LCA pin issues/ Kframe tube

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Trojmn

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So I've been unable to keep an alignment and really haven't driven the old car much recently because of it. I grabbed a pry bar and i could wobble the LCA. tore apart the barracuda tonight to see whats going on at night, in the dark with a headlamp... OK so that there is the issue PIC below ;-) the LCA pin was LOOSE about 0.25"!!! Thank god its a substantial hunk of metal. The PO installed urethane LCA bushings and all new BJs and steering linkage (all are good and tight!) I pulled the pin out, and the tube in the kframe "appears" round and welded (ugly). The LCA pin will tighten down and appears square on the shoulder of the tube so i'm not particularly worried about it but since we have everything apart...

1) Is there an "acceptable tolerance spec" of the LCA PIN in the Kframe? Its a loose fit.

2) that big semi circle under the LCA pin tube is a repair/reinforcement right?

3) Do the torsion bars just "float" in the sockets? I know there is a snap-ring to keep it from falling out the back, but what keeps the bar forward? Even with the LCA away from the K frame quite a while due to what appear to be improper strut bushing, the torsion bar is already forward about ~3/8" past the snapring.

My thinking is that the PO either couldn't hang onto the pin to tighten it, plain forgot, OR most likely was screwing with the urethane strut bushings which appear to be way too thick. Mocked up, the strut holds LCA is away from the K-frame at least 7/16" and this is at full droop.:shock: I've read this is common and will need to address it.

EDIT: this seems to be my strut issue http://www.heritech.org/cuda/bushings.html though i need to verify if have the 67 strut or 73+ strut, i guess they are different? Car came with 73+ k-frame/disc brakes etc.. Found it: http://www.forabodiesonly.com/mopar/showthread.php?t=169624

LOL i'll be taking it apart anyways I miss-clocked the LCA adjuster... hey its my first torsion bar suspension, and I'll need to cut or buy the right strut bushings.

Thanks !


IMG_05401_zps673dc07e.jpg
 
Its a common issue with poly LCA bushings. There was a thread not to long ago with lots of good info on it. I would replace the LCA with rubber if it were me though.
 
AdamR said:
Its a common issue with poly LCA bushings. There was a thread not to long ago with lots of good info on it. I would replace the LCA with rubber if it were me though.
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what is a common issue with a urethane LCA bushing? The pin was loose, and the strut is holding the LCA away from the from the K-frame, IMO excessively. I'll cut the strut bushing down ala everyone else.
 
its normal for that shoulder to be about 1/4" away or so, don't worry. and as far as the LCA bushing im getting a nylon one from firmfeel with their adjustable strut rods. something that helps to is when installing the t bar is to push the control arm forward to where it needs to be, then seat the t bar up tight and tighten the t bar. this will keep the control arm from waling back
 
805moparkid said:
its normal for that shoulder to be about 1/4" away or so, don't worry. and as far as the LCA bushing im getting a nylon one from firmfeel with their adjustable strut rods. something that helps to is when installing the t bar is to push the control arm forward to where it needs to be, then seat the t bar up tight and tighten the t bar. this will keep the control arm from waling back
Click to expand...

i shouldnt post at 130AM... the pin was LOOSE in k frame 0.25" as in not tight. I could move it in/out that far, the. 100% sure thats not right. the question i have is how much slop RADIALLY in the tube is OK for the pin? It tightens down so i think its OK but this is the first old mopar LCA that ive had off and really have nothing to compare it to.

I assume you mean that the its normal for the LCA to be off of the shoulder 1/4" or so, sure its gotta move with the arc of thes strut which is farthest away when horizontal. With the strut bushing as it is the LCA is WAY off of the kframe even at full droop where it should be pulled in the closest.
 
Trojmn said:
i shouldnt post at 130AM... the pin was LOOSE in k frame 0.25" as in not tight. I could move it in/out that far, the. 100% sure thats not right. the question i have is how much slop RADIALLY in the tube is OK for the pin? It tightens down so i think its OK but this is the first old mopar LCA that ive had off and really have nothing to compare it to.


QUOTE]

oh gotcha... there should be 0 movement in any direction with the pin seated in the k member.
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Trojmn said:
what is a common issue with a urethane LCA bushing? The pin was loose, and the strut is holding the LCA away from the from the K-frame, IMO excessively. I'll cut the strut bushing down ala everyone else.
Click to expand...

Adam's right. This is a common occurrence with LCA bushing pins and poly bushings. Do a search. That thread he's talkin about is a good one and shows what happens in depth. I agree with Adam too about the rubber LCA bushings. They transfer less road vibrations that can lead to some of the maladies he was talking about. GOOD quality rubber bushings will last a long time and have a much better road feel in a street car, as they transfer much less vibration to the steering wheel. Rubber for the LCAs is my personal preference. You can run poly everywhere else, but the lowers support the most weight and transfer the most vibration.
 
The urethane LCA bushing is staying. I don't think it has anything to do with a loose K-frame pin.

The questions remaining are:

1) Is there an "acceptable tolerance spec" of the LCA PIN in the Kframe? Its a loose fit RADIALLY. In other words how much larger diameter is/can the Kframe hole be than the pin.

2) that big semi circle under the LCA pin tube is a repair/reinforcement right?

3) Do the torsion bars just "float" in the sockets? I know there is a snap-ring to keep it from falling out the back, but what keeps the bar forward?
 
Trojmn said:
The urethane LCA bushing is staying. I don't think it has anything to do with a loose K-frame pin.

The questions remaining are:

1) Is there an "acceptable tolerance spec" of the LCA PIN in the Kframe? Its a loose fit RADIALLY. In other words how much larger diameter is/can the Kframe hole be than the pin.

there should be 0 movement in any direction with the pin seated in the k member

2) that big semi circle under the LCA pin tube is a repair/reinforcement right?

pic?

3) Do the torsion bars just "float" in the sockets? I know there is a snap-ring to keep it from falling out the back, but what keeps the bar forward?
Click to expand...

yes and no, when you have the adjuster all the way out the bar will float (or should but due to factory tolerance they may not) in and out for install. Once you start to put preload on the adjuster that bar will not move anywhere, thus the reason I said to push the control arm all the way forward, then seat the T bar into the back of the control arm so the control arm wont wiggle its way rearward.
 
1. It is nearly an interference fit. Once the nut is tight, if you loosen it up you have to tap the pin out of the k-member if all is right.

2. Yes, that is a repair.

3. The torsion bars float, although under load I don't think they really move much fore/aft.
 
Well crap. :banghead: with the nut off, the pin when was certainly LOOSE in the hole. I'll see if i can get the calipers on it in a couple days.

Its been repaired once before, So, I'll have to eventually do it myself correctly. Or swap it out, or not

Ok so the friction of the T-bar in the LCA socket keeps it together. I'll bump it forward as much as possible.


THANKS!
 
AdamR said:
Heres the thread I was talking about

http://www.forabodiesonly.com/mopar/showthread.php?t=246167&highlight=poly+bushings
Click to expand...

Yup I've been through that and i completely agree that my urethane strut rod bushings are pushing the LCA off of the pin. Its plainly obvious the strut is effectively too long.

Who knows how long the the LCA pin nut was backed off 1/4" but i suspect the previous owner had issues holding onto the pin to torque it down, or he was so befuddled by the urethane strut rod bushings that he forgot to tighten it.

a LOOSE pin going walkabout certainly will clearance the hole.
 
Trojmn said:
Yup I've been through that and i completely agree that my urethane strut rod bushings are pushing the LCA off of the pin. Its plainly obvious the strut is effectively too long.

Who knows how long the the LCA pin nut was backed off 1/4" but i suspect the previous owner had issues holding onto the pin to torque it down, or he was so befuddled by the urethane strut rod bushings that he forgot to tighten it.

a LOOSE pin going walkabout certainly will clearance the hole.
Click to expand...

the bushing does not hold anything, rubber or not... the strut rod does.

and thats a bummer they left that pin loose as it wallowed out that hole... for tightening it i like to use some big vise grips on that shoulder to keep it from turning
 
805moparkid said:
the bushing does not hold anything, rubber or not... the strut rod does.
Click to expand...

Obviously. QFT

805moparkid said:
and thats a bummer they left that pin loose as it wallowed out that hole... for tightening it i like to use some big vise grips on that shoulder to keep it from turning
Click to expand...

the C washer "repair" made it impossible to hold onto. I wound up using the BMF 4" channel locks and a old glove. I nicked the pin on the end where i slipped off the leather and made a nice raised ridge. OOPS that's a bearing surface! I knocked that spot down with a file. and then polished it with the spinloc.

I assume the folks with rubber LCA bushing don't have an issue holding the pin because they tighten it down at ride height and the weight of the car holds the pin.
 
I had to drill out the old tubes in the K frame and weld in new ones I had made at a machine shop. I had a spare kFrame and rebuilt and re-inforced it. They get beat out or wallered out (like that word) over time. I reinforced the lower control arm side with 3/16th drilled plate. I used rubber for the lca bushings and welded the plate to the bottom of the lca's. It's waiting for a new firm feel PS box, just have to get some funds for that.
 
You read my mind. I was just daydreaming about how one would go about shrinking the diameter of a wallard out LCA pin tube

Here's a nicely done reinforcement job for illustration
http://dartslantsix.wordpress.com/2012/09/23/how-to-reinforce-the-k-frame/

I need to consult my resident engineer... Im just thinking outloud but i don't see why you cant cut/weld the tube flush to K-frame then weld on the reinforcement plate with the appropriately sized hole. I can hear my brother complaining about shear but do have a bunch of area to weld. IDK Im tired maybe that's why I have found a premade fix.
 
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