Rule Proposal: Harnesses

[zip4zat]

Thanks for the input and suggestions Fred, and sorry about spilling the beans.

Stephan, Grade 5 hardware is very easy to find at Home Depot, Lowes, Hardware stores, etc. In fact, you can even find Grade 8 at the same stores relatively easily, in both standard and metric thread. I use Grade 8 when mounting harnesses & seats, with sturdy backing plates or large washers, as Fred mentioned. :thumbleft:

As a minor detail, metric grades are specified differently than SAE. For example, a metric equivalent to SAE Grade 8 is Grade 10. I think grade 9 might be a spec for metric aircraft hardware, not sure. May have something to do with corrosion resistance. I can look up the specs for various grades.

But for the rule book, Im not sure we can/should get this specific. Or perhaps state something to the effect of "... at least SAE grade 5 or equivalent.." but this also can be misleading in ways. btw- the grade type is indicated on the head of the bolt by specific demarcations, if it was ever questioned, per enforcement criteria. I dont think we should specify a rule that is not enforceable. If so we should state the intent of such rule, so at least intent can be questioned/evaluated.

My 2c's on the bolt matter, I personally wouldn't use SAE grade 5 hardware for seatbelt mounting. Grade 5 isnt really that strong. Bolts will not hold their spec'd tensile or shear strength if they are not used properly, such as existence of load concentrations (this is why we washers and backing plates!) and/or improper preloading (ie improper bolt torquing) especially in impact conditions! I would exclusively use grade 8 or stronger, problem is grade 8 or metric grade 10 hardware are not easily available in all sizes.

-joe

[boltonite]

I really have no idea what grade hardware is used for harness mounts, I used Grade 5 only as an example. The point is that the right type and quality of hardware is needed with aftermarket harnesses. -FF

[WillM]

Nice info Joe!

You are correct about grade 8 SAE being equivalent to grade 10.9 metric.
SAE/Metric grades

My local True Value has great selections of grades 5 & 8 SAE, and grades 8.8 and 10.9 metric.

[useless info]
For what it is worth, my harness installs use SAE grade 8. I sometimes re-use the OEM lap belt mounting points, and it seems that in the US, all cars must use SAE bolts to secure the seatbelts. Despite being otherwise 100% metric, Miatas have SAE hardware holding the seatbelt mounting points in place.
[/useless info]

[zip4zat]

The internet is amazing, isnt it? That site is a good general fastener reference. It even has good torque spec and material strength charts! Note the differences between lubed and dry.. its always good to lube your.. um, nuts and bolts...

As a rule of thumb, generally SAE grade 8 hardware is chromated (has a goldish coating) and grade 5 is not (looks silverish). I cant remember if the metric spec's are similar, its been a while since Ive had to deal with technically spec'd design requirements.

[SSNH]

you ain't a baller unless you are using j threads.

[Dave_G]

[useless info]
For what it is worth, my harness installs use SAE grade 8. I sometimes re-use the OEM lap belt mounting points, and it seems that in the US, all cars must use SAE bolts to secure the seatbelts. Despite being otherwise 100% metric, Miatas have SAE hardware holding the seatbelt mounting points in place.
[/useless info]

That info is not so useless. I discovered the same thing when I installed the harnesses in my Miata. I would have saved myself a few trips to the hardware store if I had known that ahead of time!

[CP]

Is there any language about the length of the shoulder belts from the back of the seat to its mounting points? I have been told by a reliable race shop that in a frontal collision, shoulder harness belts tend to stretch 3" for every foot of belt. In theory, this lessens the shock to the body due to deceleration, but I'm not sure if they are designed to stretch per se.

If the belts are placed from the seatback to the rear seat seatbelt upper anchors (@2.5'), I should expect them to stretch 7-8" during a hard impact. If this is the case, I'll come very close to eating my steering wheel. The current setup in my sedan is a Schroth 4-point system with the Anti-SubMarine (ASM) feature.

(I'm using a different belt setup in a totally different car next season. This belt safety issue was one of the deciding factors for ending the current car's track life)

[Scooter70]

I'm also using the Schroth ASM4 belts in my GTO. I looked through the Schroth website but couldn't find SFI or FIA approval. However, they are DOT approved. So the question is... in classes that doesn't require harnesses, is a DOT approved harness legal? As a follow-up question, is an out-of-date harness acceptable (as TurtleVette referenced earlier in this thread that his choices are 3-5 year old harnesses or 35 year old original 3 point belts)?

[CP]

"AS OF JAN 1, all non OEM harnesses must be SFI or FIA approved, with current certification (ie: not expired).

Harnesses must also be installed as indicated by its manufacturer or sanctioning body (SFI or FIA).

The new harness rule no longer specifies minimum belt widths, etc."

[chaos4NH]

"AS OF JAN 1, all non OEM harnesses must be SFI or FIA approved, with current certification (ie: not expired).

Harnesses must also be installed as indicated by its manufacturer or sanctioning body (SFI or FIA).

The new harness rule no longer specifies minimum belt widths, etc."

The above is not applicable to SS and ST classes. No expiration limitations for them.

[Scooter70]

Thanks Sam. I haven't seen the 2008 rulebook yet.

[chaos4NH]

Thanks Sam. I haven't seen the 2008 rulebook yet.

Hhhhhhmmmmmm, a subtle hint, huh? There is a movement in the BOD to get them out to members ASAP.

[JackFFR1846]

What is the expiration date? Although I know my belts are outdated in my racecar, any belts I've ever bought have born on dates....not expiration dates.

jack

[jlwhorf]

I found this on the 2006 bmw club racing rules QA page.

As stated in Safety 4. Safety Harnesses, A. SFI and FIA Certifications: "SFI tagged harnesses are punched with the month and year of manufacture. SFI certifications (16.1 & 16.5) shall expire on December 31 of the second year after the date of manufacture as indicated on the label. There should be three labels on each complete harness – one on a shoulder belt, one lap belt, and one sub-strap. FIA harnesses have tags printed by each manufacturer. FIA harness certifications are good for a period of 5 years from the date of manufacture. FIA harnesses may be used until December 31st of the year printed (or stamped) on the tag. There should be one FIA tag on each element of the harness."

Jonathan
900 Monte Carlo PA

[chaos4NH]

Thanks Sam. I haven't seen the 2008 rulebook yet.

Sorry I screwed up the info on harness expiration dates. If you use a non DOT harness, any class, it must be "in date". Above postings explain date determination.
Since we allow OEM (DOT) approved belts in SS and ST, I am going to push for acceptance of any DOT approved harnesses, which should include
the Schroth ASM4 belts, and others.