Mith-Busters Driveshaft a Pole Vault

I just finished watching the episode of them trying to confirm whether a car can launch itself if the front u-joint failed. We all know this can be an issue in drag racing. Drive shaft hoops are very common and available most anywhere as well as simple to self-fabricate. When I built my first car not much thought went into it but since, one has been added. On the car they used, an early seventies Mopar, what was impressive was the damage to the trunk area from the impact of the folded drive shaft. In an early hot rod that damage would, most likely, be right at the right arm of the driver. You can imagine what the impact a spinning hatchet could have on your flesh. Their car was only going thirty-five miles per hour. Now imagine seventy. If you don't have one think about adding one. Anyone else have a bad experience store about this issue? I'm going out now to design one for the roadster I'm building now. What thickness are they usually? I'm thinking 2'x1/4" for my flathead application. Any suggestion or pictures out there?

 

2" x 1/4" is a typical size (I think that's the NHRA spec), mounted within 6" of the front ujoint.

pictures? sure

http://images.google.com/images?gbv...m=0&ct=result&cd=1&q=drive+shaft+loop&spell=1

 

Had one come out at 75mph. I'm not sure how high in the air we were but it did come down hard. '72 Monte Carlo with a 383 stroker, 400 auto and a 12 bolt. Kept it on it's wheels but ended up in the median. The driveshaft hoops we installed were 2 x 1/4 the same as you mentioned which were dictated by track rules.

 

Yeah, I knew a guy that ran a conventional GMC 10 wheel tractor trailer hauling sand and gravel. They put a dig Detroit V12 in it with a RoadRanger, not sure which one though. Anyway, they blew the back of the trans off and the driveshaft hit the ground, lifted the ass end of the tractor and front end of the empty trailor and jack knifed the whole rig and put it on it's side. This was at speed on the Expressway back in 1969 or so.

 

Ive lost one in a 66 dart with a bigblock - Hit 2nd gear -dropped and stabbed - lifted and kicked the butt over - not fun and costly -- I use 3 inch pipe split with a 2 inch piece of flat stock ( 1/8 Inch ) making a nice oval - Jaxx

 

I chunked the DS in my 96 S10 at 80 about 2 years ago. Broke the front shaft and the rear u-joint egged the rear end pinion saddle and snapped the bolt. I got lucky it didn't vault

 

got up to about 90 on the freeway once and felt a vibration so I let off the gas to slow down and my driveshaft hit the floor and went out the back. I saw it in my rear view mirror about 5 feet off the ground and all bent. luckily no one was around on a sunday morning. I coasted to the next exit.

 

A friend did a burn out with his 63 c10 an lost the rear joint. There was lots of splintered wood and it tore out half the bed before he could shut down the engine. And to think that now it's cool to run a pick-up with out a bed floor!

 

Those stories scare the heck out of me. Do I avoid this by being good on the gas and keeping up with the maintanence or should I start carrying a good supply of TP with me when I nail the throttle?

 

I have a customer that is paralyzed from the waist down due to the other car losing a driveshaft at the big end of the track. He ran over it at 150+ mph and the results were catastrophic. I recommend one loop in the front, and one in the rear.

 

Had a buddy that lost one of his exhaust pipes at the header, it dropped into a crack in the pavement down Main Street of our home town and volted the car! Lifted the rear end of the car at least 3' off the ground, when it came back down, we narrowly missed a couple parked cars. What a ride! we probably weren't even doing 30 mph.
Ripped a hole in the floor pan above the rear axle before it folded the pipe around the axle. That was a 2" exhaust pipe, droping a drive shaft must be a real experience. Gene

 

amazing how this fell to the bottom so fast, had to do a search for it.

 

Glad I read this. We were moaning the other day because we have to fit one to pass rego. Now maybe we won't moan (so much).

 

I dropped the front of a tail shaft once at around 20 MPH. Fortunately it went sideways and just locked the rear end up solid. Frightened the crap out of me. I have fitted a tail shaft loop to every single car I have owned ever since.

 

Driveshafts can be VERY dangerous !!! That's why I refuse to run one. I sit in my car, in the garage, making car sounds.

 

I just use cardboard tubes, much safer.-MIKE

 

A simple way is the loop that mounts under the tranny mount. simple enough to make with a 2" slice of pipe and a strap. You need 5" pipe to get >1/4" wall in sch 40. Any pipe in sch 80. A similar deal could bolt to chunk bolts on Ford rear. I plan this as driveshaft will be at my ribs.
http://www.jbp-pontiac.com/products/dress_up_misc/dress_up_misc.html

 

A buddy lost the driveshaft on a '62 Chevy at about 90 MPH and vaulted, tore the rear end right out and ended up in the ditch on his side. Lucky thing, though, he was drunk and forgot the road, he was 1/4 mile from a 90 degree corner and a 100 foot dropoff! Sometimes luck takes strange forms.

 

Back in 76 I drove a new Impala just unloaded from the trailer at a Chev. dealer around to back of garage, and the frt.yoke schattered at splines . Only doing about 5 mph and it dug into driveway and lifted car about a foot.

 

Spohn also makes one and says "Our loop mounts to the underside of the stock transmission crossmember. You simply place the supplied 7/16” bolts and washers through the driveshaft loop mount, through the transmission crossmember, and into the polyurethane transmission mount (required). You’ll have peace of mind, and you’ll be drag strip legal."

 

IMCA used to say minimum 4" ID, 1/8 thick round tubing on their dirt modified cars.
I have cut many scraps of 4.500 x .134 driveshaft tubing for this application. Fab from there.

 

Very real. Growing up in Riverside my Dad would take his two weeks of vacation and drive us back here to MO to visit the relatives. One year we had a 70 something wagon. We kids were all sleeping in the back while coming thru New Mexico and all of the sudden we hit the freaking roof of the car and then we were getting tossed side to side until the car came to a stop off of the road.

The other incident occurred at the old Gateway Raceway. We had just pulled our cars up to tech, lifting our hoods and bullshitting we can hear two cars leave over on the track. All of the sudden it gets like freaky silent and as we turn to look towards the track this little tubbed Plymouth Arrow is sailing thru the air and the rear of the car is like almost as high as the electric wires running the length of the track. What goes up does come down and that pretty much sucked for him. The car hit nose first and then went end for end for too many times and then traded the end for end into barrel rolling. Took the safety guys almost a half hour to get him out of the car. With the exception being the driveshaft loop whoever built that car knew their shit. The guy was back at the track later that evening with only minor cuts and bruises.

The loop, any style, is a must have item.

 

A customer pulled 4th gear at Virginia Motorsports when the whole bolting ring on the ford 9" let go right at the traps. Imagine that whole mess whipping around inside the car until launching it self into orbit, we even found where the 'u' joint cup went thru the roof. The driveshaft actually hit the driver in the arm and shoulder. That was in the SoftSeal 62' bubbletop, we alomost lost a good one that day. Luckily Waltons' all aluminum 409 wasn't in the car at that time.
Kenny didn't get hurt, sore a bit the next day but there was an odd stain on his suit. Don't think they could save it.

 

I worry very little about my torque tube

Rich

 

In the late '50's, 16 year old Burke Le Sage, later of the Pennington & Le Sage A fuel roadster team, and the Alderson & Le Sage team, broke the frunt u-joint on his mom's '52 Buick sedan at El Mirage at around 100 MPH. The resulting pole vault launched the big sedan into a series of endos and barrel rolls that totaled the car, and had Burke in a coma for 3 months. He came out of it, and went on th be come a member of the 200 MPH club, and one of the first paid employees of the early SEMA.

 

'52 Buick is a torque tube car, did that one have a stock driveline? They would only have one big U-joint in the front, but all that stuff is bolted together and not exposed.

 

I must have one heck of a guardian angel watching over me because I've lost more than one front driveshaft and all I had to do was put in a new u-joint, yoke and bolts.

 

As far as I know from what Burke told me, the torque tube is what fell and caused the violent roll over. He had no clue what broke. His mother had the car hauled off for scrap while he was still in the hospital. he did tell me that he snuck the car out every chance he got, and did a lot of "late night" drag racing with it. Could have been caused by something he did, or possibly a failure of something that wasn't right from the factory. We'll neve know now.

 

I sure wish I'd spelled MYTH correctly, saw it right after the posting but couldn't edit it.....

 

Hmmm, my brother took his bud's 69 Chevy nova SS 350 down the track for a hoot and snapped driveshaft when he hit second gear in 1980s. Shaft half smashed floor up just behind driver's seat missing his ass by inches. Bent steering wheel holding on while skidding down track after mounting lane's guardrail sideways. Ruined car but engine lived on in other vehicles. Some lads were afraid of that 350 mill saying it had to much power (pussys) so it took a while to sell. What didn't help was car's owner used a hand winch to squeeze springs in an inch or so to match rear end mounts. When you are 18 you just get a bigger hammer I suppose, but totally unsafe and stupid. But what a ride! Brother remembers car bouncing a bit before hitting rail.