Check out this 727 blowup

[port-holio]

riding shotgun when 440 BB Dodge truck at 12psi WOT blew up last night at the top of third gear. Not a stutter or hickup until it let go with BANG!! followed by a comet tail of sparks, and clang-a-langing. The explosion rocked the truck, flattened the rear right tire, and hit the passenger floor pan so hard it knocked my feet in the air. It was so violent we were counting toes when it came to a stop.

We found the splined end of the driveshaft and one of the yokes, but the rest is MIA, other than a couple pieces of bell housing. It looks like the driveshaft broke AFTER the explosion. The white paint on the splines is what it scraped off the dotted line on the road.

As you can see, the bell housing is completely gone, and the trans is sittin 90 degrees from normal. The SFI converter and flexplate survived. Since much of the case is intact, I don't think this was the dreaded overrunning clutch explosion?

Opinions theories and chastizing welcome......

 

[4spdragtop]

Wow time for a diaper change!! I was looking at the 1st pic trying to figure it out, had to read to understand its rotated 90*. Glad you're ok

 

[Inertia]

Wow, You are really lucky dudes.. Be careful for the rest of the year, cuz you used up ALL of this years luck last night.. lol take care...

 

[Leadfoot]

When you say "Top of third" is that the 2-3 shift point? If it's at the shift point your front band might not have released soon enough causing 2-3 overlap but the damage looks a little excessive for something that should have just destroyed the band. When I was overlapping my tires would lock up and actually chirp going into third. It wasn't a chirp but a skid for a brief fraction of a second then third would engage. So I'm guessing your front band didn't release and locked the trans between 2-3 but that's just a guess because your tires should have locked up first. If that's the case you're lucky you lived through it.
In my head I'm trying to go through the physical movement to decide whether 2-3 overlap would do that to your drive shaft though. Maybe after another coffee I'll be able to figure it out.

 

[roadrunnerh]

:shock: Holy ****!

 

[port-holio]

nope it didn't blow up on the shift. It was topping out in third gear, and he was just about to get out of it and shut it down. It let go roughly 5000rpm.

on the plus side, the AFR was right and intake air temp was pretty good. The truck has the Eddy ProFlo MPFI set up, driven by MegaSquirt3, and boosting by a stupid big turbo. Buddy had just gotten the bugs worked out of the ignition, and got the blow off valve and wastegate set right.

 

[Burntorange70]

Yikes! Good to here you are both ok.

 

[Mad Dart]

nope it didn't blow up on the shift. It was topping out in third gear, and he was just about to get out of it and shut it down. It let go roughly 5000rpm.

on the plus side, the AFR was right and intake air temp was pretty good. The truck has the Eddy ProFlo MPFI set up, driven by MegaSquirt3, and boosting by a stupid big turbo. Buddy had just gotten the bugs worked out of the ignition, and got the blow off valve and wastegate set right.

Glad to hear you are all OK. I am at the point of making a Trans Decision. Just about everyone I talk to says to get the Billet Front Drum.

I too am running a MegaSquirt3, I had Ignition issues also. What were his ignition problems and what was the fix?? I am pretty sure I found my issues but would like to know what his were if possible.

How much power is the combination making? If you can Post up some pictures of this Boosted Big Block I am sure everyone would like to see them.

 

[Mad Dart]

On another note, do you think he might have hurt the Sprag on a different occasion and this is the end result??

Do you think a Solid Rear Trans Mount would have kept it from twisting? I heard they may crack the case though.

 

[500stroker]

I would have shat myself.

 

[port-holio]

His ignition woes were mainly the result of Eddy's backwards pig latin software and their insistance on a one of a kind distributor.

Eddy's tuning software is seriously the most convoluted illogical mess I've ever experienced. It made my old Holley commander 950 look like HookedOnPhonics. (but the old style ProFlo tunnel ram intake was worth ~50hp to the wheels on this truck in NA trim vs the dual plane)

The aha moment was when one of the local EFILive/MS kids found it was trying to use trailing edge instead of leading edge triggering. The Eddy proflo dist is a one of a kind, and uses an odd short tooth on the trailing edge for some kind of cranking advance trigger, and confuses normal ECU's. It's almost untunable with the Eddy ECU.

Estimate it was giving maybe 500-550hp. It has terrible heads and no compression. The turbo doesn't run in the effiecient part of the map, and the motor was very tired. Poor old RV motor got a few hit of 175hp spray before the turbo. Been trying to kill the motor all summer and the trans blows up.......

let me try to find some pics.

 

[crackedback]

Maybe the driveshaft started to come apart and vibration killed the rest.

 

[port-holio]

On another note, do you think he might have hurt the Sprag on a different occasion and this is the end result??

Do you think a Solid Rear Trans Mount would have kept it from twisting? I heard they may crack the case though.

I don't think it was a sprag failure, because neither the overrunning clutch nor the front drum seem to have blown up. appears to be mainly a bellhousing failure.

Since the crank is spinning CCW from the rear, I'm trying to picture how something could have jammed so that the reaction force also twisted the trans CCW?

From what I've heard, solid or urethane trans mounts are bad news. According to theory, the trans mount should be more flexible than the motor mounts, or all the torque will be taken by the bell housing which will crack.

 

[moper]

That was not transmission failure that I can see. That looks more to me like the driveshaft failed and that out of balance ripped the mount and bell. If that was the trans, the case around the gear train would have let go or completely ground itself up.