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/chassis-suspension/1405-how-to-install-chris-alstons-chassisworks-g-connector-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-chassis/1967-69-camaro-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.

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[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]

...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]

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]

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]

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]

"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.

[Nativefx]

Picture of where we are at currently. We haven't started the metal work which will have a number of slick touches. Some of the things I'm using Flush fit glass, shaving and using flush door handles and grafting an all metal rear spoiler onto the body. The dash will be reconstructed to provide space for all things I want to mount.
62715

Sub frame with level sensors installed. Hydratech Hydroboost and Baer Remaster
62716

LS3 with Wegner Diamond Cut front drive. Don't worry, the ducting is only to help us figure out spacing for mounting other items.
62717

Firebird front end which will also get some work done later on. Still mulling some ideas.......
62718

[rickpaw]

I do, here are a few.

Thanks Chris.

Nativefx, nice looking car. Is there a build thread?

[Josh@Ridetech]

Going to be a wicked car when it's done! Keep it up man, let me know if I can help out at all.

[kmart401]

What gearbox are you running? Thats one wicked ride!! Can't wait to see more pics of this one!

[Nativefx]

Thanks Chris.

Nativefx, nice looking car. Is there a build thread?

No I don't have a build thread. When this started out 3 years ago, I picked up this firebird for $2800 and figured I could get the stock motor running and have a fun driver, and then figure out what upgrades I could make. Well from there, it has morphed into this! haha Now its a full on build and much more than I imagined when I bought it for a fun bday present to myself. Never imagined it would be worthy of a pro-touring build thread.

[Nativefx]

What gearbox are you running? Thats one wicked ride!! Can't wait to see more pics of this one!

Running a close ratio T-56 Magnum mated to a 9" floater rear end with 3.89 gears.

[jlwdvm]

We have similar taste...check this out: http://www.pro-touring.com/threads/102040-1969-Firebird-TA-clone-track-car-build

I have DSE subframe connectors and a Alston 8-point cage with solid body mounts. I have about 150 miles on the car so far. Shaking it down before paint...69 Trans Am scheme. Its extremely loud and fast. I think I'm just gonna fab up some aluminum door panels and a rear seat delete. Not gonna put windows in it to save weight and hassel. It will never see rain anyway!

[Nativefx]

We have similar taste...check this out: http://www.pro-touring.com/threads/102040-1969-Firebird-TA-clone-track-car-build

I have DSE subframe connectors and a Alston 8-point cage with solid body mounts. I have about 150 miles on the car so far. Shaking it down before paint...69 Trans Am scheme. Its extremely loud and fast. I think I'm just gonna fab up some aluminum door panels and a rear seat delete. Not gonna put windows in it to save weight and hassel. It will never see rain anyway!

It's been awhile since I came across your build thread! I'll have to check out your updates. Maybe it will help on a few other things I'm thinking about.

[David Pozzi]

The front of the subframe needs support more than the rear subframe does. The stock sub is terrible in torsion ahead of the firewall. The front sheet metal contributes to half the front torsional rigidity. jlwdvm, - If you do a roll bar or cage, I highly recommend adding a diagonal brace to the main hoop. SCCA requires it, and it's a main component of any good roll bar. It can be removable by adding some double shear brackets.

[Nativefx]

The front sub needs support more than the rear does. The stock sub is terrible in torsion. The front sheet metal contributes to half the front torsional rigidity. jlwdvm, - If you do a roll bar or cage, always add a diagonal brace to the main hoop. SCCA requires it, and it's a main component of any good roll bar.

Thanks David. Any advise on how I can better support the front sub? Would something like the Alston subframe connector cross braces help with this? I'm open to other ideas as I really don't think I want to put a cage in it. thanks

[David Pozzi]

I like braces that run from the firewall down to the upper A arm mounting points. Hotchkis makes these: http://www.hotchkis.net/product/1967-1969-camaro-1968-1974-nova-chassis-max-handle-bars/?mk=&yr=&md=&sm=
They are a bit more complex and heavier than I prefer.

Pro-Touring F body makes these for second gen Camaros but not first gen's. http://www.pro-touringf-body.com/chassis_components.html

They are lighter and simpler but won't fit a first gen F body. Herb Adams invented this style and they stiffen the front sub by 1/3rd.

You could have some made up. The firewall on a first gen needs a doubler plate inside to spread the load and resist cracking if these are used.

I also tested a 69 camaro with full roll cage. The front braces went to the subframe kickup about 10" behind the upper A arm mounts. I was surprised it didn't stiffen the front sub torsionally any measurable amount.

I haven't tested the Chassisworks type underfloor braces. I'm sure they do good things, but ground clearance is usually so tight, I'd be worried about clearance. They won't help the area ahead of the firewall at all.

[rickpaw]

David

What are your thoughts on the Chassisworks forward struts? Looks like it's simpler and less complex than rhe Hotchkis handle bars.

https://www.cachassisworks.com/p-2694-camaro-67-69-f-body-exact-fit-front-struts-1-58-mild-steel.aspx

[dhutton]

David

What are your thoughts on the Chassisworks forward struts? Looks like it's simpler and less complex than rhe Hotchkis handle bars.

https://www.cachassisworks.com/p-2694-camaro-67-69-f-body-exact-fit-front-struts-1-58-mild-steel.aspx

I was looking at these but they don't say what size of brake booster will fit, only that the stock one won't fit.

I modified a set of Hotchkis braces to fit around the Holley accessory drive on an LS3. It took a fair amount of cutting and it is still quite tight. I put them on my wife's 69 Camaro convertible to try to kill the cowl shake. No shake so far....

Don

[rickpaw]

I was looking at these but they don't say what size of brake booster will fit, only that the stock one won't fit.

I modified a set of Hotchkis braces to fit around the Holley accessory drive on an LS3. It took a fair amount of cutting and it is still quite tight. I put them on my wife's 69 Camaro convertible to try to kill the cowl shake. No shake so far....

Don

Thanks for the feed back Don. It's my understanding that the Hotchkis ones dont clear the struts on billet hood hinges, which I have.

Do you have any pictures of the Hotchkis bars on the mrs' car by chance?

Tu

[dhutton]

Thanks for the feed back Don. It's my understanding that the Hotchkis ones dont clear the struts on billet hood hinges, which I have.

Do you have any pictures of the Hotchkis bars on the mrs' car by chance?

Tu

Here is a pic.

Don

[rickpaw]

Thanks Don.

Looks like the bars cleared the accessories just fine. It's the cross bar that interfered, correct?

Didn't want to hijack the thread, but it seemed relevant to the op's original question.

Tu

[dhutton]

Thanks Don.

Looks like the bars cleared the accessories just fine. It's the cross bar that interfered, correct?

Didn't want to hijack the thread, but it seemed relevant to the op's original question.

Tu

No the bars that go down to the control arm mounts hit the compressor and alternator hard. A lot of cutting and welding to get them to clear. Cross bar also hit.

Don

[rickpaw]

Thanks Don.

Looks like the Hotchkis bar is out. Too much work to make it fit.

[Nativefx]

Thanks Don.

Looks like the bars cleared the accessories just fine. It's the cross bar that interfered, correct?

Didn't want to hijack the thread, but it seemed relevant to the op's original question.

Tu

Yes this is definitely relevant to my question! Trying to figure out my options, so appreciate any/all input. thanks

[Nativefx]

No the bars that go down to the control arm mounts hit the compressor and alternator hard. A lot of cutting and welding to get them to clear. Cross bar also hit.

Don

Hey Don, do you think the Hotchkis would still need to be modified on my LS3 if I'm using the Wegner front drive assembly? They definitely pull everything much closer to the engine, but I wasn't sure which specific areas you were having clearance issues? I'm also using a Hydratech Hydroboost instead of the power brake booster so hopefully that would add clearance for the bars to mount on the firewall.

[dhutton]

Hey Don, do you think the Hotchkis would still need to be modified on my LS3 if I'm using the Wegner front drive assembly? They definitely pull everything much closer to the engine, but I wasn't sure which specific areas you were having clearance issues? I'm also using a Hydratech Hydroboost instead of the power brake booster so hopefully that would add clearance for the bars to mount on the firewall.

You will likely have to move the crossbar forward. This used to be a good thread until photobucket killed the pics:

http://www.pro-touring.com/threads/72665-Hotchkis-bars-no-shakers

Don

[jlwdvm]

The front of the subframe needs support more than the rear subframe does. The stock sub is terrible in torsion ahead of the firewall. The front sheet metal contributes to half the front torsional rigidity. jlwdvm, - If you do a roll bar or cage, I highly recommend adding a diagonal brace to the main hoop. SCCA requires it, and it's a main component of any good roll bar. It can be removable by adding some double shear brackets.

Do you mean: from the point above my head where the rear brace meets the main hoop to where the passenger side brace meets the trunk floor? I have thought about it.

[David Pozzi]

Do you mean: from the point above my head where the rear brace meets the main hoop to where the passenger side brace meets the trunk floor? I have thought about it.
From driver's side main hoop just behind the driver's head, to the passenger floor where the main hoop is welded or bolted to the floor. It keeps the main hoop from deforming to the side and is usually required for any track use. It makes it hard to get into the back seat area, but can be made a bolt-in to make it easier to work back there doing upholstery or whatever.
A diagonal on the rear supports will help in torsion but not do much for safety.

[David Pozzi]

David

What are your thoughts on the Chassisworks forward struts? Looks like it's simpler and less complex than rhe Hotchkis handle bars.

https://www.cachassisworks.com/p-2694-camaro-67-69-f-body-exact-fit-front-struts-1-58-mild-steel.aspx
They are a good start, but I think they need more bracing to be very effective.

[jlwdvm]

I already have a removable cross bar on the main hoop.