Strut Rod importance

[RazorX]

1973 Challenger, 440 BB,  How important are the strut rods? IOW, I'm updating the torsion bars, PSP,  QA1 SS front shocks, welding stiffener plates to the LCAs.  etc.
Is it necessary to upgrade Strut rods, I see the QA1, and others have an articulating end as opposed to the bushing.   Do I need to upgrade?  Pros  cons please thanks ya'll.

[BIGSHCLUNK]

Suspension is a combination of pieces not individual components. If your going thru it.... do it !

[Burdar]

I never understood the point of the adjustable strut rods.  The LCAs aren't supposed to be preloaded to the front or rear.  They are supposed to be in a neutral position and swing in an arc.  Putting a side load on them with adjustable strut rods doesn't seem right.  The strut rod is just supposed to keep the LCA in a neutral position...unless I'm missing something.

[Skdmark]

I never understood the point of the adjustable strut rods.  The LCAs aren't supposed to be preloaded to the front or rear.  They are supposed to be in a neutral position and swing in an arc.  Putting a side load on them with adjustable strut rods doesn't seem right.  The strut rod is just supposed to keep the LCA in a neutral position...unless I'm missing something.

Below is PST's explanation. I've been considering this upgrade when I build out a new front suspension for my Barracuda.
https://p-s-t.com/n-11824-mopar-adjustable-strut-rods-for-a-b-and-e-body-mopars.html

[Burdar]

I get that but any "minor" alignment issues can be solved with adjustable UCAs.  The LCA bushing isn't meant to be side loaded.  I know a lot of people use the adjustable ones but...

[ledphoot]

I put the whole QA1 front suspension setup in my 'Cuda, I had it aligned last week by an old school aligner who has been doing this for over forty years, he has done several recent E-Body alignments including one with an Alter-K-tion. He really liked the QA1 setup, he said he preferred the large diameter torsion bars I used to the coil over setup on the alter-k-tion. He was able to get 4.5 degrees of castor, unfortunately had to roll it back to 3.5 for now due to fender lip clearance, which I will be addressing with a slight roll of the lip. He did adjust the strut rods, but I didn't ask him why or what he set them to. I'll stop by his shop tomorrow when I leave the exhaust shop and get his opinion, he was a wealth of knowledge on old school muscle car suspension, although he was a Chevy guy he did admit that Mopar was ahead of their time with the torsion bar suspension.

[7212Mopar]

The strut rods pivots allows the LCA arc up and down during suspension travel while keeping the geometry minimizing side load of the LCA at the pivot pin and bushing. The stock rubber bushing is flexible, compressible to allow this to happen while the adjustable accomplish this with the solid pivot. Under braking or hard corning, the rubber bushing is compressed so there is actual movement of the suspension geometry. The adjustable has solid connection to the K frame and no movement under these conditions. I agree the strut rods should only be setup to allow and keep the LCA arc travel without binding or side load and not used for alignment. The length adjustment and pivot point make this much easier to achieve. Also eliminates the flex and wear with the rubber bushing. 

[GoodysGotaCuda]

I never understood the point of the adjustable strut rods.  The LCAs aren't supposed to be preloaded to the front or rear.  They are supposed to be in a neutral position and swing in an arc.  Putting a side load on them with adjustable strut rods doesn't seem right.  The strut rod is just supposed to keep the LCA in a neutral position...unless I'm missing something.

I'm not sure how you can ensure the LCA isn't preloaded without an adjustable strut rod?

Assuming a single fixed length works for all K frames and LCAs sounds sporty. Not many people use them to "correct" anything, rather they help ensure the LCAs are in a neutral position.


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[ledphoot]

I never understood the point of the adjustable strut rods.  The LCAs aren't supposed to be preloaded to the front or rear.  They are supposed to be in a neutral position and swing in an arc.  Putting a side load on them with adjustable strut rods doesn't seem right.  The strut rod is just supposed to keep the LCA in a neutral position...unless I'm missing something.

I'm not sure how you can ensure the LCA isn't preloaded without an adjustable strut rod?

Assuming a single fixed length works for all K frames and LCAs sounds sporty. Not many people use them to "correct" anything, rather they help ensure the LCAs are in a neutral position.


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Maybe to correct for an out-of-spec frame? Which sounds like a bad idea to me.

[HP2]

I don't doubt an adjustable strut rod could be use to add or subtract caster or as it should be used, to put the lower arm in a truly neutral position. For some of us, this confidence of true neutral is worth the price of admission. For most, it isn't a high consideration. Obviously the factory use it without huge detrimental effects for decades.

The thing with strut rods is their arc does not compliment the lower arm's arc and the further the suspension travels, the further these arcs pull on each other. This pulling creates dynamic changes in caster, camber, and toe as the suspension moves. As this change happens in a turn, the changing angles can create a greater or lesser feeling of stability. Even in straight line acceleration and braking, toe will change as a result of these arcs.

The rod end units do eliminate the compression factor that rubber or poly bushings provide, so they will impart a greater change of lower control arm position during suspension motion. Of course you could retain the k frame rubber in use with the rod end arm and simply adjust them down to length.  The smoothness of motion and reduction in friction of a rod end vs rubber usually isn't a big factor for street cars, but may be helpful for weight transfer in a drag car.

If you are just cruising the car, they may not be necessary. If you want to ensure everything is perfectly dialed in, they will help.

[JS29]

If the strut rod gets bent from curbs or potholes the LCA bushing would not be in a nutrient position and affecting the alignment.   

[ledphoot]

In trying to better educate myself on this subject I found this article, it doesn't really get in to strut rods, but goes over alignment in considerable detail:

https://www.streetmusclemag.com/tech-stories/get-aligned-alignment-techniques-for-hot-street-cars/

[dodj]

Do you 'need' adjustable strut rods ...no.
Are adjustable better?...yes.

They are not for adjusting alignment though. They can be adjusted to be in the precise neutral position.

[HP2]

 Most suspension arms are design as a wishbone to provide stability and range of motion.  Think of the Mopar strut and lower control arm as a large triangle.  Instead of an arm like a Chevy that has  a large, heavy two point mounted single arm, the Mopar, and many Fords of the era, used a single lower control arm that was then triangulated with the strut rod.  This  lightweight and effective design has been carried forward by many race chassis designers still today.  So the strut rod is a very important part of the overall suspension system effectiveness.  Does it need to be fancy, no, but some of the nwer adjustable designs certainly can help improve things.

Here is a good video on front suspension geometry and how things interact and why they are set up the way they are. While this is a race car, the principles are the same as on our street cars.
https://www.youtube.com/watch?v=IWMzO70zk_A