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Need help placing driveshaft hoop


RebekahsZ

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Please post any pictures you have that show how you mounted a driveshaft hoop/loop in a Z-car.  Most of my ideas make it too crowded to get the exhaust tucked up nice and high. It would be good if I did this project before building my exhaust if possible.

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Make the loop a "U" and bolt it to the top of the tunnel.

 

Pretty sure thats not NHRA legal, which I'm willing to bet thats what he's after, other than safety.

 

"all cars in

competition using open driveshafts must have a retainer loop 360
degrees of enclosure, 1/4-inch minimum thickness and 2 inches
wide, or 7/8-inch x .065-inch welded steel tubing, securely mounted
and located within 6 inches of the front universal joint for support of
the driveshaft in event of U-joint failure. Open drivelines passing
any part of the driver’s body must be completely enclosed in 1/8-
inch minimum thickness steel plate, securely mounted to the frame
or frame structure. Driveshaft loop required on all cars  running
13.99 (*8.59) or quicker and utilizing slicks; except vehicles running
11.49 (*7.35) seconds or slower equipped with street tires."
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Your post today got me thinking.... I bought a generic driveshaft loop with intentions of modifying it, but I'd never gotten around to it. SO thats what I did today.

 

I bought this one: http://www.summitracing.com/parts/sum-g7900

 

and hacked it up. I added it to my existing tranny crossmember, and viola!

 

2013-01-06_18-20-15_145.jpg

 

2013-01-06_18-19-44_954.jpg

 

Hope this gives you some insight.

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Thanks! Do you think that long limber-looking design is rigid enough? I don't know.... There are two bosses on the tail-housing of the diff that a similar setup could be bolted too. But I don't know that I want to risk breaking my trans case. I'm betting a broken driveshaft is like having a tornado by the tail. For rules purposes are we supposed to have driveshaft loops for our 1/2-shafts too?

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Just put a circle in the bottom of the U Imentioned above.  My point was to move the mounting of the loop off the floor pan and up into the tunned to give more room for the exhaust

 

And a good point it is.  I'll lose no clearance with this setup, which is crucial.

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  • 3 weeks later...

Plan is to use 1/2 of a standard driveshaft loop and attach it up inside the tunnel sideways with a flat plate taking the place of the other half.  I don't see anything in the rule book that says the hoop has to be round, or attached to the car in any particular way.  If you shop for driveshaft loops in the Summit catalog, the variety of style, shape and size is as diverse as the student body at McKinley High School.  (I wonder how many folks on thie forum will admit to getting that joke)?  Driveshaft is pretty close to driver side of tunnel leaving no room for hardware, so current plan is to only affix the loop on the passenger side of the tunnel with a heavy tab scabbed high in the tunnel and a second tab scabbed lower in the tunnel. Supposed to be ready for pick up tomorrow.  If it isn't sleeting tomorrow, I'll post some pictures of the finished project.  This plan should leave adequate room for a Y-pipe and a 3" single exhaust pipe.

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Don't worry-at the track it will be dual dump tubes straight thru the front fenders via electric cutouts!

 

Here's a picture that the fabricator sent me.  The flat plate will be welded to the side of the tunnel.

post-5903-0-93297000-1359147421_thumb.jpg

Edited by RebekahsZ
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It is finished.  Here's a few pictures of how we handled it.  NHRA doesn't require a loop at the rear of the driveshaft, but I wonder if it wouldn't be a good idea.  If I ever really do break a driveshaft, it would be nice if I didn't have to replace a bunch of sheetmetal in addition to having to get a new driveshaft.  I don't always know how far to run with the "what-ifs."  For now I'lll just try to do what the rule books say since most of those rules are based on bad experiences and proven over time. I'll pick up car tomorrow and try to finish installing droop limiter brackets and get straps on order before the weekend is done.  In the first photo you can see the cracked paint where the driveshaft welds onto the yoke.

post-5903-0-45881000-1359174367_thumb.jpg

post-5903-0-28265800-1359174376_thumb.jpg

Edited by RebekahsZ
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As I understand it, the loop at the front is so the driveshaft doesn't drop down and the end dig into the surface like a vaulters pole, potentially lifting/unbalancing the car sufficient to case traction loss and spins/out-of-control situations where you can veer into other cars or the surrounding scenery. The rear breaking would just cause the driveshaft end to drop down, bounce, scrape and thrash the underside, but much less dangerous to handling.

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That's right.  I'm starting to try to plan on things breaking and trying to figure out how to limit collateral damage.  I'm psycho about mocking things up 100 times before finalizing a plan and I ask other people questions beyond the point of being annoying.  I'm hoping for good reliability this year.  Pretty much going thru the car from top to bottom.

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