"Live From" Numidia Dragway

[Keith 944]

Originally Posted by Tom Goldman

Looks most likely like a TH35O intermediate sprag failure causing a drum explosion.
TH 400 will fail

It was a mopar so probably 904 or 727

[Gmirza]

Tough day for the mopars. Thats a Dakota hitting the wall and a dart or demon with the tranny explosion. That’s why they make us run blankets or shields. Any word on the driver, you know his foot was on that gas pedal.

[Tim H]

Truck looked like an S-10 to me, however I wasn't there.

[Keith 944]

Truck was an s-10
And the mopar trans issue guy was in burnout box. Got out of car fine. Should have Rattled him a bit

[gmonde]

i see a piece of snap ring on the ground ,,if was to guess it was 727 and the drum blew up and took the rest of the case out is what i am seeing ,,

[Keith 944]

Originally Posted by gmonde

i see a piece of snap ring on the ground ,,if was to guess it was 727 and the drum blew up and took the rest of the case out is what i am seeing ,,

Scares me a little the car I’m running is a small block mopar with 727 and no blanket or shield runs low 11’s street/strip. 3750# coronet Was told only do burnout in 2 and high and don’t let it snatch while spinning

[gmonde]

Originally Posted by Keith 944

Scares me a little the car I’m running is a small block mopar with 727 and no blanket or shield runs low 11’s street/strip. 3750# coronet Was told only do burnout in 2 and high and don’t let it snatch while spinning

Yeah ,,this is the second 904 I built ,turbo action manual valve body,,,second gear only burn out from the instructions, 904 stuff is smaller plus I did a aluminum front drum ,

[Paul Precht]

I run valve bodies that hold the low and reverse band in first, even if you break the sprag you'll never turn that drum fast enough with a band holding it to explode the drum. Those valve bodies that don't hold the band should be thrown out.

[CMcAllister]

People have been preaching to these guys for years. And plenty of them reply "been doing it my way for years and nothing ever happened".

No need for this to happen. With no low band apply in low gear, and the roller clutch completely fails under load in low gear, the engine freewheels. At somewhere north of 5000RPM x low gear ratio - 12000+RPM - the cast OE front drum explodes.

The use of an aftermarket steel or aluminum drum and/or a low band apply valve body, prevents this from happening if the roller clutch fails.

Just because the car moves in low gear doesn't mean the roller clutch hasn't failed. I've seen them in transmissions that came out of a car - that was being driven but had the rear end recently broken and repaired - with half the springs mashed and only half of the elements holding. This can happen with a 904, but the 727 is the one with the heavy OE drum that blows up.

Failing to follow instructions for how to drive the car and/or a driveline or rear end failure under load in low gear will kill the roller clutch. Sometimes it still works well enough to get it into the water or to the starting line, with ugly results.

[Gmirza]

Glad to here the drivers are ok. I guess I was mistaken on the truck.