I have a '69 Chevelle with a mild 461, TH 400, 12-bolt open 2.73's. The front end was rebuilt with polyurethane bushings, AGR quick turn steering box, Flaming River U-joint steering shaft, 13" steering wheel. The front springs are about 1 1/2" lower than stock. The rear springs are stock replacements. Monroe shocks in back, Edelbrock in front. Stock sway bar in front. No sway bar in back.

As far as cornering, the car stays really flat. No problems there. Due to the poly bushings, stiff springs and shocks, the ride is probably a bit too stiff on rough roads, but then again this is not a Cadillac.

While cornering is excellent, I've notice that things can get slightly squirrely as far as roll when changing lanes at 70 mph and above on rougher highway. Nothing frightening, just a little heads up to the driver every once in a while.

If I add a sway bar to the back, will it stabilize the roll when switching lanes at higher speeds (not cornering)? Or will tying the rear control arms even tighter together with a sway bar exacerbate the problem? My first impression was that a sway bar would help, but then I thought of all the modern European cars that handle really and that they have independent rear suspensions.

Yay or nay on the rear sway bar to stabilize high speed roll?

I threw a factory 7/8" bar on the back of my 72 and that was one of the best mods I did. It didn't make the ride any harsher either. Plus, at the track it launched much straighter.

I second the small(7/8) sway bar.:thumbsup:

Thanks for responding. I'm leaning towards the rear sway bar and I know a ton of people on here have said it was a great upgrade, but the endorsements are usually referring to improved cornering ability. With the stiff poly bushings and stiff springs and shocks, the cornering on my car is excellent and I wouldn't be installing it for that reason. I suspect that if I put a sway bar on back and tie the rear control arms even tighter together, that the highway-speed "wiggle" when changing lanes will worsen.

On one hand, I'd think that tying the rear control arms together with a sway bar would stabilize that wiggle, but on the other hand, that concept directly contradicts the benefits of independent suspension, which is far superior to a live axle. I'm not sure which it would be.

Does anybody have any anecdotes as to whether a rear sway bar makes that part of driving better or worse?

I would wonder why you have a wiggle in the first place?
Maybe your front and rear suspension are speaking in two different languages.:confused:
I'm not some road race chassis guru but in my experience most people with somewhat normal cars I've dealt with liked the factory sized rear bar.
And its cheap.:hurray:

So I'm sold on adding a sway bar to the rear. I have a couple of questions:

The front sway bar is between 7/8" and 15/16", depending on where I measure it. I know that the rear sway bar needs to be narrower to prevent excessive understeer. Is 7/8" in the back narrow enough with 7/8"-15/16" in the front? Seems like it would be a mismatch. The combos I see usually have at least 1/4" difference between the front and back. Should I go with a 1" bar in back and replace the front with 1 1/4"?

My lower control arms are the stock unboxed ones. Some kits I've seen include new control arms, some kits have metal plates to insert and weld in, and some kits have tubular spacers to insert into the control arms where the bolts go through. I'm sure that preboxed and welded control arms will be comparable, but will the tubular spacers make the stock control arms strong enough?

I prefer 1 1/8 in the front and a 7/8 in the back.
If you want to reduce body roll ,do it with springs not bars.
Huge bars are a band aid, higher rate springs are a fix.

Woodsman, thanks for responding.

The springs and shocks I have already take care of the body roll. That part is fixed. By that logic, adding beefier sways bars won't be any improvement. What are beefier sway bars good for then?