diy adjustable strut rods

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The member who posted this on Cbodiesonly was working on a C-body and ended up using a radius rod that was 21.5" long. anyone know the lengths of the strut rods of the C-bodies vs. A-bodies?
 
The member who posted this on Cbodiesonly was working on a C-body and ended up using a radius rod that was 21.5" long. anyone know the lengths of the strut rods of the C-bodies vs. A-bodies?

Maybe buy all the other parts and then take a measurement? Just an idea since I would like to know this as well but doubt anyone has both an A-Body and C-Body strut rod laying around.
 
I am in the process of buying parts right now. I am going a different route with the control arm connection.

ALL56196__06994.1639405935.190.285.jpg

Steel Double Adjuster 5/8in ALL56196

ALL56196
Once I have them I can measure for the right size radius rods from Allstar. When I have everything figured out I will post what worked.
 
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Finally installed the strut rods. One thing to consider when using 13” adjustable tubes that my Heim joint brackets used 1/4” thick washers. The pivot point for the heim joint can vary due to what brackets and washer you use
 
Dont hang me on the cross, but doesnt this just squash one side of the LCA bush against the tube, and possibly speeding up failure? And also how much adjustment can be had with this without compromising the bush?

Im happy to be educated
 
I think that a solid mounted fixed length with no "give", as it sweeps an arc will push and pull the lower arm as it moves above or below its normal at rest point. so i'd guess your comment is correct.

The rubber mounted strut would have some GIVE at the K member end and will still sweep an arc as the supension moves but the push and pull will be less because the K member mount allows some movement fore and aft. The impact on the lower bush would be dependent on how hard or soft the strut rod mounting was. As standard i assume some calculated effort was mode to provide a compromise.

solid mount and i think you will need less toe in.
gains in free movement and therfore better handling
loss in longevity of lower bush
potentially more changes in gemoerty as suspension travels that may or may not be of benefit dependent on roll tyres etc, i wouldn't want more bump steer for example .
greater potential to pull strut rod mount out of K frame and wrap lower arm back in a collision or clipping a curb stone at speed.
run higher spring rate and appropriate shocks and you probably limit impact becasue suspension travel will be reduced.

guess it comes down to intended use.

Dave
 
When I bought my torsion bars from Bergman Auto Craft I talked to Peter about the need and use of this type of strut rods and the delrin LCA bushings and greasable pins. After reading a number of posts on FABO, I adjusted mine with the LCA pin pulled almost tight to the K member and the torsion bars and shocks removed, I moved the suspension up and down and adjusted the strut rods till it had free movement. The length of the struts ended up being almost identical. At the current adjustment length there is no side load to the LCA bushings. Eventually I will upgrade to the delrin bushings and pins, I am just to cheap to junk the new Moog rubber bushing already on the car.
 
Greasable pins are not needed with Delrin bushings.
 
Dont hang me on the cross, but doesnt this just squash one side of the LCA bush against the tube, and possibly speeding up failure? And also how much adjustment can be had with this without compromising the bush?

Im happy to be educated

I think that a solid mounted fixed length with no "give", as it sweeps an arc will push and pull the lower arm as it moves above or below its normal at rest point. so i'd guess your comment is correct.

The rubber mounted strut would have some GIVE at the K member end and will still sweep an arc as the supension moves but the push and pull will be less because the K member mount allows some movement fore and aft. The impact on the lower bush would be dependent on how hard or soft the strut rod mounting was. As standard i assume some calculated effort was mode to provide a compromise.

solid mount and i think you will need less toe in.
gains in free movement and therfore better handling
loss in longevity of lower bush
potentially more changes in gemoerty as suspension travels that may or may not be of benefit dependent on roll tyres etc, i wouldn't want more bump steer for example .
greater potential to pull strut rod mount out of K frame and wrap lower arm back in a collision or clipping a curb stone at speed.
run higher spring rate and appropriate shocks and you probably limit impact becasue suspension travel will be reduced.

guess it comes down to intended use.

Dave

While I understand how the "theory" on this works, the simple reality is that it's not something that causes problems in practice.

First, the factory rubber bushings aren't some great thing. Yes, as the strut rod end travels in an arc up and down with the movement of the LCA, the changes created by the arc are absorbed by the bushing. So in theory the LCA moves straight up and down and less geometry changes occur. But the reality is the opposite. The large, soft rubber bushings at the strut rod don't control the movement of the LCA very well at all and with acceleration, braking and cornering the road forces that come into the lower ball joint push the LCA forward and backward. This causes unwanted geometry changes all the time, because in the real world the suspension forces are almost never just up and down. Someone had a video posted here that was focused on the strut rod bushings as they drove around town, they were frequently fully compressed or fully stretched out. That's translates into a lot of LCA movement, which is absolutely changing geometry a ton. The arc doesn't create anywhere near a 1/2" of movement over the course of the full suspension travel, but the rubber strut rod bushings allow that much or more.

The adjustable strut rods with their heim pivot on the other hand do not allow the LCA to move fore/aft with acceleration, braking and cornering. The strut rod can only deflect up and down for the most part. The arc that the LCA end of the strut rod travels in of course will place fore/aft forces on the LCA. But that comes entirely from the arc, and the radius of that arc is still large. It is also not perpendicular to the LCA, and the LCA is itself traveling in an arc. So, the forces applied on the LCA from the strut rod having a fixed pivot are SMALL. Anyone that has installed a set of adjustable strut rods and adjusted them so that the LCA can travel through its full range of travel without binding knows this. Because you can in fact adjust the strut rod length so that there is NO binding or resistance within the full range of suspension travel. That window of proper adjustment is relatively small, about two full threads of the heims on my cars at any rate take the motion from a little binding to fully free and then back to a little binding at the extreme ends of LCA travel. But set properly there should be no binding or resistance. And if you use poly or Delrin bushings at the LCA, the binding is easily detected because the movement of the LCA when free has very little resistance, unlike with rubber bushings where all the LCA movement is from flex in the rubber bushing as it twists. That creates increasing resistance at the ends of the suspension travel by itself.

I've run adjustable strut rods on both my Challenger and my Duster, with over 100k miles logged between the two. I have run rubber LCA bushings, poly LCA bushings and Delrin LCA bushings during that time as I made various upgrades to the suspensions on both cars. I have had one rubber bushing fail, and it was around the 50k mile mark. There's nothing unusual or shortened about that life span, especially considering that the rubber bushings out there now are of pretty marginal quality. I'm sure I will now hear tales of factory bushings lasting 100k+ miles, but having myself seen multiple cars well under 100k miles with completely blown apart rubber bushings I don't think it's reasonable at all to say that 100k miles on factory rubber bushings should be expected. Possible maybe in some cases with better quality bushings that used to be around, but not now. The poly and Delrin LCA bushings that I've run since then show zero wear. When I installed Delrin LCA bushings in my Duster after about 10k miles the poly bushings I removed were indistinguishable from brand new bushings. And despite running 1.12" torsion bars and being lowered my combination of parts means that the available amount of suspension travel remains almost identical to factory, and the whole range is free from binding at the LCA as that's how I adjust the strut rods.

Greasable pins are not needed with Delrin bushings.
Greaseable pins shouldn't be necessary with Delrin bushings. Based on my own experiences with fitting the Delrin bushings the Firm Feel greaseable LCA pins were by far the best fit with regard to tolerances, and I tried both stock and aftermarket pins with mine. And while the Delrin is supposed to be self lubricating, well, being able to add a shot of grease once and while isn't a bad thing. It won't hurt the Delrin any. And if the Delrin turns out not be 100% self lubricating a shot of grease might extend their life substantially.
 
Go-fish thanks for the clarification. I was wrong and was thinking of the new pins Bergman offers.
 
72BluNBlu
thanks for explanation.

my worry, which is why i still have a set of lower poly bushes on the shelf, was the fact that they are not bonded to both crush tube and case of bush
struck me that i was then depending on friction between tronsion bar sockets (both ends) and a circlip at the back to keep it all togther.

by way of tightening up the bush area in repect to flex i felt i'd be introducing a fore aft free play at the lower arm mount that was at least contained previously by the bonded bush.

but i guess this has been discussed a million times, and everyone will have a different view, so many people not having a problem etc etc.

Dave
 
Finally installed the strut rods. One thing to consider when using 13” adjustable tubes that my Heim joint brackets used 1/4” thick washers. The pivot point for the heim joint can vary due to what brackets and washer you use
What did you use to mount the Clevis to the K-Member?

In the C-Body link he used a 5/8 bolt and what looks like factory bushings and washers, which to me, defeats the whole purpose of making these in the first place if they are not mounted solid to the K-Member.

I know this thread is a year old, so are there any updates on how this is working out for you and would there be anything you would change or done different?
 
I have read here not to use poly LCA bushings on OE strut rods,
so even with poly strut rod bushing?? Just a weekend driver.
 
I have read here not to use poly LCA bushings on OE strut rods,
so even with poly strut rod bushing?? Just a weekend driver.

Here's the deal. The strut rod works in two different planes, keeping the LCA located fore/aft under acceleration and braking but also tracking the LCA up and down as it travels. In the fore/aft direction you want the strut rod bushings to be stiff, so poly seems like a good idea. But then as the strut rod moves up and down, you want the strut rod bushings to be soft, to prevent binding up the LCA travel, and in that area poly is a bad idea. The hard poly bushings will add more resistance to the up and down travel of the LCA, and you don't want that. The other thing is that because the poly doesn't compress much, the thickness of the bushing becomes more important- it can push the LCA backward from it's intended location if the poly bushings are too thick, which they sometimes are.

The factory rubber bushings, on the other hand, are the opposite. They compress very easily, so they don't add a bunch of binding when the LCA travels up and down. The problem with them is they also compress very easily in the fore/aft direction, which allows the LCA to flex forward and backward, which changes the caster. You can see how much movement the factory rubber strut rod bushings allow here, which also gives you an indiction of how much flex is allowed by the factory rubber LCA bushings. This is just a drive around the block too, not any kind of hard cornering, accelerating or braking.

✂️ Strut rod deflection

Getting back to your question, you can run poly LCA bushings with rubber strut rod bushings. The result will look different for your LCA movement though, because the LCA will slide on the LCA pivot pin when the strut rod bushings compress and stretch. Now, that movement will be exactly the same amount as allowed by the factory rubber LCA bushings, it's just slip instead of flex. The fore/aft motion of the LCA is controlled by the strut rod and its bushings, so the amount of deflection at the LCA will depend entirely on the strut rod bushings. Again, if you watch the video clip another member took, you can see the rubber strut rod bushings completely compressing on either side depending on the direction of motion. That's a lot of flex.

I covered it already here and in plenty of other places, I personally think adjustable strut rods are necessary any time you start changing out rubber for poly or delrin. The reason is simple, the factory tolerances were LOOSE and the big soft rubber bushings meant that the loose tolerances were "ok", because you had plenty of give in the system if things weren't quite lined up right. If you start replacing rubber with poly and delrin, the give and flex in the suspension system starts to go away, and the tolerances become more and more important. And things like the "one size fits most" strut rods start doing things you don't want them to do, like changing the location of the LCA. Which is why the adjustable strut rods are a big improvement, because you can set the length of the strut rod so there's no binding in the vertical travel of the LCA, and the LCA is located where it should be.
 
The result will look different for your LCA movement though, because the LCA will slide on the LCA pivot pin when the strut rod bushings compress and stretch. Now, that movement will be exactly the same amount as allowed by the factory rubber LCA bushings, it's just slip instead of flex.
I'm curious about this. Does the pivot end of the LCA really move fore/aft to the same extent as the outboard end with rubber strut rod bushings. If the LCA socket is nice and snug in the LCA, I would think the tension of the torsion bar in the LCA socket would keep that end of the LCA pretty stationary from a fore/aft standpoint, would it not?

Also, with a rubber LCA bushings, I would think any fore/aft movement on the outboard end would translate into more of a tangential force (if that's even the correct term) between the LCA pin/bushing interface than any fore/aft motion at that pivot end. In that case, poly/delrin LCA bushings be much better at resisting that type of force, wouldn't they?
 
I'm curious about this. Does the pivot end of the LCA really move fore/aft to the same extent as the outboard end with rubber strut rod bushings. If the LCA socket is nice and snug in the LCA, I would think the tension of the torsion bar in the LCA socket would keep that end of the LCA pretty stationary from a fore/aft standpoint, would it not?

Also, with a rubber LCA bushings, I would think any fore/aft movement on the outboard end would translate into more of a tangential force (if that's even the correct term) between the LCA pin/bushing interface than any fore/aft motion at that pivot end. In that case, poly/delrin LCA bushings be much better at resisting that type of force, wouldn't they?

From a "worst case" standpoint the pivot end of the LCA certainly can't move more than what the strut rod allows, the worst case would be it moves exactly as much.

Now, having said that, I agree with you that the movement of the LCA at the pivot end will not be nearly as much as the movement at the K member end of the strut rod. With rubber bushings it would just be flex, allowing the LCA to angle back and forth so the ball joint end could move with the strut rod. Poly, and Delrin especially, will not allow that much flex in the material. But, because of how those bushings work (rotating on the pivot pins), they could theoretically allow some fore/aft slip. Personally I would think those bushings resisting any flex they would reduce the motion of the LCA fore/aft even more. With the torsion bars loaded the torsion bar isn't going to slide in the socket, so the LCA's aren't going to move fore/aft. And the fit on the Delrin bushings on the pin and in the LCA is tighter than with the poly bushings, so frankly I don't see those moving fore/aft at all, even if the strut rod bushings would allow it. But even with poly LCA bushings the LCA sliding fore/aft would mean that the LCA would have to be sliding on the torsion bar, or the torsion bar would have to be sliding in the sockets. And if the bars are loaded, that's not going to happen at all. Would it be possible if somehow the torsion bar became neutrally loaded while there was still some fore/aft force on the LCA? Maybe. But anyone that's changed a few set of torsion bars knows that even when everything is unloaded the torsion bars aren't all that easy to move anywhere, and that wouldn't account for the fore/aft force that would make the LCA move on the pins and the hex end of the bars.

The idea that the LCA's would slide fore/aft on the pins while the car is traveling down the road, with any kind of bushings, is pretty much magical thinking IMHO. Theoretically possible? Perhaps. Something that would happen in the real world? Nah. I would still rather have adjustable strut rods with those kind of LCA bushings, but that's because of the binding the wrong length strut rod would have on the LCA travel, not because the LCA is gonna slide anywhere.

Now with rubber bushings that fore/aft movement is all just flex, and doesn't need any of the other stuff to move. So yeah, that's possible, as shown by the video showing the deflection of the strut rod bushings.
 
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Thanks for the input. I’m no where near doing the front end. Just trying to gather information. 72bluNblu I’ll have a lot of questions when the time comes.
 
Thanks for the input. I’m no where near doing the front end. Just trying to gather information. 72bluNblu I’ll have a lot of questions when the time comes.

Feel free to shoot me a message when the time comes, I answer a lot of questions via my inbox here and I'm happy to help if I can.
 
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