81vet

My 81 4spd car came with no rear sway bar. I have replaced the 15inch rubber with 17inch. Question being, will adding a rear sway bar be worth the time and $. Thanks for any and all opions.

big_G

If you upgrade to a rear bar, you should also up the front bar size. My preferences are 1-1/8 inch front, 5/8 inch for the rear.

turtlevette

NO its not worth it.

73, Dark Blue 454

GM thought they were,..or at least it seems Vettes with larger engines were equipped with them,..I'm sure the R&D suggested the need.

Both my BB 73's are factory equipped with rear sway bars.

wrc69v

It depends on how hard you plan to drive the car. I installed one on my '69 and had no problems, later i replaced it with a dual mount composite monospring from VB&P and have noticed no difference in performance.

turtlevette

That setup is tuned for G70 15s all around. When going to different tires everything changes. An oversteering car in a high speed turn is dangerous. Seems to me that stock setup would oversteer like crazy.

I speak from a track perspective. If you want to be NCRS correct by all means run the rear swaybar.

big_G

Na, the stock rear bar (7/16 inch) is almost useless. About as stiff as a used coat-hanger...

72 LT1

Turtlevette Not to highjack thread, but, I just installed 3/4 rear bar w/ 330lb glass spring and am going to instal 550lb coils in front w/1 1/8 bar. This is in a 72 small block coupe. This is the set up VB&P recomended. Is this car gonna oversteer? I'm running 235/60 15 on front 255/60 15 on rear BFG radail T/A's.

Gordonm

I was at VB this winter and asked about this same problem since I went to 18 inch and wide rubber. The yset me up with a 420# rear spring and no rear bar. They told me this should work just as well as the 330# with a rear bar. It seems to be just as stable. No track time with it but on some aggresive driving it seems as good as before.

turtlevette

Good point.

turtlevette

well bigger tires on the rear will help but yes i think it will.

Being able to steer the rear with the throttle in an autocross is an advantage but not in roadracing.

jimmygmartin

Sway bars are a tuning tool for handling. That is why formula cars have adjustable end links. I have a set that was matched by Addco 1" front and 3/4" rear. I have run with and with out the rear bar, with steel springs and fiberglass springs. I don't really have a problem with oversteer unless I induce it with power. Some forum members in the past have stated that these cars need a rear bar. I agree with turtlevette that they help in some situations but not others. My suggestion: get a matched set and try it with and without the rear bar. If you understeer sell the bar on the forum and get the next larger size. If you over steer do the same but go to the next smaller size, or run without the bar.

Jason Staley

If you put one on, go on the small size. I installed a 9/16" factory one and it made a difference. Car went from understeer to slight oversteer. Doesn't take much to get these cars to oversteer.

PatsLs1vette

Gordon you got an IM

turtlevette

I always chime in on these because it's a safety issue. Most of these guys putting rear bars on will never push their cars to the limits to understand what can happen. When they find out for the first time it will be too late. They put the rear bar on and the car feels firmer and more responsive so they think its great. I was the same way many years ago. I bought a 1.25" rear bar because more is better right? It was great fun at autocrosses to be able to steer the car with the throttle especially on hairpin turns even lifting one rear wheel off the ground.

On the highway in an emergency situation the car is going to swap ends when you swerve to avoid an object. No doubt about it. Leading to a crash. There is a reason the factory builds understeer into almost all passenger vehicles. It's much much safer.

If you insist on running a rear bar use adjustable end links as was mentioned below. Tighten them up when you want to play but loosen them a lot for normal highway driving. PLEASE.

Many years ago i almost rolled my car swerving to miss an Armadillo at 80mph. If the car had rolled i don't think i would be here now.


BE CAREFULL

Restorod '79

My rear sway bar(3/4") will go on and off the car with the street tires. When I pull out of the show'nshine I want the flat fishtale capability. At 100+mph on road course I want the very last bit of rear grip available. It's a tuning thing.

Jim_Harrison

I found with my Auto X car that if the rear is too stiff it has off throttle oversteer. Coming into a corner at high speeds with the brakes on the car want to come around...very bad. I do not run a sway bar. C-3 Vettes are also prone to being very unstable in a corner if there are bumps. I have a TRW 360 LB ? whatever the stiffer one is on the rear with Penski dual adjustable shocks and this works well. Stiff bars makes the car feel much more responsive but if you get in trouble as Turtlevette said Be careful. I vote no rear sway bar. Also Koni makes a single asjustable shock that is inexpensive and I found works well with these cars...not as good as the Penski's though.
Just my humble opinion.

73 LS-4

To have a rear swaybar or not to have a rear swaybar on a car, is about like asking what cam for my engine. Depends on what you are going to do with it and how the rest of the suspension is setup. In any case if your going to run a rear swaybar it must be matched to the front. I ran a mismatched front and rear bar on my 73 and it handled terribly. I upgraded the front bar and it was great. If you look at a lot of the racing vettes way back when they ran swaybars but they ran small ones becouse they ran heavy springs so body roll wasn't much of an issue. On a street car you want to have softer springs so the ride is tolerable, and to somewhat make up for it run heavier bars. Now bar choices are going to depend on vehicle weight, front to rear weight, spring and suspension choices, and use of vehicle.


Pat Kunz

bozzman3

Can somebody explain oversteer and understeer to me? I am sure I have experenced both but help me understand these actions!

Jim_Harrison

If you were to drive your car in a constant circle, slowly increasing the speed, (Skid Pad) and the rear starts to slide out that is oversteer or the car is loose. If the front slides 1st then that is understeer or tight. A balanced car will have both ends slide at the same time. I drive best if my car has a very slight amount of understeer, then use the throttle to power oversteer the car. Some drivers like a car set up on the loose side, I find this works well with a C-5 Z06 but a C-3 due to poor rear design is becomes unpredictable and very unforgiving.