G body shuffle

Rt Jam

G-Body Guru
Mar 30, 2020
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Ontario Canada
I feel like the rear upper arms are a big factor in the g body shuffle. Expecting 2 bushings on a 45 deg angle to control all side to side is asking alot.

I used to have a fox Mustang with a similar suspension. I could tell it was moving around from the tires touching the wheel wells after spirited driving. Every modification would make less and less contact but aggressive driving would still have the axle moving side to side. From stock, to aftermarket upper arms then polyurethanes in the uppers. Higher spring rate, stiffer shocks, narrowed the rear rims, smaller tire.
This was not driving around to the coffee shop. There was sticky tires and chasing lap times at Toronto Motorsports Park.
 

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The rear control arms are designed with a lot of flex to prevent binding. Boxed upper control arms are known to egg out the mounting bolt holes in the frame and poly bushings tend to stick and bind. If your rubber bushings are old they will not work as well as fresh rubber bushings.

These cars are designed to for grannies in the era of the 55 speed limit, not for spirited driving. Much of the shuffle is caused by the noodle frames flexing. Poly body bushings and bracing will help reduce the shuffle. Regals especially have missing body bushings which allows the car to twist more to make the ride smoother for grandpa.
 
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For sure the upper arms flex during articulation but there is no way they are getting longer or shorter. That is happening at the bushing as one is compressed and the other is stretched when the axle is trying to slide to one side.

The egged out mounting holes are from aftermarket arms with stiff bushings. As the axle housing articulates everything resists and the bolt hole is the next victim.
Roto joints are the answer for that problem but it comes at a cost of noise and harness.

The frames should be less of a problem once it's attached to the body with tight bushings.
 

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Don't forget to add they poor geometry in the design for our generation. The other three generation of A's/midsize cars used better angles on the upper armes than ours. Pretty much our cars are damned if you do, damned if you don't when it comes with dealing with this.
 
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For sure the upper arms flex during articulation but there is no way they are getting longer or shorter. That is happening at the bushing as one is compressed and the other is stretched when the axle is trying to slide to one side.

The egged out mounting holes are from aftermarket arms with stiff bushings. As the axle housing articulates everything resists and the bolt hole is the next victim.
Roto joints are the answer for that problem but it comes at a cost of noise and harness.

The frames should be less of a problem once it's attached to the body with tight bushings.

Tight body bushings do help and are the first place to start to stiffen a G body. Moreover, adding bracing helps even more. In my Regal I installed poly body mounts, GP front brace, F41 jounce bars, Tinman rear seat brace, and a homemade Jeff bar for the rear frame.
 
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Of course the body bushings have to be tight because they are what support the frame via the body.

The stock rear end control arm geometry is awful, repeat awful, for launching a car and create some of the g-body shuffle. But the largest contributor is the lack or, or puny rear sway bar/anti-roll bar or what ever term you want to refer to it as.

A proper rear sway bar/ARB will stop the 'shuffle'. The photo in my avatar is with proper geometry and no ARB. Addition of the ARB eliminated the shuffle completely.
 
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I don't even know why the subject comes up with 78-88 A/G bodies. If you have a stock A/G-body, the best it ever had as far as handling was when they drove it out to the assembly line parking lot after the last "quality" check. It was downhill from there. Spaghetti frames and bean-counter-controlled aspects all over the place with mushy suspension on purpose. It's an inherently bad design that married the 60s/70s and the 90s engineering. Tweener cars. After the gas crunch of the 70s, the car companies were left scrambling to get fuel economy from a full-frame car, which took away from other aspects. No power, no great handling, but the grandparents dug the heck out of them because they rode smooth. Even the F-bodies in the 80s weren't super-great at handling but those torque arms and panhard bars were way better than the G-body sway bars alone. A sad era, but still a great platform overall, IMO. And I'm biased. Mods are fairly easy and you can get where you want to be with one.
 
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What is the difference in the other 3 generations of A bodies? They all have the angled upper arms. That is all that is trying to prevent the axle housing from going side to side. If they are straight or parallel like the lower arm. That will control pinion angle. If they are perpendicular they would control side to side. So they put them on an angle to try to do both jobs. Bottom line is the angled arm is a compromise.

I have the rear seat brace. Enough GN's with pillar damage convinced my this is necessary.
What is a GP front brace, F41 jounce bar and the homemade Jeff bar? How will this help to locate the rear axle housing?

Interesting torque arms was mentioned because my friend's 02 Camaro SS has inspired my latest modification.
I'm not doing this to go fight with Trans Ams on the road course. The stability and predictability of that 02 Camaro pushed this idea. How controlled it is during an oversteer or push a G body side to side and watch how much the body moves as the rear housing stays still to understand.
 

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Keep in mind this is my theory on this but I think the original design of our cars was scaled down to be the size they ended up being. The upper arm angle should of been close to the 3rd gen A's. Dispte them being pigs by weight they did have a nice ride & fair handling for basic/normal driving from my experiances. If our cars were just given a few extra inches (incert joke here) the shuffle wouldn't be there. Have to think about why '77 up B's don't have this issue when doing the same thing on the track. Even the '77 up B's have the same rear suspesion design as the other 3 gens of A's but have those extra inches our cars should have. This issue might even be the reason '82 up F cars don't have the upper arms but the pan rod.
 
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Another thing is that G bodies sacifice pertormance for utility while performance cars do the opposite. G bodies have pretty small rear suspensions in order to fit in deep rear floor foot wells and seats. While F bodies and Corvettes sacifice rear seating for better and bigger rear suspension setups.

Here is a link to the Jeff bar. http://jeffd.50megs.com/frame_brace_page.htm It helps to tie the rear frame rails together so they twist less. With G bodies, stiffer suspensions just makes the noodle frames twist more. In fact, my Crown Vic has a factory rear bolt on brace that is similar to the Jeff bar.

As others said, the stock rear sway bar that mounts to the rear LCAs isn't too good and introduces bind. Aftermarket or 2WD Blazer rear sway bars that mount to the rear axle work much better and reduce shuffle.
 
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