LS Grand Am Frame Strengthening Questions

[smed7880]

Worried the LS2 is going to twist the 80 GAm frame like a pretzel. Just starting swap.

I see UMI offers bolt on stiffeners. Are they enough?

What weak point(s) in the gbody frame?

Has anyone twisted their frame on 400hp LS2 power?

Looking for suggestions.

Stock LS2 with 4l80e.

TIA

This is what im looking at

 

[pagrunt]

Bracing that is out there will make the frame stiffer than stronger. I add strenth it might be better to use a frame boxing kit that boxes the middle frame rails.

 

[RabbitHoleSS]

It's true our frames are like spaghetti noodles, but what's your plan with the car. Just cruise or are you gonna put om sticky tires and race it? Are you planning on lifting the body off the frame? Own a welder? Boxing the frame and reinforcing the control arm Mounts are the best bang for your buck. If you own a welder and are separating the body/frame. All those things you linked can be built for 1/10 of the cost, except the front "f41" bars. Heres what i did on my rear lca.

And boxing the frame rails

Rear uca, small bar from frame to mounts

I don't know if this was worth building but here it is anyway. Mightve been better just making a shock mount brace to bolt in.

motorheadmike built a bolt in solution for boxing the frame on his Monte.

 

[smed7880]

It's true our frames are like spaghetti noodles, but what's your plan with the car. Just cruise or are you gonna put om sticky tires and race it? Are you planning on lifting the body off the frame? Own a welder? Boxing the frame and reinforcing the control arm Mounts are the best bang for your buck. If you own a welder and are separating the body/frame. All those things you linked can be built for 1/10 of the cost, except the front "f41" bars. Heres what i did on my rear lca. View attachment 223704
And boxing the frame rails View attachment 223705
Rear uca, small bar from frame to mounts View attachment 223706
I don't know if this was worth building but here it is anyway. Mightve been better just making a shock mount brace to bolt in. View attachment 223707
motorheadmike built a bolt in solution for boxing the frame on his Monte.

Nice work!

Good questions.

No frame off.

No racing but i know myself...there will be WOT moments. Street tires.

Yes can weld.

I have to pull the tank. Once i do ill get more access and will be able to see if i can add bracing.

 

[1320chevy]

Nice work!

Good questions.

No frame off.

No racing but i know myself...there will be WOT moments. Street tires.

Yes can weld.

I have to pull the tank. Once i do ill get more access and will be able to see if i can add bracing.

The frames weakest point is between the front and rear. The design is a poor copy of a frame extension, Just flimsy. That said, you pretty much need tire lifting power to begin to need any real stiffeners. The good kits are body off though. WOT doesn't damage anything, it's the lifting of the vehicles weight during launch transfer that does that. Unless you have really sticky steamroller rear tires, you likely will light them up before lifting the car. Boxing control arms helps in handling as do good springs and shocks. Concentrate on getting all that right first.

 

[tdvick]

To strengthen the control arm mounts I used the supports from JT Raceshop. Nice stuff. https://jtraceshop.com/

 

[john87442]

I am putting in a 400 hp olds 350 into my 87 cutlass and used the fx boxing kit… needed a lot of fab work to get it done but frame is very solid and takes the flex out of it considerably, piece of mind also that it is stronger. I will also add the Umi kit to front and rear but only because I have five grand that I don’t know what to do with.

 

[Streetbu]

The UMI braces help quite a bit. More so for cornering than straight line though

 

[pagrunt]

...only because I have five grand that I don’t know what to do with.

I could help you out with that problem. My Monte still need some things.

 

[Rt Jam]

It's very hard to make a something flat strong. I have a super tall frame in my 2002 1500HD. Stronger than any G body frame but it still flexes, alot.

Real stiffing will come from a triangle. In this case a roll cage. A box in the passenger compartment with bars down to the front and rear suspension. I know that is a giant step in many cases. My car will never see a roll cage.

Consider polyurethane body mounts. The frame will have a hard time flexing if it's attached to something solid.