another suspension question

ok i decided to turn my sd.com 4link into a 3link to keep the gas tank..my question is how long are the lower bars usually on toyotas? cause it seems that to keep them off the ground they are gonna need to be back a little bit from where the stock perches are..and it kinda seems like they will be a little too short....and whatever lenth they are..should the wishbone be the same? or can it be longer?

My lower bars are like 18.5" long. My upper is longer. I set it up at a 4 inch ride height. The geometry is great from there up. As it goes down from there, the bars go out of whack with eachother. Its not too bad though.

There is no rule about bar lengths. I have built several systems that have 10" of useable travel with a 12" upper bar. If you plan to get a lot of travel you need longer bars, otherwise do what you need to. Running a shorter bar will necesitate a closer eye on geometry. Shorter bars will change geometry more. Make your instant-center around the motor (at half travel) and you should be okay.

thanks for the info max..that pic really helps alot too

is the location of instant center really that important on a 4cyl toyota? as long as its not buried in the ground you shouldnt have much of a problem in the case of having to slam on the brakes right?

Actually the instant center is very important. It's just that in most cases the instant center ends up about where it should be. If you run long bars that are close to parallel to the ground a half travel, the instant center ends up about good. It is VERY important the instant center is in front of the vehicle, a rearward facing instant center is counter-productive and will cause pinion angle issues. But the shorter the bars in the system, the more important it is to keep the instant center in check. It's not life and death, but just good to have an idea where it is.

so you are referring to instant center mainly because of the affect the bar angles would have in changing the pinion angle?

Not completely, the instant center is where the suspension applies it's energy. If the I.C. is too low it will push the vehicle down when it acelerates and if it's too high it will try and lift the vehicle up. Both designs have there place, but not so much on an adjustable suspension. The shorter bars will cause a lot more movement of the I.C. so paying more attention is more important.

Max so since you want the instant center infront of truck and not to low, do you want that point about in the middle of the grille area or higher than that? and do you have any books or anything you would recomend on suspension building wanna learn about this stuff bad

Chassis Engineering is a good book to have on the shelf.