Is a D.S. safety loop required (by NHRA) with drag radials? (running 13's)

 

According to the rulebook a loop is required by all vehicles running 13.99 and quicker except vehicles running 13.00 and slower with street tires.

You'll have to ask the question to your local tech inspectors what they'll accept. By the rulebook, you don't need a loop because a DR is a DOT tire and is considered a street tire. Hoosier QTP, Nitto and MT ET Street all fall into the same catagory.

Personally I think if you want to use a tire made with a racing compound (slicks) even if it's a DOT tire, you should have a driveshaft loop. The tire is designed to hook and if it hooks hard enough to blow the front u-joint, you'll wonder why you didn't install one.

I even installed a front driveshaft loop on my 15 second daily driven pickup.

The rules state minimum requirements, There's nothing stopping you from having too much safety equipement. Even a 6 point roll bar is a good investment for a 13 second car.

 

I bought one for the '57 when I was ordering some other things 2 years ago, didn't get it in until this spring.

Although not "required" by the rules, I'm with Stephen (although I'm not quite to the cage stage yet).

 

What is the point to a driveshaft loop anyways? To protect you from a shattered u-joint or something?

 

To keep you from pole vaulting in case of front u-joint failure.

 

If the rear u-joint blows, the driveshaft drops down and usually falls out the back of the tranny. If the front u-joint blows, the driveshaft drops down and digs into the ground. If you're going fast enough you will pole vault.

There's also a good chance if either u-joint blows that the driveshaft could go through the floor. I've seen a picture of a driveshaft sticking through the back window of a car.

That's why many racers upgrade to the large Spicer 1350 series u-joint. The larger u-joint can take more abuse before failing. Racing u-joints are even better. They're based on the 1350 series but don't have the internal passages for grease. The needle bearings in the caps are greased then installed. Without the internal passage in the cross, the u-joint is one solid piece making it much stronger.

 

I already have a Spohn loop, but when I tied to install it, it would not clear my Y-pipe. I had the Y-pipe made for my LT headers but I did not have the ds loop at the time, so the pipes come together too soon to allow the loop. I guess I just need to have another Y-pipe made (around the loop) or run true duals. The true duals wiil work because it is mostly a dragstrip car.