Normb

Has any one taken a PHRT on a track day without an add on rollbar using the hardtop as required protection? If so what sanctioning group?
I ask because I attempted this with the SCCA's track nite in America and had my preregistration voided and a new "policy " rolled out which requires V8 roadsters to have manufacturers certify their roll hoops or systems or hard tops are adaquate protection. Mazda appears to not make this claim. The SCCA and my local track indicated full rollbar with rear bracing passing through the rear deck lid to the rear structure was my only path. Looking to find different sanctioning action. Thanks.

.boB

From the NASA Club Rules:

11.4.7 Roll Bars
All open cars should have a roll bar installed to help protect the occupant(s) from injury during a roll-over. The
main hoop shall be one continuous piece with smooth Mandrel bends with no evidence of crimping or wall
failure. All welds should be of the highest possible quality, with full penetration [Ref15.6.15)]. All cars with roll
bars are required to have adequate roll bar padding per CCR section #15.6.4. In cases where the driver’s head
may come in contact with the roll bar should the seatback fail, a seatback brace is required in conformance with
section #15.6.21. Acceptable roll bars include, but are not limited to, the following:
Hard Dog
AC - Ace
D - Deuce (center-braced model only)
AB - M1 Hard Core
TB – M1 Hard Core Hardtop
9B – M2 Hard Core
NB – M2 Hard Core
30
Auto Power
Street Roll Bar
Street-Sport Roll Bar
Race Roll Bar
Blackbird Fabworx (Miata / MX5 / 2017 Fiat 124)
SD (for NA and NB)
RZ (for NC and ND)
GT3 (for NA, NB, NC and ND)
The above roll bars are examples only. NASA does not endorse any brand or model and will not be held liable
for any failures of roll bars.

https://nasa-assets.s3.amazonaws.com...282/2017.8.pdf

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Seems like the organizers of that event were afraid to have you there; since they made a special rule for your particular car. I mean, how many V8 Miatas showed up? Did they exclude 4cyl Miatas? Is the roll over protection different for different cylinder counts?

If the body is stock, as supplied from the factory and sold in the US, then it meets DoT roll-over requirements. Most tracks require a roll bar for convertibles.

Normb

boB, I, suspect the HP/weight ratio combined with the PHRT spooked them. Their action also included other V8 roadsters like MB etc, Since this was billed as an HPDE event roll bars were not required for convertibles with hard tops in place. A friend with a fast Turbo NB was allowed to run with His hard top. I conclude that they were worried the PHRT itself was not adequate. Hard Dog does make a "transformer" bar which will meet requirements and can be transformed to allow the PHRT use. Its the rear deck lid mods that are the pain. Perhaps adding a Petty bar in place of the rear bars will work.
Thanks.

.boB

The Hard Dog bar does not require any deck lid mods (AFAIK), and is legal for all non-competition track events. I'd contact Flyin' Miata directly and talk to them about it.

Normb

BoB, I will contact them again. My current understanding is that the HD bar for the PHRT is lower than the one for the conv in order to allow the top to clear the top latch. It is just about the same height as the factory roll hoops. Her's hoping.
Thanks