Monday, May 19, 2008

Suspension tech and tunning

Ok so at a GTO forum i saw a post regarding GTO suspension so i figured i would write a post here and then i will always have it for a reference.

Remember your car only effects how to tune the suspension by its suspension design. Here the information is endless, as cars were produced technology allowed suspension design to be improved upon over and over again, with that said it is up to you to find your adjustment limitations.

Here is what i can tell you.

Struts/shocks- The terms to know here are Bump,rebound,dampening. In any situation these are the things that control your ride.
Bump- This is the short compression stroke (like hitting a bump or pot hole)
Rebound- This is the rate at which the stroke returns to full length and how quickly it does it.
dampening- This is how the shock/strut compresses to compensate for weight transfer or force being applied at any corner.

With this info now you know what a true competition strut offers, most aftermarket and factory part manufacturers just find a balance and sell that rather then give this kind of adjustability to your every day Joe. If you feal like you need the best be ready to pay handsomely for some external reservoir struts or competition use shocks.

Now for springs/coilovers and ride height info
Springs- These offer no adjust ability and are generally just calculated from the manufacturer for weight and ride height. Generally springs are measured in weight and some of the better manufacturers will have diff rent spring rates for you to choose from. This is the best option when you are talking about installing new springs.
Coilovers- This is the ultimate option, it will give you ride height adjust ability as well as an infinite number of spring rates. These systems are generally also adjustable for dampening. Be aware of sleeve over coil overs, these systems allow for putting together a cheap option that allows for the same benefit as a true coil over at a fraction of the price. Sleeve over designs have been known to fail.
Ride height- There is alot of discussion over which height is right and the answer is truly the appropriate height for your situation. Keep in mind that the lower your ride height the better your car SHOULD handle. I said should only because if your car is too low your suspension cant work properly. Your car was built with limitations and was never meant to be a half inch off the ground. Without going into a huge fillabuster here i will tell you within reason any height is right as long as you have done your homework on the struts/springs or coil overs. No a one inch drop wont handle as well as a two or maybe a 2.5 inch drop. A three inch drop though may actually damage your suspension angle's and inhibit you from reaching your maximum potential. So pick a height that works with your overall expectations. If your goal is the ragged edge be ready for serious R&D.

Now for the most important thing

Corner weighting- If you ever hear of someone wanting to put a different motor in a car then what it came with immediately the topic of a faulty suspension comes up. The arguers are generally those who dont know about suspension tuning. These people almost always see coil overs as simply a dampening adjustable and ride height adjustable tool. However the true purpose is much greater then that. Corner weighting is taking a car with driver in it and putting a scale under each tire, with the weights given you can see where the weight of your car is being ditributed. The goal is to make the left front and right rear weights add up to the same amount as the right front and left rear. This puts the center of weight in the center of the car. It is also how people tune there cars for larger motors or after loosing weight. If you add weight to a car no matter were it is it will change the suspension tuning.

Tuning with a corner weighted car
If you have a balanced car this is a neutral situation. Meaning your weight is balanced neutrally. However if under real world driving conditions the car is Pushing or overstearing then you can tune this with ride height. Lowering the front can make the car rotate better or allows for more of an overstear situation. In this tuning area i will leave it up to you to find your own results. Once balanced many things can be done with your ride height (this will require more corner weighting) or with strut or shock tuning in dampening,bump, and rebound. These options are also present in coil overs. If you are at a neutral balance you may also mess with your sway bars, remember that more front bar adds push and more rear bar adds over steer.

Camber, caster, and toe
Camber- This is the angle the tires contact patch is at. For best turning results you want the patch to be flat when the cars weight is being transferred to it. Look at a drifters camber they are always using lots of rear camber so that they can have a large contact patch when there cars are flat out sideways. Drag racers here is my hint set your camber with a loaded car for best launches. You must raise the front end for front wheel drives and load the back for rear wheel drives. If i give you More you will know all my secrets.
Caster- Here my knowledge is vague but i know that an improper caster can lead to a very vague feeling in steering response.
Toe- You really want your toe to be pointing out this is the angle on the tire imagine seeing your two front tires the same as looking at your feet when you are standing and you point your toes to the side. That is a toed out situation. It makes perfect sense when you think about a car wanting to turn in. For drag racing this isnt something you want as it will slow you down a slight bit.

Last but not least i will leave you with the following
Bushings- Here the harder the better but not so hard that they are uncomfortable. Keep in mind your goals
Spherical bushings- you want these over ball joints where ever possible, since ball joint allow for play in your suspension geometry.
I hope this helps but this is mainly just so you can know where your roject stands so you can apropriatly order the parts you need.