rear link questions

[99 BUCKET]

here is goes, I have a 99 s-10 5.3/4l60 3:42 rear locker 8.5"

currently I have a front/ rear sway bar 12:1 steering box. full poly. suspension. koni adjustable shocks.

the truck handles great, but in the rear I had to run 4" blocks to get the stance I wanted. This is on top of zq8 leafs. Every couple of months I have to get in the rear, unbolt everything and line it back up. Completely insufficent, However this is my daily. I am unhappy with the leafs, so they are going.

I am looking at going to a tri. Four link, but I am on information over load. Both the sachell ( sp?) and the traditional tri, links look great and perfrom great.

Now to my questions,
Is it okay to use the lower leaf spring perch(frame side) as a mount point for the lower bar?

Should the upper bars be the same lenght, and at what angle?

coilover shock location, should it be angled or parallel to the ground?

Now I drive the truck daily, but have a beater for said project on the truck. The truck gets thrashed on once and a while, drag strip/ hard cornering. Its just a clean Pro touring inspired daily.

Thanks again for the wealth of info thus far,
Chris

[jerome]

satchell has some inherent advantages over tri-four.

just to make sure everyone is using same terms,
satchell is parallel upper arms, lower arms angled in from rearend
triangulated is parallel lower arms, upper arms angled in from rearend
plan view is bird's eye view
side view is looking from side of suspension

Assuming that you want to optimize the following factors:
near 100% antisquat
neutral roll steer or slight roll understeer
long side veiw swing arm
reasonably low roll center

roll center height will be the height at which the angled arms intersect in plan view

In side view, draw a line from axle centerline to intersection of arms for the side view swing arm. This needs to be longer than 45" (just a rough number) to prevent brake hop.

estimate the center of gravity to be the camshaft height. wheelbase is 109" if you have a regular cab. antisquat line in side view is drawn from bottom of tire to camshaft height 109" in front of rearend. (thats where the front tire centerline is)

for 100% antisquat the intersection of your arms (in side view) needs to lie on the antisquat line. above it you have over 100% antisquat.

For a long SVSAL (to prevent brake hop) and 100% antisquat, you will end up with the lower arms angled up. With a triangulated 4link your roll axis is your lower arms and with a satchell your roll axis is your upper arms. Roll axis is parallel to ground for neutral steer and pointed down towards front of car for roll understeer. You can see that with the triangulated 4link antisquat and roll steer is conflicting. To get good antisquat you have to point the lower links upward, but that makes the car have roll oversteer which is no good. You can still get good antisquat with the lowers parallel to the ground and the uppers pointing down, (so you have good roll steer and antisquat) but then you will have a short SVSAL.

Satchell link lowers will be pointed up and uppers will be parallel to ground or slightly pointed down. This gives you good roll steer characteristics, good antisquat, relatively low roll center height, you you can still have a long side view swing arm length.

Geometrically the Satchell link is more favorable because you don't have to compromise. You can have all the factors optimized. However, the triangulated 4link will be slightly easier to fabricate because it will be possible to use the leaf spring mounting holes. They are about 24 inches in front of axle centerline.

The angled bars should be around 45 degrees in order to do a good job of laterally locating the rearend. You can only realistically mount the bars axleside about 19 inches out from the center of the rearend. So with a 45 degree angle, the max you could go forward is about 19 inches.

coilover shock should be as close to straight up and down as you can get and as for outboard as you can get. This means that your coilover will be just inside the framerail.

I would strongly suggest doing the satchell link instead of the triangulated 4link. If you have any computer skills using excel or matlab to do the math, I would suggest doing that. If not, get out some graph paper and start drawing.

You need to know:
CG height
wheelbase
tire radius
the maximum width your lower and upper links can be mounted at

After measuring those things, you will need to decide how far above and below axle centerline the links will be attached. I went with 5". I wouldn't go much shorter than that

Start drawing the side view. Draw a line for the ground. On the left side of the paper, you need to draw two dots (for the rearend link mount locations). 26" tall tire and 5" seperation means 8" and 18" above ground. Now go 109" to the right of the two dots and put a dot at the CG height. Draw a line from the ground directly below your two axle points to the CG dot. There's your antisquat line. Mark 45" right of the axle. Thats the minimum intersection length of the upper and lower arms. Now connect the two dots at the rear end to a single point on the antisquat line forward of the 45" mark and there's your arm angles. For Satchell link, you would want to draw the upper arm slightly below horizontal all the the way to the antisquat line. Connect the lower rearend dot to the intersection (of the upper line and the antisquat line) and hopefully the intersection is past the 45" mark. If so, then you got your upper and lower link angles.

Now you have to determine how long your angled arms can be and how long your parallel arms can be based on your packaging restrictions.

After you determine your arm lengths, you have to go back to the drawing board and figure out what happens to the antisquat when the suspension travels up and down. This is determined by the ratio between your upper and lower arm length. The lower arms usually need to be longer than the upper arms to get the antisquat to be constant at any suspension height. That's one drawback of the satchell link, because the lowers are angled so they can't be really long and the uppers usually end up shorter than the lowers.

Anyways, transfer the two rearend points up 3" and down 3" and draw lines through to the frame mount points that you determined from the first lines. Extend them til they intersect. If the lines for the points that were moved up 3" intersect below the antisquat line, then the upper arms need to be made shorter. Guess and check until the antisquat doesn't change (or the uppers get unreasonably short).

There you have it, your final suspension numbers. All you gotta do now is go build it.

I know it sounds like alot, but once you start drawing its a piece of cake. Good luck.

Jerome

[99 BUCKET]

Wow, Thanks for the information. More than I expected for sure. Couple more questions though.
Is it even worth running a rear sway bar in this case?
I looking into using sucide doors tri link set up. however, I dont think it will be sufficent. were to go for supplies?

Thanks again for the info, I will have to spend some time going over it.
Hows yours comming?

Now to print this out and go sleep on it, possible it will soak in if I put the print out under the pillow.

Chris

[jerome]

The suicide doors kit is nice cause it is easy to put on. However, the parallel lower bars put roll steer and antisquat in a compromise. more antisquat gives you more roll oversteer and vice versa. On a low power truck, it would be a great setup, set the bars parallel for neutral steer, and accept whatever antisquat you can get, don't need much.

I would wait on the sway bar until after you thrash the truck.
It should be used more as a tuning device, it's very possible that you won't need one.

I got Johhny Joints from Currie. They are overkill, but they are rebuildable and quieter than heims.
I am getting tubing from a local place called metal supermarkets. My welder that is doing my rearend has the taps for 1-1/4" and he will tap it.

If you were to go with heim that are a more reasonable size, you could go with either tube inserts or tapping the tube. Check out speedway motors, coleman racing, chassis shop etc. for pretapped or swedged tubing. Suicide doors will also build control arms for you, although I would recommend the Johnny Joints over their super pivot joints.

My rearend is at the welders. He still doesn't have time to get to it yet. After I get it back, build a couple crossmembers and I should be done. Still gotta buy some coilovers too.

[Norm Peterson]

If you slightly skew the lower arms in a triangulated arrangement or the uppers in a Satchell, your roll steer can be made less sensitive to changes in either ride height or side view inclination of the almost-parallel-in-plan-view arms. For example, it's pretty easy to maintain vehicle roll understeer with the lowers inclined upward toward the chassis if they are also skewed inward toward the chassis pivot. This "trick" can also be made to work with a 3-link, although it may be tougher to stay out of roll oversteer if you're also trying to bring the roll center down with a lower PHB or Watts link.

Any need for a rear sta-bar depends on rear roll center height (triangulated being normally associated with a higher RCH is less likely to need one than a Satchell), rear spring rate choice (which for a street driven car is probably best chosen with "flat ride" in mind, though stiffer rear springs will be somewhat less likely to want as much bar), and personal driving and ride quality preferences (softer springs and larger bars tend to ride slightly better).

For most stick axle suspensions, don't plan on using a rear bar to affect the total amount of roll very much. Of the four elastic suspension elements that limit the amount of roll (front and rear springs and bars), the rear bar is typically the least effective, accounting for perhaps 10% or slightly more of the total roll stiffness. The huge rear bars that you may have seen on some dragstrip cars are straightline-specific pieces with about the same level of true street applicability as wheelie bars.


Norm

[99 BUCKET]

I have been going at this in autocad. I am getting some were, just not to a point I understand yet. I did go out to the parking lots and measure the cam hight. I could not get a clear shot on the cam location ( tight fit engine compartment). I used the center of water pump pulley. It was the closest thing I could reference.


whew, mind numbing!

J, when you say "For Satchell link, you would want to draw the upper arm slightly below horizontal all the the way to the antisquat line."

what angle is considered "slightly"?

after much more reading, the Satchell is the way I am going to be going. I do not want to throw this together. Any more info would be great. also, after looking a sucide doors super piviots. They look exactly like the Johnny joints. Are my eyes messing with me?

[99 BUCKET]

walked away and have another question.

Are you using the Johhny Joints and both ends of the bars?

Thanks,
Chris

[Norm Peterson]

what angle is considered "slightly"?

I would take "slightly" to mean about 3% roll steer, or about 2° downhill. With enough reserve to keep it downhill under moderately hard braking, which will depend on your spring rate and anti's. Otherwise it might get too "loose" if you're hard on the brakes right up to where you start steering or under trail-braking.

Norm

[jerome]

norm is right on with his definition of slightly.

glad you have decided to go with designing and building your own. its definitely worth it and probably really satisfying when you get done with it (haha, I couldn't tell you about this part quite yet).

I am using Johnny Joints everywhere except for panhard. I am using aurora teflon lined rod ends. Johnnys are much higher quality than the super pivots. And they are equally priced. It is a forged design with the shank forged in instead of welded (welding can warp the joint). It also uses a zerk instead of a greasable bolt (weaker).

tubing you will need for Johnnys is 1.5x.188 wall DOM, the taps are expensive. around 150 each for china ones. I was lucky enough to find a guy with the taps locally, but check pirate 4x4 vendor section, theres a guy that sells it prethreaded.

Satchell link is an excellent choice and its what I wanted to do, except the rearend I ended up had an offset pinion to the passenger side and I couldn't get the lower arm length I wanted, so I had to do something different.

I would suggest getting performance trends suspension analyzer. Its a 10 day trial, so make sure you use it and get your numbers right, cause I can't find a way to get the trial to reset.

[99 BUCKET]

I got lucky enough to run into a s-10 8.5 housing. Other wise I would be running 9"

Still trying to get my numbers right. Reason I was questioning the super pivots, after all this is my (over the top) daily. once I got the bars figured out, I could get them made. Leaving me only with mounting.
That and I dont wat to try to tap them threads.

you think measuring from the water pump pulley is okay?
I four cornered scaled the truck a few months back and got a .6 center of gravity? hell my water pump measurement was only 22"

I grow more confused with each post, lol.
I will get it figured out soon!

[jerome]

I estimated 24 for mine, but since you are lowered that much, you are right in the ballpark. I'm not sure where exactly the waterpump pulley is on a LS motor, I'll go look at my silverado tomorrow.

Actually the numbers on the Satchell link shouldn't be too hard to figure out. how long your LCA can be is already determined by how wide you can mount them on the rearend and the 45 degree angle. your upper arm angle is determined already (slight angle for roll understeer). Now all you have to do is figure out what angle uppers for whatever percentage antisquat and how long your uppers can be to give you little to no antisquat change when the suspension travels.

Also chech the front lower control arm angle, you are probably a bit lower than optimum. You want the ball joint pivot to be around an inch lower than the LCA mounting bolts so that you get alot of negative camber when the chassis rolls in a turn. Of course if the stance is already set, then don't worry too much about it.

[MrQuick]

They don't sell JJ's with left handed 3/4" threadingso I had a few bolts made to tig on to studless JJ's.

Let me know on the left hand thread bolts and taps. I can get them for around $45. LH & RH thread. The bolts are $19 each.

[jerome]

http://www.currieenterprises.com/ces...t.aspx?id=2629

these are the ones I got, they do come in LH thread also. no welding required, just need to get tapped tubing or taps.

Jerome

[MrQuick]

Thanks, I haven't seen those yet. Makes it a lot easier then.

[MonzaRacer]

Give a look at air ride Technologies setups for S10s and even consider DA ShockWaves too.
ShockWaves are Double Adjustable race shocks with air springs around them. The adjustability is pretty near perfect.
As for me I would use a triangulated 4 link a good sway bar and either the ShockWaves or CoolRide air springs and DA shocks.
You can get super critical on the designs but honestly use the KISS method (http://www.ridetech.com/productinfo/airbars10.asp) if it isnt low enough (http://www.ridetech.com/productinfo/roadgrater.asp) I know of one fella who has the RoadGrater burning corners very nicely.
Good Luck

[Norm Peterson]

Reversed upper wishbone - interesting approach.

[99 BUCKET]

hummmm, too many ideas. the air bar would allow me for little down time. even thought I have the beater, I will be missing my truck : (

[99 BUCKET]

after reading their install, dont think the air bar is my cup of tea. Plus I have already have enough shoved into that truck without adding air bags...