To go along with my earlier thread on corner balancing, when I install the coilovers on my E46M3 (possibly next week) how do I calculate the best ride height to set them at, other than "lower is better"? I figure there will be a lot I playing with them to get things set up right (a pain since each change will screw with the alignment) but I'd like to know where to start.
lowest is bestest. can you see sparks?
Too low means you'll run out of suspension travel too easily - the magic number there is determined by your spring rate. too high means your cg is higher than it needs to be and people will laugh at you. Weird stuff can happen with roll centers too, but that varies from car to car. Best thing to do is to ask other E46 guys about a good ride height with your strut/spring combo.
Keith wrote: Best thing to do is to ask other E46 guys about a good ride height with your strut/spring combo.
This. The "right" answer can be calculated through some really convoluted stuff, but in the end you can save time by asking the right people. Just make sure who you ask, if they don't know what roll centers are, probably not a good resource.
The Track, Auto-X and Drag Racing sub-forum at bimmerforums.com can have actual good information. Just don't look on the e46 M3 sub-forum or you'll end up w/ street glow, yo.
Bear in mind that some setups (eg. the AST units w/ Vorshlag camber plates) still have nearly full travel at 1.5" lower ride height than stock. Others not so much.
Once the car has been scaled, provided you're careful you can go up or down the same number of turns at every corner and not screw up the setup, so ride height isn't etched in stone.
Low is cool, but maybe not fast. You don't want to bottom out, and you have to watch camber gain/loss. Neons don't like looking cool (no suspension travel), but that kinda suits them...
Lowering the center of gravity is always a good thing, but make sure you don't ruin the camber curve. If the lower control arm is at less than 90 degrees compared to the strut, you'll have a favorable camber curve. If it is at 90 degrees or more, it will have an unfavorable camber curve. However, in real life, often times springs are stiff enough that actual travel is very minimal. I found on my E30 that I had to use about 1 degree of static camber with my H&R springs because body roll was almost non existent. I had to give it some camber because even the hardest turns didn't compress the suspension enough to give it additional camber.
It also depends significantly on your wheel/tire package. Low profile tires need less camber gain than tall skinnies.
Street driving is also a big factor. I lowered my Impala SS 2 inches and it was LOW. I dragged everything everywhere. I later swapped to 20" wheels which added about 1" to the overall diameter (a mere 1/2" to the total lift) and its spot-on perfect. Its hard to imagine, but 1/2" really made the difference between a show car and a driver.
Yup, I have learned that compromise and moderation are usually always best when it comes to lowering a car.
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