I have the alum drum with the steel sleeve. From TCS kim
TorqueFlite Burnouts
- Thread starter 69valiant21
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breakstuff
Well-Known Member
I start in second gear then shift to 3rd. Burn outs are about wheel speed and putting heat into the tire. Cant do that with a first gear burnout.
d55dave
Well-Known Member
The sprag failure isnt necessarily due to the outer race tearing loose, although this is possible. More commonly the sprag roller(s) migrate beyond their pocket, into the next. Once this happens the locking force is gone and the inner race can rotate, allowing the drum to overspeed and explode. A bolt in sprag wont prevent this. A sprag with more rolling elements is better.
Here is a pic from a running 727 that I tore down that was behind a stock 318 poly its whole life. You can see the finger spring retainers are bent and one of the rollers has migrated. This is the start of a failure.
Here is a pic from a running 727 that I tore down that was behind a stock 318 poly its whole life. You can see the finger spring retainers are bent and one of the rollers has migrated. This is the start of a failure.
Duane
Well-Known Member
Very good post. Bravo
bOb shingler
Well-Known Member
d55dave, the case is cracked.
bOb shingler
Well-Known Member
breakstuff is correct.
d55dave
Well-Known Member
Yes. It was scrapped, the trans was used for parts to build a big block 65 vintage trans.
I removed the outer race and it appeared undamaged. I don't know if the crack was there from the time the race was originally pressed in or as a result of whatever caused the sprag to roll over. Everything else in the trans appeared normal.
Duane
Well-Known Member
Doh I have to start looking at my own posts lol. Did not even notice it. In my view that is the one to get if it is reliable. Thanks for pointing that out to me.
Duane
Well-Known Member
To me those photos and your explanation of the two distinct types of roller clutch failures are one of the best explanations I have seen.
It also explains that even a 904 while not as explosion prone, can still fail the roller clutch and you have a broken transmission.
Low band apply valve bodies and upgraded roller clutches are imho wise purchases for a performance torqueflite of either version. An aftermarket drum with a higher explosion rating is also wise just in case all else fails.
I also re read the exploding torqueflite post and noted that the drum rpm on a failed sprag is engine rpm multiplied by the first gear ratio.
So if your torqueflite has a 2.74 low gear, it is much easier to get the drum to its rpm limit. Most articles I have read claim it is engine rpm multiplied by 2.2
d55dave
Well-Known Member
Thanks for the compliment Duane.
You know, it is amazing to me that all of that rotating mass inside an automatic has very little keeping it all aligned and centered. There is the slip yoke at the back (provided the bushing isnt worn and you have proper yoke engagement), the one ball bearing in the tail shaft, the direct drum suppprted by bushings on the back of the stator and the nose of the input supported in the torque converter.....provided your eng to trans alignment is good. I really am amazed that none of this vibrates.
When you load the rolling elememts into the sprag it becomes apparent how much that inner race can move around. If you twist it and push it to one side the rollers will allow if to move way off center. I believe this happens due to case distortion and the internals moving around under torque, and the rollers then jump pockets and the sprag fails...
Just my opinion though.
famous bob
mopar misfit
I am not a trans, man at all. Have had an explosion in the old hemi car back in the day. But that rear sprag set up looks like a piece of crap and weak, poorly designed ton start with.
Duane
Well-Known Member
It works fine for its intended usage. Burn outs were not its intended useage, nor trans brakes and wheelies. Lol
I would hope that this thread will save some people from a torqueflite explosion through education.
Ironracer
Gearhead
I'm wondering a out on the street. Dry?
If you are at the drag strip and are on slick. Drive threw the water box and stop so that the pavement is still wet in front of the rear tire. put it in first and rev high enough that when you put it in 2nt that it shifts. Now either feather the throttle back out or stay in it until it grabs. This is all decided on how big your slick is and how much power you have.
When i had my 340 in my car (Manual shift valve body) take of in 2nt, hit 6000 rpm, shift into high gear. it would quit spinning, then i would let of the gas and stage the car.
With my 408 i do the same process but now i have enough power to keep it spinning in High Gear past the Christmas Tree.
You use up a slick real fast that way.
So now after i hit high gear and i see smoke from my back tire i release my line lock and roll the throttle back to idle.
What brakes the sprags is shock loads. like revving it up in first gear and then just lifting the throttle or push in the clutch. There is no load, so when the tire grabs traction, there is all that slack to JACK HAMMER THAT SPRAG. Same thing happens when you bust a u-joint or drive shaft.
But you don't know it is broken until you leave the line.............and if your lucking it only destroys your car. bad luck it take of you leg at the ankle.
The Sprag fail cause the cast iron Drum to over speed, fractures, and then come out like bullet from a machine gun. Big iron sharp shrapnel Bullets!!!!!!!!
As far as a standard street tire and a dry burn out, you wont usually be spinning the tire to 100 mph and then instantly grabbing traction, like a slick will do........it can still happen but the odds are a lot more in you favor on the street.
When i had my 340 in my car (Manual shift valve body) take of in 2nt, hit 6000 rpm, shift into high gear. it would quit spinning, then i would let of the gas and stage the car.
With my 408 i do the same process but now i have enough power to keep it spinning in High Gear past the Christmas Tree.
You use up a slick real fast that way.
So now after i hit high gear and i see smoke from my back tire i release my line lock and roll the throttle back to idle.
What brakes the sprags is shock loads. like revving it up in first gear and then just lifting the throttle or push in the clutch. There is no load, so when the tire grabs traction, there is all that slack to JACK HAMMER THAT SPRAG. Same thing happens when you bust a u-joint or drive shaft.
But you don't know it is broken until you leave the line.............and if your lucking it only destroys your car. bad luck it take of you leg at the ankle.
The Sprag fail cause the cast iron Drum to over speed, fractures, and then come out like bullet from a machine gun. Big iron sharp shrapnel Bullets!!!!!!!!
As far as a standard street tire and a dry burn out, you wont usually be spinning the tire to 100 mph and then instantly grabbing traction, like a slick will do........it can still happen but the odds are a lot more in you favor on the street.
There's nothing WRONG with a stone stock 727. NOTHING. All you have to do if you decide to do a burnout is DO NOT let it hook up on the 1-2 shift. That's the killer. As long as it stays spinning into 2nd gear, it will never, ever have a problem. Stone stock, with NO manual valve body, NO bolt in sprag, nothing. It's all in knowing how to or more importantly how not to drive one. That's all.
I've been racing 727 TF for over 20 years and have never had a transmission failure. I remember reading years ago Paul Forte of Turbo Action recommended starting burnouts in second gear and shifting to third before coming out of the water. That's been my procedure for all the years I've been racing and have never had any issues to date, knock on wood!
B3422w5
Well-Known Member
727 or 904, always started burnout in second gear
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RockinRobin
Well-Known Member
727. If I blip the throttle when tires are in the water I do that in 1st gear. Then start burnout in 2nd, go immediately to 3rd and finish the burnout in 3rd.
About 5000-5500 rpm. I NEVER downshift to 1st for any reason burnout or otherwise.
About 5000-5500 rpm. I NEVER downshift to 1st for any reason burnout or otherwise.
Ironracer
Gearhead
So, if I'm driving a 727 with a shift kit, stock vavle Bobby, on the street, dont downshift to 1st gear ever? 74 duster , around 400 ho 340, 2200 stall, 4:10.
Here’s the results of my friends FRESH 727 in his small block Indy headed street strip transmissions after a few street trips doing a few things a car that runs 10.30’s shouldn’t do. My son pulled the transmission for him and another friend and I tore it apart yesterday afternoon. Metal from the drum contaminated all the clutches so it need s new drum, band, and clutches. This is the lip that holds the spring retainer.
Holy ****, I’ve never seen that. We’re they mixing and matching? Kim
Ironracer
Gearhead
Wow! That's kinda trashed looking! Doesn't look cheap either
Holy ****! Where's the pic of the guy beating the dead horse? On manual valve bodies: start in 2nd. Stone stock valve bodies: listen to RRR!!
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