Drive shaft safety loops

[bigbadbaz]

Hi there ,
I've made this drive shaft loop for my son's street / track car & want to know if it's legal?. Here's a couple of pics...




Cheers
Baz

[Justin]

Hi Baz

The NZ Hobby Car Technical Manual has a minimum specification of 50x6mm for a drive-shaft safety loop fabricated from flat-section material. I can't see any actual specifications in your post, so you'll need to check that you meet the specs to start with.

Other requirements are that the drive-shaft safety loop and it's attachment system must be extremely well engineered so as to be capable of containing the massive energy of a disengaging and rotating drive-shaft. Your LVV Certifier will need to assess whether you've met these requirements for both the loop itself (welding attachment in particular), and of it's attachment to the vehicle. The loop should also be attached to the vehicle with two bolts per side - as your design is slightly different to the norm, your certifier may ask for additional attachment bolts to be fitted between the two sections, or at the side attachment locations.

Also worth noting is that if the vehicle has a two-piece drive-shaft, it must have a drive-shaft safety loop for each shaft section.

Good luck with your project

Justin

[bigbadbaz]

Hi Justin,
Thanks for the reply.
I'll get in contact with the certifier.
Thanks again.
Baz

[woody]

HI, I have a vehicule with a independant rear end so the driveshaft doesn't move up and down. So I have welded a plate ( 50x6) which is welded across the gearbox cross member. So it is not a loop but a flat bar, also the drive shat is carbon fibre so the rotating mass is a lot less. Does this sound legal. The bar is within 150mm of the centre point of the universal.

[Justin]

Hi Woody

As you've described it, this would not meet the requirements. The Hobby Car Manual requires that a drive-shaft safety loop fitted to a modified production vehicle must provide a full 360-degree enclosure of the drive-shaft.

There is no relaxation in requirements for a carbon-fiber driveshaft. Any drive-shaft safety loop and its attachment system must be extremely well engineered so as to be capable of containing the massive energy of a disengaged and rotating drive-shaft.

Also, Where a vehicle is required by these rules to have a drive-shaft
safety-loop, and the vehicle has a two-piece drive-shaft, a drive-shaft safety loop must be fitted to each drive-shaft section.

Justin

[woody]

Thanks for that Justin, that saved wasting some time. Will build a complete loop and weld it to the rear of gearbox cross member, that would be a lot stronger than bolting it to the floor. Thanks

[Justin]

I'd suggest that if you intend to attach it to the gearbox cross-member that you run the proposed design by an LVV Certifier, or post a pic here. As the loop will be suspended back from the cross-member, it may require additional bracing or gussets.

Justin