Please bear with me on the pics. I have never posted pics before so I may mess this up.

Driveshaft came out going through the lights at 110 mph. (ran dead on with a 1 and won the round)
New, balanced driveshaft, new U-joints, new yoke. U-joints were standard greasable passenger car joints. I could not get the solid ones in time. By new I mean about 10 runs on them.

Car is a 72 Dart, footbrake, leave at idle, 3475 lbs. Runs 12.0s at 110.

I can help you post pics if you need

https://board.moparts.org/ubbthreads/show...e=0#Post5539002


What failed? The joints, straps, yoke

my first guess would be the little bity bolts for the straps

Looks to me like the the C clip wasn't properly seated on the one cap and most likly came off allowing the cap to slide out of the shaft. Once that happened it samcked and tore off the bolts.

Look closly at the cap that is still in the shaft and it looks like there is to much space between the C lip grove and the inside of the yoke for the other cap to be seated properly.

And yes, I know that from experiences

What suspension are you running? What is your pinion angle?

I found out the hard way that OEM yokes can actually spread a bit over time. That allows a little back-&-forth slop even if the straps and bolts are tight. It basically hammers itself out. Went to the steel billet versions and no issues at all.

I've spread the 1350 yokes before but I don't think that was your problem. Usually when you spit out a shaft the bearing cups will still be in the shaft end. Yours are not leaving me to believe that the one that is gone wasn't assembled correctly causing the rest to go to heII in a hand basket.

Might wanna check the sprag in the transmission while you're at it since this happened...

If it happened in high gear through the traps the sprag would have been free spinning and doubtfull it would see any damage.

I just finished welding the floor in buddys 66 Coronet. It lost a cap at the front u-joint on the X-way at cruise. The shaft had a large weight attached to it which ripped a hole in the floor and broke the console. I disassembled the trans. It broke the tail housing and cracked the governor support. The surprising thing is the output shaft is bent at about a 15 degree angle right behind the governor. It also broke the u-bolt straps and bolts in the rear yoke. Might bet is a loose,broken, or missing u-joint clip caused the failure. I've had this happen twice. Once at about 70 mph in my 4 speed Challenger. It broke the bell housing off the block. The other time was in my Max Wedge 63 Dodge going thru the traps at 130 mph. It broke the tail shaft.
Doug

Maybe it's just me but on a drag car straps and bolts on the rear yoke don't give me the warm and fuzzies, U bolts are the thing to use, but if you leave out the c clips all bets are off. Looking at the pics above the one cap still in the driveshaft has no c clip on it ????

Looking at the last pic in the middle row there is no evidence of a clip ever being in there, I would have thought there would have been a 'clean' area where the clip sat against the inside of the yoke but there's nothing.

I just seen this exact same thing the weekend before last. No previous issues, the guy upgraded to a new driveshaft and bigger joints etc. Is it a 1350 spicer joint?
Maybe theres a bad batch or some fakes going round
The guy was pitted next to me, he didn't spit the drive shaft out, just developed a bad vibration.
We helped him change it, looked like the outer needle race had cracked. This was one in the prop at the rear BTW, not the yolk, so it probably wasn't overtightened.

C clip came off ,don,t ask me how i know.

I would replace that yoke with a new billet steel yoke, there cheaper than new spicer forged yokes and stronger.
Make sure the new U joint presses or pops into place, a tight fit that will not fall out if you hold the yoke upside down and shake it The straps are on there to keep the U joint from being pryed out frontwards when the driveshaft turns, there not there to keep the U joints from flying out, that is the internal keepers job Let us know what you do and how that works

I recently lost a drive shaft in my GM toy, actually I lost every thing from the flex plate back to the rear end, smashed the trans inside and out, the driveshaft came back in two peices,my trans shops diagnosis was the uni holes in the front uni enlongated at 7000rpm & all hell broke lose from there,