KP 4-link modifications for handling?

First Post!

Anyway I was looking into some sort of link setup for my truck, and decided on using a KP triangulated 4-link http://www.jpkustoms.com/catalog/8205s10sonomaboltontriangulated4link-p-85.html

I found that you can achieve pretty good anti-squat numbers by simply lowering the upper arm frame mounts.

Here is the link of the calculator that I am using: http://mysite.verizon.net/triaged/files/4BarLinkV3.0.zip

and the numbers I am using:

Upper Links x y z
Frame End 15 .5 17
Axle End 0 7 18

Lower Links x y z
Frame End 26 20 7.5
Axle End 0 20 6.5

results:
Anti-squat: 80%
Roll center height: 16"
Roll axis angle: 2* roll oversteer
Instant center x: 109"
Instant center z: 11"

one thing to note is that KP offers 2 different kits, one for 20" and one for 18" (wheels that will lay I guess). The axle bracket under the leaf normally goes is longer on the 20" kit. I was planning on the 18" because it puts the lower bar closer to level at ride height.

Oh yeah this is on a extended cab with 26" tall tires lowered ~3"


Do these numbers look good? Any ideas?

After some more measuring, I think that the Thorbecke Bros differential bracket works out better. https://www.suicidedoors.com/S10Bolt-OnDifferentialBracket.php Not only is it available for both the 7.5 and 8.5" rears, but the axle pivot points are higher up which will mean that the frame mounts will not need to be dropped as much. Also the narrower width might fit my exhaust!

i dont like the shock angles on that kp link set

yeah... I know

I figure as long as the angle is less than 45* it will be OK...

It could be fixed in the future using the SD shock bar

even then I would still use the same lower mounting axle bracket


food for thought

http://www.s10forum.com/forum/f30/update-its-been-a-while-coilovers-on-rear-240780/

I admire the fact that the guy in that thread is trying to make his truck handle and not just lay frame, or whatever, but he needs to do a little more reading before cutting up his truck like that.

As for your setup, if you already have the wishbone setup, then I guess you can try to modify it as best you can to adapt it for better handling. You might want to check out greencactus's project and you'll notice that quite a bit of custom fab is involved in that. The problem with these trucks is that there isn't a bolt in rear coil-over conversion designed with handling in mind. If you want one, you have to build one, in most cases from scratch. Good luck either way you decide to go and keep us posted.

I was more looking at the upper link angle and shock angle.
The height of the differential bracket is a concern to me because I will be keeping my bedfloor. Ideally the axle would bottom out on the frame right around the same time the pumpkin bracket hit the bed (and driveshaft would still have clearance to the upper link frame mounts)

I think that the upper bar angles are going to be the determining point. If I can get those set with the most downward angle possible and driveshaft clearance, the lower bar angles (and length) can be calculated. right now I'm thinking that a lower link frame bracket should have multiple holes for further tuning, even though that means going with a shorter bar length to meet the worst case scenario.

As greencactus said, the shock angle is going to be an issue. I would think that moving the upper mounting point of the coilovers would be better, mostly for sway-bar clearance.

thanks, and i believe you want the lower links to be parallel to the ground at ride height.
i was told to go with 8 or 9* downwards on the upper link, and thats what im going with now, but i will have at least 2 adjustments for that.
as for the shock angles, it might not be too hard to make new mounting points

The calculator I posted at the top helps determine the angle of the bars. My thoughts are to get the upper frame mount as low as possible without interfering with the driveshaft. From there calculate the lower bar frame mounting point. All axle points are determined by the brackets that come with whatever kit I go with. I am still leaning towards KP since the lower axle bracket has the shock mount built on it. I just need to figure out if it is too low (which would make the lower bar at a greater angle to the ground).

I also thought about fabbing up some lower axle mounts using the DJM spring plates as a base http://www.djmsuspension.com/Products/ProductsByMake/Chevy/S10-Parts.htm

as for the setup on the s-10 forum... yeah... I would want some more beef on those shock tabs... but it is an interesting way of getting the shock angle straighter.


another option
http://store.summitracing.com/partdetail.asp?part=AFC%2D20250&view=1&N=700+150+

Both this and the DJM look like the shock is not placed back far enough to clear the axle (when the shock is angled up)

also this one is probably drilled for a 3" axle instead of a 2.75"


here we go... http://store.summitracing.com/partdetail.asp?autofilter=1&part=AFC%2D20250B&N=700+115&autoview=sku
just trim the side with the two tabs.... expensive though


So I was getting some exhaust work done today... and got to spend some time under my truck while it was on the lift.

Looks like I'm gonna have to put this project on hold for some time... there is just too much that is going to have to get cut/moved/eliminated. Plus compromises would still have to be made in terms of geometry.

Here's just some things off the top of my head:
- exhaust redone (and I already have a magnaflow setup that I like)
- brake lines/e-brake cable rerouted on axle and frame (frame to fab coil-over mount
- pre-made pumpkin bracket would mean <3" of travel
- upper link frame mount could not get low enough (for my liking)

so pretty much there's just not enough room to do it the right way without lots of work, and since my truck is a daily driver...


On another note, does anyone know of a good performance drop leaf?

i think budracing got the fiberglass ones?

Those would be the Flex-a-Form springs. They're 2 inch drops with a reversible eye for an extra inch or so of additional drop. I'm looking into these for my own truck.

I hope they ride better than the Belltech leafs.

No, that was Daveman with the pewter (formerly) 4wd. I don't think he would recommend them. I'm pretty sure they're prone to axle wrap, but don't quote me on that. I think that's just what I remember reading in one of his posts.

ah my bad. i just remembered blazer.

took him forever to get them too.

I have the flex-a-forms right now, and want to replace them!

They're what started me down my 4-link path. In theory they are a good idea, however you get such massive axle wrap that any hard throttle below 20 mph is a bucking bronco. Slapper bars and cal-tracs/battle bars are out of the question; both inhibit handling, slapper bars just suck, and cal-tracs/battle bars would rub against the spring (which is a big no-no). The hop shock can control it somewhat (adjustable QA1), and make it ride like shit at the same time. Plus I think that they are permanently shaped like an "S" now, which scares me (I thought they weren't supposed to settle Rolling Eyes ) I kept having to adjust my pinion angle the worse they got. Finally just gave up because I'm scared of what could happen.

They do ride wonderful though (with the 3rd shock adjusted all the way down). If you get some, plan on disassembling them and re-doing all the hardware/bushings/sanding/painting... Build quality is not even close to show. The hardware holding the eyelets on was two 3/8" bolts that were NOT grade 8. No axle pads either (use something out of stock leafs). Oh and the axle locating pin was a phillips button screw head that was too big! The bushings looked like a they were trimmed up with a chainsaw, but are easy to replace since they are stock s-10 size. The bushing sleeves had rust on them, and were too long (replace with new bushings)...

Yeah sorry about that rant there... anyway if I find some good custom springs I'd be happy to sell my composites CHEAP. I can continue on the rant also...

might be the cheapest/easiest to have your stock leafs rebent to the arch you want

I was kinda thinking that... I would probably need to get a real leaf pack instead of the ZQ8, the spring-rate isn't enough to keep it off the overloads during normal driving. I have a set of beltechs, but they're too low for me (sagged past the 3" drop) and I know the spring-rate on those is soft as well...


Don't you have z85 leafs? How are those working?

I ordered some springs from Pohl Spring Works in Washington http://www.pohlsprings.com/. Called the guy up and told him what I wanted.

It's gonna be a larger pack with thinner leafs (around 7 of them!), no overload, with the second leaf wrapped around the eye to control axle wrap. Spring-rate is unknown but it will be stiffer than stock (minus the overload). Ride height will be 1"-2" lower than zq8 or about a 3" drop.

Any suggestions? They won't be built for about 2 weeks so I can call up and make changes.

I almost forgot: I also decided on running some helper bags as well. Trying to keep some load capacity (it is a truck after all). Just trying to decide on which kit.

Does anyone have any experience with these?

stock, the z85s rode REAL stiff. too stiff with an unloaded bed for me.
so i pulled a leaf and it rode real nice. just right for an unloaded bed daily driving.

as for helper bags, it will be cheaper to piece together and fab up stuff from scratch than buying a kit

I'm looking at no overload at all... more like the beltech leafs.

Also I might have to fab up a kit due to the drop