Pro Touring 4 link setup - Lateral-g Forums

454SSguy · #1 02-05-2012, 03:22 PM

They are parallel in top view. The side view is what I'm wondering about. Curious where to set my bars both top and bottom bars. I think I read for protouring setups the top bar should be level and bottom bar slightly uphill (back to front). Does this sound right?

Bryce · #2 02-05-2012, 08:16 PM

the bottom bar should be horizontal, for limited roll steer and the uppe bars should angle down towards the chassis. I would aim for 50 to 70% antisquat with room for adjustments.

The watts link should also have adjustment. starting with the pivot at the axle centerline should be good.

454SSguy · #3 02-06-2012, 10:42 AM

So that would put the IC somewhere level with the bottom bar, but how far out? I would think around the front wheels or front bumper, but I'm just guessing really. I will definitely need help with the antisquat, I've heard the term alot and understand the concept (how hard it "hits" the tires) but do not know how to set it at all. The watts linkage will be setup at ride height to be...

Pivot centered on diff
Pivot perpendicular with ground
Bars parallel to ground

Anything sound off besides the antisquat stuff?

454SSguy · #4 02-07-2012, 01:44 AM

For anyone following, found this and helped alot. Just need to measure out the CoG of the truck.

http://mysite.verizon.net/triaged/4l...tml/index.html

454SSguy · #5 02-08-2012, 01:45 PM

Alright so I've been doing some researching and have come full circle from thinkin I might want to do a tri 4 link all the way back to the original idea of parallel 4 link and watts link.

Watts link pivot (RRCH) VS CoG line
So I want the RRC pretty low, that makes sense to me, but the question i have is how far is too far. Mainly how far AWAY from CoG line is too far. If the Roll axis is too far from CoG won't that give me LOTS of body roll? Should I make the RRC higher to fix this or keep it down around axle height?

454SSguy · #6 02-08-2012, 11:14 PM

No one has input on Roll center height of a truck? ...

Bryce · #7 02-09-2012, 06:00 AM

Quote:

Originally Posted by 454SSguy

Alright so I've been doing some researching and have come full circle from thinkin I might want to do a tri 4 link all the way back to the original idea of parallel 4 link and watts link.

Watts link pivot (RRCH) VS CoG line
So I want the RRC pretty low, that makes sense to me, but the question i have is how far is too far. Mainly how far AWAY from CoG line is too far. If the Roll axis is too far from CoG won't that give me LOTS of body roll? Should I make the RRC higher to fix this or keep it down around axle height?

This all comes back to roll stiffness. Lots of body roll can be reacted with sway bars or stiffer springs.

454SSguy · #8 02-11-2012, 12:27 AM

Okay, so I've got a few things I'm starting to get a handle on now. I think I understand the RRC. I don't need to worry about calculating it really b/c of the watts link with a chassis mounted pivot. I can just put the RRC anywhere I want correct.

On to the new questions. FRC- from some very basic ideas I've come to the conclusiong that the FRC is lower than the ground. This seems standard on truck applications. I came to this conclusing because of the upward slope (from outside - inside) of the upper control arms puts the Front IC of each side outside the tires. This automatically puts the RC below ground. Please chime in if any of this doesn't sound right.

So control arms are the wrong way, like on older chevelle or other muscle car. What's to stop me from using a set of adjustable control arms and just make a new mount on the frame side whereever I want. It seems like a nice cheap fix to my problem. Build a couple of mounts to hold bushings for the upper arm and set it with the FRC where ever I determine I'd like it (~4" above the ground). I know that it's very rare that a simple solution presents itself so someone please let me know where my thought process is skewed. Other wise I could end up with a truck that could.....turn.

Thanks for the help in advance.

Bryce · #9 02-09-2012, 05:30 AM

Quote:

Originally Posted by 454SSguy

For anyone following, found this and helped alot. Just need to measure out the CoG of the truck.

http://mysite.verizon.net/triaged/4l...tml/index.html

I use performance trends if you ever need more info than whats in that spread sheet. I also developed my own excel spreadsheet that calculates pick up points based on IC and A/S inputs and two of the four pickup points.