I didn't want to hi jack the other 727 thread but do have a few questions.

These explosions with 727's do they only occur when a trans-brake is used? or can it happen footbraking as well?

Which part actually causes the carange? The drum exploding?

Which stock parts should be updated and to what to help prevent such thing from happening.

I have a 3200 car that runs high 10's in the quarter and am looking to start top bulb racing, but not use a transbrake, but instead use 4 line locks, starting line controller, etc. My 727 has stock parts other than a TB valve body, been raced that way for many years footbraking. I do have a CSR shield installed, but didn't know what else I should upgrade.

What actually happens is the sprag rolls/breaks in low gear and allows the front drum to spin over twice engine speed. It can happen on any trans with no low band apply. I've seen it happen on a high 13 second footbrake small block car.

The cast iron front drum explodes.

You need a billet steel or aluminum drum, Super Sprag, and a low band apply valve body/brake. LBA and a sprag help, but the billet drum is what prevents the big boom.

Unless you're ET chasing, index racing and to gain .0001...Go with a Billet steel drum, it'll last longer.

And it doesn't matter if you're using a transbrake or not. My stock drum exploded footbraking, after 2 years of abuse in a 9 sec 3800 lb car. The pass before it exploded, the car spun then hooked in low gear. That probably killed the sprag, then the next pass it exploded when I hammered it at the line. Made a big mess.
Had a TA manual VB in it w/ no low band apply.

I have one with a stock drum and now thinking about just buying a billet one for it before putting it in the car.

I just have a stock valve body with a Transgo 2 shift kit.

It has a column shifter that I was hoping to just leave in DRIVE and use the governor weights to raise the WOT shift points. Sound like leaving the line in DRIVE with a regular valve body means the low band is not applied? Starting in second applies the band, but starting in second can't be good either?

Wonder how the F.A.S.T. class racing guys set theirs up? Do they shift them manually with the stock console and column shifters?

Another thing to consider, along with what was just said about spinning out of a burnout and then letting it hook hard hurting the sprag. Broke a u joint and lost the drive shaft. It allowed something to brake in the trans and my buddy did not even bother to pull the trans to check it. It let go the next time out. And his was a 400. So it can happen to all trans types.

Yes the vast majority shift their columns and stock console. I don't, my motor is all done at 6200 rpm and I have the a&a govenor for 6000 rpm. The trans is from Cope Racing Trans with low band apply. I run a blanket.

Scenario with a friends car: did burnout in 2nd, pulled to the line, left in 1st, broke the 8.75 on launch. In hindsite the gear breakage shocked the sprag and about 150ft later the STOCK drum exploded.

I don't run the super sprag, and my one Griner was not a LBA nor was the tranz-act in my old car, but we run the billet drum. Not sure if my current t-brake is LBA or not.

True but a failed sprag often wipes out the case anyhow....but less dramatic.

The failure is caused when the low roller (sprag) is shocked and fails to keep the rear drum from rotating. This in turn causes the forward drum to spin at rear gear ratio (aprox 2.3) times engine RPM. The stock front drum will not withstand much over 10,000-12,00 rpm. It weighs about 7lbs. That's a lot of force at that speed. I tried the double line lock. Found it to be slower than foot brake. What tree? .400 or .500? Can you deep stage? If your trans has a brake why are you not using it? With your car I would suggest the aftermarket drum of your choice. And a steel front planet if you're going to run the brake. At that level that"s really all it needs. If you foot brake I'd put a switch in the brake pedal for a 2 step and stage as deep as necessary (and allowed) for proper R/T.
Doug