Driveshaft and cv safety loops

So, if all goes according to plan, my challebge car will be fast enough to get me booted from an nhra track for safety regs.

however, in an attempt to NOT have this happen, and extend my life expectancy, i need to put safety loops in. The regs are fairly straightforward. However, the application in a miata isn't something that i have had much luck searching. 
my understanding is that i need driveshaft and cv axle loops due to slicks and an engine swap.

anyone have pictures/experience?

Driveshaft loops always go a minimum of 6 inches from the front U-joint.   The idea is that if the front U-joint breaks, the drivshaft wil be contained and won't pole-vault the car by digging into the ground.  If the rear U-joint breaks, nothing bad happens so who cares.  (Well, nothing worse happens, anyway)

I've never heard of needing a loop for a CV joint.  When they break, the axle stays contained by the cup.  If the stick itself breaks, it spits itself out very rapidly.

Problem with the stick on the cv getting spit out is that it will either hit my back o r fuel system. 

Ill find a way for a 6 inch from front u joint safety loop.

Since its now the workweek, hopefully someone will have pictures. Or better google skills. 

Really hope to fab this sometime this week. 

I can’t remember if we took pictures of our half shaft loops or not. They’re supposed to be 1 inch wide and 1/4 inch thick. We just did one per side but Pat did two per side and iirc it saved him some major damage. 

Looking at the miata stuff, figuring out how to fit it is going to be the hardest part.

Id love to see some pics of yours stampie. 

In reply to Dusterbd13 :

This is the best I could find.

For us we had two preexisting holes in the lower control arm. The part you see going up in the picture we bolted going into those holes. In it's final position it's upside down from the picture above. 

In reply to Knurled. :

I haven’t seen a cv come apart but I watched a guy grenade a u joint launching a big block Corvette and the half shaft tore the fiberglass floor pan all to hell and put a pretty big gouge into his seat back.

I used to race Dwarf cars with a guy who lost the rear u-joint. He limps now. the shaft bent at a 90 deg and came up through the floor and took out the drive shaft tunnel and his seat.  Shattered his hip and leg.   Please don't go with min spec.

Min spec is just that: MINIMUM. 

Ive had enough limp and arthritis causing bodily harm. Im hoping to get every joint in the system safety looped.

Wally said:

In reply to Knurled. :

I haven’t seen a cv come apart but I watched a guy grenade a u joint launching a big block Corvette and the half shaft tore the fiberglass floor pan all to hell and put a pretty big gouge into his seat back.

Yep...because the axle U joints are fixed-yoke at both ends, so if either end breaks, the shaft just whips around.

Front u-joints are generally slip yokes,  so if the rear joint breaks, the driveshaft flails around just long enough to fall out of the trans and you drive over it.

In reply to Knurled. :

This was the driver’s side half shaft. The older Corvettes used u joints on the driveshaft and both rear half shafts. They are also the upper suspension link so when it lets go you get the added excitement of the tire moving around unexpectedly until you get stopped.

Mine kept me from taking a halfshaft to the back on one side and having the fuel line bashed on the other side.  I know cv shafts don’t fail quite as spectacularly as u joint shafts but i’m not one to want to find out.  Apparently the NHRA had stepped up tech inspections on IRS cars and there are vendors making loops for corvettes and stuff that technically are fast enough to require them from the factory.  

Wally said:

In reply to Knurled. :

This was the driver’s side half shaft. The older Corvettes used u joints on the driveshaft and both rear half shafts. They are also the upper suspension link so when it lets go you get the added excitement of the tire moving around unexpectedly until you get stopped.

Yep.  That's why they now have a kind of upper link available that holds the suspension together if a U-joint snaps or the halfshaft (more of a mini driveshaft) wads itself up like taffy.

People also manage to stuff 12-bolt internals in the 'Vette rearend cases.

In reply to Patrick :

Did the one get ripped apart, or is that an optical delusion?

Also, how are you guys getting nice bends in these?

In reply to Knurled. :

That’s an impressive twist 

In reply to Dusterbd13 :

Sheared next to the weld, but did it’s job.  Those were on the car when i got it.  It was a very violent breakage, but I’m still pretty proud that I was able to destroy both sides on the same launch.  

My driveshaft loop is a slice of 1/4” thick 6” round steel tube with tabs welded on to bolt to floor.  I’m guessing you might be able to find some of that on the scrap rack at a steel supplier, the welding shop up the street sells me cutoffs for .80/lb. 

i also just bought a driveshaft loop for something completely bonkers like $16 shipped from ebay.  It’s the same dimensions as the summit racing one but cadmium plated instead of painted black.  

Dusterbd13 said:

In reply to Patrick :

Did the one get ripped apart, or is that an optical delusion?

Also, how are you guys getting nice bends in these?

Just so happens we made a video.

https://youtu.be/te72bjTO6OU

Here's the parts we used to make our die.

That's genius stampie!

Thanks!

In reply to Dusterbd13 :

One man's genius is another man's redneck engineering.