Once again I'm gonna play the cynic; I doubt that the OP's sprag failure was really that spontaneous, probably in distress before the R&P failure.

Curious of why it would be compromised before the R&P failure? The reason I say that is that when I pulled trans after the R&P failure I could not turn the driveshaft or trans output shaft by hand, need big pair channel locks, before the failure the car rolled very easily in the staging lanes.

The rolling test of a sprag proves nothing until a catastrophic failure jams it up. I just don't see the galling in the OP's pic happening in a few seconds.

Curious of why it would be compromised before the R&P failure? The reason I say that is that when I pulled trans after the R&P failure I could not turn the driveshaft or trans output shaft by hand, need big pair channel locks, before the failure the car rolled very easily in the staging lanes. [/quote]

With any rearend or driveshaft failure we check the output shaft and if it doesn't turn free the we remove the trans for inspection and repair.

Every one I have ever seen was "spontaneous" or related to a specific indecent of extreme shock to the drive train - if you break a rear-end in first gear this usually happens - the only time I ever had one saved was by the use of a air shifter - the trans shifted to second when it free-wheeled - I still had it checked out to make sure - cause your not gonna find out until the next pass......

This is what happened after we took some teeth off the R/P (dana 60)

Probably a stupid question being i have never pulled a trans apart but i assume the whole trans needs to be torn down to get to the sprag?

Yes, it is in the very back of the inside of the case.

Ok, just for argument's sake.
After how many passes/seasons should one inspect the sprag?

I generally rebuild / check the trans after 5 seasons (250 - 300 passes here). It doesn't usually wear too much. After any sort of drive line failure I check the sprag.

Back when 727 and 904's were the primary product line trans, I never once saw a tech disassemble an overrunning clutch. They would spin it and move on. That's a flat rate tech for you. I ALWAYS mark every roller for location, disassemble, diagnose condition and reassemble with new springs in their original location on the cam. I always keep the inner race orientation the same as well. Some will say anecdotal, but, all rollers are not created equal. I mic them for both diameter, length and check for identical champfer. The matched sets on the high side of spec diameter, are prized now, that the oem roller and spring packages are history. Leave no stone unturned.

Of course, the failure was spontaneous but if you hadn't physically inspected the sprag one run before the failure how do you know its condition before the failure?

I've pulled apart plenty of 727's that were working just fine but had rollers with visible flat spots

I busted my 8-3/4 on a launch once a few years back. I pulled the trans down and found the sprag to be a-ok, so back together it went.. I took the opportunity to reassemble with new clutches and steels, so the R&R time wasn't all for not. Considered myself lucky.

This past year I did a maintenance rebuild and added a bolt-in sprag just as an extra safety measure.

As far as checking the sprag on rebuild, if the pins are straight, move on. Not believing failure could occur on a new sprag when a driveline part brakes, when it free-wheels and slams back under load, no way is it strong enough to not damage or brake it. The sprag was never designed for that kind of abuse. As far as explosions, I'd say the driver is not paying attention to what the "car" is telling him. A simple test to do after your burnout, put in low, push throttle to reset the sprag rolling foward, if it feels not right, abort the run, you broke it. Never roll-coast to the line after the burnout. By the way, I've done first-second-drive burn outs forever and never broke a drum, but have broken two sprags hitting wet spots after the burn out box on dry hope and feeling the results.

Totally disagree; rollers with flat spots can co-exist with straight pins. Sudden shocks occur with Clutchflites/Neutral and failures aren't epidemic with such abuse.

Clutchflites- neutral starts? I can take a big hammer and beat the crap out of anything too.
Must have taken 100s apart in the last 50 years and never saw flat spots on rollers, unless sprag was broken, thoreticaly impossible to slide under load (they break first or the springs have lost tension from heat) seen plenty of broken, chewed up ones. Of course I should add, inspect ever part of the sprag unit to be safe before putting back in service. To each his own.

are the above statements saying neutral drops don't affect the sprag ? what fails internally when neutral drops are stupidly done ? or am i not understanding something in these statements ?

Do a few, then try looking thru the broken parts to find out what broke first. It was a starting line practice back in the sixtys but the tires where tiny. NHRA banned it after too many clean ups. Then the billion dollar converter industry came about.

Again we disagree; rollers sliding is the initial failure mode IMO, the FSM even advises checking the rollers for flat spots. You have a roller and inner race that have highly polished surfaces...in reality it's a miracle of physics that they even hold.

Yes, again we disagree, the perfect wedge till one side gives or is overcome by load.