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Project Buford T Justice Hits the Dyno and Goes KABLOOEY! CARNAGE VIDEO INSIDE!

May 08, 2012Buford - 9C1 Caprice, Project Cars39

Project Buford T Justice Hits the Dyno and Goes KABLOOEY! CARNAGE VIDEO INSIDE!


After we ran Buford T Justice at the strip and the 4,000lb tank shocked us with elapsed times in the 15-second range, we were immediately intrigued as to the actual power output of the 185,000 mile 350ci engine in the car. We were expecting far less in the performance department from the car and although it was not a strip blazer by any means, it seemed like the ol’ 350 was putting out more than the advertised 160hp at the crank. Looking to make a couple of pulls on a dyno to verify this, we called up Travis Johnson at Performance Auto and Dyno in Plymouth, Massachusetts. He agreed to put Buford T Justice on his DynoJet dyno to see what was really happening at the rear wheels.

I left the house and told my wife to stay by the phone because there was a better than average chance I would be calling her for a ride back to the house from Travis’s shop. She laughed and then I told her I was serious. We didn’t put the car on the dyno with the intention of blowing it up and/or killing it but we ended up doing just that. Buford T Justice Version 1.0 went out with his boots on, that is for sure…and with a literal bang.

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 It didn’t take long to get the car strapped down and ready for the first pull. Knowing that this this was bone stock and was rolling on some pretty sketchy rear tires, Travis decided that he would wind ‘er up to 5,000RPM in 3rd gear during the pull.

With the dual exhaust from the manifolds back, the car sounded pretty good at 5,000RPM, although judging by the smoke and haze coming from the tailpipes, the motor wasn’t all that happy to be charging to that level. We all pretty much thought it was just carbon and junk being blown out of the exhaust along with the blow by issues a 185,000 mile engine has when being run at full throttle.

When the pull ended and we looked at the graph, the engine made 169hp at about 3800RPM and peak torque of 250 lb/ft at 3,250 RPM. From 3500-4400RPM the power lived in that 160-169 range and then dropped off in a hurry. While we didn’t print the sheet with the air/fuel curve numbers on it, suffice it to say it looked bad enough to make us all laugh. Again, bone stock parts approaching 200,000 miles do not exactly mean precision in any stage of the game.

(click to enlarge)

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Here’s where things get really interesting –

Going on the generally accepted rule that the number you see at the tire is 20% lower than the hp number at the crank, our tired ass 350 was making about 200hp and about 300 ft/lbs. For the second pull we were going to repeat the same procedure as the first, with the lone exception of the air cleaner lid flip. We saw an ET drop at the track by doing this, so we wanted to see an appreciable horsepower gain on the dyno by doing the same thing. Travis did report feeling a vibration in the car at 5,000RPM in 3rd gear on the previous pull, but we attributed it to the tires, which probably had no business spinning that fast anyway. Oh, 5,000RPM in 3rd gear is 125mph by the way. That will be important in a second.

 The second pull started the same as the first with Travis bring the car through first and second gear, into third, and then laying the lumber to Buford. As the revs  climbed and both Ben Dahlgreen (Travis’s right hand man at the shop) and I looked at the rear tires and took a half a step back. The smoke and haze came back from the tail pipes as the motor climbed past 4,000 RPM and both Ben and I were laughing like idiots at the situation.

Then 4900 RPM came and

It….

Went…

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BANG –  The driveshaft shot out of the car like a missile and with zero warning. Luckily for us it came out from under the passenger side and crashed harmlessly into the base of the lift adjacent to where we were standing. Our attention then turned to Travis who had shut off the car and was very slowly making his way out of the driver’s seat. Having seen guys get seriously maimed by errant driveshafts before, I was hoping he wasn’t hurt. He said it felt like someone wound up and smashed the floor with an 8lb sledgehammer directly under where he was sitting. The driveshaft was reduced to three pieces of horribly mangled metal tube.

(click on photos to enlarge)

                                                                                                                                                  

 

 

 

 

 

Here’s some video of the situation. This was taken with the security camera in Travis’s shop, so the only sound you will hear is Travis and Ben laughing as they are watching the video on the office TV. Note that I take a step back at about 20-seconds and then the driveshaft makes an appearance!

 

The first order of business after we knew that no one had been hurt by the previous seconds’ action was to look a the graph and see what kind of snot the car had on the second pull. The lid flip was worth about 5hp, bringing our magical number up to 174hp and change. It kicked the torque up a couple of numbers as well. There were some gains all over the curve but they were small.

We then tried to figure out what the EFF had just happened.

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At first glance, things didn’t look that bad. The driveshaft was a pretzel, but the rear turned free, the tail housing of the transmission was intact and it appeared that the quick fix was going to be sticking a junkyard driveshaft into the car and heading home. Travis wanted to raise the car on the lift and see what else happened because frankly, a driveshaft spinning at close to 5,000RPM doesn’t leave quietly.

As it turns out, this one didn’t.

We discovered a fist sized hole in the floor in the footwell of the rear passenger side. Travis’s sledgehammer experience came when the flopping driveshaft tried to enter the passenger compartment of the car. One of the mufflers had been bashed just about flat and on the other side the exhaust system itself had been hit and battered so hard it was about three inches lower than it was before the excitement.

 Despite these findings, were were still planning on sticking a driveshaft in it and going home. Once back home I could close the hole in the floor up with some precision hammering and weld it all back together, at the shop the low hanging exhaust was going to be heated and moved back up towards the floor, and bolting a driveshaft in is a 15 minute job with a car on a lift and ready to go.

Then I heard someone say, “Oh f#ck! Look at this!”

The “this” we looked at was a pretty bad ass crack that seems to indicate that the transmission was no longer technically bolted to the engine. The crack on the upper edge of the bell housing goes all the way from the right hand side of the trans pan all the way over to the left side.

Perhaps even more impressively, there is a secondary crack at the base of the bell housing that is wide enough to actually see transmission innards through. Long story short, bolting a driveshaft back into it wasn’t really the greatest idea.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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So what the hell happened? To be 100% honest we’re not sure. The car starts and idles like normal without making any horrifying noises, so the transmission isn’t locked up solid, but something surely stopped spinning for a least a short time to get the driveshaft to pretzel up. We’re going to be pulling the engine and what is left of the transmission out of the car in the next week or two so we can begin the prep for the big block and  for the suspension upgrades that are coming in the short term future as well. So much for our plan of feeding this little 350 as much nitrous as we could before it spit parts at us…it didn’t need any help!

Let’s bench race this thing….what the hell happened on the dyno at Performance Auto and Dyno to cause this catastrophe?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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Caption This Photo: Drag Racing is Hard

39 thoughts on “Project Buford T Justice Hits the Dyno and Goes KABLOOEY! CARNAGE VIDEO INSIDE!”

  1. Michael Black

    I bet that a u-joint lost a couple needle bearings causing an out of round situation. This put some nasty harmonics into a very tired driveshaft tube which probably folded at the point where the internal rust pitting was greatest. As soon as it folded it encountered unmoving objects (Like the floor?), this sudden increase in torsional stress would have to go somewhere… the trans case….now no nitrous show…. dang.

    1. b3m

      I agree with this reply. I was just speaking of concentric so tight ears ring before accepting final tighten…bellhousing related on a little foriegn car. American cars just bolt up and you go with it.

      I was off by 6 hp on the guess…but remember real air also adds to it while moving down the track. Dynos scare me.

    3. Matt Cramer

      Agreed – sounds like the driveshaft misbehavior broke the transmission case, although I’m not sure if it was the tube crashing around or just the vibrations.

  3. crazyhorse

    off to south shore bearing, for a real driveshaft..
    next up the rear end to go boom

  5. C1BAD66

    So does Ron Ward win the shirt prize? (Please see other Buford article.)

    Kaboom is the same as ka-blooey and bang, right?

    That 350 oughta pull Brutus along nicely.

    Driveshaft loop kits are inexpensive. Maybe Buford should get two with the installation of the BBC.

  6. CdmBill

    Chances are the vibration was the u-jooint heading south before the dirve shaft went west. I’d agree the drive shaft ‘misalignment’ caused the case cracks. Ya’ll are lucky. Bangshaft.com indeed.

  7. squirrrel

    Saw a similar thing happen at the drags, we figured out one of the clips on the U joint had not been properly seated. It’s hard to tell from the pics if it still has the original plastic retained U joints, or if they were replaced with the C clip type.

    If the clip is not fully seated, the extreme load at sustained high rpm will force the shaft off center and cause this mayhem

  8. Geezer

    Dyno out in the open. Bystanders loitering casually in the immediate area. Yeah. Good effing idea. Not.

    These videos are really “cool” and everyone gets a good laugh but let me warn you – one of these days someone’s gonna killed badly injured, or worse yet decapitated by flying debris. Then the shit’s gonna really hit the fan.

    1. ratty

      yeah i always thought it was pretty crazy that it’s common practice to build fully enclosed, bomb hardened engine dyno rooms with bulletproof Lexan windows to keep anyone from being killed, knowing that catastrophic mechanical failures are inevitable at such high RPM’s… and yet when it comes to chassis dynos, it’s just a spot in an open garage where they accelerate a car to a 100mph on rollers, with no protection or enclosure at all, being held back by basically nothing more than string… Probably safer in a dyno room with an engine spinning 10,000rpm, than in a garage with a chassis dyno with a 2 ton car at full romp.

  9. bishir

    Wow, I ran the numbers in a 1/4 to HP calculator and adjusted it based on the reported Below sea level density altitude on the day you ran Buford at the track. Based on that, Buford was making about 176.51 HP at the crank. Thus, I deducted 20% for drivetrain loss and my guess was well short. Ol Buford was making much more than advertised! It must have been that lightweight driveshaft…

  10. Geezer

    Fat fingered it. Sentence should read: One of these days someone’s gonna GET badly injured, or worse…

  12. Scott Liggett

    And Squirrel wanted me checking total timing at 5500 rpm. The reason I stand far away from the car on the dyno during runs.

    You always wanted a reason to actually tow a car with Brutus.

    I don’t think it was a U joint failure. You would get a warning in a nasty vibration before the carnage. The fact that neither yoke is damaged shows that. I’m guessing the rear differential may be heating from lack of fluid and not moving as fast as the transmission is spinning the driveshaft.

  13. ratty

    that’s hilarious… i wish it had audio so we could hear what the guys were saying as they watched the Caprice spill it’s guts onto the floor… but hearing the guy laugh who was taping this vid (of the vid), is pretty funny… Aw the poor car… I mean, who puts old worn down cars on dynos? you know they’re gonna break! Mean humans, mean

    1. Speedy

      ROTFL

      Strapped down and bound
      Rollers up and truckin’
      We gonna do what they say can’t be done
      We got a three-fifty to blow
      And a short time to . . . . KA-POW!

  15. ChasG

    There’s a driveshaft phenomenon known as “critical speed” (a speed at which the shaft starts whipping around on it’s own)
    I’m wondering if we saw a real-life demonstration of a driveshaft hitting critical speed.

  16. Monk

    Damn that was funny seeing the drive shaft
    come flying from underneath the car.

    I’ll take this over the DF stuff in Hot Rod.

    1. Speedy

      But then DF knows the dangers inherent in the “Air cleaner flip” mod . . . .

      Maybe Lohnes should ask DF if they make hose clamps big enough to fix that transmission . . . .

  17. Yardpilot

    Years back my ’66 did something that had exactly these characteristics. In that case it was a bolt backing out just enough to tag the flex plate. I had that happen on a ‘Vair once, too. Since those days I have been a believer in Loc-tite and safety wire.

  18. Boots

    “Critical Speed” is an absolutely true phenomenon, but the way that came apart doesn’t look like it to me, but it certainly encountered a lot of other factors on the way out. But usually that’s encountered when someone tries to run too small a diameter tube, too long, too fast. That’s the factory driveshaft, and tho a little rusty on the outside, doesn’t appear rotted at all or in overall poor condition. I’ve seen stuff come in off the Islands and life by the shore with driveshafts so rotted you could see THRU them.

    The missing cap in the slip yoke spells it out for me. Those are definitely replacement u-joints as witnessed by the grease fittings that the factory ones don’t have. And those plastic injected joints usually throw up a few red flags. I see more of those particular driveshafts destroyed by well-meaning grease monkeys trying to change the joints than on any other style of driveshaft.

    First off… it’s necessary to use some heat to release the plastic. That amount of heat is usually termed as “adequate”, but that varies in different people’s opinion. I’ve seen guys barely get them above room temperature with a propane torch and then beat them unrecognizable with a hammer trying to get the still solidly installed joints out. (“But I heated it up first! Just like my uncle/cousin/sister’s boyfriend said!”)

    On the other end of the spectrum, I’ve seen whole tube yokes and ears turned blue because apparently the pyromaniac wound the rosebud onto the smoke wrench and heated the whole end of the driveshaft until it was glowing and then proceeds with the application of force. For some odd reason, new u-joints never seem to go back into those ends. It’s a mystery. [Facepalm]

    A precise application of flame (say, for example, a brazing tip for an oxyacetylene torch) applied to JUST the offending CAP (you know, the part that you’re throwing away? Which is probably no longer dimensionally critical?) will result in the pleasing pop of the plastic plug popping out, the eruption of now flexible plastic, and that gawdawful stench that never leaves. A little judicious tapping will slide the offending joint out, and you can clean up the yoke ears a bit and go to slapping in the new joint.

    HOWEVER. With heartbreaking regularity, I see new Chevy joints (this style of plastic injected joint is specific to GM, and very prevalent) that are installed without cleaning up the ears, or the surface where the snap ring has to sit. This doesn’t let the snap rings install properly. This usually results in the snap ring being hammered and pounded and chiseled into place, which usually destroys the tension of the snap ring and it ceases to hold anything. Or the snap ring is snapped into place NOWHERE in the vacinity of the snap ring groove. OR all the abovesaid needless and excessive heating has distorted the ear of the tube yoke, or somebody got in there with a barrel sander or a flap wheel and “polished” the journal out to more easily accept the new cap. So the cap just slides in and, eventually, start to spin around in the journal. Which usually spits out the snap ring in short order, u-joint cap goes byebye, (at speed, naturally) and the resulting tie up of that assembly flopping around is usually enough to taco the driveshaft and anything attached to it.

    My favorite mechanical connondrum: SPONTANENOUS DISASSEMBLY!

    Anyway. That’s what I think happened here.

    See if you have room for 3 1/2″ tubing in the driveshaft tunnel. Should be more than heavy enough for whatever you throw at it in the future. That’s pretty standard for what I build replacement chevy shafts out of, because the whole thing is going to end up getting replaced. Looks like your slip yoke might have even taken one on the chin for that. Usually when they come all the way out of the vehicle, everything is junk. Or should be.

    But those are all dirt-common components. Easy fix. Sucks about the trans tho. Collateral damage.

    1. Speedy

      So . . . bottom line is that it’s GM’s fault for installing a pootly-designed universal joint that is prone to disassembly error in the field, even when serviced by experienced fleet mechanics. I knew that Chevy was at the root cause of this fail.

      2. Boots

        Not really. Well, don’t get me wrong, the plastic injected joints are a novel idea, kind of a “brilliant solution looking for a problem” kind of thing. My other big complaint with them is that since they aren’t located by snap rings to start with, they’re very rarely centered. Some are visibly set off to one side from the factory, usually accompanied by a chunk-o-bench balancing weight on the opposite side of the driveshaft. Once you replace the u-joints with snap ring models, they have no choice but to be centered, and now that huge weight is in the wrong place. Hence the oft-heard refrain “Jeez, I changed the joints, and it STILL vibrates!” No shit.

        But they are replaceable. Just sometimes it goes better than others. Believe me, the regular Spicer stuff is just as easy to screw up. Just requiring heat to take them apart leads to some interesting results.

        The spinning cap jettisoning the snap ring also happens to axle shaft u-joints in 4wd applications. You can imagine an offroader trying to fold over the rev limiter and having a cap back out in a rapidly spinning axle shaft. All KINDS of ugly happening in there. Saw one pop a balljoint right out of an axle C. We were staring HARD at that trying to figure out how to get it back together on the side of a mountain.

        From then on, on those particular kind of rigs, I started tack-welding the caps to the shafts. If they can’t spin, they can’t spit the snap ring. And if they have to be changed, a brisk rap with the hammer breaks the tacks right off.

  20. Speedy

    Brian, I’ll give you five car-lengths against the Marauder . . . .

    But seriously, I’d like to see the math on the “twenty percent loss” wives’ tale. The amount of power it takes to rotate everything behind the engine doesn’t change when horsepower increases. Moreover, the driveline would get a lot hotter if it ate up twenty percent of the engine’s flywheel horsepower.

    I strongly suspect that the “20%” rule is simply an invention of engine builders covering for less-than-stellar dyno results.

  21. Schtauffer

    My theory: the air cleaner lid flip produced more power than the drivetrain could handle.

    LOL

  22. floating doc

    I was really looking forward to the end result of multiple pulls and tweaks. I’ve got an 88 C20 with a 350; similar engine only with TBI instead of the Quadrajet.

    Not anymore. Now I’m just glad no one got hurt. Next time, a driveshaft loop should go on as soon as the car moves out of DD status.

  23. DaveH

    As well as Boots explains it, how could I disagree?
    And while a drive-shaft loop is an excellent idea, I don’t think it would prevent a drive-shaft failure at 5,000 rpms from banging some stuff up and shooting out from under the vehicle. The driver should be safer, but standers-by would still be in the danger zone. No?

    1. Boots

      Well, in hindsight, anything would have been better than THAT. But, then again, how many times have you seen a driveshaft completely exit the vehicle speed? Let alone in multiple pieces?

      A regular driveshaft loop that would just hook to the body probably would have directed more of the force into the floor. Or the nicer loops that bolt together and actually completely encircle the driveshaft would have contained it, but it still might have thrashed itself in half. But I think it would have been hard pressed to go skating across the floor in either case.

      Bottom line? What are the odds of that happening again? But you always notice the guy who’s actually watched a vehicle burn down is always the one with a fire extinguisher handy. Maybe the guy that narrowly sidestepped a free-range driveshaft builds one bugger or a driveshaft hoop!

  24. Steve Baisden

    This same thing happened to me in my 74 nova. The rear u joint failed , and I was actually going 125 on I30 in east Fort Worth. Drive shaft launched out in two pieces, beat up rear floor and crushed the flowmaster on passenger side. Cracked turbo 400 case all the way around bell housing area, and leaked all the fluid out. The guts of the trans were new so I found a donor case and relocated all the parts, trans still works great to this day. That happened about 9 years ago.

  25. Chapel

    I’m wondering if at some point someone swapped the 9C1 driveshaft out for a civilian model… those civilian models come apart at about 120… the 9C1 shaft should hold to about 140.

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