right now i am in the process of building some new uprights for my ranger (with vertical upper and lower spherical bearings). it is a 2002 edge model, 2wd. one thing that i noticed on the the stock uprights are that there is built in caster. the upper balljoint is offset from the lower. if you were to look at the truck from the side the upright would be leaning back ( \ ). kingpin inclination its called, if im not mistaken.
now for my complicated question. do i need to retain the caster in the upright for the suspension to work right, or can it be built in somewhere else? if i can somewhere else... where?
to me, it would seem a lot easier to not have to build it into the upright. i have seen prerunners and full tube chassis cars that do not have caster in the upright... so is there something that i am missing here?
sorry if the question sounds dumb... im just confused and wanna make my dads life easier... since he's the one doing most of the hard work. lol
thanks in advance for your help!!
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the caster is there from the factory for a reason. you need to keep that in your new front end and possibly add more. and the caster angle and kingpin inclination are 2 different things. on my front end i moved the outter pivot points on the lower control arms forward one inch to add more caster. the lower arm is parallel to the ground and the upper sits at about a 3-4 deg rake. it gains caster as it bottoms out.
as far as i know for "proper" kingpin inclination you want to draw a line through your upright pivot points and that line should intersect the ground in the center of the tires tread patch. this would be viewed from the front of the truck.
so... let me run this by you then. if i were to build my new uprights with zero caster, would moving my outer pivot on my lower arm make up for it correctly, while holding the amount of caster constant?
also... does the rake that you added in your upper arms create the gain that you get from droop?
i have never built costom uprights so cant really say if the uniball cup placement in the upright is the best way to set the caster(not even sure if that is done). for me it was best to move the lower outter arm pivots to gain the caster. it also gave me more room between the tire and fire wall.
and on my truck the rake of the upper arms is set that way from the factory as is the parallel to the ground angle of the lowers.
here is a pic of my OLD front end. you can get a better idea if what im talking about. just notice the pivot plains of the arms and the blue line that is the caster angle.
If you are using factory type geometry(stock mounting points) then the factory specs are the best place to start with. The dealership or an aliagnment shop will have the factory settings for you!
Shane Robinson
Racing is all about having fun, winning is just the most fun!!!!!!
The Amount of caster is up for debate. More caster gives the car a tendency to go straight, less caster makes the car easier to steer . . . The caster is important, another big thing with stock suspension is most have anti-dive built in. A big contributor to bump steer. Then, another thing you have to consider is the attitude of the car in relation to the ground, what angle is the chassis at, when it is at speed . . . lots to confuse with. Best thing to do when adding to a stock truck is to build off what is there, keep the characteristics of the suspension, just get more travel, it sounds like an easy idea, the execution is where the troubles come into play . . . Good Luck . . .
another caster thread
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