STICKY: Front Suspension Options

As on any S10 forum there are a lot of questions about how to get such and such a drop.  On other forums there is tons of info concerning how to get a certain ride height, but not much info on the affects of handling.  I think this would be a good route to go here obviously, but I'm not the one with all the know how here nor the time to compile it all, so I'm going to lay down an outline and ask you guys to help fill it in.  I'll edit as more input is given.  Please feel to criticize what is already provided, so that we can provide the best technical info possible since this can easily get into a deep discussion.  Laying out the pros and cons of each direction while explaining the theory is something, I believe, worth including.  If the info is good enough we may be able to split each topic into its own thread and link them to the sticky.

Springs:

Shorter springs reduce your suspension travel.  With a 3" drop spring and the rest of the suspension stock there isn't much room before the LCA hits the frame or bump stop.  Riding on or hitting the frame or bump stops will change the spring rate on the corner.  While many OEMs actually design this thought into their designs this is another complete set of variables.  One should also consider that the lower control arm angle affects the roll center of the truck.  Keeping the lower control arms parallel to the ground when the truck is static is a good place to start, but not the only factor contributing to the roll center.  Lowering the truck past parallel will lower the roll center pulling it farther from the center of gravity, which affects how the mass of the vehicle reacts to changes in motion.  Like Ryo says below, there is a lot that goes into, but I'm trying to keep this to a paragraph rather than a research paper.  A 1-2" spring drop puts the truck near this.

I’m compiling a hopefully comprehensive list of stock spring rates, heights, etc.

Anyone have info on any aftermarket springs drop springs?

Shocks:

Coil-Overs:

What are popularly considered coil-overs give height adjustability that a stock setup doesn’t .  The stock setup is in essence a coil over shock design, but the spring isn’t mounted on the shock body like what you buy when you purchase a “coil-over” from the aftermarket.  The major advantages with using a coil-over are the wide range of spring rates and the height adjustment.  One has to be aware of the same problem as drop springs because the stock suspension will run out of travel with an extreme drop.  Tubular control arms designed for coil-overs can help alleviate this, but again the geometry may cause unwanted handling behavior.

Ball Joints:

Tall Ball Joints

What does this swap do?

First thing it does is raise your roll center height (RCH) On a lowered truck the roll center can actually be below ground which is bad for handling.

Second it changes the camber curve. The suspension's camber curve is backwards from where it should be and the top of the tire rolls out instead of in when under compression. The tall ball joints change this to allow the tire to camber in during compression.

Third it fixes the factory bump steer issues on this front end. The steering arm on the spindles is about 5/8" closer to the lower pivot point (ball joint) then it should be. The tall lower ball joint effectively extends this measurement to within 1/8" which almost removes all bump steer.

Fourth it will lower the front end 1/2"

What is needed to do the swap?

The ball joints from Howe, PP, upper control arms for "tall spindle swap" or you can C10 upper ball joints with UB Machine upper control arms like I did.



You can do just uppers, just lowers or both. I would recommend doing lowers first to take care of the bump steer.

Control Arms:

UB Machine upper control arms are a popular choice.  Dusterbd13, an S10 enthusiast and member of this site went through the trouble of designing these arms with UB Machine to take advantage of tall spindles or tall ball joints.  It is a shorter arm with other geometry improvements.  UB Machine provides two ball joint plate options.  Arms with either a C10 ball joint plate or S10 ball joint plate can be ordered.  Part numbers are below.

C10 Ball Joint Upper Control Arms

Left - 15-0739-6L
Right - 15-0739-6R

S10 Ball Joint Upper Control Arms

Left - 14-0739-6L
Right - 140739-6R

Spindles:


Recommended Combinations:

i do not agree that lca parallel to the ground is ideal. yes its a good starting point, but it's not the angle that matters but roll center height, and well, technically thats just the beginning too

i know that i had a roll center too low for my liking when i was really low, and at current geometry with the 275/40/17 tire, it was much closer, but could have been a tad lower.

this will be more of a trial/error thing for me, where adjustable perch 'coilovers' would make it super easy....

I also believe (along with many others) that unless you run a camber setup that is impossible to keep tires alive on regular street driving, you need a super agressive camber gain curve. this affects kinematics as well, so as usual, i dont have a good place to go except trial and error.

Well I tossed some changes up in there trying to summarize what you said to my understanding.  I had forgot about the roll center argument and was thinking it was more for camber gain, which may relate, but that just means I need to put my nose in some chassis material again and more.

Increasing the kingpin height does help with increasing camber gain, correct?

Well I tossed some changes up in there trying to summarize what you said to my understanding.  I had forgot about the roll center argument and was thinking it was more for camber gain, which may relate, but that just means I need to put my nose in some chassis material again and more.

Increasing the kingpin height does help with increasing camber gain, correct?

since kingpin is an axis, hard to say  i think you meant upper balljoint. in which case yes,
the relationship between roll center and camber gain is relatively simple.
the closer your instant center is to your wheel, the more agressive your camber gain.
an issue that may arise from that is the instant center migration with suspension travel.
 >:(tuning is hard, setting geometry even harder. too many variables.

Maybe knuckle was a better choice too.  That's what I get for trying to dust off the shelves years after I first touched this topic.

I was digging around and came across these spindles from Howe.

http://www.howeracing.com/p-7671-arca-truck-spindles.aspx

Might be useful to someone.