67 mustang sub-frame strength

[chaser89]

I am building a 67 mustang fastback and am building a strong pro street 347. Designed to be 500+hp with a possible nitros shot. How do i keep from twisting the car and destroying the body?

 

[BuckeyeDemon]

are you going to run slicks?

 

[chaser89]

67 mustang fastback sub-frame strength

Yes, I will be running slicks and it will probably see a little limited track time in the future.

 

[BuckeyeDemon]

unless your car ends up being a dog, you're going to need to run a rollbar to be legal.

 

[chaser89]

If I keep it over 10.49 sec I don't need one do I?

 

[BuckeyeDemon]

you better get a rulebook or the nitrous and slicks could be useless.

i thought a 6 point was required at 11.49.

 

[chaser89]

I just looked in the nhra 2009 and from what I can tell the break is 10.99 or 135mph.

 

[BuckeyeDemon]

a roll cage is required at 10.99.

a roll bar is required at 11.49.

 

[dennis112]

a roll bar is required at 11.49.

Yep. At 11.49 a roll bar is required (I got bounced for that one at both NHRA and IHRA tracks.) Also need a 5 point harness from 11.49 and faster.

a roll cage is required at 10.99.

The rule book also states that a roll bar can take him down to 10.00 as long as the stock firewall, floor and body remains in place. If altered substantially, the 10.99 is a valid rule for a cage..

Although the real rule book is always the best resource, here is an article with the basic guidelines:

http://www.crankshaftcoalition.com/wiki/NHRA-legal_Roll_Bar

 

[rbohm]

anything you can do to stiffen the chassis will pay big dividends down the road. subframe connectors, and a center chassis cage like that sold by total control products are good ideas, and when coupled with a 6 point cage will really stiffen up the chassis.

 

[chaser89]

Any manufacturer suggestions on a functional yet tasteful 6 point. I don't want to have crawl to much to get in and out.

 

[BuckeyeDemon]

i would think your best option is to go get the tubes custom bent and fit. years ago i purchased a 6-point for an early mustang. there wasn't anything special about it. they would have hit the door panels and seats.

i later decided that i didn't want to run a 6-point on my car for those two times out a year. so i decided on the custom subframe and the fact that my limit is going to be 11.49.

 

[dennis112]

A good hinge kit will make most 6 point roll bars livable. I used the good Chris Alston hinges and love them (old tall guy with bad back.) Hinged bars are legal down to 8.50's or so. I can remove my bars in less than a minute if I don't want the inconvenience.

You can read about my adventures in installing my roll bar last winter here:

11.50's no more--Legally! - Ford Muscle Forums : Ford Muscle Cars Tech Forum

 

[rbohm]

Any manufacturer suggestions on a functional yet tasteful 6 point. I don't want to have crawl to much to get in and out.

alston chassisworks, among others, have 6 point cages and an option of a swing out door bar.

 

[blown65]

I have the same as Dennis, but I will be going to a full cage. No thanks on swing-outs at 150+mph.

Since my car is all stock inside, the 6 point bar has been legal to 10.00. Got 3 runs in the 9's before they said NO MORE. lol