Truck Arm Rear Suspension

sawmilldmax

Active member
Apr 2, 2013
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Mount Airy,NC
I texted you some pictures. Let me know if you didn't get them or if I didn't send enough. I still haven't figured out how to post a thread, much less add some pictures. Sorry
 

WisconsinHick1

New member
Mar 11, 2009
1,231
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Minnesota
Does anyone know why most trailing arm setups are at an angle but some have straight bars? I was thinking of doing straight but wanted to understand that aspect before I picked one direction.
 

baggedLB7

Goer
May 1, 2011
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Utah
Some pics that Brett posted on another website.
 

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baggedLB7

Goer
May 1, 2011
688
4
18
Utah
our frames are wider than the 67-72 trucks by about 6 inches, if my measurements are accurate.
Could you build outriggers off the frame and adapt one of those frame mounts, sort of like the way 1500s mount their trans crossmembers? Sure you could.
The trailing arms are set up for narrower axle mounts, though. How would you deal with that? Move the axle mounts inward or create custom bars?

I can see how this setup could work on our 2wd's, as you could essentially just "copy" the design for the older trucks, but its going to take someone with a fab shop and skills to create/jig the proper fitting pieces to make it all work/fit correctly.

I do believe Porter Built will build custom pieces.
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
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Phoenix Az
I think it comes down to cost in the end. In my opinion the more parallel the arms, the more articulation you'll have with less bind.

there is an instant bind as soon as you articulate radius arms. Most oem's use decent sized bushings at the axle to allow flex and not try to twist the mounts off the axle. He'd actually have more articulation with less bind if setup with them angled in.

Eric, they mounted them that way so as the axle articulates, the bushings and arms are not under a ton of stress while loaded down. the center of the axle is the pivot point (to an extent) as one side of the axle is forced up or down. with the links near the middle, the bushings can flex with the axle. if it were straight, the bushing would be in a more complex angle and would not be able to flex as far (closer you are to the center of the axle, the less its moving as it articulates). In your situation, this is not nearly as much of an issues as it seems.

i would still have some inward angle on them at first and see how it does. then play with moving them in or out and see how the truck reacts. as you can see in brets truck, the inboard mounting didnt make the truck overly squirrly or anything.
 

WisconsinHick1

New member
Mar 11, 2009
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Minnesota
Ok good to know James thank you. I didn't think about the geometry of everything when it comes to movement of each individual parts.

I keep going back and forth as I thought my truck already had drop shackles in it but after further investigation earlier this week I do not. It is still on stock shackles. So if I buy lowering shackles for cheap that will give me few more inches in drop which is what I am ultimately looking for. Then if I work on fine tuning the Caltracs it makes me wonder what I can really do with a leaf spring setup like you said James. Also if I added a sway bar I think that would help as well.

So much to think about and I'm not trying to change too much at once so I know and understand what each thing does or doesn't do!
 

juddski88

Freedom Diesel
Jul 1, 2008
4,655
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Chesterfield, Mass.
I guess I misunderstood what direction of angle he was referring to. Sorry to confuse. I was thinking he was referring to up/down angle not left/right angle.

I'm helping to restore a 65 Chevy 2wd right now with factory suspension, making it a short bed and remount in the factory trailing arms. Bretts arms are based on that old idea and work very well by the looks of it.
 
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Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
21,670
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Phoenix Az
I guess I misunderstood what direction of angle he was referring to. Sorry to confuse. I was thinking he was referring to up/down angle not left/right angle.

I'm helping to restore a 65 Chevy 2wd right now with factory suspension, making it a short bed and remount in the factory trailing arms. Bretts arms are based on that old idea and work very well by the looks of it.


Ah I got ya. Wasn't quite making sense why you were thinking that way Tim :D