[Goatman]

Same rules should apply. Putting it to the floor without the support of the frame is stupid.

[David Holmberg]

Bruce have you ever seen a rear frame on a Firebird? There is no frame just some sheet metal welded to the floor pan, nothing that even resembles a frame. Now the front has a real looking frame, but not the rear.

There is a reason that the NHRA and the IHRA write the rules the way they do, and it's not to make it easier or cheaper on the racer...

[Goatman]

Dave, the fact is there are two rear frame rails and given the fact that subframe cars are already significantly weaker than the full frame cars, every effort should be made to get them as solid as posible.


Easier is the word for sure. And its a cop-out.

[Brian Baker]

Originally Posted by PONTIAC DUDE

You will need to move your rear bars you have mounted to the tunnel. They won't pass NHRA tech.

They have to be mounted to plates welded to the rear subframe.

Page #222 footnote D.

Those bars might not be required for a roll bar (call NHRA) but definate for a cage, so if ya upgrade later, better to moven em now.

They might, they might not. Had no problem with mine getting certified to 7.50 (before they change the rules, it would only go to 8.50 now) with them welded to the driveshaft hump in that fashion. I never understood that "subframe" aspect of it anyhow...if it's a unibody car, a plate anywhere back there on the floor should suffice.

[Brian Baker]

Egad, Probird! Get that welder out and finish welding those plates to the floor around all sides. Did an inspector actually put a sticker on that?

And, Bruce. On uni-body cars...the floor is the frame, more or less. The rear subframe on them is nothing more than C-channel stock welded to the bottom of the floor pans. Using your train of thought, if someone were to weld a 6x6 plate to the floorpan directly above the C-channel rear subframe, it would accomplish the same thing as what you're talking about.

[455Dave]

Originally Posted by dammen8

What we did with my unibody car where the windsheild bars come down is, built a outrigger off of the front subframe and welded that to the floor and suframe then put a 6X6 plate over the top with that plate welded to the rocker panel, floor and outrigger, then welded the bar to it... Should be plenty strong

Chad

That sounds like they way my 8 point is installed. Outriggers welded to the subframe tied into the side bars. The hoop is attached with plates in the rocker sill area and the inner bars off the hoop are welded to tubular subframe connectors. The rear bars are bent to follow the contour of the roof and are welded to the frame rails in the trunk. It's a full interior car so I didn't want to hack it up a lot.

[PONTIAC DUDE]

Originally Posted by Brian Baker

They might, they might not. Had no problem with mine getting certified to 7.50 (before they change the rules, it would only go to 8.50 now) with them welded to the driveshaft hump in that fashion. I never understood that "subframe" aspect of it anyhow...if it's a unibody car, a plate anywhere back there on the floor should suffice.

Full cage, they have to go to the rear subframe or they won't pass tech. That's what the Division 2 NHRA tech guy (Mike Wells) showed and told me 2 weeks ago when they failed my chassis after passing for 10 years wthout them.
Arguing won't change the rule.

[Brian Baker]

Who's arguing? I'm just sharing what my experience was with our Division 1 tech.

If you want to get down to the nitty gritty, he isn't required to have those subframe "gusset" bars on a 10.00 and slower roll bar. Not needed until you go to a cage.

[Matador-IV]

Sorry to be so critical....but I've never seen so many poorly engineered roll bars in one post before.

Most will do little to 'curb' chassis flex or provide a reasonable amount of safety for the driver at track speed.

[PONTIAC DUDE]

Originally Posted by Brian Baker

Who's arguing? I'm just sharing what my experience was with our Division 1 tech.

If you want to get down to the nitty gritty, he isn't required to have those subframe "gusset" bars on a 10.00 and slower roll bar. Not needed until you go to a cage.

Brian, for the reading challenged. LOL.
I stated FULL CAGE in my above post and if you check my other posts I stated that if he EVER UPGRADED, that it would be a good idead to move the bars he has to the tunnle to the RIGHT Place.
I agree matador IV.

FWIW:
My car has full cage with front side to side crossbar and a true X brace to the rear. No straight rearward bars. Built in 1982. You can put my car up up 4 jackstands and pull any one stand out and the car will balance without any sag. You can see in any of my wheels up pics that both sides are level in the air. Also All the unibody and front subframe seams are fully welded. Makes a difference.

[pont406]

the last issue of Hot Rod Magazine (March 07, same one with the Blown nitro pontiac motor) has several pics/tips of a roll cage installaion in a 2nd gen F body (F Bomb project) it shows how they tied the cage to the frame/ floorpan of the car, i think this is what P Dude and others were pointing out?

[Jack Ferris]

Originally Posted by Matador-IV

Sorry to be so critical....but I've never seen so many poorly engineered roll bars in one post before.

Most will do little to 'curb' chassis flex or provide a reasonable amount of safety for the driver at track speed.

Why don't you post some pics of your work. Since Im sure its far superior to all the others out there. Maybe I could incorporate your expertise into the poorly engineered cages I do for others.

[fasteddy]

Well now. If it isn't young Jack FeRRis. Jack, I used 2 inch electrical conduit in my ride-certified to 15.0 and slower. JB weld is just fine to attach to the subframe plates and 4 self taping sheet metal screws for that added strength. Tonight I am going to add the duct tape per your suggestion-gotta keep that PS wheel on the ground ya know. With my set-up, NA to boot, 3.50 60s are possible on stock suspension and wide oval tires.

[Jack Ferris]

Originally Posted by fasteddy

Well now. If it isn't young Jack FeRRis. Jack, I used 2 inch electrical conduit in my ride-certified to 15.0 and slower. JB weld is just fine to attach to the subframe plates and 4 self taping sheet metal screws for that added strength. Tonight I am going to add the duct tape per your suggestion-gotta keep that PS wheel on the ground ya know. With my set-up, NA to boot, 3.50 60s are possible on stock suspension and wide oval tires.

Oh man I cant stop laughing.....With all the information you have I can tell you have read my book "How to construct a race car out of leftover job site materials". I disagree with your use of JB weld however. I just run the tubing through the floor and then mushroom the end so it wont come out. Woops there I go again giving away my secrets. My next inovation is going to be a swing out main hoop for rear seat access. I hope nobody beats me to it.

[BVR421]

WOW! what a great resourse this post is. Imagine, so many chassis design experts in one place.

[Brian Baker]

Originally Posted by BVR421

WOW! what a great resourse this post is. Imagine, so many chassis design experts in one place.

You're welcome.

[ho428]

Originally Posted by fasteddy

Well now. If it isn't young Jack FeRRis. Jack, I used 2 inch electrical conduit in my ride-certified to 15.0 and slower. JB weld is just fine to attach to the subframe plates and 4 self taping sheet metal screws for that added strength. Tonight I am going to add the duct tape per your suggestion-gotta keep that PS wheel on the ground ya know. With my set-up, NA to boot, 3.50 60s are possible on stock suspension and wide oval tires.

Think I might have used EMT to save weight over conduit.

Reminds me, anyone see the Trucks TV show awhile back where they bought a Bronco to redo. The Roll bar was PVC pipe wrapped in black foam. Guess you'd call the county sewer inspector for Tech on that one.

[tempest455]

"Back in the day", Arnie Beswick used to fab his roll bars out of exhaust tubing!

[Jack Ferris]

Originally Posted by ho428

Think I might have used EMT to save weight over conduit.

Reminds me, anyone see the Trucks TV show awhile back where they bought a Bronco to redo. The Roll bar was PVC pipe wrapped in black foam. Guess you'd call the county sewer inspector for Tech on that one.

Soon we will have to pull a permit to construct our cars.

[ho428]

Originally Posted by Jack Ferris

Soon we will have to pull a permit to construct our cars.

That would not surprise me.