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Discussion Starter #1 (Edited)
So I tried getting info elsewhere, but no luck. Anyone here with more expertise on the 3 link subject want to shed some light and their opinion on these 3 link numbers and stats. This is on a full size truggy.

36" lower length, 40" upper length

32" panhard

Vehicle Specifications:
Wheelbase 115.0 in
Tire Diameter 38.00 in
Tire Rolling Radius 18.00 in
Sprung Mass CG 'Z' 22.00 in
Weight 5,700 lb

Suspension Geometry:
Upper Link x y z
Frame End 40.00 10.00 29.00 in
Axle End 0.00 8.00 24.00 in
Lower Links x y z
Frame End 36.00 16.00 24.00 in
Axle End 3.00 20.00 17.50 in
Pannhard Bar x y z
Frame End -4.00 18.00 30.00 in
Axle End -4.00 -16.00 21.00 in

Geometry Summary:
Anti-Squat 192.67 %
Roll Axis Angle 8.11 degrees ( - roll understeer, + roll oversteer)
Roll Center Height 26.07 in
Instant Center X-Axis 98.53 in
Instant Center Z-Axis 36.32 in
 

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8* of oversteer. & 192% antisquat. :eek:

Try again. You want understeer. Triangulate the lowers at the frame end a lot more. Mount the lowers at or just above axle center line keep them as parallel to the ground as you can.

Sprung mass CG should be about where your upper bellhousing bolt is. Likely around 36". 22" would mean your engine is setup on the ground. Upper link should also be shorter than the lowers.
 

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Discussion Starter #4 (Edited)
Ahh that is what the CG means haha. I will thow a few dif numers at it and see.

Where is the cg measured from?
 

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Discussion Starter #6
By moving my lowers in 6" per side and lowering the lower frame mounts 4 "

and putting th CG at 44" which is roughly the ground top of bellhousing. I have these numbers

Geometry Summary:
Anti-Squat -13.24 %
Roll Axis Angle -2.35 degrees ( - roll understeer, + roll oversteer)
Roll Center Height 25.34 in
Instant Center X-Axis -136.62 in
Instant Center Z-Axis 6.92 in
 

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8* of oversteer. & 192% antisquat. :eek:

Try again. You want understeer. Triangulate the lowers at the frame end a lot more. Mount the lowers at or just above axle center line keep them as parallel to the ground as you can.

Sprung mass CG should be about where your upper bellhousing bolt is. Likely around 36". 22" would mean your engine is setup on the ground. Upper link should also be shorter than the lowers.
I disagree on the upper link comment, a 2" longer upper will help the pinion point up on droop travel and combat wheel ressecion on uptravel.

By moving my lowers in 6" per side and lowering the lower frame mounts 4 "

and putting th CG at 44" which is roughly the ground top of bellhousing. I have these numbers

Geometry Summary:
Anti-Squat -13.24 %
Roll Axis Angle -2.35 degrees ( - roll understeer, + roll oversteer)
Roll Center Height 25.34 in
Instant Center X-Axis -136.62 in
Instant Center Z-Axis 6.92 in
Your roll axis at -2.35 is fine but you will be better off if you can get the antisquat in the 50-70% range.
 

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Discussion Starter #8
I disagree on the upper link comment, a 2" longer upper will help the pinion point up on droop travel and combat wheel ressecion on uptravel.



Your roll axis at -2.35 is fine but you will be better off if you can get the antisquat in the 50-70% range.
What would help to raise the anti squat?

And that is why my upper is longer
 

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The longer upper will help combat wheel recession on droop as well, typically its more of a clearance issue on up travel in a full body rig than trying to achieve proper handling. The problem with advise on link systems is there are a lot of different schools of thought on how to get the "right" #'s and whats "right" # to begin with. I can see wheel recession on up travel as a good thing givin you have the clearance but it will make the front end want to drive over the axle on droop and I'm not smart enough to figure out how to avoid it on droop but gain an acceptable amount on uptravel. If that makes any sense, an expert I am not but I have done quite a few link setups and they all seem to work very well.
 

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Discussion Starter #12
The longer upper will help combat wheel recession on droop as well, typically its more of a clearance issue on up travel in a full body rig than trying to achieve proper handling. The problem with advise on link systems is there are a lot of different schools of thought on how to get the "right" #'s and whats "right" # to begin with. I can see wheel recession on up travel as a good thing givin you have the clearance but it will make the front end want to drive over the axle on droop and I'm not smart enough to figure out how to avoid it on droop but gain an acceptable amount on uptravel. If that makes any sense, an expert I am not but I have done quite a few link setups and they all seem to work very well.
So from what I can read on threads....it seems the best rules are-

1. 8" separation at axle.

2. Put lowers as wide as i can at the axle, and angle them in as much as possible at the frame.

3. 5"-6" of separation at the frame.

4. Upper longer than the lowers

5. Keep lowers and upper as flat as possible.


If I follow these rules and make it fit the truck, I should be able to get a half decent working suspension. It should still work better than a leaf front end. And I am still only using coil springs.
 

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Discussion Starter #13
Here is my trial run 3. Seems to have better numbers. and should package better.
 

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Discussion Starter #14
Bump anyone have some advice?
 

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Those look decent just build your mounts stout and with that heavy of a rig build the lowers out of 3/8" wall or thicker. I bent 2" .250 wall dom links with my 2700lb buggy.
 

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Discussion Starter #17
Those look decent just build your mounts stout and with that heavy of a rig build the lowers out of 3/8" wall or thicker. I bent 2" .250 wall dom links with my 2700lb buggy.
Yeh I feel like the last numbers look the best, and it seems like a lot of buggies run an upper at that angle with no issues, and have the rear separation that close.

As for lowers...considering running 2x2x.25 sq with 1.5.120 wall or 1.5 .25 wall sleeved inside.

And the truck should still get lighter as this change happens. It will continue to get a diet.
 
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