I just picked up an 87 IROC parts car and noticed these two braces. The one goes from the pass. hinge to the cowl and the smaller one is also on the pass. side but from the frame to the wheel well housing. I have seen the small one before on a different IROC I parted out but I've never seen the big one. Any ideas?

 

Common.

JamesC

 

Those are specific to the Z28 and IROC and some '91-92 Trans Ams/Formulas also got them.

 

Exactly

 

My question has always been why? What's their purpose since neither appears to be strong enough for any real support? Further, why only one side?

JamesC

 

Oooh ive never seen the "bigger one"

Also James, im glad im not the only one who ever wondered this.... Just be glad they didnt put it over the battery! That used to tick me off..... Guarenteed shock when trying to boost the battery.

 

my 84 z has them im not 100% on the big one tho. i never knew they were specific to z28s and irocs. how much structural integrity can they really add? my guess is just for looks

 

Brace, Whl Hse, Pnl Reinf--RH (Z28) GM 14045394
Brace, Fdr to Upr Cowl GM 14074745

As I mention, why they're there is the puzzle for me. Cosmetics under hood? Doubtful.

JamesC

 

Would they provide any support at all for body twist under acceleration? The torque on launch twists the car and those braces might keep that side of the car from buckling. Any merit to that?

 

My thought on it is that sometime during testing, GM
probably found that something was flexing or deforming
under loading.

The cars that these were put on had the higher spring
rates, larger roll bars ect. ect.

Been to the Gm test track in AZ (Years ago), was sorta
snuck in and the cars go thru (Holy Hell) as to
finding thier weak links before release to the public.

Fords been doing it for years in their performance cars
in the bay area.
After market strut triangulation in the bay area another
example.
Cosmetics, don't think so. Why add wieght and clutter
when you don't have to.
Another thing, your going to throw a car into a turn harder
turning left than right. Hence only pass side bracing. Plus
Brake setup and steering shaft clutter on drivers side.





Later

 

I added all those little braces to my '84 T/A with WS6 and I can't say I noticed any difference. The only brace I did notice a difference is the steering box brace AKA "Wonderbar" from an IROC.

The thing that doesn't make sense is why did the Z28 and IROC get all those braces while WS6 Firebirds didn't get anything for most of the 3rd-gen lifespan. The WS6 cars had a stiff suspension, especially the '85-up cars.

 

The factory knows more about the engineering nuances of these cars than we will ever know, and you better believe that GM wouldn't have spent money allowing something to make it to production if they didn't feel it was damn well justified. I figure there was some rare stress fracture or deformation noticed during testing abuse. So they put these on the cars most likely to see such abuse as a "band aid" if you will to shrink the probability of said stress issues presenting themselves.

 

I donno for sure

Maybe a RPO combination addition.
Maybe they knew that the Camaro guys were harder on
thier cars than the Bird guys

Know mine are coming out as soon as I tie my strut bar
into the subframe and firewall.
But I'm running front coilovers and need the support.
Leave them in, or take them out, don't think it makes all
that much difference.

Correct Darkshot, unlike Ford who braced theirs
correctly.(Can't believe I just said that)!!!!!!

Later