Stupid question {Pinks drag strip accident prompted me}

**squirrel** · August 3, 2008, 10:17 PM

Re: Stupid question {Pinks drag strip accident prompted me}

Make sure all the driveline parts are in good condition and fit properly, and are properly torqued. Run a steel flywheel instead of cast, and a racing clutch instead of a stocker. Scattershield, damper, driveshaft loop, etc per rules, or get what you need for running faster than you think you'll go for added safety margin.

I know the guy who won the Tucson pinks episode (there was a story about it in the local paper)...same guy a few years back twisted the center of the rearend in his Camaro, put the driveshaft thru the floor. Also had a blown rail that could not keep the damper on. So hearing that story doesn't surprise me

**joe_rocket45** · August 4, 2008, 05:41 AM

Re: Stupid question {Pinks drag strip accident prompted me}

Originally posted by Eliteman76

There was mention, at the tires speeds during the burnout, the driveshaft would of technically been spinning at 150mph.

No way, no way man, not 150 mph, nowhere near.

**Rendid** · August 5, 2008, 01:52 AM

Re: Stupid question {Pinks drag strip accident prompted me}

Even at 8000rpm, a 3" tube is only spinning at like 50mph. I doubt he was doing 8000rpm burnouts in overdrive so the shaft speed is going to be less than that.
Then again, if he was, it would easily explain why stuff blew apart.

Google 'Driveshaft Critical Speed' for some stuff to look into. Especially if you're doing some high speed driving.

**Eric68** · August 5, 2008, 02:14 AM

Re: Stupid question {Pinks drag strip accident prompted me}

With a big car and a manual trans you are in the what I would call the "high risk for driveline carnage" category. Definitely do the scattershield and driveshaft loop. Look for SFI approved parts (flywheel, damper, etc) they have been RPM tested and should in theory hold up to the abuse of racing better.

I think part of the problem with Pinks is that guys throw together a cheap car to race because they know they could loose it on the show and it only has to last for what, 7 passes max? For the amount of actual racing on that show there is an incredible amount of carnage. I see more crap break on that show with 2 cars in a couple passes than I usually see all night at a bracket event with a 150 car field.

**SpiderGearsMan** · August 5, 2008, 03:06 AM

Re: Stupid question {Pinks drag strip accident prompted me}

good driveshaft doesn't cost much
too many people on the starting line

**Scott Liggett** · August 5, 2008, 11:18 AM

Re: Stupid question {Pinks drag strip accident prompted me}

Originally posted by Eric68

With a big car and a manual trans you are in the what I would call the "high risk for driveline carnage" category. Definitely do the scattershield and driveshaft loop. Look for SFI approved parts (flywheel, damper, etc) they have been RPM tested and should in theory hold up to the abuse of racing better.

I think part of the problem with Pinks is that guys throw together a cheap car to race because they know they could loose it on the show and it only has to last for what, 7 passes max? For the amount of actual racing on that show there is an incredible amount of carnage. I see more crap break on that show with 2 cars in a couple passes than I usually see all night at a bracket event with a 150 car field.

That's my biggest concern when I raced the Impy with the drag radials.

**BigBlockMopar** · August 5, 2008, 11:55 AM

Re: Stupid question {Pinks drag strip accident prompted me}

Regular driveshafts don't scatter during a burnout.
There's hardly any power on/through the shaft since the wheels are spinning, so not much grip.

One of the things which can make a driveshaft fail during a burnout is a hefty imbalance and/or worn/wrongfully assembled U-Joints.

I haven't seen what happened. Although, if the tires suddenly hooked during the burnout, I can imagine an already 'shaky' U-joint could fail rightaway and disintegrate.

**squirrel** · August 5, 2008, 12:15 PM

Re: Stupid question {Pinks drag strip accident prompted me}

I did see a friend's driveshaft get chucked halfway down the track, it broke the trans case and dented the floor pretty good. Turns out he had not fully seated the ujoint cups and snap rings.

**BigBlockMopar** · August 5, 2008, 12:34 PM

Re: Stupid question {Pinks drag strip accident prompted me}

I learned the hard way how to properly mount a U-joint.
Years ago, I did my first U-joint repair/replacement on my '62 wagon, but neglected to put back the snap rings on the inside of the cups. On top of that the driveshaft also always had a slight imbalance.

Anyway, later that week I was merging onto a highway, took the empty on-ramp 'at considerable speed', onto the highway and I started overtaking a few stiffs that were lurging along at 40 orso. After a short while the gauge was reading 120mph, so I eased off the power and immediatly after that there was a loud bang under the car and it started shaking very badly right after.
I checked the mirrors and noticed a white cloud behind me, but luckily no cars, so I swerved to the shoulder.
After I doublechecked my pants for fresh warm fluids I got out and had a peek under the car... There were red droplets every where.
One of the U-joint cups had popped out so the driveshaft went off-center, but was still hanging on the U-joint. But it also torn the tranny's tailshaft right of the bolts and bend the output-shaft.
'Luckily' everything stayed somewhat together and the driveshaft didn't slam into the floorboards.

**Eliteman76** · August 5, 2008, 03:45 PM

Re: Stupid question {Pinks drag strip accident prompted me}

Thanks guys; I know it probably seems a bit more common sense, but as a street guy, I just probably over think stuff way to much. I don't want to know what the part is. I want to know the "why" behind it I guess.
Then, I have to deal with the wife proding me to get the car done and take it to the local 1/8th mile...and as much as I am building my car to just beat on it, I'd like to learn from others and not kill myself in the process.
The flywheel thing is bugging me, but right now, not too worried about it.

LOL, then again, my wife said if I do something stupid, like race w/o a simple cage in the car, get hurt or worse die, she said she was going to unbury my ass, and kill me again herself.

Got to love Itailian girls.

**rightpedal** · August 6, 2008, 06:16 PM

Re: Stupid question {Pinks drag strip accident prompted me}

Wheel hop spits out joints pretty quickly. I did not see the episode but if he didn't have enough power to get a burnout going or held on the throttle too long and hooked up has the same result. Shock is what kills most street drive lines.

**Scott Liggett** · August 6, 2008, 06:24 PM

Re: Stupid question {Pinks drag strip accident prompted me}

I've seen a driveline failure at speed once during a street race. Scary as hell because he lunched the front u-joint which dropped the driveline on the street. Before he could get the car stopped the driveline caught a pot hole or something and pole vaulted the car over on it's roof. Ripped the differential right off the leaf springs in the process. I guess that's why they require drive line loops.

**Brian Lohnes** · August 6, 2008, 06:32 PM

Re: Stupid question {Pinks drag strip accident prompted me}

The freakiest driveshaft incident I have ever seen occurred when a car was doing a burnout and the rearend locked up solid. The driveshaft twisted into a pretzel and ripped through the sheetmetal floor (this was a tube drag car) and completely mangled a guys arm.

It was so bad the guy was airlifted out and has never fully regained the use of his arm.

This was a high horsepower car with thin floors, not something I could forsee happening to a stout street machine.

Brian

Stupid question {Pinks drag strip accident prompted me}

Stupid question {Pinks drag strip accident prompted me}

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