Chassis Cross Roads

[Rugby]

I am looking for suggestions on this one.

I have a bare frame that I am working on. I have rewelded 90% of the factory welds. I have some 1/4" plate to do a notch because I am there but not sure I will go through with it. I am starting to second guess doing the notch and the bracing over the rearend. Depending on which forum you read you get different answers as to weather its needed or not.

Weather or not I go through with the notch is there significant gains in welding in a cross member between the rear shocks and brace to the cross member in front?

My current goal is a mid 11 sec car that can handle well on the street but not be to harsh of a ride. I will be going back with rubber body bushings and moog replacement bushing for the front end.

 

[~JM~]

Can't answer your question, but I thought you might find some inspiration from some of the info & pictures in this link: http://www.schwartzperformance.com/1978-1988-g-body-monte-carlo-chassis/

 

[VtheGNMan]

These frames are wet noddles. Boxing in the rails under the doors adds a lot of strength. Notching is more about fitting tires over adding strength. Brace between shock towers? Might as well! Regardless what you run in the 1/4 or even if it's just a street car you won't regret taking frame flex out of the equation. Even a pure stock, restored street car it will help preserve the body against stress cracks in the pillars etc. Most will never get their disassembled to that point but since you have it there, do all you can. My 2 cents. Just did the same thing on the frame of my build.

 

[Chuck Leeper]

There are considerable foto and verbal discussions on this topic.
I, and others have posted what we've done to the frames. There is also a vendor, GNS, that has rear frame brkts to make a x brace for the end of the frame...Where the "wet noodle" syndrome is very noticeable.

 

[NY Twin Turbo]

I have been taring my brain apart on the notch issue for years. This is the one modification I'm afraid may hurt structural rigidity. And although I have participated in other threads about this, no one guarantees they know the 100% positive way to do it without getting the notorious "quarter panel dent" on the hard launch.

After a notch job, If I return from a run and see that dent in my car.........I'm certain I will do something that will put me on the 11:00 O-Clock News that evening!

Take a look at Lisa's car on this launch. You actually see it happen!

 

[Chuck Leeper]

It being a T top doesn't help.
My $.02... Best chance to avoid the wrinkles is to have a very good cage installed, frame mods done.

 

[NY Twin Turbo]

It being a T top doesn't help.
My $.02... Best chance to avoid the wrinkles is to have a very good cage installed, frame mods done.

Very true. Frame/cage reinforcing is good! Especially with T-tops.

But when it comes to the notch.......I know there are no grantees in racing, but I'd like to see 80% of the sub 9 second cars with NO dents first. Then I would feel better about a frame notch. Also I would feel better about recommending it to an OCD owner who's car has a beautiful body.

But unfortunately this isn't the case. When I go to the track, I can almost certainly see a dent in almost every single hard launching TR with a frame notch.

 

[Chuck Leeper]

Very true. Frame/cage reinforcing is good! Especially with T-tops.

But when it comes to the notch.......I know there are no grantees in racing, but I'd like to see 80% of the sub 9 second cars with NO dents first. Then I would feel better about a frame notch. Also I would feel better about recommending it to an OCD owner who's car has a beautiful body.

But unfortunately this isn't the case. When I go to the track, I can almost certainly see a dent in almost every single hard launching TR with a frame notch.

I didn't look at Dusty's car at BG. However, I saw some pics of his cage work, done at David Lemmond's shop. Dave has the "G box", a unique replacement rear x member w/ stock location mounts.
Dusty's car had the entire outer shell of the frame, in the notch area, gone.
The cage is a work of art!

 

[Rugby]

Now I am really on the fence about the notch. I don't think my car will ever launch hard enough for the dent but you never know. For now I don't want a cage in the car.

Can you box the frame and keep the stock routing for the fuel lines and brake lines?

 

[NY Twin Turbo]

Now I am really on the fence about the notch. I don't think my car will ever launch hard enough for the dent but you never know. For now I don't want a cage in the car.

Can you box the frame and keep the stock routing for the fuel lines and brake lines?

Maybe you can tweek them or something. But it would be nice to fab-up some nice new ones. It wouldn't be too hard with the body off the frame. Actually, it would be quite easy.

It's a real bitch on your back, in frozen gravel, on a 28 degree day. Ask me how I know.

 

[charlief1]

The only way to do this and keep the strength and make more room for larger tires is either a notch and full cage, or narrow the frame where the rails are. Both will require a roll bar at the very least to keep the factory strength. Yes, I'm considering doing one myself and I do have a bar that I can put in, but it's a 4 point and it may become a 6 point.