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PostPosted: Sun Jul 17, 2022 11:10 pm 
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Venturing into uncharted territory here - DIY alignment. Bought the stuff to do it. Going through my own headaches with those... Now coming to the actual adjustments.

So...

1. Are the cams supposed to be able to spin round and round... 360 degrees? Mine seem to only go roughly 180
2. What's it mean if they only go part way... say 30-40deg, then spring back? Happens both with weight of car on ground and in the air with tire off. Maybe worn bushing thats binding? Both cams were loose... which brings me to...
3. The two cams are completely independent, eh? I mean, they should both have their own full range of adjustment regardless of where the other is? Or does putting one at one extreme cause the other to bind?

These are stock 71 sbp control arms. The rebuild is decades old.... I may or may not have used offset bushings if that makes a difference.


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PostPosted: Mon Jul 18, 2022 6:20 am 
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They should spin 360 around. They will spring back in most configurations of the suspension because there is always a little bit of bind in there. They should spring back more with tires on ground.

Probably there is some rust or other schmutz in the "camways" and bolt slots, and/or you have offset bushings and that will likely make it harder to rotate them all the way around. Hmmm, if the cams were loose and you were driving it, you might have worn some grooves/depressions in the bolt slots or bushing shells? You may want to pull the cam bolts and UCAs off to see the condition of the parts.

I guess you turn plates and a way to measure caster? That is the hard one to do at home.

Happy handling!
Lou

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PostPosted: Mon Jul 18, 2022 7:02 am 
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Yeah I got turn plates and a quick trip brand kit that does camber/caster and toe.

The cam that does go smoothly 0~180 comes to a hard stop at the ends. I was afraid of damaging something if I forced it any further.

The spring back is really limiting adjustment. Yes it’s worse on the ground. In fact on the ground both on driver side spring and have very limited range when loaded. Not sure what to do here. Haven’t even touched passenger yet.

Yea looks like I’m going to be stuck and have to pull the ucas… this is becoming a much bigger project then hey let me try doing my own alignment. The fsm seems to imply you can load the control arm with a jack, get the tire in the air, then remove the uca without having to undo tension on the torsion bar.


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PostPosted: Mon Jul 18, 2022 3:42 pm 
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Lou, are you sure that the UCA adjuster cams should spin a full 360 on the end with the hex and the pressed on cam?
On the 68 Barracuda and the 83 D150 the cam end turns to a stop that kicks that end of the UCA one way then to a stop that kicks the UCA the other way.
The nut on the other end turns a full 360 to tighten the control arm bushing to hold it in place.
I am thinking that if the cam is able to turn a full 360 the slot that the cam works in is spread out.

The adjustment cams should hold their free position while the alignment is being done. If they are springing back when the wrench is released, something is awry, maybe the bolt/bushing is rusted together.

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PostPosted: Mon Jul 18, 2022 6:00 pm 
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The nut is guaranteed to turn 360 as it just threads on the bolt. The nut, lock washer and rear plate are three separate pieces. The bolt will spin in the slot - the double d shape is just so the plate spins with the bolt.


The bolts aren’t rusted or bonded to the bushing. I was able to tap them out and removed them completely and reinstalled them. No signs of scoring or anything.

As for the 180 issue - Either the cam plates are hitting those circular frames they sit in or the arm is moving so much due to the offset bushing that it’s smacking into something. That part is a nuisance but not a deal breaker.

The binding / springing renders that cam virtually useless for adjustments. Stock bushings keep the centerline of both bolts in line with each other right, or at least close enough? With offset bushings the centerlines may be pushed far enough apart that the arm binds as it is trying to pivot on two different axis at same time. Just a hunch…


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PostPosted: Tue Jul 19, 2022 3:11 am 
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John and Pierre,

I am not 100% certain, but I am pretty sure I have spun the bolts all the way around in the ways with the UCA bolted up. It is possible, as mentioned, that the UCA might run into something (cam ways frame?) near the end of its travel, but I do not recall that for stock bushings and UCAs. The cam is smooth and there is no stop or protrusion on it, so how is a "stop" built in? Hm, I will look again to verify my memory.

One way to get the cams to hold their position is leave some tension on the nut-bolt (tighten the nut) so you can still spin the bolt with a wrench, but there is enough friction to hold the cams in place. This is what i usually do.

UPDATE: I checked my 64 Dart and the cams can rotate all the way around. I am pretty sure my 68 Dart is like this too. They have never been damaged. Perhaps the ways for your cams are compressed somehow, John?

Lou

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PostPosted: Tue Jul 19, 2022 12:15 pm 
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Below is a link to an add for a replacement A body upper control arm mount

https://www.ebay.com/itm/374169416830?c ... 48403daa9c

The mounting bolt eccentric fits into the open-ended slot made by the welded tabs.
The tabs fit against the od of the eccentric and it is the force of the od of the eccentric against the welded tab that causes the A arm to move.
That movement of the A arm is what causes the caster and camber changes.

Why some eccentrics spin 360 degrees, and some don't could be due to stack of tolerances, or perhaps the welded tabs are sprung out allowing full rotation.

I remember when I did the alignment on the 68 Barracuda with the offset control arm bushings to get maximum castor the rear control arm eccentric was rolled to full stop in on direction and the front control arm eccentric was rolled fully the other way. Then there was a slight adjustment to get some negative camber. I would need to look at my notes to get the info on the direction each was rotated. Having the eccentric come to a stop made it easy to find the limits of each setting. But even if the eccentric rotated 360, one could still find the limit.


Quote:
The cam is smooth and there is no stop or protrusion on it, so how is a "stop" built in?


the cam does not have a stop built into it, the way this works is:
*the OD of the cam is a close fit to the ID of the open ended slot
* as the bolt hex is turned, the cam cannot freely spin in place in the open ended slot so it is forced to climb or lower along the walls of the opened ended slot.
* the hex head bolt that has the cam and the A arms mounted to it, moves up or down in the closed slot within the A arm frame mount depending upon which way the hex is turned and that moves the A arm with it.

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PostPosted: Tue Jul 19, 2022 9:11 pm 
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This may be a case of we’re saying the same thing in different words.

I think we can agree on this - The bolt spins along its center axis. The bolt is offset from the center of the plate. This causes the plate to spin in an oblong fashion. The slot is only 1/16 or so wider then the bolts diameter. The bolt slides in the slot.

I took a closer look. I did not find any arm to frame interference. In my instance with the car in the air - when the bolt reaches near the end of the slot instead of reversing direction and going back it keeps moving in the same direction. It appears the bolt is hitting the slots end and keeps pushing against it. The oblong movement of the plate is also pushing it against the tab instead of barely touching it and continuing to glide along

Maybe the offset bushing exaggerates the oblong movement of everything so instead of the bolt reaching the end of its travel and reversing it continues on. If I understood Lou the 360 movement on his cars were with stock bushings. Ultimately maybe this doesn’t matter - if 0deg is furthest towards the motor and 180 is closest to wheel - when the bolt is at 90 or 270 the arm is in the same spot right ?

Plan is to pull uca, inspect, clean and lube everything then see what happens with the spindle not attached. I’m still expecting the 180deg but hopefully not the springy adjustments.


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PostPosted: Wed Jul 20, 2022 1:17 am 
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Ok… maybe not oblong like I was thinking… it would still be a circle but just on a bigger radius…

I wonder how the straight tabs of that replacement piece would work via the curved stock ones.


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PostPosted: Wed Jul 20, 2022 4:41 am 
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If you can go close to 0 and 180, then it doesn't matter for your alignment adjustments.

Lou

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PostPosted: Thu Jul 21, 2022 9:14 am 
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So with the ball joint stud disconnected from the knuckle the arm moves up and down without any bind. Both adjusters move 0-180 smoothly without any springiness.

They were offset type with the removable washers. The bushings looked ok overall. Only obvious issues were the front washer on the front bushing looks like it may have been spinning on the bushing instead of turning with it because the front face rubber had some signs of wear.


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PostPosted: Sat Nov 12, 2022 7:03 am 
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A lot of times, the cam washer at the threaded end turns on the bolt, the fit is sometimes loose &/or worn, when the bolt is turned the bolt head cam gets ahead of & "out of sync" with the thread end one. When they get far enough out, the head end is starting back the other way, but the thread end hasn't quite reached full rotation the initial direction, thus the cams are pushing against opposite sides of the weldments & the bolt binds up. This ain't unique to Mopars.


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