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PostPosted: Tue Jul 30, 2019 4:38 am 
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Joined: Fri Oct 17, 2003 5:32 pm
Posts: 565
Chris,

If your stock bellhousing is .250 thick, it's legal. There is zero definition on what constitutes "explosion proof". Measure it.

Also, if the clutch has some other heavy components between you and it, your don't need one. If the plane of the clutch doesn't intersect your body, you don't need one.

The rule as written is nebulous at best, and there are a bunch of factors you could argue with the appeal or the SOM and win.

That being said, throw a .250 piece of aluminum on your firewall, and eliminate every worry.

My AS car doesn't have one, but the stock bellhousing is over .250 thick, so if I ever get it looked at, that is my argument.

Scott

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PostPosted: Tue Jul 30, 2019 4:59 am 
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Joined: Sun Dec 14, 2014 11:06 pm
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Location: Portland, OR
I think this rule is left over from a time of BP and such. In nhra this isn’t required until the car runs 11.49. Never tried but I don’t think an H, F, or E runs that fast or even launches that hard. If the flywheel bolts did shear the transmission input shaft is still holding it. It a touring car doesn’t need one then perhaps the better rule is stock or equivalent fasteners and/or the addition of dowel pins.

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PostPosted: Tue Jul 30, 2019 5:03 am 
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Joined: Sun Dec 06, 2015 5:33 am
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Location: Titusville, Fl.
Guys I'm all for adding safety for my legs & feet but I think it goes a little farther than just the driver.
A lot of cast aluminum bells can get a hole knocked in them with a hammer. (Especially Spridgets)
A clutch/flywheel assembly spinning at 8K carry's a tremendous amount of kinetic energy. A small piece of shrapnel
is like a high powered bullet. It struck home early in my youth one night at a drag strip. A Corvette clutch/flywheel exploded with no scatter shield & cut the car nearly in half. A chunk hit the front of the hood of a '54 Chevrolet we were standing next to, went through & knocked the carburetor off the 6 cyl engine.
Luckily the Corvette driver only lost a toe but the guy with the '54 had to get a ride home.
My point is, even a small light flywheel fragment from a small car can can do damage even if it's not to the driver.

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PostPosted: Tue Jul 30, 2019 5:21 am 
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For those that are planning on doing this, don't waste a lot of fab time: $120: https://www.summitracing.com/parts/sum-590300/overview/

Flexible and SFI legal, and therefore SCCA legal.

Note that the rule does not say you have to install the scattersheild on the bellhousing ( or even between the tranny and the driver) :roll: :lol: :lol: :lol:


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PostPosted: Tue Jul 30, 2019 5:59 am 
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Location: Bellevue, NE
How is this being interpreted by all of the tech folks that are signing off annuals every year without checking to see if one has a proper shield?

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PostPosted: Tue Jul 30, 2019 6:20 am 
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blamkin86 wrote:
For those that are planning on doing this, don't waste a lot of fab time: $120: https://www.summitracing.com/parts/sum-590300/overview/

Flexible and SFI legal, and therefore SCCA legal.

Note that the rule does not say you have to install the scattersheild on the bellhousing ( or even between the tranny and the driver) :roll: :lol: :lol: :lol:

That seems to be an easy button for those who wish to install, but does it become useless in 2 years when the SFI cert expires? If you buy a steel or aluminum scatter shield, it meets the regs even when the SFI cert goes invalid because the material otherwise meets the specs required.

Just something to think about.

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PostPosted: Tue Jul 30, 2019 7:10 am 
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For LP cars, we are turning the revs inside of the OE parameters. I could use the stock tach.

Maybe the Full prep cars should have some protection.

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PostPosted: Tue Jul 30, 2019 8:09 am 
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I have seen a flywheel come apart on a rabbit. The shrapnel hit a competitors helmet. The engine was what would be called a limited prep. Never under estimate the power of a missed shift.


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PostPosted: Tue Jul 30, 2019 8:40 am 
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Protech Racing wrote:
For LP cars, we are turning the revs inside of the OE parameters. I could use the stock tach.

Maybe the Full prep cars should have some protection.


6000rpm at 14" ring gear diameter (7" radius) = 250mph at the edge of the ring gear.

A limited prep rotary turns >8500rpm, depending on how long you want the engine to last. Miss a shift and I've zinged mine to over 10,000rpm before (whoops! really need to install ignition module with a rev limiter..)
At 9000rpm with an assumed 14" flywheel diameter, the ring gear is turning 375mph at the outer edge... imagine a 5lb hunk of shrapnel with teeth on it exiting the bellhousing at 375mph.. 88-o

limited prep piston engines are obviously going to be much slower, but it's something to think about..

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PostPosted: Tue Jul 30, 2019 11:15 am 
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Joined: Thu Oct 03, 2002 10:34 am
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Location: Wauwatosa, WI
Maybe a little reading of following explains whose responsible for the race car.

B. Minimum Event Safety Inspection/Logbook-Tech Sticker
Following the Annual Technical Inspection, minimum inspection for each event requires reviewing of the
current Vehicle Logbook and signing off the logbook page for the event. If it is in order, a Tech sticker is
issued. The Series Chief Tech Inspector or the Chief of Tech may delegate signing the logbook page and
issuing the Tech sticker to any worker holding a current Regional Tech license or above. The driver’s safety
equipment does not need to be reinspected.
All cars must display a Tech Sticker signifying successful completion of technical inspection to enter the
course. Technical inspection assists event officials in determining, in their judgment, eligibility to participate in a SCCA sanctioned event. The technical inspection does not ensure, certify, or warrant that the
vehicle or any part of it is safe or totally and ultimately compliant with all applicable rules nor does it in any
way change the fact that the driver, crew members, and vehicle’s owner are ultimately responsible for the
safety and operation of the vehicle and equipment. By conducting a technical inspection, SCCA and each
of its directors, officers, employees, and officials, make no representations, warranties, or assurances that
a technical inspection, including the review of any written information, will do any or all of the following:
• Detect every or any problem with a vehicle or a driver’s personal equipment or clothing; or
• Detect every problem with rule compliance; or
• Prevent bodily injury, death, or personal monetary damage.
The participant agrees that he bears the ultimate responsibility at all times to ensure the safety of his
vehicle and equipment, and compliance with all SCCA rules, regulations, and agreements, including but not
limited to those contained in the GCR.
In addition, in the case of technical violations, he acknowledges,
understands, and agrees that he is responsible to fully know every component of his vehicle and that even
if a third party (for example, an engine builder) has caused his vehicle to be noncompliant, he will still be
responsible for and will be charged with any applicable violation and penalty.

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