Suspension tuning

[Gairloch]

Originally Posted by finger

the best thing i like about my 2 is the handling i just love the bends

i would like a suspension set up for twistey roads that are bumpey and some straights i take my corners
any thing from 30 mph to 110 mph but an avrage is 80 mph i am on a tight budget
so cant afford any thing fancey
at the moment one shock is gone and one topmount
i am just about to get a second hand blistern shocks and springs
i have been thinking about which would be best
keeping this suspension that i am getting but uprating the antiroll bars with tanabe and getting a tanabe 4 point under brace
and strut braces
would this set up be ok would i be able to throw it around
and what is the advantage of stiffer springs v antiroll bars

When you're talking about optimizing your suspension set up there are basically two things you need to fit to your needs. The first thing is weight transfer and the second is compliance.

By putting in uprated springs, sway bars and bushings in your car you not only minimize the amount of travel your car experiences when it transfers it's weight but you also reduce the amount of time it takes for those transfers to happen and where it goes. Of course there are pros and cons to this, suspension tuning is all about trade offs.

First off, by increasing the stiffness of your suspension and reducing the amount of weight travel, and the time it takes to travel, you reduce the sensation of speed. This means that you need to be that much more aware of what's going on with the car in order to anticipate what it's going to do in any particular situation. Soft cars are easier to anticipate because they 'talk' more. In the HPDE clubs I'm involved in we call this "Tuning your butt dyno". Cars are almost always faster than the drivers are capable of being.

Soft cars also require you to be a smoother driver because once you're committed to a line you can't redistribute the car's weight without unsettling the chassis so much that you can lose your line or lose control altogether. This is why people stiffen up their cars at all. There is no such thing as the perfect suspension because everyone is different in how they perceive and how they handle their cars. It's a good idea to make the process of tuning your suspension an experiential one. Do as few things at a time as you can so you can be sure you're moving in the right direction. It's very easy to overshoot and end up with a suspension that falls outside your ideal parameters.

When you're modifying your suspension you want to have an idea of what you're shooting for. For people new to suspension tuning it's very difficult to say what you want and this is why I encourage people to take it one step at a time, don't go tossing a ton of parts at your car then end up with it doing something you don't want and no idea how to reduce or remove that behavior.

I chose to get the heaviest springs I could to try and manage the weight with mostly because I was going to get springs anyway and if I could tune the car without having to spend more money that's a bonus. If you get the springs in and find that the car is still rolling more than you like or that it has a tendency to oversteer or understeer that when you start looking at changing springs or upgrading sway bars. Front sways will *usually* increase understeer and reduce oversteer, conversely rear sways will induce oversteer and reduce oversteer. Front sways hold more weight on the rear tires during cornering and rear sways hold more weight to the front of the car. Don't forget that tires and tire pressures will impact a car's handling characteristics also. I've found in my car that as little as a pound or two of tire pressure can have a dramatic impact on the handling.

Cars can flex quite a bit during cornering and the point behind bracing is to reduce this behavior. Making a chassis stiffer is almost always a good idea for performance driving because it makes the cars behavior more consistent. That being said, it doesn't take a lot to have quite an impact and once you've reached a certain point adding more braces just won't have all that big an impact. I found that having a turbo strut brace in my NA car made quite a noticable difference but and don't plan to add anything else at this time.

[CyFi]

wow really helpful post, thanks

[Davis]

I don't know anything about suspension, your post helps out alot, thanks! I just installed my trd strut bars yesterday on my n/a and i felt the difference.

[Gairloch]

I'm happy that it helps. One of these days I'll go through that post and re-write it so it's a little easier to grasp if people are interested.

[Bak@EMSPowered]

Very nice write-up