Destroyed a driveline

Fuselage Years

  1. MoparFlores

    MoparFlores New Member

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    How's it going everyone. It's been a few years since I was last here but I'm back with a bit of a dumb question I guess. I bought a 73 fury alittle while ago. Finally been driving it for a few months and fixing little things here and there. So I was cruising today and a bowtie pulled up next to me. We decided we should run em and well I destroyed my driveshaft. Looks like a bolt on one of the u joint straps was loose and the strap came apart. We were already at speed and while I was slowing down the driveshaft came out of the transmission and I ran it over. Lucky for me it didn't take anything else out. My question for you guys is, when I put the car in park I can hear what almost sounds like the park pawl grinding. Drive and reverse appear to work I got the car up on jack stands and put it in gear and I can see the splines at the rear turning. So my question is did I destroy the transmission too? Should I just take a look inside and see what comes out? Also any advice on where I can look for a transmission, driveshaft, and pinion yoke for my differential? This is a 360, Small block 727, 8 1/4 diff car. I can't really measure the driveshaft to get a new one made on account of it being bent. I appreciate any and all help from you guys. Been a few years since I was last here. My first experience with a c body was my 68 fury I bought when I was around 20 years old. About 4 years ago. Maybe longer actually.

    20200926_192912.jpg
     
  2. cbarge

    cbarge World Famous Barge in a Budget FCBO Gold Member

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    Shut engine off.THEN put it in park or neutral.
     
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  3. MoparFlores

    MoparFlores New Member

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    Yea that's what I did earlier when I got the car home. But when I go to start the car again after I've got it in park i can still hear what sounds like the pawl being ground away.
     
  4. twostick

    twostick Senior Member

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    Check the tail shaft housing to make sure you didn't break it. Park SHOULD have engaged once you shut the engine off.

    If it's making noise after you restart it in Park, check to see if the output shaft is turning. If it isn't, I would suspect you have taken out the overrunning clutch or sprag if it was still in first when it spit out the drive shaft. A driveline or diff failure when on it in first with the shifter in D or doing a burnout in D and having it hook hard when you get off it can and will roll the the sprag.

    A telltale sign of a failed sprag after a driveline failure is putting it in drive and it doesn't seem to want to engage unless you rev it up a little.

    If you get on it after that the sprag can fail completely and cause a front drum explosion.

    You don't want to be around that...

    KABOOM! This 'Cuda's Transmission Explosion Ventilated Just About Everything In The Car - BangShift.com

    Kevin

    cuda-xmsn-4.jpg
     
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  5. 68plymouth383

    68plymouth383 Senior Member

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  6. Davea Lux

    Davea Lux Old Man with a Hat FCBO Gold Member

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    It probably would not hurt to pull the transmission pan and see if any parts fall out. You might also try removing the front yoke from the dead drive line and sticking it back onto the spline for the tail shaft. This assumes the yoke is undamaged. When the the rear shaft is held true by the yoke and bushing it might just kill the noise if the rear shaft is bouncing about for lack of support. Probably more likely something broke, but it won't hurt anything to try putting the yoke back in place.

    Dave
     
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  7. MoparFlores

    MoparFlores New Member

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    Appreciate all the responses guys. I'll be pulling the pan off and seeing what falls out. I'll share any pictures I get. Might as well right, the more we share the more questions can be answered for others in the future.
     
  8. MoparFlores

    MoparFlores New Member

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    Thats some gnarly stuff, pretty damn scary.
     
  9. 70bigblockdodge

    70bigblockdodge Old Man with a Hat FCBO Gold Member

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    If the driveline was under load, and even if not and you plan on reving the engine over 4,000 I would take the trans apart and have the sprag(overunning clutch per FSM) inspected. If a roller got jammed because of the driveline shock of the loss of driveshaft, it will cause the forward drum to rotate at 2.2 engine rpm (reverse ratio) cast steel drum will come apart at ~ 9000 rpm.
    2.2×4000= 8800rpm.
    Sprag failure is more common in first gear. When you see those case explosions, do you want to have your legs right above it?
    Nothing will fall out, if roller is stuck it is stuck well. As we used to say in the Navy open and inspect.
     
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  10. twostick

    twostick Senior Member

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    A lot of people mistakenly think those drum failures are horsepower related when in fact all it takes to blow one up is an engine's ability to free rev past 5000 RPM. A stone stock /6 is capable of that.

    A couple of things you should NEVER do with a 727 are big waterbox burnouts at a dragstrip unless you have a manual valve body. If you don't have a manual valve body, put the shifter in 1 so it engages the rear band as well as the sprag to hold the rear drum. In D only the sprag holds the drum. Just use enough wheel speed to get some smoke to show. When you let go of the brakes, roll out of the throttle at the same time so the driveline doesn't take a big shock when the tires bite. Don't do dry hops.

    Another no no is after doing a burnout, rolling into the staging area and then shifting to N and razzing it a couple of times to "clear it out". The problem with that other than you need to beat your carburetor guy with a crescent wrench is that it unloads the sprag. At that point if you put it in gear and gas on it, the engine gets a run at it because it takes a few revolutions for it to reset. Only slightly less shocking to it than a neutral drop which should actually be the #1 never ever under any circumstances do no no on the list.

    Kevin
     
  11. 70bigblockdodge

    70bigblockdodge Old Man with a Hat FCBO Gold Member

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    With a manual valve body (with no low band apply), second gear burnout is preferable. If it won't spin in second, you can start in first and shift very quickly into second, limiting the settle on the suspension to reduce shock.
    With a regular automatic as Kevin stated, put it in low and shift to second before backing out of throttle.
    I agree with not having to clean it out after burnout, in a perfect world sure. Do it back a ways from staging beams so the sprag has to load to push you forward toward beams, once you stick it in gear going toward beams keep it in gear, no in and out.
     
  12. furious70

    furious70 Well-Known Member

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    Fwiw I would take the trans out to thoroughly inspect the case and tailshaft. Plenty of stories of a 727 held together by it's mount points that was actually broken after something like that. I'll 'send it' as much as the next guy but not in this case.
     
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  13. bluefury361

    bluefury361 Old Man with a Hat

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    To determine the correct drive shaft length. Insert the front yoke into the tail shaft as far as it will slide, (don't force it. just slide until it stops). measure from center of the joint yoke front and rear then subtract 1/2 to 3/4". That's the needed length of the driveshaft.
     
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  14. MoparFlores

    MoparFlores New Member

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    20200927_145115.jpg 20200927_145019.jpg this is what the pan looks like, there isnt any huge pieces in there but it still looks like too much for me to trust it. What do you guys think?
     
  15. MoparFlores

    MoparFlores New Member

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    20200927_145957.jpg
     
  16. furious70

    furious70 Well-Known Member

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    Like I said I'd want to make sure the case isn't cracked on top. And the tailshaft assembly is ok
    Might not be any pieces in the pan...yet
     
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  17. 1970cat

    1970cat Senior Member FCBO Gold Member

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    you shouldn't have chunks in there. normal wear would be grey sludge on the bottom of the pan. looks like it's time to pull it and check closer.
     
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  18. MoparFlores

    MoparFlores New Member

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    Sounds like a plan I'll pull the transmission out tomorrow when I grab some tools from work
     
  19. Yeahrightgreer

    Yeahrightgreer Senior Member

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    Any other big no no’s on a 727 w/o manual valve body? Especially in regards to racing?
     
  20. twostick

    twostick Senior Member

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    Not pulling the trans apart to inspect the sprag after a driveline/diff failure from a launch is no no. The trans can seem to operate OK with a wounded sprag but could let go the next time you launch it.

    Kevin
     
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