Options to stiffen chassis 69 Firebird?

[Nativefx]

I've been thinking about my project I've been working on and what I'd like to use it for. It will be mainly a street car, but I am hoping to take it out on some big road tracks a few times a year.

I've already decided and purchased the Ridetech Air Ride setup and a Thompson Motorsports built forged LS3 (roughly 550hp) with T-56 magnum which have already been installed in my stock subframe. Using a Baer full floater rear end with a 9" Moser housing and Strange 3rd member True-track and 3.89 gears. We are currently working on the mockup before finishing the replacement of quarter panels, roof, and tail panel which are just tacked in place. Everything was sand blasted and smaller repairs done, while also smoothing entire fire wall. This is just some back ground of what we're doing.

My question is, what are some of my options to help stiffen the chassis?
Because I finally decided Air Ride was a must and not knowing of any aftermarket options that was designed to use Shockwaves at the time, I decided to use my stock subframe and already had it modified, sandblasted & powdercoated. I already have Hotchkis subframe connectors, which once finished will be welding together rather than just bolted. I'm not sure at this point that I want to install a full cage as the rear seating is already limited, and I'd like to be able to get the kids in the back for short periods of time. I've been learning as I go along, and this is something I hope I can get some advise from more experienced builders or people what came into this same dilemma as they were having their cars built? I think even on the street, with this drivetrain, a stiffer chassis would make for a much nicer setup. Thanks for any help!

PS - I was hoping to post some pictures of where my car is currently in the build, but Photobucket now wants $400/year to 'host' images on the site. Any other options I can use?

[Tinker]

My Firebird has subframe connectors I welded to factory subframe. I included two more cross braces that also serve as driveshaft loops and two more diagonal struts. The ridetech rear cradle for the four link stiffens out back. Don't underestimate the additional stiffness from solid body mounts. I can have the front on two jackstands, Jack up in front of one rear wheel, the car comes up very level with virtually no twist. It's not perfect, but it's a world of difference sitting behind the wheel. My next step may be some sort of downtubes from firewall to frame.

[simon455]

Chassisworks has connectors with a brace that works with their as well as stock sub. I have it but not at a point of installing it yet, here is sample:

http://www.superchevy.com/how-to/cha...nector-system/

Other nice option is a complete spec frame from roadster shop, would need to look into fitting shockwaves instead of coil overs. Saw it a the Syracuse nationals, a really nice piece and I think price (under 10k) is really attractive when you think of loading stuck sub with nice parts, or buying complete sub, frame connectors, brace, rear 4 link or torque arm and then a tiger cage for instance or custom cage. Here is a link and there are few videos in there as well few floating around the net with that frame on a track, check it out.

http://roadstershop.com/product/full...-spec-chassis/

I'm personally went with stock modified stock sub also with all ridetech set up and shockwaves, dse mini tub, modified chassisworks g link/fab 9" all to get a low stance that I personally desire, also with ridetech shockwaves on the back of the modified glink. Lot of work went into modifying front sub, rear floor and the g link to achieve my desired ride height and truly slammed look when fully aired out. Don't think I would even achieve same desired stance with a spec frame, but everyone's taste is different and everyone has different capabilities.

But if i were to do it again, I d really consider trying out the rs spec frame, that it also comes with rear 9" housing and 31 spline axles included,no floater end tho, but pretty sure that could be an option...
Won't get a first gen much stiffer and squared up then a full frame. There will always be some pros and cons with whatever set up you go

[Build-It-Break-it]

Just take camera phone pics and post those? Chassis works makes an "exact fit" "pro touring" Roll cage. I have one in my camaro and the fit is descent but the cage is pricey to have to do all the tube notching ,welding etc yourself. The cage fits a little tighter to the body but nothing to justify the price in my opinion.

The only way to truly stiffen the car up is a cage,subframe connectors and the cage tied into the subframe connectors and forward down tubes into the engine bay.

I made my Roll cage Harness bar removable for passengers but in reality who wants to sit in the back of these old death traps. Without a cage getting hit by a news car would be bad for the old car. A cage could also make it worse for any passenger if your not properly secure to your seat etc.

[simon455]

Full frame is still a better option on a STREETCAR, chassis already becomes pretty rigid ( I think he's more after that) and can benfit from using conventional body mounts which somewhat do help a lot with NVH.

I have a full cage in my 69, being 6' plus tall with a bucket seat already as low and as far back as it can be, if not strapped properly with a harness (usually use just the lap portion of the harness during cruising) and sitting relaxed in a comfortable manner it appears that the head will impact against the roll cage upper bar weather from the front or the side during unexpected impact. Hope that never happens to anyone!

There is no win win situation with these old cars when it comes personal safety especially when driven around today's society where a there is a lot of cluelss drivers around you driving distracted on top of it all. Maybe I'm basing this on the area where I live a little.

[rickpaw]

Originally Posted by Tinker

...I included two more cross braces that also serve as driveshaft loops and two more diagonal struts.

Chris,

Do you have any pictures of this set up? I'm contemplating doing something similar to my 67 Firebird.

Thanks.

[Build-It-Break-it]

Originally Posted by simon455

Full frame is still a better option on a STREETCAR, chassis already becomes pretty rigid ( I think he's more after that) and can benfit from using conventional body mounts which somewhat do help a lot with NVH.

"My question is, what are some of my options to help stiffen the chassis?
Because I finally decided Air Ride was a must and not knowing of any aftermarket options that was designed to use Shockwaves at the time, I decided to use my stock subframe and already had it modified, sandblasted & powdercoated"

I think he already modified his front factory subframe and is trying to find ways to stiffen everything from there.

[Tinker]

Originally Posted by rickpaw

Chris,

Do you have any pictures of this set up? I'm contemplating doing something similar to my 67 Firebird.

Thanks.

I do, here are a few.

[Nativefx]

Originally Posted by Tinker

My Firebird has subframe connectors I welded to factory subframe. I included two more cross braces that also serve as driveshaft loops and two more diagonal struts. The ridetech rear cradle for the four link stiffens out back. Don't underestimate the additional stiffness from solid body mounts. I can have the front on two jackstands, Jack up in front of one rear wheel, the car comes up very level with virtually no twist. It's not perfect, but it's a world of difference sitting behind the wheel. My next step may be some sort of downtubes from firewall to frame.

Yeah I'm planning to weld the subframe connectors to the sub. I'm wondering what kind of room I might have to look at some cross bracing. I am also running solid body mounts to take that out of the equation. I've see some down tubes from the firewall to the frame, but I wasn't quite sure what/how that provided added support?

[Nativefx]

Originally Posted by Build-It-Break-it

"My question is, what are some of my options to help stiffen the chassis?
Because I finally decided Air Ride was a must and not knowing of any aftermarket options that was designed to use Shockwaves at the time, I decided to use my stock subframe and already had it modified, sandblasted & powdercoated"

I think he already modified his front factory subframe and is trying to find ways to stiffen everything from there.

Yes, I have already purchased the Air Ride, Baer Brakes, and 9" rear end with the Baer floater system so I may be to far to really consider a full frame. If it would have been an option when i started buying all of this, it might have been a strong consideration. I'm just looking for options to would improve what I have, and the Alston sub connector might take some research. I will have the exhaust custom made later on so that won't be an issue.