G-body frame upgrades

[john87442]

Good morning, I have a question for the group, I have a 1987 442 T-top and will be doing a frame off resto on it. I live in north east Ohio and we are the rust belt of the country so naturally my frame is garbage, I have reached out to a salvage yard in Arizona to have a frame sent over I believe from the info. I have found that any g-body 1978-1988 will work. However since I am putting a Mondello built 403 with 550HP in it I know I have to reinforce the frame. I have noticed companies like Hellwig have a kit for this but I wanted to get the opinion and recommendation of the years of knowledge in this group before I start throwing money at this and yeah its going to be a lot. This is not a track car its a street cruiser that will have the HP it deserves for the badge it wears. Thanks in advance for your advice.

 

[Clone TIE Pilot]

For that much power a frame boxing is a must. Some G body frames have different front and rear rail horns. Also older frames lack the mounting extension for the TH2004R. G body frames are not painted, instead they are wax dipped which makes flux welding preferable.

Besides boxing, there are various factory and aftermarket braces as well as home made bracing like the Jeff bar. Rear LCA mount reinforcing would be a good idea. Don't forget that the body also reinforces the frame once they are bolted together. Good body mounts go a long way to help stiffen the frame. Again with that much power you probably will want a rear seat brace to avoid roof cracks.

 

[Streetbu]

Also note, NOT every frame from 78-87 will work. This has been discussed multiple times. Early frames are slightly different in the front where the bumper mounts.

 

[melloelky]

Mr Streetbu is correct.also steer clear of the el camino frames for you sedan as the rear body mounting is different..

 

[L92 OLDS]

To be safe I would look for some thing 1984 or newer to make sure you get the correct transmission crossmember mount. If you plan on keeping the 200 4R you will need this.

 

[79 USA 1]

Mr Streetbu is correct.also steer clear of the el camino frames for you sedan as the rear body mounting is different..

El Camino frames are also a longer wheelbase.
Photo below from Conrad Lozier's web site shows difference in rear body mounts between frames.
El Camino left, Coupe/Sedan middle, Wagon right.

 

[303'505rollin]

If your going to weld it in yourself, Hoppos hydraulics sells a Gbody frame reinforcement kit and it's precut and shaped. I know your not putting hydraulics on the car but for frame reinforcement this could be an option

 

[Goldhawg]

I welded in the Hellwig kit. Made the frame super stiff but I haven't finished the restoration yet. But I'm very happy with the result.

 

[john87442]

For that much power a frame boxing is a must. Some G body frames have different front and rear rail horns. Also older frames lack the mounting extension for the TH2004R. G body frames are not painted, instead they are wax dipped which makes flux welding preferable.

Besides boxing, there are various factory and aftermarket braces as well as home made bracing like the Jeff bar. Rear LCA mount reinforcing would be a good idea. Don't forget that the body also reinforces the frame once they are bolted together. Good body mounts go a long way to help stiffen the frame. Again with that much power you probably will want a rear seat brace to avoid roof cracks.

Thanks for that info, I did not know that about the rail horns. I will be having the frame powder coated before i start assembly so its good to know that they are waxed dipped. I watched the video where hutch put in the seat brace so I agree its a must do also.

 

[john87442]

To be safe I would look for some thing 1984 or newer to make sure you get the correct transmission crossmember mount. If you plan on keeping the 200 4R you will need this.

Thanks, I am taking the advice and also purchased a th400 from Mondello that will match well. I can see I'm going to have to do some more frame research before i have one sent out. Thanks to everyone for your suggestion and knowledge. I think this is going to be a community build but I'm still the only one who gets to drive it.