and band.
Doug

 

[dvw]

Ok mines apart. Here's what Alto front clutches, stock rear clutches, and red line band look like after 420 passes. Aprox 900hp@3350#.
Doug

 

[383man]

I run a very stock 727 behind my 440/493 street car. It has been together since 2011 behind this eng and its holding up good and has run 10.70's. I race it now and then which is about once a year lately. I worked at a Dodge dealer for 24 years and did trans work along with everything else. So I have a few 727 clutches and steels laying around. I use all stock Mopar clutches and bands. I modded my servo piston and added a bolt in sprag (overrunning clutch). I use a Turbo Action reverse manual valve body and a Dynamic 9.5 converter. I do want to update my stock front drum when I can afford to get the drum and I use a trans blanket. Its a 99% street car that I drive a lot. Just raced it about 2 months ago and its still working great. If I raced it a lot I would definetly put the good front drum in it right away but I just start my burnout at the track in second gear. For a car like mine that's mostly just street driving with a trip to the track maybe once a year its holding up fine. Ron