Matching the Rear Sway with Front

[69-er]

The 69 Camaro I am working on has a 7/8" rear sway bar installed. I would assume that since only an 11/16" front bar was installed at the factory, I need to install a front one that is larger in diameter than that to mach the rear. Am I correct? Any ballpark figures that someone would like to throw at me as to what size I should get? This car won't be raced, at least competitively, so it's really just for looks and in case the driver needs to make an abrupt maneuver to prevent an out-of-control situation.

I saw in a Camaro catalog that they had available a 1" and 1 1/8". I really don't know if these would work together with a rear sway bar or if they are designed to work by themselves.

Specs:

Rear: Aftermarket 4-leaf, 2-3" lowered, rate unknown, QA1 Shocks, single adjustable.
Front QA1 coilovers, single adjustable, rate unknown, 2" drop spindles.

Is there anything else that would be needed to get a close estimate?

Thanks!

Larry

[cobraguy65]

I'm sure there are some members on here with first hand experience that can give you a recomendation. I will just say that a bigger sway bar in the rear should cause the car to oversteer at its limits. You could take the rear bar off and try it with the 11/16" front. With your car being lower and possibly higher rate springs, It might have acceptable roll characteristics for a mostly street driven car.

[LeighP]

If you're running the 7/8" back bar, I'd personally run the 1 1/8" front.....when I was much younger, I was on the receiving end of having the back end stiffer than the front, all I can say is I'm glad the road on that corner was WIDE!

[j-rho]

Is there anything else that would be needed to get a close estimate?

How does the car handle now? If it pushes, go bigger in the rear bar. If it's loose, go smaller. If it handles fine, don't change it.

[exwestracer]

How does the car handle now? If it pushes, go bigger in the rear bar. If it's loose, go smaller. If it handles fine, don't change it.
Exactly. The bar is a tuning aid, not an integral part of the suspension design. Take it out and thrash it around the cones and figure out what it does at the limit. That will make your decision easier.

[clancj]

the pivot points are also critcal. get one that allows you to move the pivots inward and outward.

[JRouche]

V8 engine. Wide tires? Heck, put the 1-1/8" bar in. And thats the simple reply.

The complicated reply goes more to what the others have said. The sway bar is a tuning aid ONCE you have everything else set up how you like it.

And personally I like a car that allows some sway with control during hard driving. If the control arms are able to plant the tires (mainly the outside tire in a turn).

Too stiff of a body with a largish bar on the rear and then an even larger bar on the front to get a good coupling will make the car feel like a board going down the road. Not enough sway ends up making the car heavy in the turns and prone to scuffing the tires in a turn instead of letting the tires and suspension do the work they are supposed to do. Thats when you are driving fast.

On city streets its prolly a dream to drive (with the larger bars). You can make a semi quick turn and the car feels stable. Instead of leaning alot and looking like a wallowing beast of a car. For common city driving you might really like the stiffer body. Gives the car a more stable feel, and look.

And I get the idea for limiting body roll. Cars do feel faster if they are flatter. But thats not always the case. I have driven some cars that were very heavy, and tended to roll in the turns more than what seemed good enough. But what I found out was my speed was faster than it felt. And yes, I was prolly eating tires like they were free (they were). And this was on a closed road course with many sharp fast turns. Lots of understeer and heavy throttle and braking. Eating tires like no ones business, using brake pads up like butter. But for an inexperienced driver (me) driving a car they are not COMPLETELY used to under steering will get them through the tight turns faster (Im talking about keeping it within the lanes and not looping it, maybe why many production cars are under steering, better to eat a curb or go off the road on your side of the road VS looping it or getting out of shape into the on coming traffic)

On a high speed track where the turns are not as sharp a stiffer body will prolly help. On a short track the oversteer made for a slower speed compared to the same car that was under steering. And that was for a car that I was not used to. I still like an over steering car. Takes alot more steering, braking and throttle control to keep it in the lane without whipping the rear around. But once you are used to it the overall control is greater, also helps to have a lil power to easy the butt around if you do get a lil out of shape.

Kinda watch out for using too stiff of a bar up front. It removes some of the independent qualities of the independent suspension that we are looking for. Too stiff of a bar links the two front tires more so the influence on one wheel is carried over to the other wheel. And thats really a concern for a street car. You dont want the two front wheels links so stiff that any rough road conditions on one wheel transmits the same wheel movement to the other wheel. It make for an unstable ride at times.

One thing that gets lost with some folks is the suspension NEEDS so have a certain degree of compliance. The ability for the tires to stay in contact with the road. That includes sway bar rates, spring rates and shock valving. And street cars need more compliance, the roads are rough, you have to keep the tire planted on the surface. That means not a massive wheel spring rate, not a heavy shock valve compression rate (a loose compression and stiffer rebound rate will benefit many cars), and not a massive roll bar rate.


But with not many options for sway bars. Like either a 1" or a 1-1/8" for the front it kinda limits you. So you have to make a choice or go with a three piece bar and a huge number of spring rates. Ok, you see where Im going? Yeah. I have a three piece bar on the rear and the front. And lemme say, I had just as hard of a time finding the correct rates as you. Even with ALL the rates avaiable. Mainly because I didnt have any opinions from anyone that has a similar setup as mine. So it was a crap shoot.

You have a lil more help though cause the bars you are looking at are widely used. And your car is common for many folks.

So with that some general setups I have seen for cars like yours are a 7/8" rear bar and a 1-1/8" front bar. Thats the only reason I suggested that setup. JR

[lzdick]

69-er,
I am in the process of doing the same on a '69 Camaro street car (making 'big' hp) that I will give some 'track time' on weekends. It currently has a 1" swaybar on the front (don't know the manufacturer) and wanted to add a rear swaybar. Looking at Summit Racing online gave me many manufacturers and I chose Addco, recommended by several friends. In speaking with an Addco tech, he said for their 1" front swaybar (#136), the rear should be 3/4" (#226). For their 1 1/8" (#599) and 1 1/4" (#2268) front swaybars, it would require their larger 7/8" rear swaybar (#671). For the stock 11/16" and COPO 13/16" front swaybars I would ASSUME the #226 would be right; it was the smallest diameter listed. Basically,the rear diameter needs to be small than the front and the #226 is the smallest they manufacture. If you want to speak with the tech live, the number is (800) 338-7015 and his name was John.

Good luck...and let me know what you decide.

LZDICK