1979toy,
You'll probably find that your spacers are correct. Mine, for some reason, had been changed to shorter ones.
Gator81 gave me a very good explanation of sway bars on C3's a couple of years back. In essence, what he said was that when you rush headlong into a corner much too fast & yank on the steering wheel, the car tends to understeer, & you may hear the inside front tire squeel, because the front end wants to keep going in a straight line. With a fat front sway bar, the front tires regain their grip & follow the direction they are pointed in (I hope!). This twists the car as the rear end is still trying to go in the original direction, so it's the turn of the rear inside tire to slip as the rears are still rolling in the original direction, while the car is heading in the new direction. This gives oversteer as the back tends to slide out. With no rear sway bar (as I have) the transition from understeer to oversteer is gradual. Fitting a rear sway bar will allow the car to go around the corner flatter and faster as the loading on the rear tires will be spread more equally (like it is on my front tires). However, when you again take the same corner even faster, the transition from understeer to oversteer will be much more sudden & you can end up watching the rear of your car overtake you :) Fitting stronger springs also has the same effect. With a thin, or no, rear bar the loading on the tires is unequal, so the inner one losses it's grip first. With a fat sway bar the loading will be close to equal & they can both lose grip simultaneously :(
That's how I remember his thorough explanation of it (& I hope I've got it right!). Last Sunday I took a favourite bend as fast as I dared (no other traffic on the road & nothing to hit if I slide off the road). Sure enough, I could hear the front tire squeel followed by the rear tire squeeling (both needing slight steering corrections) & I could feel the body roll when I was well into the corner. So, I reckon that a rear sway bar will prevent some of the roll & let me take the bend faster & flatter, but the trick is getting the right size of bar for my style of driving (erratic!!) which will give me a bit of warning that the rear is about to let go. Why do I want to do that? I've never driven anything around that corner as fast as I took the Vette round it on Sunday! :crazy:
Also, optimum sway bar sizes also depend on the springs fitted.
:cheers:

 

Also, optimum sway bar sizes also depend on the springs fitted.
:cheers: [/QUOTE]

My thoughts exactly, but you know I think it was only the BB sharks that had factory rear bars....to counteract that extra weight up front, and too boot they were very thin...I would not mind trying a factory bar just to see, but am not interested buying one just for try out....I suspect a factory bar would be mucho better on these roads here, my neighborhood is on a hill here in the sand bar state, and all those underground springs, rivers, limestone formations, tend to wash out protions of roads and cause potholes to form where nothing existed before,...constant formation and patching around here, and with all the rain recently, it's gotten MUCH worse, they literally can't keep up with it....so conceding the obvious somehow, wether it was bars or springs, or shocks, something had to give, as I was tired of beating the poor car to death, and myself included, and too boot Linda is happy to hear of the improvements....

GENE

 

The factory bar is a different design and I don't think you can compare the sizes of them directly with the aftermarket bars. So, a 9/16" factory bar *may* be stiffer than a 5/8" aftermarket bar. I have not compared (heck, I haven't seen either bar in person), but I'd believe a thinner bar with shorter "arms" would be stiffer than a thicker bar with longer "arms".

 

I've been reading the book Herb Adams put out on performance suspensions. The basic idea of the sway bar is to prevent body roll and by doing that it keeps the cars alignment in spec which would otherwise try to pull positive camber on the inside tires. Well you would think the bigger the bars the better, well not so. Any given tire has a maximum amount of grip it can hold with a maximum tire contact patch. The heavier the swaybar the more load your going to put on an outside tire of a turn, exceed the tires limit on the front and you have understeer, exceed it on the back and you have oversteer. You can tune a suspension for oversteer or understeer by increasing or decreasing the size of the front or rear bars. For example if your oversteering you can decrease the size of the rear bar putting more of the load on the front, or increase the size of the front bar to do the same. For understeer you can do the opposite. The swaybar you want to run is the one that is just enough to keep the body roll down low enough to not effect the alignment and not so big that it overloads the outside tires in a turn. An important thing to remember is that the tire has a finite amount of grip that must be distributed between turning, braking, or acceleration, and at many times many combinations of these. For example the tire will have more grip while accelerating in a straight line then it will while accelerating and turning.

:cheers:
Pat Kunz

 

What's the name of Herb's book?

 

hey were did you find that book, i bought his corvette suspenion stuff for my old 79, 15 years ago but dont see if he's in busness any more???? :steering:

 

No.
FE-7 has a larger ft. & a rear bar & stiffer springs. Duntov experimented ...
Works great for performance- I'm keeping mine.

:cool:

 

Gene,
Pre-1975 SBs and BBs with RPO F41 had 15/16" front and 9/16" rear bars. Post- 1974 RPO FE7 SBs (no BBs of course) had 1 1/8" front and 7/16" rear bars. The pic below is a 7/16" unit. There is also the seven-leaf vrs. nine-leaf rear spring matter: the seven-leaf being the stiffer.

 

I can't recall the exact name of the book, it's at work. I got it through Summit though.

:cheers:
Pat Kunz

 

Quote:

Gene,
Pre-1975 SBs and BBs with RPO F41 had 15/16" front and 9/16" rear bars. Post- 1974 RPO FE7 SBs (no BBs of course) had 1 1/8" front and 7/16" rear bars. The pic below is a 7/16" unit. There is also the seven-leaf vrs. nine-leaf rear spring matter: the seven-leaf being the stiffer.

The exception is FE7 1974...the rear 7/16" was not introduced until 1975.

The irony is that here we have the lowest output hp and from a smallblock yet we have the most aggressive suspension system with FE7. In contrast, with ZR1s...F41s less rear sway bars was the best that it got. I think it was stated above...rear sway bars were standard on big block suspension...and therefore not included with high-performance heavy-duty suspension packages.

 

I tripped on the pre- and the post- ;) .

 

Beater - I think you have it backwards - a smaller diameter bar with longer lever arms can equal a larger diameter bar with shorter arms.
Zora used small bars with long arms. Adams uses huge bars with very short arms.
VB and Addco use bar sizes and arm lengths in between.

 

My car doesnt have a rear sway bar and im not plannin on gettin one since I dont think I need it. Besides I used the factory tapped sway bar mount hioles to hang extra muffler clamps in front of the mufflers as well. The Energy suspension kit I installed came with poly graphite rear sway bar mount bushings and clamps that I will never use. Ill give em away to anyone who is willing to pay the shipping charges. Thet're stamped 7/16" on the bushings. I didnt know the sway bars came that small. I might have the end links too.


[Modified by Jvette73, 11:02 PM 8/15/2003]

 

The shorter the arm the stiffer the bar. The arm is the same as a lever. The longer the lever the less force needed to move an object.

Sway bars are ment to be a final fine tuning adjustment. If you have the correct spring/shock combination for the tire/road surface conditions you do not need a sway bar. But because road condition change you need a sway bar for final tuning. With the Winston Cup cars we remove the sway bars, then test multible spring/shock combinations to get the best handling car. Once that is accomplished, then we remount a sway bar and use it for the final adjustments, always tring to use the softest bar that will give the handling charictaristics you are trying to achieve. If it take a large bar to acomplish this then you have the wrong spring/shock package.

The larger the bar you use the less feel you will have when the car is right on the edge. When you hear someone say that the car "just got out from under me", that is ussually a sign of too large of a bar that did not give the driver the feedback he needed.

When C3's were designed the rule of thought was stiff springs, stiff shocks, and big bars. In the mid 80's vehicle dynamics took a huge leap forward with the invention of the shock dyno and CAD shock tuning. Todays performance/race cars now use much softer spring and much smaller bars, allowing the shock to do most of the suspension control. A good example is the 84 Corvette with Z51. Chevrolet used big bars, stiff springs and stiff shocks on the Z51 package. The end result was a car that handled worse than the base suspension. In 85 Chevy soften the spring and revalved the shocks and ended up with a package that handled vastly better than the 84.

With todays knowledge of vehicle dynamics, bigger bars are just about always NOT better.