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Tech Tips: GM G-Body

MEET OUR EXPERT:
Bret Voelkel
President, Ridetech
ridetech.com
(812) 481-4787

As with any project, I always look for the best body I can find in a color I can live with. Body and paint work typically comprise 50 percent of the build budget, so if you can avoid that portion, you have more money and time to spend on other go-fast goodies. The ’78-’88 G-body vehicles are mechanically near identical, varying only by body shape and interior style. It’s your time and money going into this project, so make sure you pick out the body style you truly like the best.

The G-body suffers the same inverted camber curve problems that the first-generation Camaros and Chevelles did. We use a taller upper ball joint to resolve that.

GM also used a generous amount of rubber in the front suspension control arm pivots to improve ride quality. While polyurethane has long been considered an “upgrade,” poly also imparts a huge amount of “sticktion” in the suspension that results in uncontrolled initial spring rate and squeaky bushings. We use Delrin bushings that require no lubrication, allow no uncontrolled lateral movement, and allow smooth rotational movement. The net result is dramatically improved ride quality and handling, with no noise.

We use a dropped spindle and dual-rate coil springs (in our StreetGrip kit) or coil-overs to lower the ride height and optimize ride quality and handling.

From there we up the diameter of the front sway bar–which is also mounted in Delrin bushings–to minimize body roll, and include rebound-adjustable monotube shocks so the customer can tune the ride and handling to their liking.

On the rear we include dual-rate coils (also in our StreetGrip kit) or coil-overs, and a slightly larger rear sway bar. We specifically do not use Delrin or poly bushings in the rear four-link bars because those bars need to articulate to do their job properly. Limiting that articulation binds the rear of the car up and creates excessive stress on the bars and their mounts.

Turn One and Borgeson offer a faster-ratio steering box for the G-body. We like to use a flow-matched pump from Turn One to get the best feel and performance.

A 17- or 18-inch wheel diameter seems to offer the widest selection of tire choices for about any style of driving you may want. These cars will fit a 275/35R18 tire in the back and a 255/35R18 in the front. Braver hotrodders have fit a 275mm tire even on the front, depending on final ride height. Nineteen- and 20-inch wheels seem to look a bit awkward on these cars and have a smaller selection of tires. Performance tire selection is also limited for 15- and 16-inch wheels.

If your main purpose is cruising with only an occasional autocross, the BFG Sport Comp 2 is a nice tire. The more serious autocrosser or track day guy might like the Falken RT615K+. The current king of the grippy tire wars is the BFG Rival, but they do sacrifice tire life to achieve that.

The stock brakes on any car up to around 1995 are marginal in a performance setting. Any time you intend to accelerate and corner faster, you will also want to stop faster. Baer and Wilwood both have fine offerings for these cars.

The GM G-body is a great platform for any kind of racing or performance driving. The G-body’s 108-inch wheelbase is the same as the early Camaro– short enough to turn well and long enough to ride comfortably. In addition they are lightweight– around 3300 pounds, about the same as an early Camaro as well. OEM and aftermarket parts are plentiful and mostly interchangeable. It’s certainly a fun car for any budget.

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Comments

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yupididit
yupididit Dork
9/16/17 10:51 a.m.

I want to build one just like that. I'll only accept 4 colors. Black, white, grey, and tan. 

Nick (Bo) Comstock
Nick (Bo) Comstock MegaDork
9/16/17 11:37 a.m.

It's like you are reading my mind. I was just running through a G-body CAM build in my mind over the last couple days.

Coincidence or sign from the universe?

stan_d
stan_d SuperDork
9/16/17 4:42 p.m.

02 blazer zr2 front spindles bolt right up and give you 11.75 rotors and dual piston calipers. 

David S. Wallens
David S. Wallens Editorial Director
9/17/17 10:57 a.m.
Nick (Bo) Comstock said:

It's like you are reading my mind. I was just running through a G-body CAM build in my mind over the last couple days.

Coincidence or sign from the universe?

Plate of shrimp. 

Nick (Bo) Comstock
Nick (Bo) Comstock MegaDork
9/17/17 11:05 a.m.

In reply to David S. Wallens :

Ooh, so close.

 

curtis73
curtis73 PowerDork
9/17/17 1:24 p.m.

I've owned so many G-bodies its scary.  Love them.  Everybody had one but they were so cool.

Only reason I ditched my latest one (85 Elky) was because I sold it to buy Duke's 67 LeMans.

ncjay
ncjay SuperDork
9/17/17 4:34 p.m.

I'm going to take issue with two statements in the opening story. 1)The stock brakes are marginal in a performance setting. 2) The GM G-body is a great platform for any kind of racing or performance driving. The metric chassis is crap for racing. The front end geometry is completely wrong for performance use. The upper trailing arms in the rear are way too short. Lowering the car much quickly gets things in a bind without some fabrication. The rear ends are weak, designed more for runs to the grocery store than anything else. Luckily, upgrades are plentiful, if not always inexpensive. The brakes are barely acceptable for daily use, never mind any kind of racing that involves stopping or slowing down often, but again, upgrades are available everywhere. The street stock crowd has developed a crap ton of performance parts, so finding used stuff is pretty easy. With a little bit of fabrication and welding the upper A-arms in the front can be relocated to a better position easily enough. Being a GM car, there's also a boatload of parts that interchange between the different GM divisions, even Cadillac. With some luck, once I rearrange my finances, I'll be building some new A-arms and rebuilding the front end on my Monte Carlo over the winter.

z31maniac
z31maniac MegaDork
9/17/17 4:42 p.m.

I would love a T-Type built to "Pro Touring" specs, even though the interiors were hideous even back then.

nutherjrfan
nutherjrfan Dork
9/17/17 8:36 p.m.
yupididit wrote:

I want to build one just like that. I'll only accept 4 colors. Black, white, grey, and tan. 

At first I thought you said 4 doors and saw this. https://baltimore.craigslist.org/cto/d/1983-chevy-malibu/6306758464.html Never mind. blush

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