Torqueflite Exploded on Freeway

[-Mike-]

Hi everyone,

while accelerating full throttle at around 4000rpm doing about 100mph, my transmission suddenly and with no previous sign of failure, exploded. No one was hurt, no shrapnell inside the car. Drive shaft yoke at the tranny has sheard off. I was able to coast and stop safely on the breakdown lane. Apart from the destroyed transmission and the driveshaft, everything else is fine. Does anyone have any idea what could have caused this?
69 Road Runner, 76 440 with purple cam, TF727, 3.23 gears, 2500 stall, no extra tranny cooler, only stock transmission oil cooling through stock (wide version) radiator.
I've had the car for six years now, engine/transmission worked absolutely fine until then. Small oil leak at the rear of the transmission. Tranny oil changed two years ago. Everything seemed to be balanced just fine. No vibration or anything.

I was driving for roughly 15 minutes when the tranny failed and had been rolling around at 2000rpm until then. I always try to give everything time to reach proper operating temp. Engine water temp has reached 180F ca. 5min before I put the pedal to the metal and the transmission destroyed itself. Water temp was still at 180F when it happened.
Thanks for any ideas on why this could have happened or how to avoid this in the future. No speed limit, by the way, as the "Freeway" is an Autobahn here in southern Germany. Regards Mike

 

[dvw]

Spit the U joint cap out of the front yoke or the front of the drive shaft due to poor fit or clip failure. My bet is it bent the output shaft, broke the tail housing. The floor probably took a good whack as well. look for a missing u-joint cap. Not the first tie I've seen this. Trans damage actually wasnt bad
Doug

 

[F4R/T]

The only thing that comes to mind is a sprag failure to cause an explosion... without seeing the remains I’m guessing.. very glad to hear your okay and it didn’t cause an accident or hurt the bird other than that causality... be safe and keep us posted it may be a good idea to ask a tranny pro to look at the carcass.... at lest it will give you an idea hopefully.i agree with Doug look at the drive shaft closely and look at floor pan for telltales.

 

[Officer Higgins]

Had front u joint fail on mine same thing heavy vibration then bam.

 

[F4R/T]

Wow I really thought you’d get a little more warning with a front u joint failure coming on... that’s pretty scary stuff there.. makes a front drive shaft loop look pretty good..even on a stocker.

 

[myk r sanchez]

Jesus. Glad you're ok and it sounds like minimal damage to the car itself.

So, how do the rest of us check our cars to make sure this doesn't happen to us as well? What parts do we check and what are we looking for?

 

[68Moparmaniac]

Jesus. Glad you're ok and it sounds like minimal damage to the car itself.

So, how do the rest of us check our cars to make sure this doesn't happen to us as well? What parts do we check and what are we looking for?

I check mine by crawling under the car and grab the driveshaft and give it a shake, shouldn't move much if at all you'll feel a bad u-joint.

 

[dvw]

Usually it is not joint or yoke failure itself. The retaining clip for the u-joint cap breaks. Most often because the cap wasnt fully seated in the yoke or shaft. Then the cap flys off. Now there is way to much play and vibration. Then failure. Has nothing to do with the low roller (sprag). Just had a buddys race car do this at the top end of the track. I'll be fixing the trans next week when he pulls it. Last one I fixed that did this only needed a tail shaft housing and shaft. Along with floor and console repair. The rest of the trans was fine.
Doug

 

[66Satellite47]

Hi everyone,

while accererating full throttle at around 4000rpm doing about 100mph, my transmission suddenly and with no previous sign of failure, exploded. No one was hurt, no shrapnell inside the car. Drive shaft yoke at the tranny has sheard off. I was able to coast and stop safely on the breakdown lane. Apart from the destroyed transmission and the driveshaft, everything else is fine. Does anyone have any idea what could have caused this?
69 Road Runner, 76 440 with purple cam, TF727, 3.23 gears, 2500 stall, no extra tranny cooler, only stock transmission oil cooling through stock (wide version) radiator.
I've had the car for six years now, engine/transmission worked absolute fine until then. Small oil leak at the rear of the transmission. Tranny oil changed two years ago. Everything seemed to be balanced just fine. No vibration or anything.

I was driving for roughly 15 minutes when the tranny failed and had been rolling around at 2000rpm until then. I always try to give everything time to reach proper operating temp. Engine water temp has reached 180F ca. 5min before I put the pedal to the metal and the transmission destroyed itself. Water temp was still at 180F when it happened.
Thanks for any ideas on why this could have happened or how to avoid this in the future. No speed limit, by the way, as the "Freeway" is an Autobahn here in southern Germany. Regards Mike

When you say that the trans "exploded", what damage to the case & tailshaft? Check the internal components to see if the front clutch drum is intact. Not likely the trans internal components failed under those circumstances, sounds like a drive shaft failure that took out the trans. It happened to ME at 116 going through the traps, 7000 RPM. Tossed the drive shaft out the back, right over the windshield of my best friend in the other lane. Broke the bell housing off the block, disintegrated the tail housing, bent the output shaft about an inch. You obviously need a new 727 & complete drive shaft. Get a big new aftermarket shaft & 1350 U joints. Drive shaft loops are a real good idea, make sure it has enough clearance(or ability to take apart) to remove the drive shaft. One near each U joint, front & rear is a good idea too.

 

[-Mike-]

Doug's idea makes sense. Thanks everybody for the replies, so far.
Had the car towed to a repair/transmission shop. They claim to be specialized in old American transmissions and have several 727s laying around. I will post here what they found out. However, they said it will take them a few days till they have time for my case.
When the transmission (or the remains thereof) is out, I will also look at the floor panels more closely.

 

[747mopar]

Glad your O.K. Post a picture of the tranny once you get it out.

I lost a front U joint in an old Polara years ago, it broke then stuck in the pavement... Scared the **** out of me, felt like I ran over the transmission it kicked up so high in the *** end.

 

[-Mike-]

When you say that the trans "exploded", what damage to the case & tailshaft? Check the internal components to see if the front clutch drum is intact. Not likely the trans internal components failed under those circumstances, sounds like a drive shaft failure that took out the trans. It happened to at 116 going through the traps, 7000 RPM. Tossed the drive shaft out the back, right over the windshield of my best friend in the other lane. Broke the bell housing off the block, disintegrated the tail housing, bent the output shaft about an inch. You obviously need a new 727 & complete drive shaft. Get a big new aftermarket shaft & 1350 U joints.

The tailshaft housing as well as the main transmission housing cracked where they attach. See photo.
1350 u joints and a decent drive shaft are definitely on my shopping list now.

 

[-Mike-]

The thought of the car pole vaulting because the driveshaft gets stuck in the pavement is quite scary. Might also get a shaft loop while I'm at it...

 

[myk r sanchez]

Doug's idea makes sense. Thanks everybody for the replies, so far.
Had the car towed to a repair/transmission shop. They claim to be specialized in old American transmissions and have several 727s laying around. I will post here what they found out. However, they said it will take them a few days till they have time for my case.
When the transmission (or the remains thereof) is out, I will also look at the floor panels more closely.

So are all 727's the same, internally, with the same ratios between the speeds, or whatever they're called? What if you get one with the incorrect ratios or something?

The thought of the car pole vaulting because the driveshaft gets stuck in the pavement is quite scary. Might also get a shaft loop while I'm at it...

So a loop would completely prevent this from happening? How hard is it to install one?

 

[493 Mike]

So are all 727's the same, internally, with the same ratios between the speeds, or whatever they're called? What if you get one with the incorrect ratios or something?
Torqueflites all use the same gear ratios.
Mike

So a loop would completely prevent this from happening? How hard is it to install one?

Not bad. There are universal models available and Mopar specific units that bolt on the transmission cross member attachment bolts. The universal models bolt thru the floor pan.
Mike

 

[turbine68rt]

So are all 727's the same, internally, with the same ratios between the speeds, or whatever they're called? What if you get one with the incorrect ratios or something?


So a loop would completely prevent this from happening? How hard is it to install one?

Yes, 2.45:1, 1.45:1, 1:1

 

[66Satellite47]

So are all 727's the same, internally, with the same ratios between the speeds, or whatever they're called? What if you get one with the incorrect ratios or something?

Yes the 727 ratios are same. BUT there are MANY different versions of internal parts, depending on the OEM application and model year. Different number of clutches & springs in front drum , front band lever ratios & servo spring combination, valve bodies & governors.

 

[Dodge Bros]

Probably need to look at the driveshaft closely and if possible figure out which end of the driveshaft was closer to the failure.

I had this happen to me years ago going 110 mph in our 69 charger. The only thing we could figure out was the differential was running dry(took it apart and it was dry) and a piece of debre fell into the pinion/ring gear and locked it up momentarily. We didn’t save the drive shaft, but the u joints were fine, it broke off the straps holding on the back u joint. The drive shaft some how fell to the ground after we stopped. The whole exhaust system got ripped off. Drums and sprag appeared to be intact. My dad and brother were a 1/8 mile behind us and the front of the pickup up was covered in Tranny fluid. They watched it happen, parts flying everywhere. Nothing was left of the tranny, even the starter fell out. I coasted for nearly a half mile after it happened.

I had another one that the drive shaft was out of balance on the transmission end and it broke the tail shaft, but saved the rest of the tranny. That happened on a race track.

 

[BDF6]

Glad YOU are OK!
Here is an option I like & need to install:
http://www.manciniracing.com/bofrdrlo.html

 

[Dipstick]

I wouldn't call a slip yoke failure a "transmission explosion". Same thing happened to me under the same circumstances but I had a driveshaft loop.