Lower Control Arm rebuild

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RAT ROD AL

RAT ROD AL

MOPAR ARCHEOLOGIST - one parts hoard at a time!
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I'm trying to understand how this works, I pressed the factory pins and bushings out. Removed the inner metal sleeve off the pin. Pressed in some new Moog K791 bushings then upon pressing the pins back in , once they press into the sleeve past the opening they press real easy to bottom out. All looks good . BUT I can just pull the pin back out by hand AND push it back in by hand. I have 5 pairs of these LCAs taken apart and all the pins had to be pressed out and the sleeve removed, all where very tight.
Now I see the new style Poly bushings just push easily onto the pin and into the LCA. I don't understand what holds the LCA assembly on the K frame once installed. Once you bolt the Pin into the K frame you can Just pull it back off the bushing/pin . So the only thing holding this all on the car is the little snap ring at the rear of the T/Bar.

WHAT'S THE STORY LARRY ?
 
I know the factory setup should be pressed fit tight. Is my problem the Moog bushings are to big for the pin ? Are all my pins wore out somehow ?

Calling the PST guy & or the Bergman guy !!!!
 
the *rubber* factory style bushings are a tight press fit on the pin and in the arm.

aftermarket poly or other, non-rubber bushings, are a very snug push fit on the pins and in the arm-- but must use the correct associated hardware for the installation. and lube. ALL of the lube.

ETA: your procedure sounds correct, i'm guessing the problem is with the shitty QC and build quality of the moog bushings. their lowers are utter crap.
 
junkyardhero said:
the *rubber* factory style bushings are a tight press fit on the pin and in the arm.

aftermarket poly or other, non-rubber bushings, are a very snug push fit on the pins and in the arm-- but must use the correct associated hardware for the installation. and lube. ALL of the lube.

ETA: your procedure sounds correct, i'm guessing the problem is with the shitty QC and build quality of the moog bushings. their lowers are utter crap.
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I have some Proforged bushings on the way, hopefully they fit right. I'guess I'll give PST a call sometime see what the have . But what keeps the poly arms in place ?
 
Moog quality is garbage and has been for a while. Other brands also have this problem, indicating that many major brands come off the same manufacturing line overseas. I have an AC Delco here that has the same problem. The inner sleeve on the bushing is too big. I have not heard of Pro Forged having this problem. LCAs with poly bushings generally stay in place due to friction and the strut rod.
 
Jim Lusk said:
Moog quality is garbage and has been for a while. Other brands also have this problem, indicating that many major brands come off the same manufacturing line overseas. I have an AC Delco here that has the same problem. The inner sleeve on the bushing is too big. I have not heard of Pro Forged having this problem. LCAs with poly bushings generally stay in place due to friction and the strut rod.
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Thanks Jim, I watched your videos and pressed them on & off basically the same as you do.
 
Rubber and poly bushings function in completely different ways.

With a rubber bushing there has to be a press fit into the inner shell. Nothing in the bushing rotates on the pivot or shells when the LCA moves up and down, the rubber flexes between the shells to allow the movement. That movement is limited because the rubber only can flex so far, which is why the pivot has to be tightened at ride height. The rubber is just friction fit into the shells, so, it doesn’t locate anything despite what many people falsely believe. If the pin is loose in the OE style rubber bushing though what will happen is the inner shell will rotate, metal on metal, on the pivot when the LCA travels up and down because there won’t be enough friction to hold the inner shell on the pivot and force the rubber to flex. That will destroy the bushing and LCA pivot shaft in short order.

With a poly or Delrin bushing all you have is bushing material. The bushing material is hard, so, you can’t press it into place and expect it to flex, it won’t. So the Poly and Delrin bushings rotate on the pin. Thr harder material can tolerate that, but since it’s a slip fit you need to lubricate the bushings. They still need to be a tight slip fit so the LCA doesn’t have any radial play on the pivot.

With either type of bushing, the LCA is located by the strut rod and also somewhat by the tension on the torsion bars in the hex ends. But the only real purpose of the strut rod is controlling the forward and backward movement of the LCA under braking, accelerating and cornering forces. If the LCA was positively located on the pivot by the bushing the strut rod would be unnecessary.
 
The rubber bushings should be tight on the pin. They have had this problem for a few years now. Your pins are not worn out, they w should have no wear on them as the bushing is pressed onto the pin, no movement or wear there.

Best to press the pin into the bushing while supporting the inner sleeve of the bushing. Then press the pin and bushing into the control arm with a pipe that will press on the outer shell of the bushing, and long enough to not be pressing on the pin.
 
RAT ROD AL said:
I have some Proforged bushings on the way, hopefully they fit right. I'guess I'll give PST a call sometime see what the have . But what keeps the poly arms in place ?
Click to expand...
I think it's just "friction and natural juices"
After using BAC's delrin bushings, I'll never use anything else.
 
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The best part of the delrin bushings is the ability to adjust ride height at any time just by using the adjusting bolt. I hear talk about have the weight of the car being on the suspension/wheels before before tightening suspension parts. That's all well and good on a lift, but try doing it on the ground.
 
Mojoe9955 said:
The best part of the delrin bushings is the ability to adjust ride height at any time just by using the adjusting bolt. I hear talk about have the weight of the car being on the suspension/wheels before before tightening suspension parts. That's all well and good on a lift, but try doing it on the ground.
Click to expand...

Yeah not having to think about resetting the LCA pivot torque if you change the ride height substantially is nice! It’s also true of the poly bushings though, only the rubber bushings have that issue and it’s just because they have to be neutral at ride height otherwise they get overextended and can tear
 
Once the ride height is set with the LCA bumper off the frame you do not need to loosen the pin to reset it. All the adjustment does at that point is rotate the arm around the torsion bar socket.
 
Well the Proforged bushings came in today. I'll give these a test fit this evening. See how they go !
20250513_143309.jpg
 
72bluNblu said:
Rubber and poly bushings function in completely different ways.

With a rubber bushing there has to be a press fit into the inner shell. Nothing in the bushing rotates on the pivot or shells when the LCA moves up and down, the rubber flexes between the shells to allow the movement. That movement is limited because the rubber only can flex so far, which is why the pivot has to be tightened at ride height. The rubber is just friction fit into the shells, so, it doesn’t locate anything despite what many people falsely believe. If the pin is loose in the OE style rubber bushing though what will happen is the inner shell will rotate, metal on metal, on the pivot when the LCA travels up and down because there won’t be enough friction to hold the inner shell on the pivot and force the rubber to flex. That will destroy the bushing and LCA pivot shaft in short order.

With a poly or Delrin bushing all you have is bushing material. The bushing material is hard, so, you can’t press it into place and expect it to flex, it won’t. So the Poly and Delrin bushings rotate on the pin. Thr harder material can tolerate that, but since it’s a slip fit you need to lubricate the bushings. They still need to be a tight slip fit so the LCA doesn’t have any radial play on the pivot.

With either type of bushing, the LCA is located by the strut rod and also somewhat by the tension on the torsion bars in the hex ends. But the only real purpose of the strut rod is controlling the forward and backward movement of the LCA under braking, accelerating and cornering forces. If the LCA was positively located on the pivot by the bushing the strut rod would be unnecessary.
Click to expand...
Aren't rubber bushes moulded to the shells, or are they Vulcanized. I know they're no press fit, that rubber is too soft & would turn in the shells.
On another thread I posted about using a countersunk 1/4" bolt & aluminum spacer to keep poly bushing from walking, as you butter it with special teflon grease before assembly. I threaded the pivots in my lathe. & I would've rifle drilled the front for a zerk too, if I'd thought of it, 12 plus yr ago.
 
Woody500 said:
Aren't rubber bushes moulded to the shells, or are they Vulcanized. I know they're no press fit, that rubber is too soft & would turn in the shells.
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Nope. They’re just a friction fit. You’ve seen the assembled bushings, this is the rubber removed from a brand new bushing.

IMG_4862.jpeg


Doesn’t look an anything like an assembled bushing, it’s shorter than the shell, and much larger diameter. The rubber is compressed, it become thinner, and it exerts force on the surfaces of the shells. That friction force on the surface of the shells is stronger than the rubber, so, it doesn’t spin, it yields in the rubber.

IMG_1834.jpeg


I suspect people think that the rubber is bonded or vulcanized because usually we take apart old worn out bushings, and the deteriorating rubber does end up stuck to the shells over time. But that’s not how they’re built, that’s how they fail. Take apart a brand new bushing and you can see that.
Woody500 said:
On another thread I posted about using a countersunk 1/4" bolt & aluminum spacer to keep poly bushing from walking, as you butter it with special teflon grease before assembly. I threaded the pivots in my lathe. & I would've rifle drilled the front for a zerk too, if I'd thought of it, 12 plus yr ago.
Click to expand...

There’s no reason to try to prevent the poly bushing from walking, because if the suspension is fully assembled and assembled properly there’s no where for the bushing to go. Spacers and set screws are a waste of time.
 

RAT ROD AL said:
I already watched those Steve. No help with my issue. That's how I did them. I think the Moog bushings are to big. I have some different ones coming hope they fit better. I can't believe all 10 of my pins are wore .
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NO, they aren't all worn.
 
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