NHRA approved driveshaft loop ?

Funny I read all this, I also just installed a Summit Racing brand loop just like the one Casey pictured. Had an issue with it hitting on my exhaust under load, nothing a large pry bar didn't help.

Mine however did not come with lock washers, just serrated nuts which had the washer built it. I'm not to sure how good I feel about that but I plan on checking them after awhile.
 
Also, just to poke fun on Mike :D

I read your sig 93 SC - before: 275hp/343tq 13.709 @ 104.25 After: 441hp/462tq Best so far 13.449 @ 111.59

I think you need to spend more time at the track and less time researching fastener vibrational loosening.
 
Also, just to poke fun on Mike :D

I read your sig 93 SC - before: 275hp/343tq 13.709 @ 104.25 After: 441hp/462tq Best so far 13.449 @ 111.59

I think you need to spend more time at the track and less time researching fastener vibrational loosening.

Yeah...........dork!!
 
Also, just to poke fun on Mike :D

I read your sig 93 SC - before: 275hp/343tq 13.709 @ 104.25 After: 441hp/462tq Best so far 13.449 @ 111.59

I think you need to spend more time at the track and less time researching fastener vibrational loosening.

Considering the length of time i've been willing to live with a non-functional trac lock it is important that other parts I've installed don't fall off waiting for me... thus the research.;)
 
yes, vibrations the same for each test. The company has something they call a junker which is a machine that is able to create shearing forces to duplicate vibrations over time but within a much shorter period. they've tested a number of fasteners and locking devices.

Their double nut test was pretty interesting as well.

I think most of what you guys are trying to apply involves misunderstanding and misapplication of engineering and scientific fact.

1) Traditional split lock washers do not hold anything via spring action. Therefore any reference to the spring nature of the lock washer attempting to hold anything is pure misapplication of the design intent and therefore results in fallacy, regardless of who tests it. A traditional split washer is made of a type of hardened or spring steel and cut at a diagonal such that two sharp opposing "blades" are produced. These "blades" are intended to bite into the softer clamped and clamping materials creating a bur as they are tightened. It is this bur that is intended to prevent or at least delay loosening. The spring action is only there to provide enough tension to generate the bur that will help hold the fastener in place. For this reason split lock washers are also inneffective when used on hardened nuts. Split washers also cause damage to the nut and surface when installed and therefore should not be used where frequent assembly/disassemble is required. Split lock washers are also not generally used in applications subject to extreme vibration.

2) The ability to resist loosening under conditions of vibration is a misnomer and the use of vibration testing to determine the holding ability of a faster is also largely fallacy. To the untrained mind it is an impressive demonstration, but for someone able to think things through, typical vibration testing is little more than a circus side show. Testing a fastener to the point of failure does not necessarily provide any useful data for the actual application of the fastener. For example, in order for any loosening to occur, the forces of vibration and the resulting load placed on the fastener have to be high enough to temporarily unload the threads. The threads simply will not back off if the fastener is sufficiently strong enough and torqued correctly to the point where tension can be maintained at all times. If you are experiencing unloading of the faster to the point that it unscrews, even under conditions of vibration, you have either overloaded the bolt or you have not sufficiently torqued it. Case in point: Connecting rod bolts. Think about this for a moment.

Bolt locking devices of any kind should not generally be used to hold a nut in place! To presume to think that a locking device is necessary most often demonstrates a lack of understanding of the engineering involved and an underestimation of the size or quality of required fasteners. This does not mean that locking methods should not be used, but it does mean that a locking device should not be used as a primary holding device.

One proper use of locking devices is when the clamped component is insufficiently strong to hold the required clamping force of the fasteners. There are many cases where the amount of torque required to properly stress the fastener would damage the component (like exhaust headers, for example). In this case double nut (using two nuts of equal size) is an appropriate solution.

The whole topic is much more complex than could be covered here, and I am only presenting a few tidbits for your consideration. If properly installed, split lock washers on the driveshaft loop is an appropriate application. Nylock nuts in this case would be better though because clamping force in this case is more or less irrelevant and so even if the bolts are not tightened properly, the Nylocks will not rattle off. The only thing the bolts are doing in this case is connecting the two halves of the loop. As long as they don't fall out completely, they will continue to do their job, and the amount of clamping force provided by the fasteners is largely irrelevant.
 
Nyloc for the win

>As long as they don't fall out completely, they will continue to do their job, and the amount of clamping force provided by the fasteners is largely irrelevant.

And I'm sure an NHRA Inspection Team would share the same opinion if they found rattleing fasteners :)
 
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Even if they serve no definable purpose? Perhaps if you define "properly installed" their purpose will be made clear?

All I meant is properly torqued according to the bolt strength. If the bolts are tightened correctly then no lock locking device is needed at all but the lock washers can provide a degree of additional security which is the point in the first place. The lock washers don't hold the nuts on, but they can provide a measure of security against accidental failure of some sort.
 
While installing the dual fuel pumps a couple days ago, we installed this driveshaft loop in my 91. Other than needing to bend a little hump in the lower bar to clear the exhaust, it fit perfectly. It was also necessary to unbolt the transmission support to lower the tail of the transmission a little to get the upper portion of the bracket around the driveshaft, but that only took a minute. Now I just need another one for my 93.

IMG_0100_Small.JPG


David
 
This is what I did for a loop.

nononono, thats not even close to being legal. re-read what i posted earlier in this thread...


In place of a crossmember, in the vicinity of the front universal joint, all cars in competition using open driveshafts, must have a retainer loop 360-degrees of enclosure, 1/4-inch (6.35 mm) minimum thickness and 2-inches (5.1 cm) wide, or 7/8-inch (22.2 mm) x .065-inch (1.65 mm) welded steel tubing, securely mounted and located within 6-inches (15.2 cm) of the front universal joint for support of the driveshaft in event of U-joint failure


i dont know what you have on the top of it, but the loop cant be made up of bolts.
 
nononono, thats not even close to being legal. re-read what i posted earlier in this thread...


In place of a crossmember, in the vicinity of the front universal joint, all cars in competition using open driveshafts, must have a retainer loop 360-degrees of enclosure, 1/4-inch (6.35 mm) minimum thickness and 2-inches (5.1 cm) wide, or 7/8-inch (22.2 mm) x .065-inch (1.65 mm) welded steel tubing, securely mounted and located within 6-inches (15.2 cm) of the front universal joint for support of the driveshaft in event of U-joint failure


i dont know what you have on the top of it, but the loop cant be made up of bolts.

Its a 1/2 solid steel loop. It has to be as strong as a 7/8 x .065 wall tubing, right?
 
Its a 1/2 solid steel loop.

Looks legal to me.

Nice planning to get it all in there so close :)

Are there nuts on the hoop, upper side of the crossbar too? Looks good with the tapped threads/holes - how did you lock those bolts in place?
 
Looks legal and is legal are two different things. While 1/2" thick steel bar may be strong, I doubt it has the same area of 1/4"x2" plate (which is what is required by NHRA).

It would be dissapointing if some hardcore rule following official did not let you race because of that.

On the other hand, any loop is better than nothing.
 
Its a 1/2 solid steel loop. It has to be as strong as a 7/8 x .065 wall tubing, right?

i looked at it again, all i see is the flatbar on the bottom, thats fine. but where is the "loop" part? all i see is bolts or is that solid threaded shaft bent into a U? either way, it would fail any inspection.

im not trying to nitpick im just trying to make sure your legal, and safe.
 
I did the calculations and the 7/8 dia x .065 wall cold roll steel tube has a UTS of 10,590 lbs and the 1/2 316 SS rod has a UTS of 16,600 lbs. So my calculations says the the rod is stronger. Now if it will not pass the test; I will change it to a rolled bar 1/4 x 2" wide.

Mike
 
I have been sent home already

Has anyone running over 11.5 had someone ask to inspect their driveshaft loops? Just curious.

They sent me home once for that, they used that as a reason. I only had the rear ford strap and they said that it needed to be 360. The more they look at your car the more trouble you will get into.I also had a crack in the windsheild once and that was a NO GO as well. That crack was not even on the drivers side, and it was down at the bottom right side.....Rich
 
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