I had a 800+ car on the dyno yesterday. On the first pull I was going to go to 6500rpm's then change out the pills and do a full pull. On the first pull I let out at 6400rpm and thats when everything came apart. The driveshaft broke (into 3 pieces) tore out the exhaust, ripped through the floorboard and broke the transmission (th400) case in half. There was no vibration or any other signs anything was wrong before or during the run. The car gets run hard all the time so this wasnt the first time it was spun up.

 

Dyno's are rough on the drivetrain. On the street or at the track the momentum of the car alone will keep things from binding. On a dyno however when you let off the rollers are still loaded so the deceration isn't as smooth.

 

Happened on my car around the 6400rpm mark. Did not do near the damage you are reporting and only broke in half. It did tear up the exhaust, bent the torque arm and dented the floor pan. Having a loop installed.

 

DS loop is something I wouldn't run the car without. the thought it it shattering is making me wonder if I should get a ds before the a new rear.

 

steel shaft?

 

happened to me too..Broke my drive shaft in two,and broke my TA,and tailshaft/inputshaft,and a nice hole in the floorboard

 

Sorry to hear this bro.

 

Damn thats a bad deal. Was there a driveshaft loop on the car though? Kind of curious as a car with that much power should've had one on.

 

I've had this happen to me.. And people wonder why I don't let them stand around the dyno. A driveshaft will do an incredible amount of damage before you even realize what is happening.

 

who's car was it.

 

Yeah, what kind of shaft was it?

 

Just FYI...alot of times when you see driveshafts broken on the dyno its really not the DS fault. Many times its a tranny faliure or some other component failure. The drums are alot of momentum.

And of course old school steel DS's do suck as well...especially unbalanced ones..lol.

Anyways...I have seen that happen a few times and it is scary..lol.

SOme guy brought in an old tired 3rd gen camaro one time, it was put on the rack and the tranny was just making aweful sounds. The dyno operator wanted to know if the owner wanted to continue...he said yes. He made a pull and the power was WAY down from what they expected. Again the dyno operator asked if he wanted to continue...and the owner said yes. LOL...the very next run around 5500 rpm everything let loose like a bomb. Tranny parts all over the shop followed by driveshaft parts...follwed by the rest of the DS taking out exhaust and the tunnel.

 

I saw car up @ Vengeance where the DS exploded and took out EVERYTHING including the motor itself. Pretty sweet unless you're the guy payin for it.

 

I had a Tahoe on 24's with a 6.0 and a radix blower grenade the driveshaft also. It took out the floor pan, evap canister, exhaust, and busted the tranny all the way up the case while ripping the tailshaft out. Made some nice marks on the floor! One of the guys across the shop got hit with a ujoint cap! I'm pretty bad bout making everyone get away from the car during a pull now.

 

Hopefully I can anwser all the guestions asked. This was in an old Nova with a big block. Its just a show car with a with a big motor. There really isnt any kind of safety stuff on the car for that kind of hp. The owner bought the car with the motor in and just fixed the car up. It was a steel driveshaft but it looks really small compaired to the ones I run. The car doesnt get raced and has never been raced, it just a show car that gets drove on the street some. Im sure now since this happen the owner is going to install atleast a ds loop and maybe some other safety items.

 

Wow, that sucks on a show car that doesn't get raced. Bet that guy never goes more than 1/4 throttle again for the rest of his life.

 

I broke my driveshaft dyno testing in my '69 Nova 3 years ago. It let go at 5600 rpm while still at WOT. Even though I had a loop it still busted the TH-350 case, knocked out one side of the exhaust, and put holes through the floor. There were needle bearings all over the floor. I found out that stock drive shafts are only rated for around 5,000 rpm. I now have a 3" heavy wall driveshaft, and it has been load tested to 660 rwhp. For some reason everyone cleared they dyno bay for my return test.

In my case it's not a show car. Here is a picture from last Saturday night. I ain't scared to go WOT... this is actually the first picture I have showing a wheels-up launch.

 

^^ sweet

 

It's happened a few times at my buddies dyno, the DS didn't break on one of them, it just twisted it like a pretzel!

 

the problem is usually exceeding critical speed of the shaft. It doesn't matter if it's balanced or not.

That's how i figured it was steel. If it wasn't made for high speeds, torsional vibration caused it to pretzel. All the balancing in the world won't help it.