How well could a g-body actually handle? What's the limit?

81cutlass

Comic Book Super Hero
Feb 16, 2009
4,218
113
Western MN
Yeah ditch the KYB excel G's for handling. I had KYB gas-adjust which were fine for an entry level shock that is comfortable (I wouldn't buy any shock lower than a gas-adjust) but they are on a different level than bilsteins and again a different planet than adjustable Viking or others. I convinced myself the $100 for KYB gas adjust was justifiable over the $75 for excel-G but the $200 for bilsteins wasn't. Instead I spent $800 on viking DA's for all 4 corners.

Ditto on checking bushings. If they are OEM they are toast. Can't have stuff moving around unexpectedly.

The stock upper arms are tough to get caster in with tall upper ball joints. As the spindle gets taller the upper ball joint moves up & out and pushes the tire out so to get good camber at static ride height you have to shim the UCA in a lot. I had the rear bolt with max shim and front at like 3/4 to get camber in and caster was so-so.

I bought these MCAR arms (he is on the forum here) as they allowed me to pull the camber in, run a 1" taller upper balljoint that is rebuildable, and put caster in. The aftermarket UCA from UMI or whatever which is a great option requires you to run both their upper and lower arms because it relocates the front front LCA point forward 3/4" or whatever AND pulls the UCA point back so it keeps the wheelbase the same. These arms are the 'cheap' way and shorten the wheelbase a bit but save you the $1200 or whatever over full aftermarket arms that I can't justify.

Only issue with this is you are limited to how much caster you run as the tire rubs the fender at full lock if you put in a ton of caster. The camber gain on turns is more than enough with this setup so I just set the caster as much back as I can before the tire starts rubbing hard and it's fine. The tire isn't 100% centered in the wheel well visually but it doesn't bother me.
1659116508902.png



I don't like pimping out my 'tube channel on here but I did this video a year or so ago. It's essentially a video ripoff of Chris B's 2+2 setup that he spoke highly of on the forum for years here before he jumped ship.

 
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motorheadmike

Geezer
Nov 18, 2009
8,993
113
Saskatchewan, Truckistan
How about a parts & mods list so that people have a better idea of what it might take to achieve higher level performance? Obviously the 'driver mod' is something everyone should invest in as well but many (most?) don't.

Per the archives of the internetz:

The car was factory optioned with PS, PW, PB, PT, T-tops, A/C, delay wipers, and cruise control. It is 1 of 200 cars that was able to be optioned with black paint and the black-out package in late-1986 (1987 MY), and lighter than a Grand National of the same vintage.

ENGINE
Stock unopened 3.8L SFI V6 longblock
Modified stock S/S tubular headers
Ported front timing cover
Sealed Power high volume/high pressure oil pump w/ booster plate
Roller cam button
Viton valve seals
Comp Cams 980-12 valvesprings
RJC Power Plate
HKS SSQV Blow off valve
Speed Pro double roller timing chain
LT1 mini-starter
HRpartsNstuff driver's side motor mount
K&N valve cover breathers

TURBO & INTERCOOLER
T-bolt hose clamps & heavy duty silicone couplers
Garrett T63e turbocharger w/ heady duty adjustable wastegate
4" Turbo inlet pipe
12" Long K&N cone air filter w/4" inlet
Front mount intercooler w/ custom fit 2.5" aluminum charge pipes

IGNITION
8.5mm MSD SuperConductor sparkplug wires
Stock ignition module
Stock ignition coil

FUEL SYSTEM
Modified factory fuel hanger w/ATR dual high pressure fuel pumps
Modified stock fuel rail for -10AN fitting
Seimens 83pph injectors (6)
Braided S/S Fuel lines -10 AN & -8 AN
SX Performance billet adjustable fuel pressure regulator
OGS Propain injection system (propane)
SMC alcohol injection system

EXHAUST
3" Mease Performance Engineering downpipe (internal wastegate)
4" custom S/S exhaust system w/ Magnaflow race muffler

ENGINE MANAGEMENT
MAFT Pro speed density conversion
Extender Pro custom PROM (chip)
Modified stock ECM for Low-Z injector drivers
EGT signal converter
High boost solenoid
Fuel pressure transducer
Oil pressure transducer
GM TTA 3 Bar MAP sensor
PowerLogger scan tool
BstC electronic boost controller
Caspers Electronics plug & play MAFT Pro Harness
Innovate LC-1 wideband oxygen sensor w/custom installation box

TRANSMISSION
BOP Turbo Hydramatic 400 (3spd)
9.5" West Coast Racing torque converter 3500 stall
Reverse manual valvebody
Redneck Transbrake
Alto Red clutches
Kolene steel plates
Alto direct Power Pak
Alto Red oversized direct band
Roller bearings throughout
Hardened intermediate shaft
HD intermediate direct drum
HD 34 tooth sprag & race
Boost valve kit
Case saver kit
HD centre support
AISI 1045 steel forward clutch hub
Hardened stator
HD output shaft
Rebuilt front pump w/ restrictor
Teflon ring seal kit
TCI Deep cast pan
Trans speedomoter ratio adapter

REAREND & DRIVELINE
Custom 4130 seamless chromemoly 3" driveshaft
HD Spicer 1350 yoke
HD Spicer solid U-joints
Custom driveshaft loop
Factory 8.5" G80 (positraction) rearend w/welded axle tubes
HD 3.08 ring & pinion set

SUSPENSION & BRAKES
Front
Vacuum brake conversion w/B-body 1-1/8" bore master cylinder
Robert Adams' 12" 1LE brake system w/Hawk HP+ pads
Tubular UCAs
Boxed LCAs w/ Global West Del-A-Lim bushings & Moog HD lower ball joints
Moog Z28 spec springs (5664) 800lb/in
Bilstein shocks
1LE 36mm hollow swaybar w/ Moog G2 bushings & endlinks

Rear
2002 LS1 disc brake conversion
Brake pressure booster solenoid
UMI LCAs
Bennets' single adjustable UCAs
KYB Gas-A-Just shocks
Hellwig Pro-touring swaybar
Moog HD springs (5659) 200lb/in

WHEELS & TIRES
Black Plastidipped Simmons FR17
Front: 17x9.5s w/275/40R17 Falken 452s
Rear: 17x11s w/315/35R17 Nitto NT05R Drag Radials

BODY & CHASSIS
Fiberglass front bumper
Aluminum front bumper shocks
Custom 6-pt chromemoly roll bar

INTERIOR
G-Force 6-pt racing harness
Kenne Bell "ash tray" switch plate
Custom reverse pattern console shift indicator plate
Custom two tone interior using factory colours
Late-model GM "map lite" rearview mirror

ELECTRICAL
Custom fuel pump hotwire kit
Custom Chassis/engine ground upgrade

COOLING
Modine aluminum radiator (951)
Modified 160* Mr. Gasket SBC thermostat
Derale transmission oil cooler w/ fan & relay


It boils down to the car was made lighter, the weight balance was adjusted (lightened front end), the car had the benefit of being somewhat mid-engined (tiny little v6 set back behind the spindle centreline), and really good brakes.
 
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81cutlass

Comic Book Super Hero
Feb 16, 2009
4,218
113
Western MN
Also, good example

Mike's car is AGRESSIVELY low, but in order to get caster/camber in spec the stock uppers need to be pulled in a lot. So much the stock UCA studs are too short. I went with these aftermarket UCA's because my UCA hit the long tubes at any more than 3/4" shim.


Generally my ride height is here with the aftermarket upper arm and the 26" to the fender ride height the LCA is parallel and the UCA is just pointing up slightly. Stock Ball joints even at a decent ride height pull the UCA down a decent number of degrees so when you hit a bump or steer the UCA goes out as it goes up. The goal is to get your UCA level-ish so it pulls in as it goes up.

1659118139563.png


This is full compression
1659118284214.png


And that's roughly full drop. The UCA is a lot shorter pivot to pivot than the LCA so you want to pull in as it goes up.
1659118317639.png
 
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Streetbu

Know it all, that doesn't
Supporting Member
May 22, 2011
3,292
113
Central NY
Be careful on rear sway bars... bigger is NOT always better, unlike the front bar. Size for the rear bar will 100% depend upon your individual setup. Several top drivers that run G bodies have found they don't use any rear bar at all...
 
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64nailhead

Goat Herder
Supporting Member
Dec 1, 2014
4,845
113
Upstate NY
Be careful on rear sway bars... bigger is NOT always better, unlike the front bar. Size for the rear bar will 100% depend upon your individual setup. Several top drivers that run G bodies have found they don't use any rear bar at all...
Hopefully this was noted in my setup I listed. The big rear bar was fabulous for that car. But that doesn't mean it would be for everybody. Consider that the car I referenced had a T6 turbo mounted forward of the water pump on a frame rail with all of the additional IC and exhaust piping that is in front of the motor - that extra 150lbs on the nose probably had an effect. We need some BB guys to chime. Where's 565bbchevy ?

Streetbu what's your tire/rim combination?
 
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Streetbu

Know it all, that doesn't
Supporting Member
May 22, 2011
3,292
113
Central NY
OP. You really should spend a week and read this entire thread. From beginning to end, without skipping. There is so much information in it, it will make your head spin.

 
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Bonnewagon

Geezer
Sep 18, 2009
8,745
113
Queens, NY
Great thread. The part about " why would you" sticks in my head. I have a friend that has been trying to Frankenstein a complete C4 suspension onto his 1968 Firebird convertible. A Firebird is already a better handling car than a G-body. He scrounged a 1965 Pontiac 421 out of a station wagon and rebuilt it to 428 HO specs. He has a Corvette 6 speed manual trans he adapted to a BOP bell housing. He figured the C4 suspension was light years ahead of 1968 suspension technology and he has a place to work and a welder so.....The rear was actually easier because the C4 parts lined up pretty well with the Firebird frame supports. The front has been a challenge. He has been at this for over 20 years. Will he ever finish? Who knows . Will it have been worth it? That is the question.
 
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SRD art

G-Body Guru
Jun 16, 2011
546
63
St. George, UT
I started out with improving my car's handling about 12 years ago by reading the book mentioned at the end of my thoughts, and then experimenting a lot with my car. I later worked for Speedtech Performance for 5 years and furthered my performance handling education through that, and am always trying to learn more about this subject. YES you can make a G-body handle really well! Ultimately my goal is to have Pumkinator be able to keep up with and beat a Speedtech Extreme suspension equipped Camaro. I pick on that set up because it's the most advanced Pro Touring suspension design available right now. And no, unfortunately it's not available for G-bodies, but not a big deal because they cost upwards of $30,000. :oops:

I don't have a lot of time right now to thoroughly read all the replies, sorry if this is duplicate info in any way. Consider a G-body is basically the same wheelbase, track width, and near the same weight as a 1st gen Camaro or Firebird. If that's the case then there's no reason you can't have your G-body handle just as well as a well set up Pro Touring Camaro. There's a lot to do though because initially these cars were never engineered to handle well, it's a family car made for comfort and safety. How much you want to spend on it will determine the level of how well it can potentially handle. I've had 3 different suspension set ups on Pumkinator and am now working on it's 4th. Each set up got better and better. With my most recent (3rd) set up on Nitto 275-40-17 NT555 300 tread wear daily street tires I could keep up with a C6 Corvette at our local SCCA auto cross, he and I were similar driving skill levels.

It's important to point out that there are many things you can do to make a G-body handle "Better" than stock. You can add drop springs that will make the car feel better but that covers only one aspect of the inherent problems with the car. You can add different control arms that can make the car feel better but that's also only one aspect. You can do more things to correct geometry but that's only one aspect. You can install decent shocks but that's only one aspect. ... What I'm getting at is like I said above it depends on how much you want to spend. Each step is only part of a large puzzle to complete. It isn't all required but if you do ALL the steps the car will handle amazing!

I saw the Schwartz chassis mentioned in the comments. If you have the money that's a good bet but you can piece together a good set up for a factory frame at about 1/3 the cost and it'll perform just as wells a Schwartz if not better. Basically you'd be doing all the same things Schwartz did to correct all the problems only you'll still be using the factory frame rails. May not look as pretty and might be a little bit heavier but it'll get the job done.

I saw sway bars were brought up and someone said a sway bar can't make a car push. That's absolutely INcorrect. The basic key to good handling is to keep as much contact patch as possible on all 4 tires around the corners, a big part of that is balancing the car's weight as it moves around by G-forces. Spring rate is a combination of springs and sway bars. Too much front spring rate will make a car understeer/ push and too much rear spring rate will make a car oversteer/ back end come around. In other words if you put Moog 5662 springs and a large front sway bar but no upgrades out back you'll push through corners all day long. Add maybe some UMI rear springs and a 3/4" frame mounted rear bar and it'll BALANCE out better. You have to balance the rear of the car to the front or you'll be constantly fighting it. My car has a 1 5/16" front sway bar with legit 700 lb front springs in my coilovers, on the rear I don't have a sway bar because with my 350 lb rear coilovers it had a tendency to oversteer with a sway bar. IIRC in comparison UMI's lowered rear springs are 135 lb. But it doesn't just equate to spring rate, I have double adjustable shocks that help me fine tune that last little bit of control and can actually make the car under or oversteer a little just by adjusting the dials and changing the compression and rebound characteristics.

There's so much to talk about on this subject if a person was serious about handling performance, there's like a whole book's worth ;) and too much time to just type it all out here. A great place to start and remove a lot of the guess work and opinions- "I heard that if you do this..." that we find on social media, get a book called "How To Make Your Muscle Car Handle". It should be required reading before anyone spends any money at all on suspension parts because it goes over each aspect of those upgrades individually and illustrates how and why each part is an important piece of the complete puzzle.

Finally if you look at the link in my signature for my original build thread from 2011 you can see the basics of what I started with. The suspension has changed a lot since then but you have at least an idea of how I set the car up to start my handling adventures. feel free to pic my brain with questions about my experience. If I don't know, I have friends like Ramey at UMI and Lance Hamilton who drive some of the leading G-body autocross cars as well as I have lots of friends in the Pro Touring community, and I'll try to get an answer. Good luck!

A couple pics of my Pumkinator and my son's Coppertop ...


Pumkinator 14 72.jpg
hotchkis-autocross011.jpg
Copper Calendar.jpg
Meissner Proof 05.jpg
New engine 1.jpg
315 Pumk 008.jpg
 

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wayoutthere007

Not-quite-so-new-guy
Feb 2, 2022
21
13
As the old saying goes "Speed costs money, how fast do you want to go?". Same could be said for handling.
There was a guy on turbobuick (dsapper) that had very deep pockets and wanted his GN to give his friends Ferrari a run for its money.

DSAPPER GN very deep pockets
 
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