The Jegs S-loop is made to be bolted to holes drilled up through the floor for steel bodied cars

This is just after I was tack welding it in place to the cross frame. Yes, it did get nicely welded and painted. I was going for max protection next to my seat.

Keisler drive shaft and 1330 U-joints behind tko 600

 

George, I did see a GTO jump about 3 feet off the ground at the rear when the front U-Joint let go. Kicked him sideways quite a bit too!

 

I dont know what the bottom of a GTO looks like, but we have crossmembers there, no way the shaft hits the ground. The point of the loop is to protect your ***(literaly)

 

Which brings me to my question on this subject...my vette is a street car that that sees a few bursts of acceleration while I'm out cruising.

I always thought the crossmember would contain the driveshaft if a ujoint came loose. Is this overkill for a street car?

 

I had a 66 Impala pretty hot rodded. This is a fairly long drive shaft in a big boat car. Being young and dumber. I had done some tranny swap from it's orginal 2 speed glide to a 3 speed without any thought to tail shaft length or the fact that I didn't really have alot of rear yoke engagement. Well on one of the first real 2-3 shift at 90+ mph the drive shaft came apart from the tranny. I just heard a bunch of bad noises and maybe a few big thumps before getting stopped.

I only had a short crumpled piece of drive line still attached to the rear end. Lots of floor damage.

It does scare me how close the Vette drive line really is to where my custom seat is mounted.

 

AussiJohn,
Nice to hear from an inspector, I take it you would not disqualify someone if they had the above bracket? Or Am I reading too much into your message??

Also you say "NHRA approved" as far as I know the NHRA does not approve things like driveshaft loops, I even called them about it. They said I can say buit to NHRA specs is all.

Can loops be 'approved'?

Yes, I am definitly listening to all of the concerns voiced here. You gotta remember I'n not running some huge profit driven corperation here. I'm trying to make a few speciality items that people want and feel good about. Yes I do make a little money, but I'm not going to be quitting my day job anytime soon!

I'm thinking the Mark II will be one piece 1/4" plate lazer cut bracket with a bolt on loop. It would have the edges bent down for rigidity and loop attachment rather than a welded on center rib as shown above.

 

i may not be able to drop alot of fancy tittles after my name, but i can tell you that it is impossible for a c3 driveshaft to fall out of the front because of our crossmembers. so alot of the previous statements are worth zero, as far as a c3 is concerned. as for the bracket, it only needs a plate or another tube welded in to support it in the horizontal axis. the two bolts in the crossmember offer very little support in that direction. and the bent tubes would need help somewhere to deflect any hits it recieved in the up direction as the tubes would bend more easily that way. i have welded and thought of just about every possible combination of metal things to dirt cars. that experience alone should be equivalent to a fancy name or tittle.

 

Sadly, I believe NHRA intentionally leaves themselves 'wiggle-room' on many issues of this type matter, but, generally-speaking, their men on-the-ground (Divisional-level and especially the Safety Safari ) do a very good job of policing tracks from coats-to-coast.

I ran the Staging Lanes at my home-track for a few seasons, while my racing-partner/buddy did some Tech Inspection work, and various places in the NHRA Rule Book directly-contradicted other places in the same book.....

 

redC3,
Oh I am definitly listening to what you are saying!
I like your ideas and definitly plan on incorperating them into the next design.

Keep on keeping on.
Keith

 

Even though I agree with others that the C3 shaft can't hit the ground I installed a loop on mine. My thinking is that if the driveshaft is contained within an inch or two of alignment at the forward joint there is a lot less potential for damage to the car than if the driveshaft drops to say 8" from alignment. Hopefully the loop will hold up the few seconds it takes to get the car stopped. If it will last long enough to accomplish this I would be satisfied with the investment.

 

My only comment is the drive shaft is round and should be surrounded in a round casement. In your design the top is round but the bottom is not. Even a very worn out bushing will contain a round shaft better than a square bushing containing a round shaft.

I look forward to see what you come up with.

 

I use a universal Summit driveshaft loop which is bolted to the floor. I use large washers and aluminum plates for it not to break through the floor... I passed tech even at NHRA owned tracks with that setup..
I believe that driveshaft loops don't need a SFI number that they are approved but the material has to be a certain thickness..

 

I would be more interested in loops for the 1/2 shafts.

If an inboard U-joint lets go, there is nothing to contain these and these can do a world of hurt. Certainly did on my '64 when the U-joint let go and the 1/2 shaft came through the floor into the car and took out a lot of stuff on its way.

 

They did a car pole vault episode a while back. They could never get it to work.

 

http://www.tomsdifferentials.com/tomp.htm is just one of the places selling the half shaft loops

 

 

I don't see them on their site.

 

Keith,
I was wrong with the above - I should have said "NHRA recommended" . Let me quote from the ANDRA Rule Book (probably borrowed straight from the NHRA)

"In place of a crossmember in the vicinity of the front universal joint, all rear wheel drive competition cars with elapsed times quicker than 12.99 seconds, using open drive shafts, must have a container loop: 360 degrees of enclosure, 3mm (1/8 inch) minimum thickness and 50mm (2 inches) wide, or 22mm (7/8 inch) x 1.62mm (.065 inch) welded steel tubing, securly mounted and located within 150mm (6 inches) of the front universal joint for support of the drive shaft in event of universal joint failure. It is recommended that the loop be round to minimise loading."

The operative terms there are "securely mounted" and "6 inches" which we always take from the centre point of the trunnion (?) in the middle of the U joint. A loop that was of the correct dimensions, but bolted to the fibreglass floor with two quarter inch bolts would not meet the definition of "securely mounted" in my opinion. On a steel bodied car we recommend that the stock steel floor is "sandwiched" by the loop's horizontal mounting bracket on the bottom and a similarly sized piece of steel on the top, using at least two 3/8 inch bolts on each side of the tunnel.

As your loop must be affixed several inches rearward of where it mounts to the crossmember, the bracket between the loop and crossmember must be strong enough to counter the twisting and leverage effect caused by a broken drive shaft running at up to several thousand rpm. For this reason, I believe that the bracket shown by shafrs3 will resist twisting better than the one you have made initially.

Remember that the loop is to stop the shaft from piercing the thin fibreglass floor and injuring the occupants. The area of the body at most risk is the genitalia and upper thigh. On the inside of the upper thigh is the femoral artery and if this is cut, blood will gush out and death will follow in two or three minutes. I say this with confidence based upon once being on a jury in a murder case where such a death occured. A long knife rather than a drive shaft was the instrument there.

In answer to your question about whether I would disqualify someone if they had "the above bracket", I'll be straight up and say I'm not sure. I would like to receive an answer from the NHRA with regard to loops that are not mounted immediately on either side of the loop as shown in the drawing in the Rule Book. I believe that you would do well to consult the NHRA before you bring out your "Mark II" version so that you can then say something along the lines of...."Conforms or built to NHRA recommendations for drive shaft loops for fitment to 1963 to 1983 Corvettes..." (Remember, the last 1982 Corvette was built in early 1983).

As you've already opened the door to NHRA, I'm sure that they'll accomodate you with such a request. Keep me posted.

Regards from Down Under

aussiejohn

 

http://www.tomsdifferentials.com/catalog.asp?pg=26

 

These two items would make it no good. Mine is really heavy steel

(1/8 inch) minimum thickness and 50mm (2 inches) wide,

It is recommended that the loop be round to minimize loading."