GM Stocker rear end

[XSTOCKER]

Are the 9” rear ends in the COPO’s considered a corporate replacement to the older stocker’s or are they limited to the COPO’s only? I think I know the answer, but I have to ask….
Thanks, Mike

[njk53]

That's a really good question. The rear suspensions on the Chevrolet, Ford, and Chrysler factory racers are nowhere near stock configuration, which in my opinion these cars should be using the stock suspensions with the same approved modifications the older cars are allowed. Are the older stockers allowed to use the same technology as the factory built cars? I think not. Also, the newer designed engines have features which allow them to make more horspower and torque per cubic inch than the older engine designs. One item that comes to mind is a roller cam.

[ss3011]

The older IRS Corvettes have been allowed to install a solid axle in for years. The COPO rearend, which is based on a 9" Ford, is not legal in the other GM stockers.

[HandOverFist]

Originally Posted by ss3011

The older IRS Corvettes have been allowed to install a solid axle in for years. The COPO rearend, which is based on a 9" Ford, is not legal in the other GM stockers.

I'm not so sure about that...

"Original rear end may be replaced with another from the same
automobile manufacturer; truck rear end prohibited. Aluminum
center section permitted only on vehicles that were originally
equipped with same. Distance between backing plates may not
be changed. Any gear ratio that fits third-member case or
housing permitted. Limited-slip or ratchet-type rear ends
permitted. Reinforcement of spring perch permitted. Spools
permitted only with aftermarket axles. Aftermarket axles not
required for front-wheel-drive vehicles. Larger brakes may be
used. Replacement rear end may be narrowed or widened to
obtain original rear-end width. Bracing or beefing up the rearend
housing permitted.
Swing axle differential may be replaced with conventional
housing; stock trailing arms must be retained, may be beefed up
and adapted to housing, must retain transverse spring. Must
install Panhard bar. Frame may be notched for driveshaft
clearance. Distance between OEM backing plates and OEM
wheelbase must be maintained. Coil-over shock or four-link
adaptations prohibited. See General Regulations 2:11."

As I see it, GM's '(9")" is now in the mix. We already run aftermarket 12-bolts...what is the difference with this one? "Original rear end may be replaced with another from the same
automobile manufacturer" Let the legal interpretation of the rules begin.

[Dave1695]

The 9 inch rear end in the COPO cars, is built by Strange exclusively for GM and the COPO program. Not available to the public, unless you buy a COPO of course.

[HandOverFist]

Originally Posted by Dave1695

The 9 inch rear end in the COPO cars, is built by Strange exclusively for GM and the COPO program. Not available to the public, unless you buy a COPO of course.

"Original rear end may be replaced with another from the same
automobile manufacturer"

That wording is not in the rulebook. In my mind it makes no difference who made the housing...it is still from the same car manufacturer. Did the COPO cars not have to meet the minimum requirements to qualify for Stock classes? My Mosier or Strange 12-bolt housing was not built by Chevrolet, but are none the less considered legal...correct?

[Bob]

Originally Posted by HandOverFist

I'm not so sure about that...

"Original rear end may be replaced with another from the same
automobile manufacturer; truck rear end prohibited. Aluminum
center section permitted only on vehicles that were originally
equipped with same. Distance between backing plates may not
be changed. Any gear ratio that fits third-member case or
housing permitted. Limited-slip or ratchet-type rear ends
permitted. Reinforcement of spring perch permitted. Spools
permitted only with aftermarket axles. Aftermarket axles not
required for front-wheel-drive vehicles. Larger brakes may be
used. Replacement rear end may be narrowed or widened to
obtain original rear-end width. Bracing or beefing up the rearend
housing permitted.
Swing axle differential may be replaced with conventional
housing; stock trailing arms must be retained, may be beefed up
and adapted to housing, must retain transverse spring. Must
install Panhard bar. Frame may be notched for driveshaft
clearance. Distance between OEM backing plates and OEM
wheelbase must be maintained. Coil-over shock or four-link
adaptations prohibited. See General Regulations 2:11."

As I see it, GM's '(9")" is now in the mix. We already run aftermarket 12-bolts...what is the difference with this one? "Original rear end may be replaced with another from the same
automobile manufacturer" Let the legal interpretation of the rules begin.

A copy and paste of the rule book means absolutely nothing. Once again, the rules apply to some and not others.

A prime example would be a red Olds stocker that recently moved from the west coast to the east coast. It has been through tech many times and always passes. I believe it just won a divisional as well. But it clearly has a narrowed rear axle and altered frame rails. There is no other G body car that sits as low to the ground and has the tire clearance this car does. How is that possible??

A simple check of the distance between the backing plates and between the wheel wells may shed some light on this. But NHRA NEVER checks these things. They must not own a tape measure.

I doubt they even care about bogus stuff like that. Otherwise they wouldn't allow even half the junk they do. So I say, stick the nine inch Ford in. IF they catch it, as for forgiveness.

[stocker396]

Officially NOT I repeat NOT for use in ANYTHING except COPO cars. Was told that with EXTREME prejudice by GM officials AND NHRA tech when wanting to replace my 12 bolt. Huge debate on the floor at SEMA Went rounds explaining and arguing my case and was finally told"You want to use the new rear end? Buy a new car and get rid of your old one!"

[HandOverFist]

Originally Posted by Bob

A copy and paste of the rule book means absolutely nothing. Once again, the rules apply to some and not others.

A prime example would be a red Olds stocker that recently moved from the west coast to the east coast. It has been through tech many times and always passes. I believe it just won a divisional as well. But it clearly has a narrowed rear axle and altered frame rails. There is no other G body car that sits as low to the ground and has the tire clearance this car does. How is that possible??

A simple check of the distance between the backing plates and between the wheel wells may shed some light on this. But NHRA NEVER checks these things. They must not own a tape measure.

I doubt they even care about bogus stuff like that. Otherwise they wouldn't allow even half the junk they do. So I say, stick the nine inch Ford in. IF they catch it, as for forgiveness.

A copy and paste of the rulebook means exactly what it reads. If a housing is narrower than specified it is clearly illegal for use...period.

[kdanner]

Originally Posted by njk53

The rear suspensions on the Chevrolet, Ford, and Chrysler factory racers are nowhere near stock configuration, which in my opinion these cars should be using the stock suspensions with the same approved modifications the older cars are allowed. Are the older stockers allowed to use the same technology as the factory built cars? I think not.

Not letting this one slide. COPO and Dragpak yes. But tell me what is nowhere near stock configuration about a CJ rear suspension, and what they are allowed to use that older cars are not?