Body Roll

[pontiacgp]

I run Afco 10 series shocks...#7 valve up front and #5 valve in back. They are not those self adjusting shocks which IMO adjust after the fact

http://www.smileysracing.com/shopping/p ... 696&c=1538

 

[custom442]

Hey i have an 87 cutlass supreme brougham with massive amounts of body roll.

lol me too. I think a lot of us have tons of body roll. The car would need a lot of bracing to control the roll entirely, but stiff suspension will make it less noticeable.

 

[beermonkey9417]

http://gbodyforum.com/viewtopic.php?f=14&t=8126&hilit= SHABLAM!

Shablam, indeed! :lol:

 

[bmxer_coon]

Adding a rear sway bar is a good start. Regardless of whether you stay with the standard front bar or upsize, urethane sway bar bushings and harder end link bushings are a must. Probably the most important factor in controlling roll are your shocks, so don't scrimp in that area. Good shocks and sway bars can help to compensate for a softer spring, but absolutely nothing can offset bad shocks, so that's where I would pay the most attention.

Bill

Thanks dude, got the rear sway bar already. Just gotta pick up some shocks

 

[Burnhard]

When you lower a car does it not help body roll ? I have found good tires make a big differance.

 

[billyjack]

When you lower a car does it not help body roll ?

It sure does. The most influential factors in roll are relationship between the center of gravity and the roll center, which is a longitudinal axis, determined by the suspension geometry, around which the car actually "rotates" under cornering loads.
Lowering the CG is always a good thing. That's the reason why any paved surface race car is built as low as possible.

Tires have no influence on body roll. However, better,stickier,wider tires will maintain better adhesion to the road surface when the car is undergoing severe roll.

Bill

 

[Burnhard]

Thanks for the reply. If you were to make a list to make your car handle better what would you start with? Street car on a budget best bang for the $$$$? What mods and why you would make them?

 

[billyjack]

Thanks for the reply. If you were to make a list to make your car handle better what would you start with? Street car on a budget best bang for the $$$$? What mods and why you would make them?

This is just one man's opinion, but you asked, so here's my plan to get the most impact for least $$ on a street driver. I will assume things like springs, bushings, body mounts, ball joints, steering linkage etc. are all in good shape. If not, fix the weak parts first before any mods.

1) Shock absorbers. Shocks affect virtually every aspect of vehicle dynamics, including wheel control over road irregularities, roll control, brake dive, acceleration squat, as well as the transitions from acceleration to braking, corner entry and exit.
Buy the best shocks your budget will allow. Popular brands are Bilstein, Edelbrock and KYB among others.
2) Roll control. Roll control allows you the maximum use of the contact patch of all 4 tires by minimizing the weight transfer to the outside tires in a corner, as well as minimizing the resultant camber change at the front tires. The stock F41 bars are a decent cheap upgrade for a non-F41 car. Swap the front bar's rubber bushings for aftermarket urethane bushings and use hard end link bushings. Mount the rear bar as far forward as possible without forcefully wedging it in the control arms and causing a bind. The resulting shorter arm length will make the bar more effective. Aftermarket larger bars are even better, but much more expensive, If you do go aftermarket, keep the front / rear size ratios similar to the F41 setup, with maybe a little more bias toward the rear. When I used to autocross, I would run a stock front bar with an F41 rear bar, since I wanted the car to be loose so I could toss the rear end at will, but that kind of setup could get you in trouble at higher speeds.
3) Tires and wheels. Run as much tire as you can, especially on the front, and as wide of a wheel as possible. 7 inches is the absolute minimum wheel width to consider; 8 is even better. Given a choice, run the lightest weight wheel possible.
4) Camber curve. G-bodies, like most American sedans, have a horrible camber curve. Ideally, a tall spindle setup like Global West or Hotchkiss helps keep the front tires flat on the pavement, but again speed costs money. In the absence of $$, get your front end aligned to performance specs, i.e. Camber as close to vertical as possible, maximum attainable positive caster and a minimum of toe-in.
5) Structure. Structural reinforcements have been discussed in this forum at length, so no need to rehash. By themselves, structural reinforcement or bracing does absolutely nothing to improve handling. But, by reducing the chassis flex and/or twist while cornering, the suspension is better able to do its job. At the very least, find a set of F41 bars or a Grand Prix bar for the front and tie the ends of the frame rails together front and rear with some fabricated tubing.

I could go on a lot longer, but this will keep you busy for a while. Reply if any questions.

Bill

 

[custom442]

good post bill,
I disagree with the recommendations on toe and camber. If he's going for cornering he must use some negative camber, and if doing so toe in will restrict his cornering ability more so than it would do otherwise. Negative camber and toe out.

Negative camber is important because under stress and body roll camber is becoming positive. A negative camber will offset that tendency, control roll for suspension geometry and give a planted feel to the tires. The contact patch of tires with less weight in a corner we want more grip, since ours are front heavy rwd cars weight is transfered to the outside rear i.e. oversteer. Anything we can do to #1 make the outside rear looser, and #2 make the front inside wheel tighter and hold more contact patch (in the corner/rolling not static) will help in cornering.

I'd like to add some to this question-

Thanks for the reply. If you were to make a list to make your car handle better what would you start with? Street car on a budget best bang for the $$$$? What mods and why you would make them?

for a g body on a budget to get the maximum cornering for the least money, I'd cut the front springs, add an f41 front roll bar, remove the rear bar. Check bearings or worn end links or rotten rubber bushings and replace. If on a budget rubber bushings will work fine. A quick ratio steering gear box from a 3rd gen camaro, and set toe out a little, negative camber, positive caster. This should be around 75-125$. Thats the cheapest I can think of for the best return in handling.

your tires won't last forever this way, but you'll be surprised at the handling results. Bill has some good recommendations try those if you want to spend a some more money or if you want to do it the correct way (wheels/tires + shocks make a huge difference)

 

[billyjack]

good post bill,
I disagree with the recommendations on toe and camber. If he's going for cornering he must use some negative camber, and if doing so toe in will restrict his cornering ability more so than it would do otherwise. Negative camber and toe out.

Negative camber is important because under stress and body roll camber is becoming positive. A negative camber will offset that tendency, control roll for suspension geometry and give a planted feel to the tires. The contact patch of tires with less weight in a corner we want more grip, since ours are front heavy rwd cars weight is transfered to the outside rear i.e. oversteer. Anything we can do to #1 make the outside rear looser, and #2 make the front inside wheel tighter and hold more contact patch (in the corner/rolling not static) will help in cornering.

I'd like to add some to this question-

Thanks for the reply. If you were to make a list to make your car handle better what would you start with? Street car on a budget best bang for the $$$$? What mods and why you would make them?

for a g body on a budget to get the maximum cornering for the least money, I'd cut the front springs, add an f41 front roll bar, remove the rear bar. Check bearings or worn end links or rotten rubber bushings and replace. If on a budget rubber bushings will work fine. A quick ratio steering gear box from a 3rd gen camaro, and set toe out a little, negative camber, positive caster. This should be around 75-125$. Thats the cheapest I can think of for the best return in handling.

your tires won't last forever this way, but you'll be surprised at the handling results. Bill has some good recommendations try those if you want to spend a some more money or if you want to do it the correct way (wheels/tires + shocks make a huge difference)

You make some good points. Setting up a front end with static negative camber definitely does help a bunch. I just don't consider it practical for daily driving, as it's really tough on tires. I preferred to carry a set of 3/8" shim packs to an autocross and add them to the upper control arms in the pits before an event. Steering box is also a good point. I have a T-Type box in my Camino and while it technically doesn't change a thing with the vehicle dynamics, it sure makes it easier and more fun to drive hard.
I definitely don't agree with removing the rear bar. Having added a rear bar to a few of my cars over the years, I consider it to be the single best bang-for-the-buck change you can make. By inducing roll resistance at the rear of the vehicle, you make life easier on the outside front tire in a corner and decrease the dreaded understeer tendency.
Hopefully, some others will chime in also. I know I certainly can't be the only idiot who's taken his oversized, overweight American sedan out to dodge cones with the imports.

Bill