Originally Posted by
Sam Strano
Having some time, and having dealt with some interesting conversations over the last week, I feel it's time I post something explaining my thought processes on setting up car. Mind you, each car is different, each situation is different, but there is a general trend I follow... Here goes.
May as well start with shocks. " Seem to be the most mis-understood part of the car.... Shocks do not control the amount of pitch and roll in a car, only the RATE of the pitch and roll. Any semi-properly valved shock rides pretty well. Better shocks do a lot of things for a car. They make it change direction more quickly and in a much more stable manner. They make the car much more stable in cross-winds and on rolling roads. Better shocks help the car stop faster by slowing the movements of the car. The cars with the best shocks in OE form are the German cars. It's no coincidence that they are very stable platforms and have communicative chassis'. F-body shocks, as has been beaten to death, suck. They are in my opinion the single worst part of the car and the single biggest improvement you can make.
Springs. These are what hold the car up. You don't have to have a stiffly sprung car to have a really great handling car. Again, I'll go back to the German example. Audi's, BMW's and Mercedes are not stiffly sprung cars, yet they handle extremely well and can be driven very quickly easily. There is nothing wrong with wanting a stiff car if there is a reason. The assumption that you want the car to feel like a race car and race cars are stiff it not a good reason. Real life is not a track. Tracks are generally smooth, they are a controlled environment, and you don't have issues with the real-world thing like bumps and people slick roads to deal with most of the time. The 4th gen certainly is not sprung as stiffly as a 3rd gen, yet it manages to make skidpad numbers just as high. The grip is there, the transistional stability is not (see shocks). I prefer to only run as much spring as necessary to do the job. That means enough to keep the car off the bumpstops continually, and enough to keep the contact patch of the tires on the road as best we can. If you can do those things with a 500 pound spring, there is no reason to run a 600. And more spring requires even more shock damping to control it too. Anyone who's ever driven pick-ups knows what too much rear spring feels like. The rear end bounces around and generally isn't stable, plus the traction is limited without a load. 1-ton trucks are worse than 1/2 ton trucks are in this regard. Well, adding really heavy rear spring to what's essentially a sporty pick-up (live axle, limited rear weight) you get the same issues.
Front sway bars. As many of you know, I like to run very large front sway bars. I do this for a couple of reasons. First and foremost sway bars are much more effective devices for controlling body roll. You need a lot more spring to flatten the car out than you need sway bar, and more spring obviously makes the car ride harder, and less compliant over bumps. Second, because bars keep the car flatter, you lose less of the all important camber. You get a better camber curve and tire contact patch. Big front bars really help turn-in response while also help corner exit power down issues. Less lean keeps the inside rear wheel better planted (the same happens on the brakes too). Bigger bars ride better than heavy springs. Bars are not damped by the shocks, so a larger bar does not require the shock valving heavy springs do. Big bars do add wheel-rate, and too much can cause a loss of grip. You don't want to run real heavy springs AND a really big bar, that'd be too much. However, the better camber control and subsequent contact patch make more grip trumping the higher wheel rate. Many cars are like this, not just the Camaro-Firebird.
Rear sway bars. I tend to stay pretty small on the rear bars. Sway bars actually try and pick up on the inside rear tire when cornering. This forces the outside rear tire to do most of the work, limiting the traction. Of course this is when turning. Drag racers like big rear bars because they don't have to deal with that and they keep the car more level. Other reasons I don't run a lot of rear bar. You don't have to be as concerned with roll control. We have a solid axle, it doesn't gain or lose camber as the body rolls like the front or a car with an Independent suspension. When 4th gens have a good alignment and good shocks, they do not understeer. Actually and especially when thrashed they become prone to oversteer. Making the rear stiffer in wheel rate makes this tendency worse.
Lower control arm relocation brackets: Not IMHO a must have. I feel they are more important for a drag racer. As more of a handling guy, I actually don't use them. Why? Pretty simple actually. Stability. the nose down angle you get after lowering causes the outside (loaded) rear tire to toe-in under cornering. This helps the rear end from stepping out, especially under power. I have no problem with someone wanting to run them, but they are not a necessity by any means.
Lower control arms: Again, much more important for guys with power and traction, draggers. The stock arms are not particularly strong, and prone to flex. However, you need to have enough traction to apply the forces to make them flex in the first place. We have cars that will pull about 1.2 g's on R-compound tires and can launch @ 4000 RPM on concrete without aftermarket arms or brackets. Again, not a bad thing to do, but nowhere near as important as the major handling components like springs, shocks and sway bars.
Panhard bars. This is another one that gets changed before the big 3. At least this one is more important for the handling minded person. First, lets realize that even though it's not the most stout piece, we DO HAVE a stock panhard bar. Most solid axle RWD cars do not. Because of that we already have much better lateral control than most (can you say Mustang or G-Body???). And we can pull about .9g's on good skidpad in stock trim. Teh PHB setup can handle that. Add bigger tires and the grip will rise some, putting more sideload on the car, deflecting the PHB more. Cars that do not see really hard cornering do not need an aftermarket PHB so much for the active location action of it as they do for re-centering the axle if they've been lowered. Our race cars use really stout PHB's where legal. But they are subject to forces that most street cars will never see, and we run on very wide, very sticky tires which exert even more side loadings. There are all kinds of PHB's. Street cars are generally fine with Urethane bushings in the bar. Cars that are lowered have the option to run adjustable versions to recenter the axle if need be. It should be noted that you can't assume you're out of whack just because you lowered it. It really depends on if the axle was centered to start with.
Control Arm Bushings.... There is nothing inherently wrong with urethane bushings. They are durable, inexpensive, and keep deflection to a minimum. They are not noisy like metal on metal bushings, nor subject the wear those bushings are. Now for the big one.... There is nothing wrong with running urethane in the rear LCA's. PROVIDED you are aware of the results and how to tune the suspension around them. The way the urethane works in the rear causes some stiction. This results in a higher wheel rate, and a car more prone to oversteer. As a result, if you want to run urethane rears, you need to realize that you may need less aggresive springs or sway bars. This is only pertinent to the rear supsension on the 4th gen. The front doesn't have a stiction problem like the rear.
Because my fingers are tired, this'll be the last one for now. Torque Arms..... Again the fact we have them stock is already a plus. However you can gain things from an aftermarket Torque Arm. Probably the biggest gain, especially on the LS1's is the much reduced tendency for the car to axle hop under hard braking. But there are also other reasons too. Because of the increased rigidity of them (I use Random Tech parts) and the adjustability of the pinion angle an aftermarket arm can really help getting power hooked to the pavement. This is true either when cornering or going straight ahead. The Random part is also lighter than a stock piece too! I also prefer that this arm is of a stock length. Longer arms are better under the brakes, but still work really well for cars that are not making ridiculous amounts of power on acceleration. Again, we could leave at times @ 4000 rpm on autox compound tires with this Torque Arm and without LCA's or relocation brakets.
Sorry for the length of this. Sheeh, it's any wonder my fingers hurt..... Hopefully it explains why I do some of things I do in setting up cars. Please do not forget that this is not in stone. It can change with different situations or styles. Just a general "where I'm coming from" post.
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