Fragged U-joint: How Dangerous?

[Ant]

Come to think of it I had a C Clip come out once at 100mph, this destroyed the Universal joint, ie the needle rollers turned into paste with the grease, there was a horrible vibration and the alloy bellhousing fractured badly, all this was after the engineering shop modified the shaft, and I failed to check it when I installed it.........!

I havent read any articles on driveshaft failure, but I wouldn't think there is any need to cover the U/Js, as normally when they are worn or break the needles and cross get all munched up, and I assume if the cross comes out all together its the actual D/S that causes any problems, but I could emagine a huge whip and boom if under a drag racing situation!

The old cars with the enclosed D/S were very safe, and when modern D/S's came out I guess there was skepticism on the safety of them! Run a hoop and fit a cover of 14- 16 gauge metal close over the top half of the shaft!

[1985 CCX]

For the low cost of $24.95 Summit Racing offers a loop that passes requirements of both the NHRA & IHRA authorities. The loop is in four parts and appears to be very versitile for mounting to just about everything auto.

It is part #SUM-G7900......................

Cheap and easy installed insurance!
Jeff

[Lowell W]

Jerry,

Thanks for the tip. I recall you asking me about the driveshaft angle at the party. The driveshaft does angle quite a bit to the right from the transmission to the diff; I'll check the horizontal angle too. I've been considering having another driveshaft built with solid 1350's. I'll give you a call at the shop in the next day or two regarding setting up my rear end with a Truetrac.


767,

I started wondering about a car "pole vaulting" over the driveshaft long before I ever heard any of the horror stories. Makes ya wonder why the manufacturers don't put in a front loop.


Ant,

Yep, that seems to me to be the best alternative.


All,

The big advantage of the totally enclosed "Buckshot" system is that you can probably leave the fuel and electric lines where they are and still be pretty safe in the event of a separation. Everything has its pros and cons...

Lowell

[Jerry Clayton]

With battery and fuel system comp[onents in the rear--much care and thought should go into the design and routing of components--any battery cables/connections near anything in the fuel system could be very nasty if your upside down
The possibility even exists to do damage with a jack in your garage

Jerry

[TWOOD]

This particular "urban legend" was tested and proven to be true on the TV show Myth Busters. I remember that they used a full size sedan at a moderate speed of 50 mph (as I can best recall). They towed the car and let the drive shaft drop into a "pole vault" style pocket in the road bed. After resolving timing issued and after several trys, they caused the rear end of the car to jump several feet into the air, but not flip over. THe drive shaft did break away from the differential and was driven well into the trunk area.

[olddog]

I was involved in the installation of a large industrial drive shaft going to a pump (about 10 yr ago). The rpm is bellow 50, but the torque is above 10,000 lb-ft. The company recomended a minimum of a 3 deg angle. If the angle is straight the needles will not turn in the cups, and the grease will not be rolled around the bearings, causing failure. The maximum angle is fuzzy in my mind, but it was a single digit number or slightly above. The maximum load capability was at 3 deg and dropped as the angle increased. The drop off was exponential as the angle increased, as I remember the chart.

I believe these concepts directly applies to autos, as well.

[olddog]

When I was about 14, a neighbor bought a Vette that had been set up to drag race, with a 12 bolt straight axle under it. The housing was apparently too far out of alignment. He broke about a half dozen rear U-joints. I saw the whole shaft come flipping out several times.

He was on his way to taking it to a shop to get the housing mounted at the propper angle, when me and some other kids talked him into one more burn out. This time the front U-joint broke just has he slammed 2nd gear. The shaft jammed into the pavement and kicked the rear end up into the air about 2-3 feet on one side. About a foot on the other side. The car went up on two side wheels next. He was all over the road. The back U-joint broke off, too and the shaft kicked about 10 feet into the air, taking a large chunk of pavement with it. It pretty much destroyed the car, but the rear end stayed under it. Frame was twisted and body cracked.

Anyone who could have seen this would believe in some system to contain the driveshaft.

[Jerry Clayton]

well, what if its the rear joint? drive shaft one foot long--2 ft circlex Pi(3)=6 foot per rev x 6000=36000 minutex 60 min divided 5280 = one hell of a whack

Oh, and since the shaft is about one foot long the force will be equal to your torque/horsepower numbers on your precious dyno sheet

Make it straighter, stronger, better and then cover it up and drive carefully

Jerry

[RedBarchetta]

Check out this pic that I just noticed in the archive (circa 2003). This is arguably the best solution that all of us have been jawing about, though the construction and clearances for same would be slightly different for each manufacturer.



-Dean

[767Jockey]

Originally Posted by RedBarchetta

Check out this pic that I just noticed in the archive (circa 2003). This is arguably the best solution that all of us have been jawing about, though the construction and clearances for same would be slightly different for each manufacturer.



-Dean

Wow - I thought my driveshaft was tight getting in and out of the car. This one has to be a real treat to work on.

[Lowell W]

Thanks, guys, for all your input. Great points regarding imparted energy. The suggestion was made elsewhere, that a wire mesh or blanket lining the inside of the tunnel might be sufficient protection against fragments, assuming the driveshaft itself is restrained.

Olddog,

Good reason not to let yourself get egged on by teenagers, huh?

Jerry,

You've talked ME into a new 1350 driveshaft!

Dean,

That looks like aluminum. Ya think it would hold that driveshaft? I dunno... On the other hand, the driveshaft wouldn't have much "running room" to start flopping. Fabbed from steel, yes; aluminum, . A good solution if you don't mind not being able to grab hold of the driveshaft and check the slop. Actually, it's similar in concept to the Buckshot tunnel.

All,

Jerry made another good point: Has anyone done anything to shield the gas line and battery cable, ie. passing either/both through say, an 18" length of stainless heavy wall tubing, pipe, etc.? I kinda like having them in the center of the frame, but there's the busted driveshaft problem again... And again, the Buckshot tunnel solves this problem, too, but I just want to be able to get at the darn driveshaft.

Thanks,

Lowell