I would also go panhard bar setup.

I follow a couple of Facebook groups and one of the big swaps is installing the rear independent mustang axle under their trucks.

Bearing Bob wrote:

I've got triangulated arms in the 69, and 4 bar parallel with Panhard (Panhard was a dude) bar in the 56 F100, which I've not driven. You'll have to ask MS how he liked the 4 bar. I mostly agree with TKO, but the Cup cars today have IRS. For years the plan with my next 56 was to put the shivy truck arms in the rear. Their pivot bushings are large and allow movement, unlike the small bushings in aftermarket control arms. I've yet to find the perfect pivotalable rear control arm connector for the triangulated rear that doesn't wear prematurely and/or bind.

I like the idea of the triangulated in that it keeps the axle centered. Even with a 60 inch Panhard bar you'll get side shift.

I stopped caring about NASCAR when all the cars became a NASCAR supplied chassis, so I didn't know they were now IRS.  Thanks for the info. 

There's something Currie makes for off road applications called a Johnny Joint that might be what you're looking for Bob.  Check this out:

https://www.rockjock4x4.com/products/johnny-joints-rod-ends?gclid=CjwKCAjwzuqgBhAcEiwAdj5dRpiqLWTUWONK-jXExplyypfNMbofA0Dck08wHbvO5NC7RKHQ9HoMGRoCPr4QAvD_BwE

I have strongly considered the Mustang S550 IRS & the Thunderbird IRS, Cost is really the only thing holding that back. I have an extra Explorer 8.8 with trac-loc and 3.73 that will only cost me a fresh bearing and seal kit with some new leaf spring plates. I started thinking about the adjustability of the coil overs and that sent me towards a 4-link.
I may just throw the 8.8 in it with leaf springs and do the IRS at a later date.

TKOPerformance wrote:

There's something Currie makes for off road applications called a Johnny Joint that might be what you're looking for Bob.  Check this out:

https://www.rockjock4x4.com/products/johnny-joints-rod-ends?gclid=CjwKCAjwzuqgBhAcEiwAdj5dRpiqLWTUWONK-jXExplyypfNMbofA0Dck08wHbvO5NC7RKHQ9HoMGRoCPr4QAvD_BwE

 
I have those on the inner lower control arms. I've thought of using them on the rear, but with them being so wide I'd have to redo all of the mounts. And I'm kinda lazy.

A track bar and a panhard rod are the same thing.  Typically you hear the term "panhard rod" used to refer to a part of a rear suspension, and the term "track bar" used to talk about part of a 4WD front suspension.  Both mount one need to the frame and the other to the axle.  The degree of side to side movement is based on the design.  A good design can give almost no side to side movement.  If you truly must have no side to side movement you're better off with a Watts linkage.  Watts linkage isn't typically used in OEM applications because it costs more than a panhard rod. 

As for triangulated 4 link vs. parallel with a panhard rod the later is better.  Fox cars had a triangulated 4 link.  Due primarily to the length disparity between the upper and lower arms Fox cars would encounter bind under high cornering loads that could stop suspension movement, cause the tires to break loose, and the car to spin.  I always head this referenced as "snap oversteer".  I experienced it first hand and it was terrifying.

A third possibility not discussed yet is a trailing link, torque arm, and panhard rod setup.  It's what 3rd and 4th gen GM F cars used.  I have an '89 GT and an '86 IROC.  I like the Mustang a lot better, but there's no comparison in terms of how the two cars handle stock vs. stock.  The IROC is much more stable, less rear happy, much more predictable, and much more confidence inspiring.  I've added a Maximum Motorsports panhard rod to the GT.  Eventually I will probably abandon the stock upper arms and also use their torque arm kit.  That will give me the best of both worlds. 

IRS to me depends on what you want the truck to do.  It will ride somewhat better with IRS.  The downside to IRS is the handling is totally different due to a lack of anti-dive during braking and anti-squat during acceleration (including cornering).  They require totally different driving styles to run fast.  To me, unless the goal is to look super cool at a car show, I'd rather save the IRS money and put it elsewhere in the truck.  You'll get a fine ride with coil overs and handling will be excellent with a properly designed solid axle suspension system.

Nos681 wrote:

What about a trapezoidal leaf spring setup?

 
Expound please. Is not a trapezoidal leaf spring its shape? Would you use then in a parallel setup, or some other way?

Buggy springs...Model A's and Model T's had them.  Worked fine for the last 113 years.  'Course most of those cars didn't go racin'.

My main goals for my rear suspension are:
Ride quality
Space for lots of rubber
Adjustable to dial in pinion if required with lowered height

I want a really really really enjoyable cruiser with a nice rake and aggressive look.

Any performance benefits would just be a bonus.

Maybe a lil tooo much-of-the-good-stuff ?!?
6sal6

Last edited by 6sally6 (3/25/2023 6:13 PM)

I think the idea is to remove potential side to side movement from the system.  The issue is that the springs are still going to need shackles, and that's where the movement gets introduced.  I'd rather just go to Del-Alum bushings in the springs and shackles to remove potential flex.  I think angling the springs would exacerbate the movement of the axle fore and aft as the suspension compresses, which changes pinion angle.  It would be simple enough for OEMs to build cars like this, yet I've never seen it. 

Simplest is always best

That is by all means the theme for this Truck,