Driveshaft Safety Loop Q's
 

Does it matter where the driveshaft safety loop is placed in relation to where the exhaust crossover pipe (h-pipe/x-pipe) is located?

Is anyone running a loop that attaches to the transmission mount. I don't want to bolt it to the floor boards. The only other option seems to be to use the subframe connector bolts and do a fair amount of fabrication (for an amatuer at best welder). This is for a '67 Camaro.

I haven't drag raced it yet, and I'm not on slicks, so I don't "need" a loop, but the rear end and driveshaft are out right now, so I figured it was a good weekend project to keep me out of trouble.

I think "typical" location is 3/4 toward the rear of the shaft, I imagine to catch it if it breaks at the rear axle. A friend broke the joints at the front of his driveline at 120+, that made a mess of his floor and his underpants!

:thumbsup:
Dan

I would mount it to tword the front of the DS. I'd rather have the rear of the DS hit the ground then the front.. NHRA rules say 6" back from the transmision

Thanks guys, I don't think I was very clear. I know the safety loop needs to be within 6" of the centerline on the front U-joint.

My question was whether there was a rule about where the H-pipe or X-pipe falls in relation to the loop (i.e. does it have to be in front of the loop or behind it, or does it not matter?)

Most rule books specify the DS loop be located no more than 6" behind the front U-joint. If you happen to have sub frame connectors installed that is a good place to mount a DS loop. There is no rule pertaining to the exhaust that I have ever seen.

I think Mythbusters did an episode on the pole vault theory and couldn't make it happen.

I posted a similar question on TC and got the same answer that it didn't matter where the pipe went.

Here's the thread that I was referencing:http://www.camaros.net/forums/showthread.php?t=193442

They mention that the X-pipe has to go behind the safety loop. But in reading it again, maybe they meant it was the only place it would fit, rather than that it was a requirement.

Here are the quotes:

And

Learn something new everyday. Let me ask ya, if its mounted 6" off the front and the rear joint breaks would it hit the ground?

The only loop I've put on is our Studebaker and its more toward the rear. I know that where its located either end can break and neither hit the ground. Just curious.

Dan

Yes, it would still hit the ground, but it would just drag. I think the real fear is that if the front lets go, it could tear up the tunnel and anything (anyone) directly above it.

There's no reason why you couldn't run two loops. One front and one rear, but the NHRA rules require only the front one.

Not to mention, possibly pole vaulting the car ass over tea kettle.

Has this ever really happened?

i HAVE HEARD IT HAS BUT NEVER SEEN ONE LIVE (THANK GOD) I HAVE SEEN THE FRONT OF A DS BREAK, HIT THE GROUND AND THEN FOLD IN HALF AND TAKE OUT A REAR TIRE

THEY SAY THIS HAPPEN BECAUSE OF THE DS BREAKING AT THE FRONT IDK HARD TO TELL

@ 8 SEC

SOME CARS IN NHRA REQUIRE 2 LOOPS

I wasn't even thinking about those classes. That was me speaking out of ignorance, thanks for pointing that out.:snapout:

Fighting a similar packaging issue, it seems magnaflow likes to put the x-pipe in there exhaust kits right inline where a DS loop would go per NHRA spec

You have to follow the rules. But in reality an X pipe will keep the DS from hitting the ground..How can the DS get passed the X :headscratch:

An X pipe MIGHT keep the drive shaft from hitting the ground or, more likely, the DS would simply rip the exhaust out from under the car. Regardless, the X pipe would do nothing to prevent the shaft from tearing through the floorboard. In any case an X pipe would never be considered an alternative for the DS loop by any santioning body.

I still need to see if I want to connect the loop to my subframe connectors or run it straight back off the transmission mount.

But, if I ran it straight back from the trans mount, would the NHRA view two 1.5"x1/4" pieces of steel running parallel, but not connected to each other as good as one 2"x1/4" piece of steel. The ONLY reason I ask is that I already have some 1.5"x1/4" steel stock lying around. The loop itself would be 2"x1/4", and the plate that bolts to the trans would be something like 4"x3"x1/4"

Forgive my Microsoft Paint sketch. If I run a DS loop off the trans mount, this would be a top view with the transmission on the left of the picture. The DS would pass through the loop and out to the right.

http://i228.photobucket.com/albums/e...ps4d4e35a6.png

I think Myth Busters did an experiment with trying to launch the car with a broken driveshaft....if I'm remembering correctly, they couldn't get a car to do it....

I was never saying to use the X pipe in place of a DS loop

Let me give you my 2 cent experience with d-loops. Drag racing in the lat 80's I broke the front yoke at about 75 mph. It totally demolished the turbo 400 tail shaft and broke the mount dropping the engine and trans down; it ripped the Lakewood flat strap style loop out of the floor (bolted in the stock floor pan of my 67 Firebird). Luckily I was not hurt just my wallet. In 2002 racing the same car I broke a driveshaft at 160 mph. I had a tubular front loop and it was destroyed. The shaft can openered the floor but a double frame rail next to my leg saved me from major bodily damage. 3/4 of the shaft exited out the back of the car. The noise was horrendous and after that day I installed a full 4130 enclosure that went from front yoke to the rear yoke in addition to front and rear loops. Do not skimp on the loop!

Just an update...I ended up making a driveshaft safety loop out of 1/4"x2-1/2" steel plate. I got the solid loop from Jegs, and the rest is bar stock. I mounted this between the T56 mount and the trans itself. I thought I'd get lucky and make a straight run back, but the loop needed to be about 1" higher than the front mount.

Jegs loop:
http://i228.photobucket.com/albums/e...ps17c841b9.jpg

Bar stock:
http://i228.photobucket.com/albums/e...psfa1bd4c6.jpg

http://i228.photobucket.com/albums/e...psbd27e78b.jpg

Basic shapes:
http://i228.photobucket.com/albums/e...ps628c3d36.jpg

This is what I came up with:
http://i228.photobucket.com/albums/e...ps395a8fa1.jpg

http://i228.photobucket.com/albums/e...ps5343c080.jpg

Here it is installed:
http://i228.photobucket.com/albums/e...ps7c057ac8.jpg

http://i228.photobucket.com/albums/e...ps5ab761a3.jpg


Notice the hack job on the exhaust H-Pipe. That's not my work, and yes I paid to have that done. When I get back from Jamaica, it's going to a real exhaust shop and I'm having them install a Magnaflow X-Pipe, with new pipe running from the new headers to the existing Magnaflow mufflers.

Keep it to the front. If you break a front u joint, the shaft is still bolted to the pinion...there is no way to stop the pinion from spinning. Plus the flying front end is to close to me for comfort. If you break a rear joint, your first reaction will be to put it in neutral, or push in the clutch. Therefore removing the force that is spinning it. Also, the transmission has a slip joint, so the broken shaft will more than likely slip out.

Just my .02,
Joe