In reply to GameboyRMH:
I guess I could see it if he was going off road. With long enough links you minimize the binding and what's left is probably preferable to having a centering link limiting articulation but for pavement I'd rather have less bind and in exchange for less range.
GameboyRMH wrote:Wall-e wrote: I wouldn't swap a triangulated fourlink into anything.Triangulated 4-links are the best suspension system for offroading with solid axles.
And how does that apply here?
Bobzilla wrote:GameboyRMH wrote:And how does that apply here?Wall-e wrote: I wouldn't swap a triangulated fourlink into anything.Triangulated 4-links are the best suspension system for offroading with solid axles.
It doesn't really, I'm just saying they're not without merit. The ability to easily move the roll center is a pretty meaningful advantage of a 3-link w/ Watts link, but a triangulated 4-link could work and would reduce the space requirements and unsprung weight while giving you excellent lateral axle stability. Triangulated 4-links get a bad reputation because they're often set up with with the wrong kind of bushing which creates a lot of bind.
Still not seeing how bushings "create bind" assuming they're decently round inside and out. Bushings that "don't allow for arm length change" seem like they might be the problem.
pres589 wrote: Still not seeing how bushings "create bind" assuming they're decently round inside and out. Bushings that "don't allow for arm length change" seem like they might be the problem.
Check out my post on the last page about how all the arms in a triangulated 4-link need to move freely on more than one axis. A cylindrical bushing (the most commonly used type) is going to greatly resist deflection on the axis of its length, a deflection which is necessary to the proper operation of this kind of suspension, thus creating bind. A spherical bearing of some kind, or a Land Rover style hourglass-in-torus bushing arrangement won't have this problem. Arm length change is unnecessary and undesirable.
A 4-link with all spherical bearings would have an enormous range of compression/droop and roll motion before running into bind, but bind would prevent any lateral axle motion.
I just finished a custom 3-link w/ panhard bar. It definitely eats bed space if done correctly, and was very fabrication-heavy. That truck arm setup looks way easier. 4-links often bind and have weird roll characteristics, unless designed right. They also usually change pinion angle, which is not great. 3-links just articulate better and are more forgiving to design when armed with nothing but a tape measure, paint pen, and angle grinder 
And the key word you're looking for is "heim joint", but yes they are basically just spherical bearings.
I replaced all the bushings in a G-body rear suspension with spherical bearings, then I needed to add a pan hard bar to keep the rear end centered. It added weight and was still a compromise. As soon as the rules changed I replaced the two upper links with one centered link and had a much happier car. To build one without a panhard bar relies on the bushings to keep it square and bushing firmness becomes an issue as rubber lets the axle squirm around but stiffer bushings like polyurethane or delrin can add wheelhop with any horsepower. When we had to run the stock configuration we tried all kinds of combinations to try help like poly in one end of the arm, rubber in the other. We were most successful with removing most of the rubber in one of the upper arms so it was just there to satisfy the rules but not do anything. That gave us the best movement and least hop but then it introduced a bit of rear steer. It helped us on an oval but turning both ways it would be one more problem.
A panhard is great if you are only going to turn one direction...
A truck arm has little or no adjustment.
The compromises you make now will dictate your level of success and satisfaction with the finished product.
In the end your first iteration will likely get changed anyway if you get serious, dont get frustrated or mad with it if you find something is not right. Few if any come out of the chute with everything spot on.
GO to the nearest Ultimate Street car challenge, they are at Pikes Peak this weekend. There will be more than one C10 there. Look at some Emod cars at the local autoX (and scale up). Find a SOLO event and look at the modified cars.
One advantage of the torque arm is it won't eat bed space, all the parts can be pretty low. I don't know much about their deficiencies but they were good enough GM used them on four different chassis over the course of 27 years and they are available in the aftermarket. You can use one with leaf springs too, like traction bars but better.
Wall-e wrote: introduced a bit of rear steer. It helped us on an oval but turning both ways it would be one more problem.
Rear steer is an interesting point. It can be helpful in moderation, provided the suspension provides it equally in both directions.
It does cause some handling quirks though. Take a left through an intersection with a majorly crowned road. Once you cross the road crown, the body rolls over further, rear steer increases and now you have to reduce steering angle to hold your line through the turn. It works out well grip-wise, but it can be a little harder to drive.
In reply to bentwrench:
I already go to a lot of events. The CAM challenge East will be here next month (we host with National support). I already know this will never be a nationally competitive truck. A.) it weighs too much. 2.) I refuse to hack it up to make it competitive and iii) I want a good runner and something that is multi-purpose.
seriously considering these arms extra caster is good, right?
Using those with this: all the goodies but shocks
Then some Viking shocks to complete that.
Yeah you want more caster than the typical production car for racing. An exception would be if you already find steering effort to be too high, because more caster will increase it further.
Also a lot of FWD Hondas come with a ton of caster but that's not relevant here.
Caster is good. Although too much caster with an open diff is bad, as it will want to lift the inside rear tire in tight turns.
bentwrench wrote: A panhard is great if you are only going to turn one direction...
How so?
You are just a case of beer away from more caster.
You can move the lower arms forward 3/4" super easy. Steering effort is not an issue - these trucks have 70's pinky-finger-steering-goodness built in.
SkinnyG wrote: You are just a case of beer away from more caster. You can move the lower arms forward 3/4" super easy. Steering effort is not an issue - these trucks have 70's pinky-finger-steering-goodness built in.
I did this to my truck also, it's spooky easy to get whatever caster you wish, though make sure you don't hit whatever is in front of your control arms.
In reply to rslifkin:
open diff ends this winter as well.
So for the front, stay with stock arms, put in new bushings and ball joints for $350 and call it a day then? That would let me save $450 that I could put into master cylinder/prop valve to make the rear discs work better. They currently "work" but not that well.
My thinking on staying with the rear leafs for right now is this kit gets me the ride height and helps correct some of the hackery in the front end while giving me more axle clearance in the back. Later, if I want to fabricate a 2-link, 3-link, 4-link, 12-link I can do that and not really be out much in time.
Simple recipe:
Lower it around 4" front and 6" rear, preferably with a 2" front spring and a 2" spindle; our springs are 1500# front and 380# rear.
GOOD shocks; Varishocks and QA1 would be OK; Fox Racing (ours or Ridetech) or some Afco's would be better.
BIG sway bars; our front is 1-7/16" and something like 1-1/4" rear would work well
More caster and camber; we run at least -1.5° camber and +9° caster
maschinenbau wrote:bentwrench wrote: A panhard is great if you are only going to turn one direction...How so?
A panhard bar has an inherent bias since the mechanism is asymmetrical.
rslifkin wrote: Caster is good. Although too much caster with an open diff is bad, as it will want to lift the inside rear tire in tight turns.
I believe Mr Sutton recommends caster should be the same as the KPI.
In reply to Nessumsar:
SA QA1 ok or do I need to pony the cash for the DA? $150 per compared to $260 per. ($600 or $1040)
I would run a DA QA1. With them being a twin-tube design their pistons are quite small for the body size and they have a fairly narrow operating range and the DA would let you tweak the range further; their 2" diameter shocks have a piston smaller than a US quarter.
I would get you a set of our SA Fox shocks for what the QA1's cost. I know the fronts are the right length, you just need to fab an upper mount; I don't know about rear shocks, but our's are 16.9" extended and 11.15" collapsed with 1/2" mounting eyelets.
That would likely be close. stock is ~21" ext 14" comp. Drop the rear 5" and we're close.
EDIT: 22.5 ext rear and 14.5 collap. front is 14.6 and 10. All 4 are 1/2" mounting eyelets.
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